Physik Instrumente PI CAT125E R3 Piezoelectric Ceramic Products
PI_CAT125E_R3_Piezoelectric_Ceramic_Products Fundamentals of Piezo Technology
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Piezoelectric Ceramic Products FUNDAMENTALS, CHARACTERISTICS AND APPLICATIONS PIEZOCERAMIC MATERIALS COMPONENTS INTEGRATION PIEZO TECHNOLOGY Contents PI Ceramic – Leaders in Piezoelectric Technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Fundamentals of Piezo Technology Piezoelectric Effect and Piezo Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Electromechanics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Dynamic Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Piezo Ceramics – Materials, Components, Products Material Properties and Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Soft and Hard Piezo Ceramics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Lead-Free Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Material Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Temperature Dependence of the Coefficients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Manufacturing Technology Pressing Technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Co-firing, Tape Technology, Multilayer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Flexibility in Shape and Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 PICMA® Multilayer Actuators with Long Lifetime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Metallization and Assembling Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Piezo Ceramic Components: Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Testing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Integrated Components, Sub-Assemblies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Applications Application Examples for Piezoceramic Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Pumping and Dosing Techniques with Piezo Drives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Ultrasound Applications in Medical Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Ultrasonic Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Piezoelectric Actuators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Vibration Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Adaptronics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Energy from Vibration – Energy Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Ultrasonic Machining of Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Sonar Technology and Hydroacoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 PI Milestones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 . 2 W W W. P I C E R A M I C . C O M PI Ceramic LEADERS IN PIEZOELECTRIC TECHNOLOGY PI Ceramic is one of the world’s market leaders for piezoelectric actuators and sensors. PI Ceramic provides everything related to piezo ceramics, from the material and components right through to the complete integration. PI Ceramic provides system solutions for research and industry in all high-tech markets including medical engineering, mechanical engineering and automobile manufacture, or semiconductor technology. Core Competences of PI Ceramic ! ! ! Materials Research and Development PI Ceramic develops all its piezoceramic materials itself. To this end PI Ceramic maintains its own laboratories, prototype manufacture as well as measurement and testing stations. Moreover, PI Ceramic works with leading universities and research institutions at home and abroad in the field of piezoelectricity. Flexible Production In addition to the broad spectrum of standard products, the fastest possible realization of customer-specific requirements is a top priority. Our pressing and multilayer technology enables us to shape products with a short lead time. We are able to manufacture individual prototypes as well as high-volume production runs. All processing steps are undertaken in-house and are subject to continuous controls, a process which ensures quality and adherence to deadlines. Certified Quality Since 1997, PI Ceramic has been certified according to the ISO 9001 standard, where the emphasis is not only on product quality but primarily on the expectations of the customer and his satisfaction. PI Ceramic is also certified according to the ISO 14001 (environmental management) and OHSAS 18001 (occupational safety) standards, which taken together, form an Integrated Management System (IMS). PI Ceramic is a subsidiary of Physik Instrumente (PI) and develops and produces all piezo actuators for PI’s nanopositioning systems. The drives for PILine® ultrasonic piezomotors and NEXLINE® high-load stepping drives also originate from PI Ceramic. ! ! ! ! tandard piezo comS ponents for actuators, ultrasonic and sensor applications System solutions anufacturing of piezoM electric components of up to several million units per year Development of custom-engineered solutions igh degree of flexibiH lity in the engineering process, short lead times, manufacture of individual units and very small quantities ll key technologies A and state-of-the-art equipment for ceramic production in-house ertified in accordance C with ISO 9001, ISO 14001 and OHSAS 18001 Company building of PI Ceramic in Lederhose, Thuringia, Germany. 3 PIEZO TECHNOLOGY Reliability and Close Contact with our Customers OUR MISSION PI Ceramic provides ! ! ! ! ! ! ! ! ! ! iezoceramic materials P (PZT) Piezoceramic components ustomized and appliC cation-specific ultrasonic transducers/transducers PICMA® monolithic multilayer piezo actuators Miniature piezo actuators ICMA® multilayer P bender actuators ICA high-load piezo P actuator PT Tube piezo actuators reloaded actuators P with casing iezocomposites – P DuraAct patch transducers Our aim is to maintain high, tested quality for both our standard products and for custom-engineered components. We want you, our customers, to be satisfied with the performance of our products. At PI Ceramic, customer service starts with an initial informative discussion and extends far beyond the shipping of the products. Advice from Piezo Specialists You want to solve complex problems – we won’t leave you to your own devices. We use our years of experience in planning, developing, designing and the production of individual solutions to accompany you from the initial idea to the finished product. We take the time necessary for a detailed understanding of the issues and work out a comprehensive and optimum solution at an early stage with either existing or new technologies. 4 W W W. P I C E R A M I C . C O M After-Sales Service Even after the sale has been completed, our specialists are available to you and can advise you on system upgrades or technical issues. This is how we at PI Ceramic achieve our objective: Long-lasting business relations and a trusting communication with customers and suppliers, both of which are more important than any short-term success. PI Ceramic supplies piezo-ceramic solutions to all important high-tech markets: ! Industrial automation ! Semiconductor industry ! Medical engineering ! Mechanical and precision engineering ! Aviation and aerospace ! Automotive industry ! Telecommunications Experience and Know-How STATE-OF-THE-ART MANUFACTURING TECHNOLOGY Developing and manufacturing piezoceramic components are very complex processes. PI Ceramic has many years of experience in this field and has developed sophisticated manufacturing methods. Its machines and equipment are state of the art. Rapid Prototyping The requirements are realized quickly and flexibly in close liaison with the customer. Prototypes and small production runs of custom-engineered piezo components are available after very short processing times. The manufacturing conditions, i.e. the composition of the material or the sintering temperature, for example, are individually adjusted to the ceramic material in order to achieve optimum material parameters. Precision Machining Technology PI Ceramic uses machining techniques from the semiconductor industry to machine the sensitive piezoceramic elements with a particularly high degree of precision. Special milling machines accurately shape the components when they are still in the “green state“, i.e. before they are sintered. Sintered ceramic blocks are machined with precision saws like the ones used to separate indivi dual wafers. Very fine holes, structured ceramic surfaces, even complex, threedimensional contours can be produced. Automated Series Production – Advantage for OEM Customers An industrial application often requires large quantities of custom-engineered components. At PI Ceramic, the transition to large production runs can be achieved in a reliable and low-cost way while maintaining the high quality of the products. PI Ceramic has the capacity to produce and process medium-sized and large production runs in linked automated lines. Automatic screen printers and the latest PVD units are used to metallize the ceramic parts. Automated processes optimize throughput 5 PIEZO TECHNOLOGY Product Overview IN-HOUSE DEVELOPMENT AND PRODUCTION Piezoelectric Components ! ! arious different versions in many difV ferent geometries such as disks, plates, tubes, customized shapes High resonant frequencies to 20 MHz OEM Adaptations ! ! ! iezo transducers for ultrasonic P applications ssembly of complete transducer A components 2D or line arrays DuraAct Piezo Patch Transducers ! ! ctuator or sensor, structural health A monitoring endable and robust, preloaded due to B lamination Control Electronics 6 W W W. P I C E R A M I C . C O M ! Different performance classes ! OEM modules and benchtop devices PICMA® Multilayer Piezo Actuators ! Low piezo voltage to 120 V ! High stiffness ! Travel ranges to 100 µm PICA High-Load Actuators ! Travel ranges to 300 µm ! Forces to 100 kN PICMA® Multilayer Bending Actuators ! Bidirectional displacement to 2 mm ! Low operating voltage to 60 V ! Contractors, variable contours Piezo Actuators with Customized Equipment ! For use in a harsh environment ! Position and temperature monitoring ! For cryogenic temperatures 7 PIEZO TECHNOLOGY ∆L Polarisation axis C1 (Z) 3 L1 6 P Impendanz Z + o L C0 5 Piezoelectric Effect and Piezo Technology 2(Y) R1 4 Piezoelectric Ceramics … Piezoelectric materials convert electrical energy into mechanical energy and vice versa. The piezoelectric effect is now used in many everyday products such as lighters, loudspeakers and signal transducers. Piezo actuator technology has also gained acceptance in automotive technology, because piezocontrolled injection valves in combustion engines reduce the transition times and significantly improve the smoothness and exhaust gas quality. – – – + + – – – – + + + + – – – – + + + + – + – + – + – – – – – + – + + – – + + – + – – + – + – + – + + – + The word “piezo“ is derived from the Greek word for pressure. In 1880 Jacques and Pierre Curie discovered that pressure generates ∆L electrical charges in a number of crystals fn such as Quartz and Tourmaline; they called O2 this phenomenon the “piezoelectric effect“. Pb Later they noticed that electrical fields can Ti, Zr deform piezoelectric materials. This effect is Fig. 1. called the “inverse piezoelectric effect“. The (1) Unit cell with symmetrical, 0 with piezoindustrial breakthrough came cubic Perovskite structure, electric ceramics, when scientists discovered 1(r) T > T Radialschwingung Frequenz f that Barium Titanate assumes piezoelectric-Ps (2) Tetragonally distorted unit characteristics on a useful scale when an cell, T < T electric field is applied. + + + + Pr … with Polycrystalline Structure Ps At temperatures below the Curie temperature, the lattice structure of the PZT crystallites becomes deformed and asymmetric. -Ec This brings about the formation of dipoles and the rhombohedral andEctetragonal cryE kV/cm V stallite p hases which are of interest for piezo technology. The ceramic exhibits spontaneous polarization -Pr (see Fig. 1). Above the Curie temperature the piezoceramic material loses its piezoelectric properties. – – + – – – C Dickenschwingung + – – ++ C – + – + + 3 – + – + From the Physical Effect to Industrial Use fm – + – (2) The piezoelectric effect of natural mono crystalline materials such as Quartz, Tourmaline and Seignette salt is relatively small. Polycrystalline ferroelectric ceramics such as Barium Titanate (BaTiO3) and Lead Zirconate Titanate (PZT) exhibit larger displacements or induce larger electric voltages. PZT piezo ceramic materials are available in many m(1) odifications(2)and are most widely used (3) for actuator or sensor applications. Special dopings of the PZT ceramics with e.g. Ni, Bi, Sb, Nb ions make it possible to specifically optimize piezoelectric and dielectric parameP C/m2 ters. + (1) + (X) 1 + OD D P TH OD Direct Piezoelectric Effect Mechanical stresses arising as the result 3 of an external force that act on the piezoelectric body induce displacements 1 of the electrical dipoles. This generates an elec2 tric field, which produces a corresponding electric voltage. This direct piezoelectric effect is also called the sensor or generator effect. 3 + 3(r) U – 1 Inverse Piezoelectric Effect 3 TH When an electric voltage 6is applied to an TH 5 2 unrestrained piezoceramic component it brings about a geometric deformation. The ID movement achieved is aP function of the L polarity, of the voltage applied and the Längsschwingung direction of the polarization in the device. The application of an AC voltage produDickenschwingung ces an oscillation, i.e. a periodic change of the geometry, for example the increase or reduction of the diameter of a disk. If the body is clamped, i.e. free deformation is constrained, a mechanical stress or force is generated. This effect is frequently also called Lthe actuator or motor effect. P W Längsschwingung L 8 W Dickenschwingung L TH P P Radialschwingung W W W. P I C E R A M I C . C O M TH W 3 1(r) axis C1 (Z) 3 L1 + o L C0 6 P 5 ∆L 2(Y) Polarisation axis (X) R1 4 1 C1 fm (Z) 3 L1 2(Y) R1 which is d egraded again when the mechanical, t hermal and electrical limit values of the m aterial are exceeded (see Fig. 3). The ceramic now exhibits piezoelectric properties and will change dimensions when an electric voltage is applied. Some PZT ceramics must be poled at an elevated temperature. – – – – Fre – + + + – – – – + + + + – – – – + + + + – + – – + – + – – + + – + + – – + + – – – + – + – + – + – + + + – – + + – + + – – – – + + + + When the permissible operating temperature is exceeded, the polarized ceramic depolarizes. The degree of depolarization is depending on the Curie temperature of the material. (1) (2) – – – + – One effect of the spontaneous polarization is that the discrete PZT crystallites become piezoelectric. Groups of unit cells with the same(1)orientation are called ferroelectric domains. Because of the random distribution of the domain (2) orientations in the ceramic material no macroscopic piezoelectric beh avior is observable. Due to the ferroelectric nature of the material, it is possible to force permanent reorientation and alignment of the different domains using a strong electric field. This process is called poling (see (2) Fig. 2). – 1 (1) (2) – – – + – + – – + + + + (3) – + – + – + – + + + – – + – + – – – – – – + + + + + – + – + – P C/m2 An electric field of sufficient strength can reverse the polarization direction (see Fig. 4). The link between mechanical and electriP C/m2 cal parameters is of crucial significance for the widespread technical utilization of piezo P ceramics. Ps Pr Fig. 2. Electric dipoles in domains: (1) unpolarized, ferroelectric ceramic, – – -Ec (2) d uring and – P + + – – ++ s (3) a fter the poling (piezoelectric ceramic). + + Ec E kV – – r – 3 + – Pb The poling process results in a remnant Ti, Zr p olarization P r which coincides with a remnant expansion of the material and + + O2 Polarization of the Piezoceramics + + (3) – + – + + + Ferroelectric Domain Structure (X) Impendanz Z 5 4 + + o P (1) + O2 ++ Ps – – Radialschwingung + -Ps + – -Ps – Pr Dickenschwingung – + – + + – S 3 1(r) – + -Ec P – Radialschwingung Ti, Zr -Pr – 1(r) Pb + L C0 6 + Ec E kV/cm -Pr Dickenschwingung -Ec 3 3 Ec 1 3(r) E Dickenschwingung 2 3 Längsschwingung Längsschwingung 3 E 3(r) 1 -Ps Fig. 3. The butterfly curve shows the typical deformation of a ferroelectric “soft“ piezo ceramic material when a bipolar voltage is applied. The displacement of the ceramic here is based exclusively on solid state effects, such as the alignment of the dipoles. The motion produced is therefore frictionless and non-wearing. 3 -Pr 2 Dickenschwingung 1(r) 1 Fig. 4. An opposing electric field will only 3 depolarize the material if it exceeds the 6 TH coercivity strength Ec. A further increase in the 5 1 opposing field leads to2repolarization, but in the opposite direction. 6 TH 2 3 5 Längsschwingung Längsschwingung Dickenschwingung Dickenschwingung 9 Radialschwingung Radialschwingung PIEZO TECHNOLOGY Electromechanics F U N D A M E N TA L E Q U AT I O N S A N D P I E Z O E L E C T R I C C O E F F I C I E N T S T mechanical stress E electric field S mechanical strain d piezoelectric charge coefficient εT dielectric permittivity (for T = constant) sation xis sE elastic coefficient (for E = constant) 6 P 5 2(Y) (X) 1 4 Fig. 5. Orthogonal coordinate system to describe the properties of a poled piezoelectric ceramic. The polarization vector is parallel to the 3 (Z)-axis. ε33T permittivity value in the polarization direction when an electric field is applied parallel to the direction of the polarity (direction 3), under conditions of constant mechanical stress (T = 0: “free“ permittivity). D = d T + εT E S = sE T + d E These relationships apply only to small e lectrical and mechanical amplitudes, so-called small signal values. Within this range the relationships between the elastic deformation (S) or stress (T) components and the components of the electric field E or the electric flux density D are linear. permittivity if the electric field and ε11S dielectric displacement are in direc tion 1 at constant deformation (S = 0: “clamped“ permittivity). Piezoelectric Charge or Strain Coefficient, Piezo Modulus dij C1 Assignment of Axis (Z) 3 Examples Polarized piezoelectric materials are characterized by several coefficients and relationships. In simplified form, the basic relationships between the electrical and elastic properties can be represented as follows : The piezo modulus isfmthe ratio fnof induced electric charge to mechanical stress or of achievable mechanical strain to electric field applied (T = constant). The directions are designated by 1, 2, and L C0 3, corresponding to axes X, Y and1 Z of the classical right-hand orthogonal axis set. The rotational axes are designated with 4, 5 and 6 R1 (see Fig. 5). The direction of polarization (axis 3) is established during the poling process by a strong electrical field applied between the two electrodes. Since the piezoelectric material is anisotropic, the corresponding physical quantities are described by tensors. The piezoelectric coefficients are therefore indexed accordingly. Impendanz Z D electric flux density, or dielectric displacement Example d33 mechanical strain induced per unit of Frequenz electric field applied in V/m for charge density in C/m2 per unit pressure in N/ m2, both in polarization direction. Piezoelectric Voltage Coefficient gij The piezoelectric voltage coefficient g is the ratio of electric field E to the effective mechanical stress T. Dividing the respective piezoelectric charge coefficient dij by the corresponding permittivity gives the corresponding gij coefficient. Permittivity ε – – – – The relative permittivity, or relative dielectric coefficient, ε is the ratio of the absolute permittivity of the ceramic material and the permittivity in vacuum (ε0 = 8.85 x 10-12 F/m), where the absolute permittivity is a measure of the polarizability. The dependency of (1) (2) (3) the permittivity from the orientation of the electric field and the flux density is described by indexes. – + + + + – – – – + + + + – – – – + + + + – – – – + – – + – + – – + – + + – – + + – + – + – + – + – + – + Example + – + + + + + + – – – + – + – ++ + – + + + – Ec + – – 10 hwingung hwingung -Ps – Ps Pr – U g31 describes the electric field induced in direction 3 per unit of mechanical stress acting in direction 1. Stress = force per unit area, not necessarily orthogonal. P C/m2 -Ec + -Pr W W W. P I C E R A M I C . C O M E kV/cm W L T Elastic Compliance sij The elastic compliance coefficient s is the ratio of the relative deformation S to the mechanical stress T. Mechanical and electrical energy are mutually dependent, the electrical boundary conditions such as the electric flux density D and field E must therefore be taken into consideration. Examples s33E the ratio of the mechanical strain in direction 3 to the mechanical stress in the direction 3, at constant electric field (for E = 0: short circuit). s55D the ratio of a shear strain to the effective shear stress at constant dielectric displacement (for D = 0: open electrodes). The often used elasticity or Young’s mo dulus Yij corresponds in a first approximation to the reciprocal value of the corresponding elasticity coefficient. Frequency Coefficient Ni The frequency coefficient N describes the relationship between the geometrical dimension A of a body and the corresponding (series) resonance frequency. The indices designate the corresponding direction of oscillation N = fs A. Examples is the frequency coefficient of the NP planar oscillation of a round disk. is the frequency coefficient of the Nt thickness oscillation of a thin disk polarized in the thickness direction. Mechanical Quality Factor Qm The mechanical quality factor Qm characterizes the “sharpness of the resonance“ of a piezoelectric body or resonator and is primarily determined from the 3 dB bandwidth of the series resonance of the system which is able to oscillate (see Fig. 7 typical impedance curve). The reciprocal value of the mechanical q uality factor is the mechanical loss factor, the ratio of effective resistance to reactance in the equivalent circuit diagram of a piezoelectric resonator at resonancem (Fig. 6). Coupling Factors k The coupling factor k is a measure of how the magnitude of the piezoelectric effect is (n o t an efficiency factor!). It describes the ability of a piezoelectric material to convert electrical energy into mechanical energy and vice versa. The coupling factor is determined by the square root of the ratio of stored mechanical energy to the total energy ab sorbed. At resonance, k is a function of the corresponding form of oscillation of the piezoelectric body. Examples k33 the coupling factor for the longitudinal oscillation. N3 describes the frequency coefficient for the longitudinal oscillation of a k31 the coupling factor for the transverse slim rod polarized in the longitudinal oscillation. direction. kP the coupling factor for the planar radial oscillation of a round disk. N1 is the frequency coefficient for the transverse oscillation of a slim rod the coupling factor for the thickness kt polarized in the 3-direction. oscillation of a plate. N5 is the frequency coefficient of the thickness shear oscillation of a thin disk. the coupling factor for the thickness k15 shear oscillation of a plate. 11 PIEZO TECHNOLOGY Dynamic Behavior O S C I L L AT I O N M O D E S O F P I E Z O C E R A M I C E L E M E N T S 3 5 2 1 3 2 OD TH R1 1 0 Most piezoelectric material parameters are OD 3 determined by means of mea2 impedance TH U P OD >> TH U P OD >> TH L according surements on special1 test bodies U 3 2 EN L50324-2 atP L >> W >> TH to the European Standard TH U 1 3 resonance. U P L >> W >> TH 2 Fig. 6. Equivalent circuit diagram OD 3 of a piezoelectric resonator 2 TH 1 L 3 ∆L – – – OD D P TH – – – – – TH W OD + + + + P OD >> TH U W – – – – + + 2 TH U P OD >> TH L 1 + + + + – – + + + + – Shape Oscillations + U 3 U 3 – + + + + 1 – P L >> W >> TH 2 P L >> W >> TH – – – 2– – – – – – – – – – + TH –+ –+ +– +– TH 1 1 + Type Mechanical Series resonance + + + + + + + + + + + + + + U – W W W >> TH P L >> – TH – OD W L– – 3 2 + + + – – + + 1 – – TH + – – + + – – + – – 2 – – – 31 – + (X) 2(Y) 4 1 OD TH L1 Impendanz Z 6 P C0 + + – – + – – + – – – – + – + – (1) (2) 3 1 TH TH 2 3 TH 2 L Plate 3 1 2 Pr 1 2 U UP U W TH 3 LOD W LL TH W P OD >> TH P L >> W >> TH L >> W >> TH U P L >> W >> TH P U s P L >> W >> TH W 1 -Ec – – + + – ++ + – – + + ++ – – Shear plate + – 3 + P TH ELc OD ID TH 1 L L 1 1 33 THP 2TH L 2 Längsschwingung 3 OD 1 L 2 2 L ID 1 Dickenschwingung 3 L 1 2 3 WP L L 6 P L TH 1 3 P TH OD TH 3 ID 2 L OD U P L >> W >> TH 1 transversal P 1 TH ID Längsschwingung 1 L >> OD >> TH 3 L L L P U U L ≈ W >> TH 231 3 3 TH U L ≈ W >> TH 2 LTHW U L >> TH U WP L >> W >> TH 2 ODW >>>> TH W PL >> 3 L >> OD >> TH U ODL 21 Dickenschwingung thickness U L ID 3 PW 1 P 1 L >> OD >> TH L >> OD >> TH L 1(r) 3 L U U Radialschwingung 23 L U L ≈ W >> TH TH U L ≈ W >> TH 2 W W L THDickenschwingung P OD W W W. P I C E R A M I C . C O M ID P TH 3 2 ƒs = NP – OD ƒs = Nt TH ƒs = N1 L L W TH OD ID TH P 32 WL L W 12 U WW + + -Ps Tube TH radial frequency TH P ƒs = N3 L ƒs = N5 TH ƒs ≈ N1 L ƒs ≈ Nt – + – Rod OD >> TH E kV/cm U P L >> W >> TH 3 – – TH 2 U L P L >> W >> TH 1 1 2 L Ec U P L >> W >> TH L L E kV/cm W L L 1 3longitudinal W L U L ≈ W >> TH + 1 U 13 TH -PsU 2 3 -P W P L >> W >> TH r L 1 2 2 P L >> W >> TH L L 3 TH W U L ≈ W >> TH W L TH L U L ≈ W >> TH 21 TH TH 1 3 W TH 2 W W P TH W -Pr L 3 L 1 3 1 2 L U L P P L >> W >> TH L LU P LU>>LW >>>> THTH L P 32 L ≈W U L ≈ W >> TH 1 3 thickness shear TH TH 2 1 2 W W + TH – -Ec – – – deformation U P OD 3 3 THL TH >>WTH 2 L UU P OD L >> >> TH 3 2 P L >> W >> TH – P C/m2 2 3 1 1 TH 2 U thickness L P L >> W >> TH 1 W W 1 Ps TH Pr W 3 L 2 L UU P L >> W >> TH 3 12 transverse P L >> W >> TH TH – – P C/m2 1 1 + 32 + + 3 1 + – (3) Thin disk + + + + + – + OD – + (2) + + (3) TH 2 + + (1) g ng C1 Impedance Z (Z) 3 The electromechanical behavior of a piezo electric element excited to oscillations can C1 be represented by an electrical equivalent fm fn circuit diagram (s. Fig. 6). C0 is the capaciOD 3 L C0 of the dielectric. The2 fseries tance TH1 circuit, U P OD >> TH fn conm OD change 3 sisting of C1, L1, and R1,1 describes the 2 TH U P OD >> TH >> TH P OD U the in mechanical properties, such as elastic 1 deformation, effective massR1 (inertia) and mechanical losses3 resultingODfrom internal 2 U P OD >> TH TH U P OD >> TH friction. This description of the oscillatory 1 Frequency f circuit can only be used for frequencies in the vicinity of the mechanical intrinsic Fig. 7. Typical impedance curve Frequenz f resonance. TH TH Radialschwingung 1(r) TH OD OD TH Dickenschwingung T Figure 7 illustrates a typical impedance curve. The s eries and parallel resonances, fs and fp, are used to determine the piezoelectric parameters. These correspond to a good approximation to the impedance minimum fm and maximum fn. Oscillation States of Piezoelectric Components Oscillation states or modes and the de formation are decided by the geometry of the element, mechano-elastic properties and the orientations of the electric field and the polarization. Coefficients see p. 10, specific values see p. 18. dimensions see p. 27. The equations are used to calculate approx imation values. Electrically induced displacement (small signal) Mechanically induced voltage (small signal) ∆OD = d31OD U TH ∆TH = d33U U = – 4 g 33TH F π OD 2 3 ∆L = d31L U TH U = – g 31 F1 W ∆L = d33U U = – g 33 L F3 W TH ∆L = d15U U = – g15 TH F3 LW ∆L = d31L U TH ∆TH = d33U 13 PIEZO TECHNOLOGY Material Properties and Classification PI Ceramic provides a wide selection of piezoelectric ceramic materials based on modified Lead Zirconate Titanate (PZT) and Barium Titanate. The material properties are classified according to the EN 50324 European Standard. In addition to the standard types described here in detail, a large number of modifications are available which have been adapted to a variety of applications. Internationally, the convention is to divide piezo ceramics into two groups. The terms “soft“ and “hard“ PZT ceramics refer to the mobility of the dipoles or domains and hence also to the polarization and depolarization behavior. “Soft“ Piezo Ceramics Characteristic features are a comparably high domain mobility and resulting “soft ferroelectric“ behavior, i.e. it is relatively easy to polarize. The advantages of the “soft“ PZT materials are their large piezo electric charge coefficient, moderate per mittivities and high coupling factors. 14 W W W. P I C E R A M I C . C O M Important fields of application for “soft“ piezo ceramics are actuators for micro positioning and nanopositioning, sensors such as conventional vibration pickups, ultrasonic transmitters and receivers for flow or level measurement, for example, object identification or monitoring as well as electro-acoustic applications as sound t ransducers and microphones, through to their use as sound pickups on musical instruments. “Hard“ Piezo Ceramics “Hard“ PZT materials can be subjected to high electrical and mechanical stresses. Their properties change only little under these conditions and this makes them particularly ideal for high-power applications. The advantages of these PZT materials are the moderate permittivity, large piezo electric coupling factors, high qualities and very good stability under high mechanical loads and operating fields. Low dielectric losses facilitate their continuous use in resonance mode with only low intrinsic w arming of the component. These piezo e lements are used in ultrasonic cleaning (typically kHz frequency range), for example, the machining of materials (ultrasonic w elding, bonding, drilling, etc.), for ultra sonic processors (e.g. to disperse liquid media), in the medical field (ultrasonic tartar removal, surgical instruments etc.) and also in sonar technology. Lead-Free Materials Piezoelectric ceramics, which nowadays are based mainly on Lead Zirconate-Lead Titanate compounds, are subject to an exemption from the EU directive to reduce hazardous substances (RoHS) and can there fore be used without hesitation. PI Ceramic is nevertheless aiming to provide high-perfor mance lead-free piezoceramic materials and thus provide materials with a guaranteed future. PI Ceramic is currently investigating technologies to reliably manufacture lead-free ceramic components in series production. First Steps Towards Industrial Use with PIC700 The PIC700 material, which is currently in laboratory production, is the first lead-free piezo ceramic material being offered on the market by PI Ceramic. PIC700 is based on Bismuth Sodium Titanate (BNT) and has very similar characteristics to Barium Titanate materials. PIC700 is suitable for ultrasonic transducers in the MHz range as well as sonar and hydrophone applications. Characteristics of the Lead-Free Piezo Ceramic Material The maximum operating temperature of the BNT-based ceramic is around 200 °C. The permittivity and piezoelectric coupling factors of BNT components are lower than those of conventional, PZT materials. Even though PIC700 is suitable for a number of applications, an across-the-board replacement for PZT piezoelectric elements in technical applications is not in sight at the moment. Typical dimensions of current PIC 700 components are d iameters of 10 mm and thicknesses of 0.5 mm. Crystalline Piezo Material for Actuators Lead-Free and with High Linearity Piezoceramic actuators exhibit nonlinear displacement behavior: The voltage applied is thus not a repeatable measure for the position reached. Sensors must therefore be used in applications where the position is relevant. The crystalline PIC050 material, in contrast, has a linearity which is significantly improved by a factor of 10 so that a position sensor is not necessary. Since it is used in positioning systems the PIC050 material is only supplied as a translational or shear actuator in predefined shapes. The standard dimensions are similar to those of the PICA shear actuators (see www.piceramic.com). High-dynamics nanopositioning system with Picoactuator® technology. PIC050 is used for actuators and nanopositioning systems with the tradename Picoactuator®. They have the high stiffness and dynamics of actuators made of PZT material but their displacement is limited: Travel of up to +/-3 µm results with a maximum profile of 20 mm. Picoactuator® in Nanopositioning In precision positioning technology, Physik Instrumente (PI) uses these actuators precis ely where this small displacement with high dynamics and accuracy is required. The high linearity means that they can operate without position control which otherwise sets an upper limit for the dynamics of the system as a result of the limited control bandwidth. The PIC050 crystal forms translucent layers in the Picoactuator®. PIEZO TECHNOLOGY 15 Material Properties and Classification Material designation General description of the material properties “Soft“-PZT Classification in accordance with EN 50324-1 ML-Standard DOD-STD-1376A PIC151 Material: Modified Lead Zirconate-Lead Titanate Characteristics: High permittivity, large coupling factor, high piezoelectric charge coefficient Suitable for: Actuators, low-power ultrasonic transducers, low-frequency sound transducers. Standard material for actuators of the PICA series: PICA Stack, PICA Thru 600 II PIC255 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Very high Curie temperature, high permittivity, high coupling factor, high charge coefficient, low mechanical quality factor, low temperature coefficient Suitable for: Actuator applications for dynamic operating conditions and high ambient temperatures (PICA Power series), low-power ultrasonic transducers, non-resonant broadband systems, force and acoustic pickups, DuraAct patch transducers, PICA Shear shear actuators 200 II PIC155 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Very high Curie temperature, low mechanical quality factor, low permittivity, high sensitivity (g coefficients) Suitable for: Applications which require a high g coefficient (piezoelectric voltage coefficient), e.g. for microphones and vibration pickups with preamplifier, vibration measurements at low frequencies 200 II PIC153 Material: Modified Lead Zirconate-Lead Titanate Characteristics: extremely high values for permittivity, coupling factor, high charge coefficient, Curie temperature around 185 °C Suitable for: Hydrophones, transducers in medical diagnostics, actuators 600 VI PIC152 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Very high Curie temperature Suitable for: Use at temperatures up to 250 °C (briefly up to 300 °C). 200 II 16 W W W. P I C E R A M I C . C O M Material designation General description of the material properties “Hard“-PZT Classification in accordance with EN 50324-1 ML-Standard DOD-STD-1376A PIC181 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Extremely high mechanical quality factor, good temperature and time constancy of the dielectric and elastic values Suitable for: High-power acoustic applications, applications in resonance mode 100 I PIC184 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Large electromechanical coupling factor, moderately high quality factor, excellent mechanical and electrical stability Suitable for: High-power ultrasound applications, hydroacoustics, sonar technology 100 I PIC144 Material: Modified lead zirconate titanate Characteristics: Large electromechanical coupling factor, high quality factor, excellent mechanical and electrical stability, high compressive resistance Suitable for: High-power ultrasound applications, hydroacoustics, sonar technology 100 I PIC241 Material: Modified Lead Zirconate-Lead Titanate Characteristics: High mechanical quality factor, higher permittivity than PIC181 Suitable for: High-power acoustic applications, piezomotor drives 100 I PIC300 Material: Modified Lead Zirconate-Lead Titanate Characteristics: Very high Curie temperature Suitable for: Use at temperatures up to 250 °C (briefly up to 300 °C). 100 I Lead-Free Materials PIC050 Material: Spezial crystalline material Characteristics: Excellent stability, Curie temperature >500 °C Suitable for: High-precision, hysteresis-free positioning in open-loop operation, Picoactuator® PIC700 Material: Modified Bismuth Sodium Titanate Characteristics: Maximum operation temperature 200 °C, low density, high coupling factor of the thickness mode of vibration, low planar coupling factor Suitable for: Ultrasonic transducers > 1MHz 17 PIEZO TECHNOLOGY Material Data S P E C I F I C PA R A M E T E R S O F T H E S TA N D A R D M AT E R I A L S Soft PZT materials Unit PIC151 PIC255/ PIC155 PIC153 PIC2521) Physical and dielectric properties Density ρ g / cm3 7.80 7.80 7.80 7.60 Curie temperature T °C 250 350 345 185 ε /ε 0 2400 1750 1450 4200 ε Τ/ ε 0 1980 1650 1400 20 20 20 30 k 0.62 0.62 0.62 0.62 k 0.53 0.47 0.48 k 0.38 0.35 0.35 k 0.69 0.69 0.69 c Relative permittivity in the polarization direction to polarity Dielectric loss factor 33 Τ 11 tan δ 10-3 Electromechanical properties Coupling factor p t 31 33 k 0.66 15 Piezoelectric charge coefficient -210 -180 -165 500 400 360 -11.5 -11.3 -12.9 22 25 27 16 N 1950 2000 1960 1960 N 1500 1420 1500 d 31 d 10 33 -12 C/N d 550 15 Piezoelectric voltage coefficient 600 g 31 10-3 Vm / N g 33 Acousto-mechanical properties Frequency coefficients p 1 Hz · m N 3 N t Elastic compliance coefficient S E 11 S E Elastic stiffness coefficient C D Mechanical quality factor Q 33 33 10-12 m2 / N 1010 N / m2 m 1750 1780 1950 2000 1990 15.0 16.1 15.6 19.0 20.7 19.7 10.0 1960 11.1 100 80 80 50 6 4 6 5 Temperature stability Temperature coefficient of εΤ 33 (in the range -20 °C to +125 °C) TK ε 33 10-3 / K Time stability (relative change of the parameter per decade of time in %) Relative permittivity Cε -1.0 -2.0 Coupling factor C -1.0 -2.0 K 18 W W W. P I C E R A M I C . C O M Lead-free materials Hard PZT materials PIC152 PIC181 PIC184 2) PIC144 2) PIC241 PIC300 PIC110 PIC7002) 7.70 7.80 7.75 7.95 7.80 7.80 5.50 5.6 340 330 295 320 270 370 150 2003) 950 700 15 30 Recommended operating temperature: 50 % of Curie temperature. 1) Material for the Multilayer tape technology . 2) Preliminary data, subject to change 1350 15 0.48 1200 1015 1250 1650 1050 1500 1250 1500 1550 950 3 5 4 5 3 3) Maximum operating temperature The following values are valid approximations for all PZT materials from PI Ceramic: Specific heat capacity: WK = approx. 350 J kg-1 K-1 0.56 0.55 0.60 0.50 0.48 0.30 0.15 0.46 0.44 0.48 0.46 0.43 0.42 0.40 0.32 0.30 0.30 0.32 0.25 0.18 0.66 0.62 0.66 0.64 0.46 0.63 0.65 0.63 0.32 -120 -100 -110 -130 -80 -50 265 219 265 290 155 120 475 418 265 155 -11.2 -11.1 -10.1 -9.8 -9.5 25 25 24.4 25 21 16 -11.9 Static compressive strength: > 600 MPa 2250 2270 2195 2180 2190 2350 3150 1640 1590 1590 1590 1700 2300 2010 1930 1550 1700 2500 2110 2035 2020 2140 2100 The data was determined using test pieces with the geometric dimensions laid down in EN 50324-2 standard and are typical values. 11.8 12.7 12.4 12.6 11.1 14.2 14.0 15.5 14.3 11.8 16.6 14.8 15.2 13.8 16.4 100 2000 400 1000 400 1400 2 3 5 0.58 300 1920 Specific thermal conductivity : WL = approx. 1.1 W m-1 K-1 Poisson‘s ratio (lateral contraction): σ = approx. 0.34 120 Coefficient of thermal expansion: α3 = approx. -4 to -6 × 10-6 K-1 (in the polarization direction, shorted) α1 = approx. 4 to 8 × 10-6 K-1 (perpendicular to the polarization direction, shorted) All data provided was determined 24 h to 48 h after the time of polarization at an ambient temperature of 23 ±2 °C. 250 A complete coefficient matrix of the individual materials is available on request. If you have any questions about the interpretation of the material characteristics please contact PI Ceramic (info@piceramic.com). 2 -4.0 -5.0 -2.0 -8.0 19 PIEZO TECHNOLOGY Temperature Dependence of the Coefficients Temperature curve of the capacitance C ∆ C/C (%) ∆ C/C (%) Materials: PIC151, PIC255 and PIC155 Materials: PIC181, PIC241 and PIC300 Temperature curve of the resonant frequency of the transverse oscillation f ∆ f / f (%) ∆ f / f (%) s s s s s Materials: PIC151, PIC255 and PIC155 Materials: PIC181, PIC241 and PIC300 Temperature curve of the coupling factor of the transverse oscillation k ∆ k / k (%) 31 ∆ k / k (%) 31 31 31 Materials: PIC151, PIC255 and PIC155 Materials: PIC181, PIC241 and PIC300 20 W W W. P I C E R A M I C . C O M 31 Temperature curve of the piezoelectric charge coefficient d ∆ d / d (%) ∆ d / d (%) 31 31 31 31 31 Materials: PIC151, PIC255 and PIC155 Materials: PIC181, PIC241 and PIC300 Specific Characteristics isotropic. The coefficient of expansion is approximately linear with a TK of approx 2 · 10-6 / K. Thermal properties using the example of the PZT ceramic PIC255 The thermal strain exhibits different behavior in the polarization direction and perpendicular to it. ! The preferred orientation of the domains in a polarized PZT body leads to an anisotropy. This is the cause of the varying thermal expansion behavior. ! ! Non-polarized piezoceramic elements are ! The effect of successive temperature changes must be heeded particularly in the application. Large changes in the curve can occur particularly in the first temperature cycle. Depending on the material, it is possible that the curves deviate strongly from those illustrated. ! Thermal strain in the polarization direction ∆ L / L (%) 1. Heating 1. Heating Cooling Cooling 2. Heating 2. Heating Thermal strain perpendicular to the polarization direction ∆ L / L (%) 1. Heating 1. Heating Cooling Cooling 2. Heating 2. Heating 21 PIEZO TECHNOLOGY Manufacturing Technology EFFICIENT PROCESSES FOR SMALL, MEDIUM-SIZED AND LARGE PRODUCTION RUNS Manufacture of Piezo Components Using Pressing Technology Mixing and grinding of the raw materials Pre-sintering (calcination) Milling Granulation, spray drying Pressing and shaping Thermal processing Sintering at up to 1300 °C Lapping, grinding, surface grinding, diamond cutting Application of electrodes: Screen printing, PVD processes, e.g. sputtering Polarization Assembling and joining technology for actuators, sound transducers, transducers Final inspection 22 Piezoceramic disks with center hole W W W. P I C E R A M I C . C O M Piezo Components Made by Pressing Technology Piezoceramic bulk elements are manufactured from spray-dried granular material by mechanical hydraulic presses. The compacts are either manufactured true to size, taking into account the sintering contraction, or with machining excesses which are then reworked to achieve the required precision. The sintered ceramic material is hard and can be sawn and machined, if required. Screen printing is used to metallize the piezo elements and sputtering processes (PVD) are employed for thin metallizing layers. The sintered elements are then polarized. Stack Design for Actuators Piezo actuators are constructed by stacking several piezoceramic bulk elements and intermediate metal foils. Afterwards an outer insulation layer made of polymer material is applied. Co-firing Process / Multilayer Technology / Piezo Components inCeramics Tape Technology Film Technology for Thin Ceramics Components Fine grinding of the raw materials Thin ceramic layers are produced by tape casting. This process can achieve minimal individual component thicknesses of only 50 µm. Slurry preparation The electrodes are then applied with special screen printing or PVD processes. Tape casting Application of electrodes by screen printing Laminating Isostatic pressing Thermal processing Binder burn out and sintering at up to 1100 °C Grinding Application of contact electrodes, termination Polarization Multilayer Piezo Actuators: PICMA® Multilayer co-firing technology is an especially innovative manufacturing process. The first step is to cast tapes of piezoceramic materials which are then provided with electrodes while still in the green state. The component is then laminated from individ ual layers. In the following electrodes and ceramic are sintered together in a single processing step. The patented PICMA® design comprises an additional ceramic insulation layer which protects the inner electrodes from environmental effects. Any further coatings made of polymer material, for example, are therefore not required. This means that PICMA® piezo actuators remain stable even when subject to high dynamic load. They achieve a higher reliability and a lifetime which is ten times longer than conventional multilayer piezo actuators with a polymer insulation. After the mechanical post-processing is complete, the multilayer actuators are p rovided with contact electrodes and are polarized. Final inspection PICMA® actuators with patented, meander-shaped external electrodes for up to 20 A charging current PIEZO TECHNOLOGY 23 Flexibility in Shape and Design Shaping of Compacts Components such as disks or plates can be manufactured at low cost with a minimum thickness from as low as 0.2 mm. Inboard automatic cutoff saws produce such pieces in large numbers. Modern CNC technology means the sintered ceramic elements can be machined with the highest precision. Holes with diameters of down to 0.3 mm can be produced. Almost any contours can be shaped with accuracies to one tenth of a millimeter. Surfaces can be structured and the components can be milled to give a three-dimensional fit. Ultrasonic machining processes are used to manufacture thin-walled tubes with wall thicknesses of 0.5 mm. Robot-Assisted Series Production Automated assembly and production lines use fast pick-and-place devices and comput er-controlled soldering processes, for example. An annual production run of several million piezoelectric components and more is thus no problem. All Possible Shapes Even with Full-Ceramic Encapsulation PI Ceramic can manufacture almost any shape of PICMA® multilayer piezo actuator using the latest production technology. Hereby, all surfaces are encapsulated with ceramic insulation. We can manufacture not only various basic shapes, e.g. round or triangular crosssections, but also insulated center holes on benders, chips or stack actuators, making it easier to integrate them. Special milling machines work the sensitive ceramic films in the green state, i.e. before sintering. The individual layers are then equipped with electrodes and laminated. The co-firing process is used to sinter the ceramic and the internal electrodes together, the same process as with PICMA® standard actuators. Centerless, cylindrical grinding of piezoceramic rods 24 W W W. P I C E R A M I C . C O M PICMA® Multilayer Actuators with Long Lifetime Automatic soldering machine with PICMA® actuators The internal electrodes and the ceramic of PICMA® multilayer actuators are sintered together (co-firing technology) to create a monolithic piezoceramic block. This process creates an encapsulating ceramic layer which provides protection from humidity and from failure caused by increased leakage current. PICMA® actuators are there fore far superior to conventional, polymerinsulated multilayer piezo actuators in terms of reliability and lifetime. The monolithic ceramic design also gives rise to a high resonance frequency, making the actuators ideal for high-dynamic operation. Large Temperature Range – Optimum UHV Compatibility – Minimal Outgassing – Neutral in Magnetic Fields The particularly high Curie temperature of 320 °C gives PICMA® actuators a usable temperature range of up to 150 °C, far beyond the 80 °C limit of conventional multilayer actuators. This and the exclusive use of inorganic materials provide the optimum conditions for use in ultra-high vacuums: No outgassing and high bake-out temperatures. PICMA® piezo actuators even operate in the cryogenic temperature range, albeit at re duced travel. Every actuator is constructed exclusively of non-ferromagnetic materials, giving them extremely low residual magnetism of the order of a few nanotesla. Low Operating Voltage In contrast to most commercially available multilayer piezo actuators, PICMA® actuators achieve their nominal displacement at operating voltages far below 150 V. This characteristic is achieved by using a partic ularly fine-grained ceramic material which means the internal layers can be thin. The PICMA® actuators are at least partially protected by the following patents: German Patent No. 10021919 German Patent No. 10234787 German Patent No. 10348836 German Patent No. 102005015405 German Patent No. 102007011652 US Patent No. 7,449,077 25 PIEZO TECHNOLOGY Metallization and Assembling Technology THE COMPLETE PROCESS IS IN-HOUSE Thick-Film Electrodes Screen printing is a standard procedure to apply the metal electrodes to the piezoce-ramic elements. Typical film thicknesses here are around 10 µm. Various silver pastes are used in this process. After screen print ing these pastes are baked on at tempera-tures above 800 °C. soldering machines at our disposal to solder on miniaturized components and for larger production runs. Soldered joints which must be extremely reliable undergo special visual inspections. The optical techniques used for this purpose range from the stereomicro-scope through to camera inspection systems. Thin-Film Electrodes Mounting and Assembling Technology Thin-film electrodes are applied to the ceramic using modern PVD processes (sputtering). The typical thickness of the metallization is in the range of 1 µm. Shear elements must be metallized in the polarized state and are generally equipped with thin-film electrodes. The joining of products, e. g. with adhesives, is carried out in the batch production using automated equipment which executes the necessary temperature-time-regime (e.g. curing of epoxy adhesives) and hence g uarantees uniform quality. The choice of adhesive and the curing regime are optimized for every product, taking into consideration the material properties and the intended operational conditions. Specifically devel-oped dosing and positioning systems are used for complex special designs. The piezoceramic stack actuators of the PICA series, high-voltage bender-type actuators and ultrasonic transducers are constructed in jointing processes and have proved successful many times over in the semi-conductor industry and in medical engineering thanks to their high reliability. PI Ceramic has high-throughput sputtering facilities which can apply electrodes made of metal alloys, preferably CuNi alloys and noble metals such as gold and silver. Soldering Methods Ready-made piezo components with connecting wires are manufactured by specially trained staff using hand soldering processes. We have the latest automatic 26 Fully loaded sputtering equipment W W W. P I C E R A M I C . C O M 0 V ∆L P W ∆L L P TH OD D W P fm ∆L fn OD W 0 ID 0 TH Piezoceramic Components PV DIMENSIONS L V L TH P W OD D Frequenz f P TH 0 Disk / rod / cylinder V Outer diameter OD: 2 to 80 mm Thickness TH: 0.15 to 30 mm OD D ! OD P ! ID V P Plate / block LengthOD L: 1 to 80 mm, OD L TH D ID P W Width LW: 1 to 60 mm, P Thickness TH: 0.1 to 30 mm P TH L OD ID Shear plate L Length L: max. 75 mm, Width W: max. 25 mm, Thickness TH: 0.2 to 10 mm P L + TH ID P L L TH L – TH OD W Ring Outer diameter OD: 2 to 80 mm, L P L P W W L W L TH P OD TH OD OD TH W L L: 3 to 50 mm, Width W: 1 to 25 mm, Thickness TH: 0.4 to 1.5 mm L Round bender elements on request. Preferred dimensions: P Diameter: 5 to 50 mm, P Thickness: 0.3 to 2 mm P fired Dimensions, as ± 0.3IDmm resp. ± 3 % Length L, width W (dimensions; tolerance) TH < 15 mm; ± 0.15 mm < 40 mm; ± 0.25 mm < 20 mm; ± 0.20 mm < 80 mm; ± 0.30 mm Outer diameter OD, OD OD inner diameter ID TH (dimensions; tolerance) Radialschwingung OD < 15 mm; ± 0.15 mm < 40 mm; ± 0.25 mm P TH < 20ODmm; ± 0.20 mm < 80 mm;ID ± 0.30 mm Dickenschwingung P TH Thickness TH (dimensions; tolerance) ID L < 10 mm; ± 0.05 mm < 40 mm; ± 0.15 mm P < 20 mm; ± 0.10 mm < 80 mm; ± 0.20 mm Dimension TH W Tolerance Deviation from flatness (slight bending of thin disks or plates is not taken L into account) < 0.02 mm L P P Deviation from parallelism TH < 0.02 mm Deviation from concentricity < _ 0.4 mm Frequency tolerance Tolerance of electric capacitance The minimum are determined by physical and technological limits. The thickness or wall thickness, for example, is limited by the mechanical strength of the ceramic during machining. aximum thickness M for polarization: 30 mm Labeling of the polarity WLength TH Standard W tolerances P ! P TH Bender elements constructed in series / parallel TH P TH L Inner diameter ID: 0.8 to 74 mm, Thickness TH: max. 70 TH mm ID L Inner diameter ID: 0.8 to 74 mm, P Length L: max. 30 mm P W P TH L Tube Outer diameter OD: 2 to 80 mm, W UP he dimensions are T mutually dependent and cannot be chosen arbitrarily. P dimensions L TH OD P ! indicates the P poling direction. The surface of the electrode which is at the positive potential during polarization is marked with a dot or a cross. Alternatively and particularly for thin-film electrodes the direction of polarization is marked by coloring the electrode material: A reddish color indicates the electrode which was at the positive potential during the polarization. L P OD TH ± 5 % (< 2 MHz) > 2 MHz) ± 10 % ( = P ID ± 20 % 27 OD P ID PIEZO TECHNOLOGY Standard Dimensions Electrodes: Fired silver (thick film) or PVD (thin film, different materials: e. g. CuNi or Au) Points: Resonant frequency > 1 MHz Circles: Resonant frequency < 1 MHz Electrodes: Fired silver (thick film) or PVD (thin film, different materials: e. g. CuNi or Au) Electrodes: Fired silver (thick film) or CuNi or Au (thin film) Components with standard dimensions can be supplied at very short notice on the basis of semi-finished materials in stock. Extreme values cannot be combined. Geometries which exceed the standard dimensions are available on request. Disk / rod / cylinder D isk / rod with defined resonant frequency TH in mm 0.20 0.25 0.30 0.40 0.50 0.75 1.00 2.00 3.00 4.00 5.00 10.00 20.00 OD in mm 3 • • • • • • • • • • • • • 5 • • • • • • • • • • • • • TH 10 16 20 25 35 40 45 50 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • OD in mm in MHz 3 • • • • 10.00 • • • • • • • • • • • • • • • • • • • • • 5.00 • • • • • • • • • • • • • • • • • • 4.00 3.00 • • • • • • • • 2.00 1.00 5 10 16 20 25 35 40 45 50 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • o o o o o o o o o o o o o o o o o o o o o o o 0.75 0.50 0.40 0.25 0.20 o o o o o Plate / block TH in mm 0.20 0.25 0.30 0.40 0.50 0.75 1.00 2.00 3.00 4.00 5.00 10.00 20.00 L x W in mm2 4x4 • • • • • • • • • • • • • 5x5 • • • • • • • • • • • • • 10 x 10 • • • • • • • • • • • • • 15 x 15 • • • • • • • • • • • • • 20 x 20 • • • • • • • • • • • • • 28 W W W. P I C E R A M I C . C O M 25 x 20 25 x 25 50 x 30 50 x 50 75 x 25 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • + U 0 V 0 V L P – L OD D OD OD D TH ID P TH LP P TH L P TH W P OD ID P TH W P OD L ID P L L TH TH P P L TH P W W Disks with special electrodes (wrap-around contacts) Design L TH L OD in mm TH in mm Electrodes: Soldering instructions for users 10 / 16 / 20 / 20 / 25 / 40 0.5 / 1.0 / 2.0 Fired silver All our metallizations can be soldered in conformance with RoHS. We recommend the use of a solder with the composition Sn 95.5. Ag 3.8. Cu 0.7. If the piezoceramic element is heated throughout above the Curie temperature, the material is depolarized, and there is thus a loss of, or reduction in, the piezoelectric parameters. (thick film) P W or PVD (thin film) P TH W Rings Design OD in mm L P OD OD TH L ID in mm TH in mm Electrodes: 2.7 0.5 / 1.0 / 2.0 Fired silver 4.3* L 0.5 / 1.0 / 2.0 (thick film) L 0.5 / 1.0 / 2.0 or CuNi 5.2* 0.5 / 1.0 / 2.0 (thin film) 25 16* 0.5 / 1.0 / 2.0 38 13* 5.0 / 6.0 50 19.7* 5.0 / 6.0 / 9.5 10 10* 10* P TH 12.7 *Tolerances as fired, s. table p. 27 TH W TH 5* W OD TH ID Tubes P OD P TH P Design H H P ID OD in mm ID in mm L in mm Electrodes: 76 40 20 10 10 6.35 3.2 2.2 60 38 18 L 9 L 8 5.35 2.2 1.0 50 40 30 30 30 30 30 20 Inside: Fired silver (thick film) Outside: Fired silver (thick film) or CuNi or Au (thin film) P P This can be prevented by adhering to the following conditions under all circumstances when soldering: ! contacts must be point contacts. ! ! P Tubes with special electrodes P TH ID Quartered outer electrodes Wrap-around contacts OD in mm The specific soldering temperature must not be exceeded. ID OD Design The soldering times must be as short as possible (≤ 3 sec). OD TH All soldered ID in mm L in mm 20 18 30 10 9 30 10 8 30 6.35 5.53 30 3.2 2.2 30 2.2 1.0 30 Electrodes: Inside: Fired silver (thick film) Outside: Fired silver (thick film) or CuNi or Au (thin film) 29 PIEZO TECHNOLOGY Testing Procedures S TA N D A R D I Z E D P R O C E D U R E S P R O V I D E C E R TA I N T Y Comprehensive quality management controls all production process at PI Ceramic, from the quality of the raw materials through to the finished product. This ensures that only released parts that meet the quality specifications go on for further processing and delivery. sorting categories. Visual peculiarities must not negatively affect the functioning of the component. The finish criteria relate to: Electrical Testing surface finish of the electrode pores in the ceramic ! chipping of the edges, scratches, etc. Small-Signal Measurements Quality Level The data for the piezoelectric and dielectric properties such as frequencies, impedances, coupling factors, capacitances and loss factors is determined in small-signal measurements. All tests are carried out in accordance with the DIN ISO 2859 standardized sampling method. The AQL 1.0 level of testing ap plies for the electrical assessment, for example. A special product specification can be agreed for custom-engineered products. This includes the relevant release records, plots of the measured values or individual measured values of certain test samples through to the testing of each individual piece, for example. Large-Signal Measurements DC measurements with voltages of up to 1200 V are carried out on actuators to determine the strain, hysteresis and dielectric strength in an automated routine test. Geometric and Visual Testing Processes For complex measurements, image processing measurement devices and whitelight interferometers for topographical examinations are available. Visual Limit Values Ceramic components must conform to certain visual specifications. PI Ceramic has set its own criteria for the quality assessment of the surface finishes, which follow the former MIL-STD-1376. A large variety of applications are taken into account, for special requirements there are graduated 30 W W W. P I C E R A M I C . C O M ! ! Measurement of Material Data The data is determined using test pieces with the geometric dimensions laid down in accordance with the EN 50324-2 standard and are typical values (see p. 14 ff). Con-formance to these typical parameters is d ocumented by continual testing of the individual material batches before they are released. The characteristics of the individual product can deviate from this and are determined as a function of the geometry, varia-tions in the manufacturing processes and measuring or control conditions. Integrated Components, Sub-Assemblies FROM THE CERAMIC TO THE COMPLETE SOLUTION Ceramics in Different Levels of Integration PI Ceramic integrates piezo ceramics into the customer’s product. This includes both the electrical contacting of the elements according to customer requirements and the mounting of components provided by the customer, i. e. the gluing or the casting of the piezoceramic elements. For the custom er, this means an accelerated manufacturing process and shorter lead times. Sensor Components – Transducers PI Ceramic supplies complete sound transducers in large batches for a wide variety of application fields. These include OEM assemblies for ultrasonic flow measurement technology, level, force and acceleration measurement. Piezo Actuators The simplest form for a piezo actuator is a piezo disk or plate, from which stack actuators with correspondingly higher displacement can be constructed. As an alternative, multilayer actuators are man ufactured in different lengths from piezo films with layer thicknesses below 100 μm. Shear actuators consist of stacks of shear plates and are polarized such that they have a displacement perpendicular to the field applied. Bender actuators in different basic forms are constructed with two layers (bimorph) by means of multilayer techno logy and thus provide a symmetric displacement. Piezo actuators can be equipped with sensors to measure the displacement and are then suitable for repeatable positioning with nanometer accuracy. Piezo actuators are often integrated into a mechanical system where lever amplification increases the travel. Flexure guiding systems then provide high stiffness and minimize the lateral offset. Piezo Motors Piezo ceramics are the drive element for piezomotors from Physik Instrumente (PI), which make it possible to use the special characteristics of the piezo actuators over longer travel ranges as well. PILine® piezo ultrasonic motors allow for very dynamic placement motions and can be manufactured with such a compact form that they are already being used in many new applications. Piezo stepping drives provide the high forces which piezo actuators generate over several millimeters. The patented NEXLINE® and NEXACT® drives from PI with their complex construction from longitudinal, shear and bender elements and the necessary contacting are manufactured completely at PI Ceramic. 31 PIEZO TECHNOLOGY Application Examples for Piezo Ceramic Products V E R S AT I L E A N D F L E X I B L E Acousto-Electrical Transducers ! Sound and ultrasound receivers, e.g. microphones, level and flow rate measurements ! Noise analysis ! Acoustic Emission Spectroscopy Inverse Piezoelectric Effect The piezo element deforms when an electric voltage is applied; mechanical motions or oscillations are generated. Electro-Mechanical Transducers Actuators, such as translators, bender elements, piezo motors, for example: ! Micro- and nanopositioning. Laser Tuning Vibration damping ! Micropumps ! Pneumatic valves ! ! Medical engineering, biotechnology, mechanical engineering or production technology through to semiconductor technology – countless fields benefit from the piezoelectric characteristics of the components. Both the direct and the inverse piezoelectric effect have industrial applications. Electro-Acoustic Transducers Signal generator (buzzer) High-voltage sources / transformers ! Delay lines ! High-powered ultrasonic generators: ! ! Direct Piezoelectric Effect The piezo element converts mechanical quantities such as pressure, strain or accel eration into a measureable electric voltage. Mechano-Electrical Transducers ! ! ensors for acceleration and pressure S ibration pickups, e.g. for the detection of V imbalances on rotating machine parts or crash detectors in the automotive field ! Ignition elements ! Piezo keyboards ! Generators, e. g. self-supporting energy sources (energy harvesting) ! Passive damping 32 W W W. P I C E R A M I C . C O M Cleaning, welding, atomization, etc. Ultrasonic signal processing uses both effects and evaluates propagation times, reflection and phase shift of ultrasonic waves in a frequency band from a few hertz right up to several megahertz. Applications are e. g. Level measurement Flow rate measurement ! Object recognition and monitoring ! Medical diagnostics ! High-resolution materials testing ! Sonar and echo sounders ! Adaptive structures ! ! Pumping and Dosing Techniques with Piezo Drives Increasing miniaturization places continuously higher demands on the components used, and thus on the drives for microdosing systems as well. Piezoelectric elements provide the solution here: They are reliable, fast and precise in operation and can be shaped to fit into the smallest installation space. At the same time their energy consumption is low, and they are small and low-cost. The dosing quantities range from milliliter, microliter, nanoliter right down to the picoliter range. The fields of application for piezoelectric pumps are in laboratory technology and medical engineering, biotechnology, chemical analysis and process engineering which frequently require reliable dosing of minute amounts of liquids and gases. Micro-Diaphragm Pumps, Microdosing Valves The drive for the pump consists of a piezo-electric actuator connected to a pump diaphragm, usually made of metal or silicon. The deformation of the piezo element changes the volume in the pump chamber, the drive being separated from the medium to be pumped by the diaphragm. Depending on the drop size and the diaphragm lift thus required, and also the viscosity of the medium, they can be driven directly with piezo disks, piezo stack actuators or by means of levered systems. Their compact dimensions also make these dosing devices suitable for lab-on-a-chip applications. Piezo drives are also used for opening and closing valves. The range here is from a simple piezo element or bender actuator for a diaphragm valve, preloaded piezo stack actuators for large dynamics and force through to piezo levers which carry out fine dosing even at high backpressure. In the automotive industry, fuel injection systems driven by multilayer stack actuators are also microdosing valves. Peristaltic Pumps, Jet Dispensers So-called peristaltic pumps are ideal in cases where liquids or gases are to be dosed accurately and also as evenly and with as little pulsing as possible. The external m echanical deformation of the tube forces the medium to be transported through this tube. The pumping direction is determined by the control of the individual actuators. The drive element consists of flat piezo bend er elements, compact piezo chip actuators or piezo stack actuators, depending on the power and size requirements. Bender actuators are suitable mainly for applications with low backpressure, e.g. for liquids with low viscosity. Piezo actuators are better able to cope with higher backpressure and are suitable for dosing substances with higher viscosity, but require more space. Piezoelectric Microdispensers, Drop-on-Demand Piezoelectric microdispensers consist of a liquid-filled capillary which is shaped into a nozzle and a surrounding piezo tube. When a voltage is applied, the piezo tube contracts and generates a pressure wave in the capillary. This means that individual drops are pinched off and accelerated to a velocity of a few meters per second so that they can travel over several centimeters. The volume of the drop varies with the properties of the medium transported, the dimensions of the pump capillaries and the control parameters of the piezo actuator. Micro-channels etched into silicon can also be used as nozzles. 33 PIEZO TECHNOLOGY Ultrasound Applications in Medical Engineering The piezoelectric effect is used for a large number of applications in the life sciences: For example, for imaging in medical diagnostics, in therapy for the treatment of pain, for aerosol generation or the removal of tartar from teeth, for scalpels in eye surgery, for monitoring liquids, such as in the detection of air bubbles in dialysis, or also as a drive for dispensers and micropumps. If high power densities are required, as is the case with ultrasonic tartar removal or for surgical instruments, for example, “hard“ PZT materials are used. Ultrasonic Instruments in Surgical and Cosmetic Applications Nowadays, instruments with ultrasonic drives allow minimally invasive surgical techniques in eye and oral surgery, for example. Devices for liposuction are also often based on ultrasonic technology. Piezo elements have long been used as ultrasonic generators to remove mineral deposits on human teeth. 34 Instruments for the removal of tartar with ultrasound, OEM product. The piezo disks can be clearly seen. W W W. P I C E R A M I C . C O M The principle is always similar and works just like ultrasonic material machining: Piezoceramic composite systems made of ring disks clamped together are integrated in a sonotrode in the form of a medical in strument. This transmits vibration amplitudes in the μm range at operating frequencies of around 40 kHz. Ultrasound Imaging – Sonography The big advantage of sonography is the harmlessness of the sound waves, which is why the method is widely used. The ultra sonic transmitter contains a piezo element, which generates ultrasonic waves and also detects them again. The ultrasonic transmitter emits short, directional sound wave pulses which are reflected and scattered by the tissue layers to different degrees. By measuring the propagation time and the magnitude of the reflection an image of the structure under investigation is produced. Ultrasound Therapy Aerosol Production This method involves irradiating the tissue with ultrasonic waves by means of an ultrasonic transmitter. On the one hand, mechan ical, longitudinal waves generate vibrations in the tissue, on the other, they convert part of the ultrasonic energy into heat. Ultrasound makes it possible to nebulize liquids without increasing the pressure or the temperature, a fact which is of crucial importance particularly for sensitive sub stances such medicines. Typical working frequencies are in the range 0.8 to over 3 MHz, both continuous wave and pulsed wave ultrasonic techniques being used in the application. The vibration amplitudes transmitted are in the range around 1 µm. Different effects are achieved depending on the energy of the radiation. High-energy shock waves are used to destroy kidney stones, for example. Low-energy shock waves effect a type of micro-massage, and are used for the treatment of bones and tissue and in physiotherapy among other things. The process is similar to high-frequency ultrasonic cleaning – a piezoceramic disk fixed in the liquid container and oscillating in resonance generates high-intensity ultrasonic waves. The drops of liquid are created near the surface by capillary waves. The diameter of the aerosol droplets is determined by the frequency of the ultra sonic waves: The higher the frequency, the smaller the droplets. For direct atomization, where the piezo element oscillating at high frequency is in direct contact with the liquid, the piezo surface is specially treated against aggressive substances. In cosmetic applications ultrasonophoresis, i.e. the introduction of drugs into the skin, is becoming increasingly important. Ultrasonic Sensors: Piezo Elements in Metrology Flow Rate Measurement In many areas the measurement of flow rates is the basis for processes operating in a controlled way. In modern building services, for example, the consumption of water, hot water or heating energy is recorded and the supply as well as the billing is thus controlled. In industrial automation and especially in the chemical industry, volume measurement can replace the weighing of substance quantities. Not only the flow velocity, but also the concentration of certain substances can be detected. The measurement of the propagation time is based on the transmitting and receiving of ultrasonic pulses on alternating sides in the direction of flow and in the opposite direction. Here, two piezo transducers operating as both transmitter and receiver are arranged in a sound section diagonally to the direction of flow. The Doppler effect is used to evaluate the phase and frequency shift of the ultrasonic waves which are scattered or reflected by particles of liquid. The frequency shift between the emitted wave front and the reflected wave front received by the same piezo transducer is a measure of the flow velocity. PIEZO TECHNOLOGY 35 Ultrasonic Sensors: Piezo Elements in Metrology Level Measurement Detection of Particles and Air Bubbles For propagation time measurements the piezo transducer operates outside the medium to be measured as both transmitter and receiver. It emits an ultrasonic pulse in air which is reflected by the content. The propagation time required is a measure of the distance travelled in the empty part of the container. The ultrasonic bubble sensor provides a reliable control of liquid transport in tubes. The sensor undertakes non-contact detection of the air and gas bubbles in the liquid through the tube wall, and thus allows continuous quality monitoring. This allows non-contact measurements whereby the level of liquids, and also solids, in silos for example, can be measured. The resolution or accuracy depends on how well the ultrasonic pulse is reflected by the respective surface. Submersible transducers, or tuning fork sensors, are almost exclusively used as level switches; several of these sensors at different heights are required to measure the level. The piezo transducer excites a tuning fork at its natural frequency. When in contact with the medium to be measured, the resonance frequency shifts and this is evaluated e lectronically. This method works reliably and suffers hardly any breakdowns. Moreover, it is independent of the type of material to be filled. The application possibilities are in the medical, pharmaceutical and food technol ogy fields. The sensors are used to monitor dialysis machines, infusion pumps or transfusions. Industrial applications include control technology, such as the monitoring of dosing and filling machines, for example. Acceleration and Force Sensors, Force Transducer The key component of the piezoelectric acceleration sensor is a disk of piezoelec tric ceramic which is connected to a seismic mass. If the complete system is accelerated, this mass increases the mechanical deformation of the piezo disk, and thus increases the measurable voltage. The sensors detect accelerations in a broad range of frequencies and dynamics with an almost linear characteristic over the complete measurement range. Piezoelectric force sensors are suitable for the measurement of dynamic tensile, compression and shearing forces. They can be designed with very high stiffness and can also measure high-dynamic forces. A very high resolution is typical. Example of a tuning fork for level measurement, OEM product 36 W W W. P I C E R A M I C . C O M Piezoelectric Actuators Piezoelectric translators are ceramic solid state actuators which convert electrical energy directly into linear motion with theoretically unlimited resolution. The length of the actuator changes by up to 0.15 % in this process. The actuators simultaneously generate large static and dynamic forces. Their special characteristics mean that piezo actuators are ideal for semiconductor, optical and telecommunications applications. They are also used in the automotive field, in pneumatic valve technology and vibration damping, and for micropumps. PI Ceramic provides not only hundreds of standard versions but also special custom-ized versions quickly and reliably. The actuators can be equipped with position sensors for applications requiring high closed-loop linearity of motion. Piezo Systems with High Force Generation: PICA So-called high-voltage piezo actuators are manufactured from piezoceramic disks in a stack construction. The individual layers are produced by pressing technology. Applica-tions for the high-load actuators can be found in mechanical engineering for outof-round rotations, for example, in active vibration control or for switching applications. Many modifications are possible: ! Customized materials ! Layer thickness and thus voltage range ! Dimensions and basic form ! Force ranges resp. custom load ! Design and material of end pieces ! Extra-tight length tolerances ! Integrated piezoelectric sensor disks ! Special high / low temperature versions ! Vacuum-compatible and non-magnetic Piezo Actuators from PI Ceramic ! ! ! ! ! ! ! ! ! versions ! otion with subM nanometer resolution igh forces (up to H over 50,000 N), high load capacity (up to 100 MPa) Microsecond response ree of play and fricF tion inimum power M consumption when maintaining its position Non-wearing igh reliability H (> 109 switching cycles) uitable for vacuum S use and cleanrooms an operate at C cryogenic temperatures agnetic fields have M no influence and are themselves not influenced Choice of piezo stack actuators 37 PIEZO TECHNOLOGY Piezoelectric Actuators Reliable Piezo Actuators with Low Operating Voltage: PICMA® PICMA® multilayer actuators are constructed using tape technology and are subsequently sintered in the multilayer co-firing process. The special PICMA® PZT ceramic and its manufacturing technique produce an ideal combination of stiffness, capacitance, displacement, temperature stability and lifetime. The typical operating voltage of the PICMA® multilayer actuators is 100 to 120 V. Piezoelectric PICMA® actuators PICMA® piezo actuators are the only multilayer actuators in the world with ceramic encapsulation. This technology protects the PICMA® actuators from environmental influences, in particular humidity, and ensures their extremely high reliability and performance even under harsh industrial operating conditions. The lifetime of PICMA® actuators is significantly better than that of piezo actuators with conventional polymer encapsulation. Since PICMA® piezo actuators do not require additional polymer insulation and can be operated up to 150 °C they are ideal for use in high vacuum. They even work, at a reduced travel, in the cryogenic temperature range. Lever amplified system 38 Many fields of application benefit from this reliability: Precision engineering and Piezo nanopositioning system with parallel kinematics and displacement sensors W W W. P I C E R A M I C . C O M recision machining as well as switches p and pneumatic or hydraulic valves. Further applications can be found in the fields of active vibration control, nanotechnology, metrology, optics and interferometry. Preloaded Actuators – Levers – Nanopositioning PICMA® piezo actuators from PI Ceramic are the key component for nanopositioning systems from Physik Instrumente (PI). They are supplied in different levels of integration: As simple actuators with position sensor as an optional extra, encased with or without preload, with lever amplification for increased travel, right through to high-performance nanopositioning systems where piezo actuators drive up to six axes by means of zero-wear and frictionless flexure guidings. What they all have in common is a motion resolution in the nanometer range, long lifetimes and outstanding reliability. The combination of PICMA® actuators, flexure guiding and precision measurement systems produces nanopositioning devices in the highest performance class. The fields of application range from semiconductor technology, metrology, microscopy, photonics through to bio technology, aerospace, astronomy and cryo genic environments. Vibration Control If a mechanical system is knocked off balance, this can result in vibrations which adversely affect plants, machines and sensitive devices and thus affect the quality of the products. In many applications it is not possible to wait until environmental influences dampen the vibration and bring it to a halt; moreover, several interferences usually overlap in time, resulting in a quite confusing vibration spectrum with a variety of frequencies. The vibrations must therefore be insulated in order to dynamically decouple the object from its surroundings and thus reduce the transmission of shocks and solidborne sound. This increases the precision of measuring or production processes and the settling times reduce significantly, which means higher throughputs are possible. Piezoelectric components can dampen vibrations particularly in the lower frequency range, either actively or passively. Passive Vibration Insulation Elastic materials absorb the vibrations and reduce them. Piezo elements can also be used for this: They absorb the mechanical energy of the structural vibrations and convert it into electrical energy at the same time. This is subsequently converted into heat by means of parallel electrical resistors, for example. Passive elements are installed as close to the object to be decoupled as possible. The conventional passive methods of vibration insulation are no longer sufficient for many of today’s technologies. Movements and jolts caused by footfall, fans, cooling systems, motors, machining processes etc. can distort patterns e.g. when micromachining to such an extent that the result is unusable. Active Vibration Insulation In this process, counter-motions compensate or minimize the interfering vibrations, and they do this as close to the source as possible. To this end a suitable servo loop must initially detect the structural vibrations before the counter-motions are actively generated. Adaptive materials, such as piezoceramic plates or disks, can act as both sensors and actuators. The frequency range and the mass to be damped determine the choice of suitable piezo actuators. This also requires an external voltage source and suitable control electronics. Multilayer ceramic construction produces increased efficiency. Multilayer piezoelec tric actuators, such as the PICMA multilayer translators, for example, can be used anywhere where precisely dosed alternating forces are to act on structures. The main application fields are in aeronautics and aerospace, where fuel must be saved, for example, or the oscillations of lattice constructions for antennas are to be damped. One of the objectives when building vehicles and ships is to minimize noise in the interior. In mechanical engineer ing for example, the vibrations of rotating drives are increasingly being insulated and actively suppressed. 39 PIEZO TECHNOLOGY Adaptive Systems, Smart Structures Industrial Applications of the Future The development of adaptive systems is increasing in significance for modern industry. Intelligent materials are becoming more and more important here, so-called “smart materials“ which possess both sensor and actuator characteristics. They detect F U A deformation of the substrate gives rise to an electrical signal. The DuraAct transducer can therefore detect deformations with precision and high dynamics. F Piezo ceramics belong to this group of adaptive materials. The piezoelectric Dura Act patch transducers provide a compact solution. They are based on a thin piezoceramic film which is covered with elec trically conducting material to make the F electrical contact and are subsequently embedded in an elastic polymer composite. The piezoceramic element, which is brittle U in itself, is thus mechanically preloaded and electrically insulated and is so robust that it can even be applied to curved surfaces with bending radii of only a few millimeters. The transducers are simply glued to the corresponding substrate or already integrated into a structure during manufacture, where they detect or generate vibrations or contour deformations in the component itself. The size of the contour change here is strongly dependent on the substrate properties and ranges from the nanometer up into the millimeter range. F U changed environmental conditions such as impact, pressure or bending loads and react to them. U The DuraAct patch transducer contracts when a voltage is applied. Attached to a substrate it acts as a bender element in this case. Even under high dynamic load the construction guarantees high damage tolerance, reliability and a lifetime of more than 109 cycles. They have low susceptibility to wear and defects because the transducers are solid state actuators and thus do not contain any moving parts. Energy from Vibration – Energy Harvesting 40 To dispense with the need for batteries and the associated servicing work, it is possible to use energy from the surrounding environment. Piezo elements convert kinetic energy from oscillations or shocks into electrical energy. The robust and compact DuraAct transducers can also be used here. Deformations W W W. P I C E R A M I C . C O M of the substrate cause a deformation of the DuraAct patch transducer and thus generate an electrical signal. Suitable transducer and storage electronics can thus provide a decentralized supply for monitoring systems installed at locations which are difficult to access. Ultrasonic Machining of Materials Ultrasonic applications for the machining of materials are characterized mainly by their high power density. The applications typically take place in resonance mode in order to achieve maximum mechanical power at small excitation amplitude. The ferroelectric “hard“ PZT materials are particularly suitable for these high-power ultrasonic machining applications. They exhibit only low dielectric losses even in continuous operation, and thus consequently only low intrinsic warming. Their typical piezoelectric characteristics are particularly important for the high mechanical loads and operating field strengths: Moderate permittivity, large piezoelectric coupling factors, high mechanical quality factors and very good stability. Ultrasound for Bonding: Joining Techniques Ultrasonic bonding processes can be used to bond various materials such as thermo plastics, and metallic materials like aluminum and copper and their alloys. This principle is used by wire bonders in the semiconductor industry and ultrasonic welding systems, for example. The ultrasonic energy is generated primarily via mechanically strained piezo ring disks, amplified by means of a so-called sonotrode and applied to the bond. The friction of the bonding partners then generates the heat required to fuse, or weld, the materials together around the bond. Shaping by Machining Apart from the welding processes, the ultrasonic processing of hard mineral or crystalline materials such as ceramic, graphite or glass, especially by ultrasonic drilling or machining, like vibration lapping, is increas ingly gaining in importance. This makes it possible to produce geometrically complex shapes and three-dimensional contours, with only a small contact pressure being required. Specially shaped sonotrodes are also used here as the machining tool. Sonar Technology and Hydroacoustics Sonar technology systems (sonar = sound navigation and ranging) and hydroacou stic systems are used for measuring and position-finding tasks especially in maritime applications. The development of high-resolution sonar systems, which was driven by military applications, is now increasingly being r eplaced by civil applications. Apart from still used submarine positioning sonars, systems are used for depth measurements, for locating shoals of fish, for subsurface relief surveying in shallow waters, underwater communication, etc. A diverse range of piezo components is used, ranging from the simple disk or plate and stacked transducers through to sonar arrays which make it possible to achieve a linear d eflection of the directivity pattern of the ultrasonic wave. PIEZO TECHNOLOGY 41 The PI Group Milestones 42 70 WWW AM MIICC. .CCOOMM WW W..PP II C CE RA 2001 1998 1994 1993 1992 1991 1987 1970 A SUCCESS STORY 2015 2014 2011 2007 2002 2004 43 71 PPI IEEZZOO TT E C H HN N OOLLOOGGYY Headquarters Subsidiaries GERMANY USA (East) & CANADA USA (West) & MEXIKO PI Ceramic GmbH Lindenstrasse Lederhose Phone +49 36604 882-0 Fax +49 36604 882-4109 info@piceramic.com www.piceramic.com PI (Physik Instrumente) L.P. Auburn, MA 01501 www.pi-usa.us PI (Physik Instrumente) L.P. Irvine, CA 92620 www.pi-usa.us USA (San Francisco Bay Area Office) UK & IRELAND Physik Instrumente (PI) GmbH & Co. KG Auf der Roemerstrasse 1 76228 Karlsruhe Phone +49 721 4846-0 Fax +49 721 4846-1019 info@pi.ws www.pi.ws PI miCos GmbH Freiburger Strasse 30 Eschbach Phone +49 7634 5057-0 Fax +49 7634 5057-99 info@pimicos.com www.pi.ws Visit us on youtube! PI (Physik Instrumente) L.P. Sausalito, CA 94965 www.pi-usa.us PI (Physik Instrumente) Ltd. Cranfield, Bedford www.physikinstrumente.co.uk ITALY NETHERLANDS Physik Instrumente (PI) S. r. l. Bresso www.pionline.it PI Benelux B.V. Sint-Oedenrode www.pi.ws FRANCE SPAIN PI France SAS Aix-en-Provence www.pi.ws Micos Iberia S.L. Vilanova i la Geltrú www.pimicos.es JAPAN PI Japan Co., Ltd. Tokyo www.pi-japan.jp PI Japan Co., Ltd. Osaka www.pi-japan.jp CHINA © Physik Instrumente (PI) GmbH & Co. KG All contents, including texts, graphics, data etc., as well as their layout, are subject to copyright and other protective laws. Any copying, modi fication or redistribution in whole or in parts is subject to a written permission of PI. Although the information in this document has been compiled with the greatest care, errors cannot be ruled out completely. Therefore, we cannot guarantee for the information being complete, correct and up to date. Illustrations may differ from the original and are not bind ing. PI reserves the right to supplement or change the information provided without prior notice. Physik Instrumente (PI Shanghai) Co., Ltd. Shanghai www.pi-china.cn Physik Instrumente (PI Shanghai) Co., Ltd. Beijing www.pichina.cn SOUTHEAST ASIA TAIWAN PI (Physik Instrumente) Singapore LLP Singapore www.pi-singapore.sg For ID / MY / PH / SG / TH / VNM Physik Instrumente (PI) Taiwan Ltd. Taipei www.pitaiwan.com.tw KOREA PI Korea Ltd. Seoul www.pikorea.co.kr W W W. P I C E R A M I C . C O M CAT125E R3 Piezoelectric Ceramic Products 12/2016 . 0; Subject to change without notice . © Physik Instrumente (PI) GmbH & Co . KG 2016 PIEZO TECHNOLOGY
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