幻灯片 1 Quectel LTE Module Thermal Design Guide V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

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Thermal Design Guide

Quectel LTE Module

September, 2018

@ Quectel Wireless Solutions | September, 2018 | Page 2 Rev.: V1.0 | Status: Released

General Overview

Design Guidelines

Test Example

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General Overview

This document mainly introduces the thermal considerations for the design of application devices

incorporating the following Quectel LTE modules:

•LTE Module Series

ECxx: includes EC25/EC21/EC20 R2.0/EC20 R2.1 modules NOTE

EG9x: includes EG91/EG95 modules

EM05 module

•LTE-A Module Series

Ex06: includes EP06/EG06/EM06 modules

•Automotive Module Series

AG35 module

NOTE: EC2x includes LCC modules, Mini PCIe modules and Mini PCIe-C modules.

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Why Need Thermal Design?

•The module’s internal electronic circuits will generate more and more heat, due to the increasing demand of high-speed

communication and embedded applications.

•Complex workspaces, which is more and more common to see, require modules to have high heat dissipation performance.

•Heat accumulation of modules gives rise to the risk of damage on devices.

May cause burning sensations on skin/result in high surface temperature.

Some ICs may not work properly.

•Users may undergo limited device performance due to thermal mitigation algorithms.

•The module will disconnect from network automatically if the device temperature is higher than the absolute maximum

temperature.

•The module offers high performance when the internal baseband (BB) chip stays below 105℃. If the peak temperature of the

BB chip reaches or exceeds 105℃, the module will not be able to provide high-performance as usual (may offer decreased RF

output power, limited data rate, etc.). Therefore, the modules are recommended to optimize thermal design so as to keep the

peak temperature of BB chip lower than 105℃. AT+QTEMP command can be executed to get the peak temperature of BB

chip. The first return value of AT+QTEMP indicates the peak temperature of BB chip.

Proper thermal design significantly extends the high performance operating time without taking the risk of device failure

which affects user experience adversely.

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General Overview

Design Guidelines

Test Example

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Thermal Concept 1

A(m2)

Δx(m) T1(K)

T2(K)

k(W/m*k)

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Thermal Concept 2

•Materials with higher thermal conductivity (k) transfer heat better.

Graphite (in-plane): k > 370 W/m*K

Aluminum: k = 205 W/m*K

Magnesium: k = 156 W/m*K

Plastic: k = 0.2 W/m*K

Air: k = 0.024 W/m*K

•Housing/enclosures with larger surface area (A) dissipate heat better.

Heat sink dissipates the heat by increasing the surface area in contact with the cooling fluid around

the module, such as air.

The PCB ground plane’s thickness and width (cross-sectional surface area), number of layers, and

vias are critical parameters for IC to reduce its peak temperature by spreading heat energy.

•The smaller distance between the cooling system and heat source is preferred.

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Structure Design 1

•Select walls with thinner thickness because of smaller thermal resistance.

•Try to expand the internal space as much as possible for better convection.

GoodWorse

Worse Good

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Structure Design 2

•Reserve enough space to add a heat sink on the top of the module as well as the opposite side of the

PCB area where the module is mounted.

•If the internal space is small, it is recommended to add a thermal pad with high thermal conductivity

between the module and the housing/enclosure.

•Do not install any battery or other components that may generate heat both at the top and bottom of the

module.

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Heat Sink Design

•If the housing/enclosure is made up of aluminum alloy, it is recommended to integrate the heat sink with

the housing/enclosure.

•If the housing/enclosure is made up of plastic, it is recommended to design an independent heat sink

whose heat dissipation surface should be outside the housing/enclosure.

•Increase the number of heat sink fins as many as possible.

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Thermal Pad Design 1

•Selection:

Select thermal pads with high thermal conductivity (k > 3 W/m*k).

•Heat conduction area:

It is recommended to select thermal pads with almost the same size with the module’s shielding cover.

Take AG35 module with size of 32.5mm×37mm as an example, its preferred thermal pad size is about

32.5mm×37.0mm.

Module’s shielding cover

Thermal Pad

32.5mm x 37.0mm

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Thermal Pad Design 2

•Thermal pad thickness:

The thermal pad thickness is recommended to be 0.5mm greater than the distance between the module’s top/bottom

side and the heat sink (or housing/enclosure). The maximum thickness is recommended to be 3mm.

•Thermal pad position:

Cooling system on top side of the module: the thermal pad is used between the module’s shielding cover and the heat

sink (or housing/enclosure).

Cooling system on bottom side of the module: the thermal pad is used between the PCB area on opposite side of

which the module is mounted and the heat sink, or directly between the module’s bottom side and the PCB.

•Example:

Taking Mini PCIe module as an example, the thermal pad is placed between the module’s bottom side and the PCB. In

such case, please do not apply solder mask on the connection area so as to ensure better heat dissipation

performance. The solder mask size should be almost the same as the bottom size of the module.

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PCB Design 1

•Larger PCB size is beneficial for components placement and has the better performance for heat

dissipation

•Keep the module away from the ARM, audio amplifier, and other components that may generate heat.

•Keep the module away from the heat sensitive elements such as the TCXO/XO.

Module

TCXO/XO

Heat sensitive

element

Module

Audio

Amplifier

ModuleARM

Module

Other Hot

Components

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PCB Design 2

•Best design:

To facilitate adding of the heat sink when necessary, please do not

place components on the opposite side of the PCB area where the

module is mounted, and do not place components on both the PCB top

and bottom areas where the PCIe module is installed.

•Good design:

Place only some passive components with small packages, such as

resistors, capacitors, and inductors, on the opposite side of the PCB

area where the module is mounted, and leave a large blank area for

adding the cooling system.

•Bad design:

Placed many components with large packages and even heat sources

on the opposite side of the PCB area where the module is mounted.

PCB board

Many capacitors

and resistors

LTE module

Heat IC

Bad

PCB board

Few capacitors or resistors

LTE module

Good

PCB board

LTE module

Best

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PCB Design 3

•Add layers as many as possible and increase the copper area at each layer.

•Increase the size of the GND plane as much as possible.

•Do not design GND pads of the module into thermal relief pads.

•Fill empty layers with copper wherever possible.

•Increase the power supply plane using thick/wide traces as many as possible.

•Try to keep the copper plane as a whole.

Worse Good

Copper Dielectric

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PCB Design 4

•Flotherm V12.0

•PCB Size:

90mm×150mm×1.6mm

2 layers PCB, L1

filled with GND

4 layers PCB,

L1/L3 filled with

GND, and 10 GND

vias used.

4 layers PCB,

L1/L3 filled with

GND, and 20 GND

vias used.

6 layers PCB,

L1/L3/5 filled with

GND, and 5 GND

vias used.

6 layers PCB,

L1/L3/5 filled with

GND, and 10 GND

vias used.

BB(℃)115 102 101 99 98

115

102 101 99 98

Temperature (℃)

Simulation: The Effect of PCB Layers and GND Vias

to Heat Dissipation

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10 Through Holes 20 Through Holes

PCB Design 4 –Through Holes

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PCB Design 4 –Thermal Image

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PCB Design 5

PCB Size: 90mm*150mm*1.6mm PCB Size: 90mm*75mm*1.6mm

BB Chip Temperature (℃)103 110

103

110

100

102

104

106

108

110

112

Temperature (℃)

Simulation: The Effect of PCB Size to Heat

Dissipation

•Flotherm V12.0

•PCB:

90mm×150mm×1.6mm, 6 layers

90mm×75mm×1.6mm, 6 layers

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•Vias design:

a) Add adequate vias under and near the module.

b) Connect the vias to a large GND plane for better heat

dissipation.

c) Large vias are better than small vias.

d) Through holes are better than buried vias and blind vias.

e) Stacked vias are better than staggered vias.

•About solder mask:

Do not apply solder mask on the PCB area where the module is

mounted or installed to provide better heat dissipation

performance.

Module

Stacked vias

Staggered vias

PCB Design 6

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Heat Dissipation Diagram

•Aluminum alloy shell and

recommended cooling system design

of LCC/LGA module

Heatsink

Aluminium alloy shell

Shielding Cover

Heat Source

Customer PCB Board Module

Thermal Pad

Shielding Cover

Heat Source

Customer PCB Board

Heatsink

Aluminium alloy shell

Module

Thermal Pad

Better

Good

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•Aluminum alloy shell and

recommended cooling system design

of Mini PCIe module

Shielding Cover

Heat Source

Customer PCB Board

Heatsink

Aluminium alloy shell

Thermal Pad

MINI PCIE Connector

Upholder

Thermal Pad

MINI PCIE Module

Shielding Cover

Heat Source

Customer PCB Board

Heatsink

Aluminium alloy shell

Thermal Pad

MINI PCIE Connector

Upholder

MINI PCIE Module

Better

Good

Heat Dissipation Diagram

@ Quectel Wireless Solutions | September, 2018 | Page 23 Rev.: V1.0 | Status: Released

Heat Dissipation Diagram

•Aluminum alloy shell and

recommended cooling system design

of Mini PCIe-C or M.2 module Better

Good

Shielding Cover

Heat Source

Customer PCB Board

Heatsink

Aluminium alloy shell

Thermal Pad

MINI PCIE-C Module

Thermal Pad

MINI PCIE Connector

Upholder

Shielding Cover

Heat Source

Customer PCB Board

Heatsink

Aluminium alloy shell

Thermal Pad

MINI PCIE-C Module

MINI PCIE Connector

Upholder

Mini PCIe-C/M.2 Module

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Heat Dissipation Diagram

•Plastic shell and recommended

cooling system design of

LCC/LGA module

Shielding Cover

Heat Source

Customer PCB Board

Plastic shell

Module

Thermal Pad

Heatsink

@ Quectel Wireless Solutions | September, 2018 | Page 25 Rev.: V1.0 | Status: Released

•Plastic shell and recommended

cooling system design of

Mini PCIe module

Shielding Cover

Heat Source

Customer PCB Board

Plastic shell

Heatsink

Thermal Pad

MINI PCIE Module

Thermal Pad

Upholder

MINI PCIE Connector

Heat Dissipation Diagram

@ Quectel Wireless Solutions | September, 2018 | Page 26 Rev.: V1.0 | Status: Released

•Plastic shell and recommended

cooling system design of

Mini PCIe-C or M.2 module

Shielding Cover

Heat Source

Customer PCB Board

Plastic shell

Heatsink

Thermal Pad

MINI PCIE-C Module

Thermal Pad

Upholder

MINI PCIE Connector

Heat Dissipation Diagram

Mini PCIe-C/M.2 Module

@ Quectel Wireless Solutions | September, 2018 | Page 27 Rev.: V1.0 | Status: Released

General Overview

Design Guidelines

Test Example

@ Quectel Wireless Solutions | September, 2018 | Page 28 Rev.: V1.0 | Status: Released

Test Environment

Aluminum Alloy Shell Heat SinkMini PCIe Module

Thermal Pad on the Top Side Thermal Pad on the Bottom Side

@ Quectel Wireless Solutions | September, 2018 | Page 29 Rev.: V1.0 | Status: Released

Test Condition

•Power the EVB by 5V DC power supply

•Connect the main antenna of the Mini PCIe module to CMW500 through RF cable

•Set the max power, max data rate, and UDP transfer mode

•Set different test temperatures, such as 55℃, 65℃, 75℃, and 85℃

•Use AT+QTEMP command to get the current temperature every 10s

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Test Results

•The Best Solution: Cooling system available on both sides of Mini PCIe module

It can lower the BB temperature by 8℃@T=85℃, and lower the XO temperature by 9℃@T=85℃.

•Good Solution: Cooling system on the top side of Mini PCIe module

It can lower the BB temperature by 7℃@T=85℃, and lower the XO temperature by 8℃@T=85℃.

7th Floor, Hongye Building, No.1801 Hongmei Road, Xuhui District,

Shanghai 200233, China

Tel: +86-21-5108 6236 Email: info@quectel.com

Website: www.quectel.com

Thank you!

www.quectel.com

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幻灯片 1 Quectel LTE Module Thermal Design Guide V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

Quectel_LTE_Module_Thermal_Design_Guide_V1.0

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