Solving Heat Management Issues with Thermally Conductive Plastics

transcript

SOLVING HEAT MANAGEMENT ISSUES

IN ELECTRONICS APPLICATIONS

USING THERMALLY CONDUCTIVE PLASTICS

Webinar

PRESENTED BY:

ALLISON HOWARD YESKE DR. CHANDRA RAMAN

GLOBAL MARKETING MANAGER GLOBAL TECHNOLOGY LEADER

• Review the basics of heat transfer

• Share simplified models of heat dissipation from chips in three electronic

devices

• Show how thermally conductive plastics can be used to create more

favorable operating conditions

• Present specific benefits of BN-based thermally conductive plastics in

electronics applications

AGENDA

Mega-Trends

• Increasing miniaturization with more functionality

• Reducing weight

• Introducing more complex designs with easier assembly

Thermally conductive plastics (TCP)

containing boron nitride (BN) can

help solve today’s challenges

devices

AGENDA

Basics of Heat Transfer

Three Modes of Heat Transfer

𝑄 = 𝑘𝐴(𝑇𝐻 − 𝑇𝑐)

𝑙 Conduction

𝑄 = 𝑕𝐴(𝑇𝐻 − 𝑇𝑐) Convection TH

𝑄 = 𝜖𝜍𝐴(𝑇𝐻4 − 𝑇𝐶

4) Radiation TH

Theoretical Solution of Heat Transfer

Heat transfer equation

Bottom view

Top view

Element Model Inputs

Heat Source 2.4 W

Heat transfer

coefficient (h) 4.7 W/m2K

Emissivity e = 1

Plastic plate with heater

Top and bottom surfaces dissipate heat

by convection and radiation

𝜌𝐶𝑝𝜕𝑇

𝜕𝑡= 𝛻 ∙ 𝑘𝑖𝛻𝑇

Boundary conditions

−𝑘𝑖𝜕𝑇

𝜕𝑥𝑖= 𝑕 𝑇 − 𝑇∞ + 𝜍𝜖 𝑇4 − 𝑇∞

(oC) Predicted Actual

Heater 125 124

surface 119 110

Neat resin – 0.35 W/mK

Plastic Plate Case

Heat transfer calculations closely reflect reality

(oC) Predicted Actual

Heater 93 96

surface 83 80

Plastic Plate Case

TCP housing: 2 W/mK (X-Z); 0.6 W/mK (Y)

Heat transfer calculations closely reflect reality

devices

AGENDA

Set top box

Three application case studies

Mobile phone Wireless router

MOBILE PHONE CASE STUDY

Chip 1

Chip 2

Chip 3

Battery

Boundary conditions

Battery 0.1 W

Chip 1 0.5 W

Chip 2 0.2 W

Chip 3 0.2 W

Bottom face (image above)

3.8 W/m2K, e = 1.0

Max Temp (oC) Predicted

Chip 1 67

Chip 2 72

Chip 3 72

Baseline case: unfilled plastic housing (0.2 W/mK)

SET TOP BOX CASE STUDY

Boundary conditions

Heat Source 3 W

Wall thickness 2 mm

Heat transfer coefficient

5 W/m2K

Emissivity e = 0.9

Box dimensions 50 mm x 50 mm x 100 mm

source

Steel heat

spreader

Plastic

housing

Chip 94

Bottom surface 82

Baseline case: unfilled plastic housing (0.2 W/mK)

WIRELESS ROUTER CASE STUDY

Element Heat input

Chip 1 8 W

Chip 2 3 W

Chip 3 3 W

RAM 1 2 W

RAM 2 2 W

Total 18 W

Chip 3

Chip 2

Chip 1

Chips could be mounted on either

• Steel heat spreader (TC = 60 W/mK)

• Aluminum heat spreader (TC = 100 W/mK)

Heat transfer coefficient

5 W/m2K

Emissivity e = 0.9

dimensions 230 mm x 150 mm x 35 mm

Chip 3

Chip 2

Chip 1

Steel heat spreader (TC = 60 W/mK) with

unfilled plastic housing (TC = 0.2 W/mK)

Aluminum heat spreader (TC = 100 W/mK)

with unfilled plastic housing (TC = 0.2 W/mK)

Element Temperature (oC)

Chip 1 89

Chip 2 82

Chip 3 82

RAM 1 80

RAM 2 80

Bottom face 80

Chip 1 99

Chip 2 86

Chip 3 86

RAM 1 84

RAM 2 84

Bottom face 88

DO YOU CONSIDER THE DEVICE

HOUSING TO BE PART OF THE

OVERALL THERMAL MANAGEMENT

SOLUTION?

Tell Us What You Think!

OPTIONS – Pick One

• Yes

• No

• Sometimes

Share your

input now!

Do you and your

peers have the

same opinion?

devices

AGENDA

TCP housing: 3 W/mK (X-Z) ; 0.9 W/mK (Y)

Wide range of TCP

formulations possible

HOW MUCH OF A TEMPERATURE

CHANGE DO YOU EXPECT TO SEE

MOVING TO A THERMALLY

CONDUCTIVE PLASTIC SOLUTION?

• < 10 oC

• 10 - 20 oC

• > 20 oC

Share your

input now!

Do you and your

peers have the

same opinion?

Max Temp

Baseline

Neat Plastic

0.2 W/mK

2 W/mK

3 W/mK

5 W/mK

Chip 1 67 49 46 43

Chip 2 72 46 43 40

Chip 3 72 43 37 40

-35o -32o

Thermally conductive plastics can effectively lower operating

temperatures and potentially reduce failure rates

Note: Test data. Actual results may vary

Chip 1 42

Chip 2 42

Chip 3 40

Aluminum housing (TC = 100 W/mK)

Disadvantages of Al:

• Weight

• Painting required

• Interference with

wireless signals

Very similar to 5 W/mK TCP

Chip 72

Bottom surface 67

Thermally conductive plastics can effectively lower operating

temperatures and potentially reduce failure rates

Chip 3

Chip 2

Chip 1

Steel heat spreader (TC = 60 W/mK) with

TCP housing 2 W/mK (X-Z), 0.6 W/mK (Y)

Aluminum heat spreader (TC = 100 W/mK)

with TCP housing 2 W/mK (X-Z), 0.6 W/mK (Y)

Chip 1 77

Chip 2 70

Chip 3 70

RAM 1 68

RAM 2 68

Bottom face 73

Chip 1 87

Chip 2 75

Chip 3 74

RAM 1 72

RAM 2 71

Bottom face 82

operating

temperatures

with TCP

devices

AGENDA

Various Material Solutions for Thermal Management

Die-Cast Aluminum

Graphite-loaded Plastic

BN- / CoolFX* hybrid filler-

loaded Plastic

Heat Transfer OS OK OK

Electrical Insulation X X EX

Electro-magnetic Interference X X EX

Design Freedom / Parts Integration X OK EX

Light Weight OK EX EX

Mechanical Properties EX OK OK

Color/Aesthetics X X EX

Mass Production Capability X EX EX

Process ability (low abrasion, wear, ease) X** OK OK

Price OK EX OK

** If high volume (100k shots = lifetime of tool)

EX = excellent OK = sufficient X = not sufficient OS = overshot

BN-based plastics offer unique benefits

in thermal management applications

*CoolFX is a trademark of Momentive Performance Materials Inc.

IS ELECTRICAL INSULATION

IMPORTANT FOR THE DEVICE

HOUSING?

• Yes

• No

• Sometimes

Share your

input now!

Do you and your

peers have the

same requirements?

With the proliferation of wireless connectivity, more devices are

transmitting and receiving wireless signals (= electromagnetic waves)

Electrically conductive materials interfere with electromagnetic waves

PRIMER ON EMI & SHIELDING

𝑆 = 20 𝑙𝑜𝑔10𝐸𝑖𝑛𝑐𝐸𝑡𝑟𝑎𝑛𝑠

Incident

Field (Einc)

Absorbed (A)

Reflected (R)

Transmitted Field (Etrans)

Where:

• EMI = electromagnetic interference

• MR = multiple reflections

• S = shielding (in decibels)

𝑆 = 20 𝑙𝑜𝑔𝜂0 + 𝜂 2

4𝜂0𝜂+ 20 𝑙𝑜𝑔 1 −

𝜂0 − 𝜂

𝜂0 + 𝜂

𝑒−2𝑡

𝛿 𝑒−𝑗𝛽𝑡 + 20𝑙𝑜𝑔 𝑒𝑡𝛿

𝑆 = 𝑅 +𝑀𝑅 + 𝐴

𝑅 𝑀𝑅 𝐴

𝜂 =𝑗𝜔𝜇

𝜎+𝑗𝜔𝜖

𝛿 =1

𝜋𝑓𝜇𝜍

Where:

• 0 is the impedance of free space (~377 )

• is the complex impedance of the medium

• d is the skin depth

• b is the phase constant of the shield material

• S is shielding (in decibels)

CALCULATING SHIELDING

Electrical (volume) resistivity

EMI IMPACT ON SIGNAL STRENGTH

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E-07 1.0E-05 1.0E-03 1.0E-01 1.0E+01 1.0E+03 1.0E+05

r (-cm)

8.3 dB

Housing thickness

Frequency 1 GHz

@ 20 dB: signal power reduced

by a factor of 100

Final signal is 1% of

original

@ 10 dB: signal power reduced

by a factor of 10

Final signal is 10% of

original

Thermally conductive and electrically insulating plastics

offer unique benefits in thermal management applications

Typical TCP formulations containing graphite/carbon fiber (30-50 wt%)

WOULD YOU CONSIDER THE

DEVICE HOUSING TO BE PART OF

THE OVERALL THERMAL

MANAGEMENT SOLUTION?

• Yes

• No

• Sometimes

Share your

input now!

Do you and your

peers have the

same opinion?

SUMMARY

• Demands for performance and functionality keep increasing in electronic devices

• Thermally conductive plastics can effectively lower operating temperatures and potentially reduce failure rates

• As number of wireless communication devices grows, potential for signal interference is increasing

• BN-based thermally conductive and electrically insulating plastics offer unique benefits, including strong signal transmission

• BN-based plastics are also lightweight and enable color and design freedom

• Momentive can help solve your thermal management issues and

accelerate new developments

Coatings

Follow Momentive on SpecialChem for the latest news about BN-

based thermally conductive plastics and TCP applications

http://polymer-additives.specialchem.com/centers/thermally-conductive-plastics--tcp--containing-boron-nitride

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THANK YOU FOR YOUR ATTENTION

Solving Heat Management Issues with Thermally Conductive Plastics

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