Thermal Design for Dynamic Products - SEMICON · PDF fileThermal Design for Electronics Products ... • Design Flow: Integration of ECAD and MCAD led to ... against transient measurement

Thermal Design for Dynamic Products

John Wilson

Topics

• Introduction

• Uncalibrated models

– Risks

– Development Challenges

• Developing a calibrated model

– Development strategy

– Benefits

Thermal Design for Electronics Products

IntroductionConsumer Handheld Temperature Management

• Historical

• Design Flow: Integration of ECAD and MCAD led to longer design cycles

• Model Inputs: worst case environment and component power dissipations assumed

• Current Best Practice

• Design Flow: Full Integration of ECAD and MCAD data

• Model Inputs: actual environment(s) and power dissipations included

• Benefits - Better product designed in less time

• Less power consumption

• Longer product life

• Better end-user experience

An un-calibrated model leads to:

Emerging Trend

• Overdesign - where the model’s inaccuracy is

recognized

• Underdesign - where it is not, resulting in more

field failures

• Longer design cycles - due to first physical

prototypes performing differently

to expectation.

Using thermal design models calibrated against transient measurement

Un-calibrated model

Calibrated model

Calibration Process: Historical Challenges

Steady state Temperatures at Discrete Points

Out of time: Good Enough?

• Risks and Limitations

• Increased chance of “Right answer for wrong reason”

• Model only valid for steady state thermal design

Best Guess model inputs

Leveraging the Electrical Test Method

New Calibration Approach

P1

P2

t

P

ΔP

Structure Function

Temperature vs. Time

measurement data is used to

develop a Structure Function

Infinite Capacity Ambient

Heat source at Junction

Structure Function Analysis

The Structure Function can be interpreted as the RC path that the heat

takes from the junction, through the device, and to the ambient.

Die

Die Attach

Copper

Solder/Insulation

Copper Frame

TIM

Cold Plate

Ambient

Calibrating with the Structure Function

Somewhat known inputs such as interface thermal resistance or die

active area are adjusted until the Structure Functions match

Calibrated Un-calibrated

Models calibrated against Structure Functions

• Accurately predict the 3D temperature field

• useful for component reliability

• Will respond correctly for all driving power

profiles

• useful for system integrators

• All from a single transient measurement

Benefits

Thank You