Microprocessor Interposer Cooling for Vibration-Robust On-Board Computers

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Solution Overview

Problem

On-board computers in vehicles face challenges in effectively dissipating heat generated by microprocessor chips due to constraints such as vibrations, high temperatures, and the need for a reliable cooling system without complex or costly manufacturing and assembly, especially when traditional cooling methods like fluid circulation are not feasible.

Innovation Solution

The use of an interposer with a large heat exchange surface area, a metallic material, and a thermal paste between the microprocessor chip and interposer, along with a thermal mattress between the interposer and the housing, enhances heat transfer and provides robustness against vibrations without requiring precise manufacturing tolerances or moving parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contact thermal diffusion cooling is used to evacuate heat from the microprocessor chip, then the cooling system is simple and reliable, but the heat evacuation efficiency is insufficient due to clearance between components

Engineering Contradiction:
Improvecooling system reliabilityVSAvoidheat evacuation efficiency
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

A thermal pad is introduced as an intermediary element between the microprocessor chip and the radiator. This thermal pad fills the clearance gap that exists due to dimensional tolerances and vibrations, ensuring continuous thermal contact and maintaining efficient heat transfer from the chip to the radiator without requiring complex adjustment mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The thermal properties of the interface between components are changed by introducing a thermal pad with specific thermal conductivity characteristics. This modifies the thermal transmission parameter across the interface, compensating for the negative effects of clearance and maintaining effective heat evacuation despite mechanical tolerances and vibrations.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If elastic elements such as springs or gel are provided to take up clearances between components, then mechanical retention is ensured, but the components can undergo relative movements due to vibrations which jeopardize cooling

Engineering Contradiction:
Improvecomponent clearance compensationVSAvoidcooling stability under vibration
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The thermal pad serves as a mediator that is specifically designed to maintain thermal contact under vibrational conditions. Unlike elastic elements that may allow relative movement, the thermal pad's material properties enable it to conform and maintain continuous contact, ensuring both mechanical retention and thermal stability during vehicle operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If very low manufacturing tolerances are provided, then dimensional accuracy is improved, but manufacturing costs considerably increase and assembly is complicated

Engineering Contradiction:
Improvedimensional toleranceVSAvoidmanufacturing cost and assembly complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The thermal pad acts as a compensatory intermediary that allows the use of standard manufacturing tolerances. By introducing this flexible thermal interface material, the system can accommodate normal dimensional variations without requiring expensive precision machining or complex assembly procedures, thus maintaining manufacturing feasibility while ensuring proper thermal contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Manufacturing precision

If a thick thermal pad is used to compensate for dimensional tolerances, then assembly is facilitated, but the efficiency of heat evacuation towards the housing is reduced

Engineering Contradiction:
Improvedimensional tolerance compensationVSAvoidheat evacuation efficiency
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The thermal pad's parameters (thickness, thermal conductivity) are optimized to achieve a balance between mechanical compliance and thermal performance. The pad is designed with specific thickness to compensate for tolerances while maintaining sufficient thermal conductivity to ensure efficient heat transfer, avoiding the trade-off between assembly ease and cooling efficiency.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution significantly improves heat evacuation efficiency, maintaining effective cooling of the microprocessor chip while being robust to vibrations and avoiding the complexities and costs associated with traditional cooling methods.

Implementation Method 1

a thermal paste is placed between the microprocessor chip and the interposer

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a thermal mattress is placed between the interposer and the computer housing

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the interposer being arranged between the microprocessor chip and the housing and being configured to diffuse the heat transmitted by the microprocessor chip towards the housing

Methodology Applied
Scientific EffectHeat diffusion: Diffusion

Data Source

PatentEP4062259B1On-board computer with interposer on the microprocessor chip
Publication Date: 2023.11.01 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP4062259B1 patent drawingFigure 1~3
  • EP4062259B1 patent drawingFigure 4

AI summary

An on-board computer comprising a microprocessor chip (1) with a lower face (1b) and an upper face (1a), a chip support (2) having an upper face (2a) on which the microprocessor chip (1) is mounted, and a housing (4) configured so as to evacuate the heat released by the microprocessor chip (1) during operation, an interposer (6) being arranged between the upper face (1a) of the microprocessor chip (1) and the housing (4), the interposer being supported by the upper face of the microprocessor chip (1) and being configured so as to diffuse the heat transmitted by the upper face (1a) of the microprocessor chip (1) to the housing (4), the interposer (6) having an upper surface for exchanging heat with the housing (4) the area of which is at least twice as large as the area of the upper face (1a) of the microprocessor chip (1).