Localized Catalyst TIM for IC Package Heat Transfer
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Solution Overview
Problem
Existing IC device packages face challenges in accurately locating multiple material thermal interface materials (TIMs) to efficiently remove heat from high power utilization regions due to material flow and bleeding, and suffer from curvature changes caused by coefficient of thermal expansion mismatches, leading to TIM strain and potential failure.
Innovation Solution
A polymeric thermal interface material (TIM) with catalytically enhanced and non-catalytically enhanced regions is used, where the catalytically enhanced region has increased cross-link density for efficient heat transfer and the non-catalytically enhanced region has reduced cross-link density for flexibility, connected between the IC device and the lid, with a method involving catalyst and poison deposition to control cross-linking during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple material TIMs are used to efficiently remove heat from high power utilization regions, then heat transfer efficiency is improved, but material flow and bleeding occur making accurate location difficult
Solution Approach 1:
The TIM is segmented into multiple distinct material regions (first TIM material, second TIM material, third TIM material) with different properties. Each material is localized to specific regions: the first TIM material in high power utilization regions, the second TIM material in low power utilization regions, and the third TIM material at interfaces. This segmentation prevents material flow and bleeding by creating distinct zones with different rheological properties.
Solution Approach 2:
Different TIM materials are applied to different locations based on local thermal requirements. The first TIM material with higher thermal conductivity is placed in high power utilization regions, while the second TIM material with lower viscosity is placed in low power utilization regions. This local quality approach optimizes heat transfer efficiency in each region while preventing material mixing.
2Strength
If uniform cross-linking is applied across the entire TIM, then structural integrity is improved, but flexibility is lost leading to TIM failure under thermal cycling
Solution Approach 1:
The TIM exhibits local quality variations in cross-link density: the first portion (under high power regions) has high cross-link density for structural integrity, the second portion (under low power regions) has low cross-link density for flexibility, and the third portion (at interfaces) has medium cross-link density for adhesion. This gradient structure allows the TIM to withstand thermal cycling without failure.
Solution Approach 2:
The TIM is divided into three distinct portions with different cross-link densities. The first portion provides structural support, the second portion provides flexibility, and the third portion provides adhesive bonding. This segmentation of mechanical properties prevents TIM failure under repeated thermal cycling.
3Strength
If high cross-link density is used throughout the TIM, then adhesion strength is improved, but the TIM becomes too rigid and fails under thermal strain
Solution Approach 1:
The TIM has spatially varying cross-link density: high in the first portion for adhesion, low in the second portion for flexibility, and medium in the third portion for balanced performance. This local quality variation allows the TIM to maintain strong adhesion while remaining flexible enough to accommodate thermal expansion mismatches.
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 enhances heat transfer efficiency and maintains structural integrity by ensuring strong adhesion in high power regions while allowing flexibility in low power regions, reducing the likelihood of TIM failure due to thermal cycling and power on/off cycles.
Implementation Method 1
The first catalytically enhanced region includes a first extent of polymer chain cross-linking that has a first cross-link density enhanced by a catalyst localized upon a first portion of the upper surface of the IC device or upon a first portion of the under surface of the lid
Implementation Method 2
a polymeric thermal interface material (TIM)... connected between the IC device and the lid... enhances heat transfer efficiency
Data Source
AI summary
An IC device package includes an IC device that is connected to a lid by a thermal interface material (TIM). A catalyst material is formed upon one or more regions upon an upper surface of the IC device and/or an under surface of the lid. The catalyst material increases the rate of crosslinking of polymer chains of the TIM during TIM curing and/or increases the strength of crosslinks that link polymer chains of the TIM during TIM curing. The catalytically enhanced regions have a higher coefficient of heat transfer relative to non-catalytically enhanced regions. Therefore, the catalytically enhanced regions efficiently transfer heat from the IC device to the lid.