Thermally Conductive Sheet for Multi-Chip Height Gap Heat Dissipation
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Solution Overview
Problem
The increasing size of semiconductor packages and the need for efficient heat dissipation in devices like CPUs and GPUs pose challenges with traditional thermally conductive greases, which can lead to pump-out during thermal cycling and fail to adjust to height differences between heat generating bodies, resulting in inadequate heat dissipation.
Innovation Solution
A method involving a thermally conductive sheet with a compression modulus of 1.40 MPa or less under 0.10 MPa compressive stress at 150°C, applied between heat dissipating and generating bodies, ensuring effective adhesion and heat transfer by adjusting to height differences and providing a tack strength of 5.0 N·mm or more at 25°C, with thermal conductivity of 7 W/(mK) or higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If grease is used as a thermally conductive material, then heat dissipation can be achieved, but pump-out occurs during thermal cycling and adhesion becomes insufficient
Solution Approach 1:
The invention changes the physical state parameter from liquid grease to solid sheet material, and specifies a compression modulus of 1.40 MPa or less under 0.10 MPa compressive stress at 150°C to enable the material to deform and fill gaps while maintaining stable adhesion during thermal cycling without pump-out
Solution Approach 2:
The thermally conductive sheet is constructed as a composite material combining a base resin with thermally conductive fillers (such as metal particles, oxides, or nitrides), achieving both high thermal conductivity and appropriate mechanical compliance to conform to surface irregularities and maintain reliable thermal contact
2Temperature
If grease is used as a thermally conductive material, then heat dissipation can be achieved, but it cannot adjust to height differences between heat generating bodies
Solution Approach 1:
By controlling the compression modulus to be 1.40 MPa or less under 0.10 MPa compressive stress at 150°C, the solid sheet material gains sufficient compliance to deform and conform to height differences between heat generating bodies, enabling reliable thermal contact across non-uniform surfaces while maintaining structural integrity
Solution Approach 2:
The thermally conductive sheet exhibits dynamic deformation capability under compressive stress, allowing it to adapt its shape to match the topography of heat generating bodies with different heights, ensuring optimal thermal contact area and heat dissipation performance
3Adaptability or versatility
If multiple heat generating bodies are mounted on a substrate, then functional integration is improved, but the manufacturing process becomes complicated when using grease
Solution Approach 1:
The invention merges the thermal interface material function into a single solid sheet that can simultaneously interface with multiple heat generating bodies, eliminating the need for separate grease application steps for each component and simplifying the manufacturing process while maintaining effective thermal contact across all devices
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 approach simplifies the manufacturing process while ensuring excellent heat dissipation properties by maintaining contact and adjusting to height differences between multiple heat generating bodies and a heat dissipating body, preventing pump-out and enhancing thermal conductivity.
Implementation Method 1
a thermally conductive sheet having a compression modulus of 1.40 MPa or less under a compressive stress of 0.10 MPa at 150° C.
Implementation Method 2
by applying pressure to the heat dissipating body and the plurality of heat generating bodies in a thickness direction of the thermally conductive sheet
Data Source
AI summary
A method of manufacturing a semiconductor device includes adhering together a heat dissipating body and a plurality of heat generating bodies via a thermally conductive sheet, by applying pressure to the heat dissipating body and the plurality of heat generating bodies in a thickness direction of the thermally conductive sheet with the thermally conductive sheet disposed therebetween, the thermally conductive sheet having a compression modulus of 1.40 MPa or less under a compressive stress of 0.10 MPa at 150° C.