Thermally Conductive Sheet Assembly for Warpage-Resistant Chip Cooling
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Solution Overview
Problem
The increase in size of semiconductor chips and packages leads to issues with heat dissipation due to pump-out of grease and detachment of thermally conductive sheets, causing inadequate thermal management.
Innovation Solution
A method of manufacturing semiconductor devices using a thermally conductive sheet with a compression modulus of 1.40 MPa or less and a tack strength of 5.0 N·mm or more, applied under specific pressure conditions to maintain adherence between heat generating and dissipating bodies, ensuring effective heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If grease is used as a thermally conductive material, then heat dissipation is improved, but pump-out occurs during thermal cycling when size increases
Solution Approach 1:
The patent changes the physical state parameter from liquid grease to solid sheet form, fundamentally altering how the thermally conductive material maintains contact under thermal cycling conditions. This parameter change eliminates pump-out while preserving heat dissipation function.
Solution Approach 2:
The thermally conductive sheet is constructed as a composite material combining a base sheet with adhesive layers on both surfaces. This composite structure provides both thermal conduction capability and reliable adhesion to prevent detachment during thermal cycling.
2Reliability
If a thermally conductive sheet is used as a thermally conductive material, then pump-out is prevented, but detachment occurs when heat generating body size increases
Solution Approach 1:
The thermally conductive sheet is constructed as a composite material combining a base sheet with adhesive layers on both surfaces. This composite structure provides both thermal conduction capability and reliable adhesion to prevent detachment during thermal cycling.
Solution Approach 2:
The patent specifies precise parameter ranges for adhesive strength (5.0 N·mm or more) and compression modulus (1.40 MPa or less) to ensure the material can accommodate warpage while maintaining secure adhesion, even as heat generating body sizes increase.
3Power
If heat generating body size increases, then heat generation increases, but warpage increases causing thermally conductive sheet detachment
Solution Approach 1:
The patent specifies precise parameter ranges for adhesive strength (5.0 N·mm or more) and compression modulus (1.40 MPa or less) to ensure the material can accommodate warpage while maintaining secure adhesion, even as heat generating body sizes increase.
Solution Approach 2:
The thermally conductive sheet functions as a flexible thin film that can conform to and accommodate warpage in the heat generating body, maintaining thermal contact despite shape changes caused by increased size and heat generation.
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
The method ensures stable heat dissipation by preventing detachment and maintaining contact areas, even with increased warpage, thus improving the thermal performance of semiconductor devices.
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., and a tack strength of 5.0 N·mm or more at 25° C.
Implementation Method 2
adhering together a heat generating body and a heat dissipating body via a thermally conductive sheet, by applying pressure to the heat generating body and the heat dissipating body 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 generating body and a heat dissipating body via a thermally conductive sheet by applying a pressure on the heat generating body and the heat dissipating body 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., and a tack strength of 5.0 N·mm or more at 25° C.