Thermally Conductive Silicone Sheet for Low-Stress Vibration Fit
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Solution Overview
Problem
Existing thermally conductive sheets for automotive electronic components require a balance between low maximum stress during assembly and adequate resilience to handle vehicle vibrations, while maintaining excellent thermal conductivity and flexibility.
Innovation Solution
A thermally conductive silicone sheet composed of organopolysiloxane, organohydrogenpolysiloxane, thermally conductive filler, platinum-based catalyst, and dimethylpolysiloxane, with specific ratios and properties to achieve a hardness of 7 or less, maximum stress of 0.7 MPa or less, residual stress of 0.1 MPa or more, and a stress ratio of 7/1 or less, using fillers like aluminum oxide and aluminum nitride with controlled particle sizes and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thermally conductive sheet is made softer to reduce maximum stress during assembly, then the load on heat-generating components is reduced, but the resilience to follow vibrations after mounting deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the silicone polymer by specifying the ratio of crosslinkable groups (0.01-0.5 mmol/g) and using specific organopolysiloxane structures with alkenyl groups in side chains. This chemical parameter optimization enables the sheet to achieve both low maximum stress (0.7 MPa or less) and adequate residual stress (0.1 MPa or more), resolving the contradiction between softness and resilience
Solution Approach 2:
The invention creates a composite material system combining silicone polymer base resin with thermally conductive filler particles (1,000-4,200 parts by mass). This composite structure allows the material to exhibit both the flexibility and low stress characteristics of silicone rubber and the thermal conductivity (2.0 W/m-K or more) and structural integrity needed for vibration resistance, simultaneously addressing both requirements
2Temperature
If the thermally conductive filler content is increased to improve thermal conductivity, then heat dissipation performance is improved, but the maximum stress during assembly increases
Solution Approach 1:
The invention optimizes the filler content parameter to a specific range (1,000-4,200 parts by mass relative to 100 parts of organopolysiloxane) and controls the crosslinkable groups ratio (0.01-0.5 mmol/g). This parameter optimization ensures sufficient thermal conductivity (2.0 W/m-K or more) while maintaining low maximum stress (0.7 MPa or less) through balanced polymer-filler interaction and crosslinking density
Solution Approach 2:
The invention creates local quality differentiation by specifying that alkenyl groups are positioned only in side chains of the polysiloxane backbone rather than at terminal positions. This structural arrangement optimizes the local polymer-filler interface and crosslinking distribution, enabling the material to achieve both high thermal conductivity and low stress characteristics without uniform compromise
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 sheet achieves a balanced compressibility and resilience with excellent thermal conductivity, suitable for automotive components, addressing the need for both flexibility and resilience under varying conditions.
Implementation Method 1
a cured product of a silicone composition, comprising: (a) organopolysiloxane having 2 to 10 alkenyl groups only in a side chain; (b) organohydrogenpolysiloxane having hydrosilyl groups at both ends
Implementation Method 2
a thermally conductive filler: 1,000 to 4,200 parts by mass
Data Source
AI summary
The present invention is a thermally conductive sheet of a cured product of a silicone composition, including: (a) organopolysiloxane having 2 to 10 alkenyl groups only in a side chain; (b) organohydrogenpolysiloxane having hydrosilyl groups at both ends; (c) a thermally conductive filler; (d) a platinum-based curing catalyst; and (e) dimethylpolysiloxane having one end blocked with a trialcoxysilyl group, wherein the thermally conductive sheet has a hardness of 7 or less, maximum stress of 0.7 MPa or less when compressed by 50% at a compression speed of 3 mm/min, residual stress of 0.1 MPa or more, and a ratio of the max stress to the residual stress of 7/1 or less. This can provide a thermally conductive sheet with excellent thermal conductivity, a small difference between maximum stress and residual stress, and a suitable balance between compressibility and resilience, as a heat dissipation member for automotive components.