Thermally Conductive Sheet with High Compressibility
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Solution Overview
Problem
Current thermally conductive sheets face challenges in achieving high flexibility and thermal conductivity in the thickness direction while maintaining low thermal resistance, especially when used in high-temperature environments and under load, due to limitations in filler content and surface roughness during cutting processes.
Innovation Solution
A thermally conductive sheet composed of a curable resin composition, thermally conductive fibers, and particles, with a compressibility of 40% or more and a filling amount of 70% by volume or less, is developed. The sheet is produced by extruding a thermally conductive composition and cutting it in a perpendicular direction to maintain fiber orientation, using a two-part addition reaction type liquid silicone resin with a specific blend ratio and surface treatment of particles to enhance flexibility and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filling rate of inorganic filler is increased to improve thermal conductivity, then thermal conductivity is improved, but flexibility is impaired and powder falling occurs
Solution Approach 1:
The patent uses a composite material system combining organic filler (cellulose fibers) with inorganic filler (alumina, aluminum nitride, or boron nitride particles) in a silicone rubber matrix. This composite approach allows the organic filler to maintain flexibility while the inorganic filler provides thermal conductivity, resolving the contradiction between these two properties.
Solution Approach 2:
The patent applies local quality by using different types of fillers with different functions: organic cellulose fibers provide flexibility and structural integrity, while inorganic particles provide thermal conductivity. Each filler type is optimized for its specific function rather than using a single filler for all purposes.
2Reliability
If carbon fibers and scaly particles are oriented in the sheet thickness direction to improve thermal conduction, then thermal conduction is improved remarkably, but surface roughness increases and irregularities occur during slicing
Solution Approach 1:
The patent changes the physical parameters of the filler particles by using spherical or substantially spherical inorganic particles instead of scaly particles or aligned fibers. This shape modification allows the particles to be embedded in the matrix without creating surface irregularities during slicing, while still providing effective thermal conduction pathways.
3Manufacturing precision
If cutting methods are used to obtain uniform thickness sheets, then uniform thickness is achieved, but surface roughness of cut surface becomes large and thermal resistance at interface increases
Solution Approach 1:
The patent changes the surface finish parameter by using spherical filler particles that create a smoother cut surface compared to fibrous or scaly fillers. The spherical shape allows cleaner cutting with lower surface roughness, reducing thermal resistance at interfaces while maintaining uniform thickness control.
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 exhibits improved close adhesiveness and reduced thermal resistance over time, even in high-temperature environments, with a peak thermal conductivity of 15 W/mK or more and minimal thermal resistance under load, effectively enhancing heat dissipation in electronic devices.
Implementation Method 1
the direction of the carbon fibers and the plane direction of the scaly particles are thus made to be the same as the thickness direction of the sheet, which is the heat transfer direction. That is, by orienting carbon fibers and scaly particles in the sheet thickness direction, the thermal conduction can be improved remarkably.
Implementation Method 2
a curable resin composition, thermally conductive fibers, and thermally conductive particles
Data Source
AI summary
A thermally conductive sheet, comprising a curable resin composition, thermally conductive fibers, and thermally conductive particles, wherein the thermally conductive sheet has a compressibility of 40% or more.