Thermal Interface Material Composition for Conductive Yet Tough Pads
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Solution Overview
Problem
Existing thermal interface materials (TIMs) face challenges in balancing mechanical and thermal performance, leading to issues such as delamination, voids, cracks, and material degradation under extreme conditions, which affect the reliability and durability of electronic devices.
Innovation Solution
A thermal interface material composition utilizing a different matrix, such as polymeric blends or block copolymers, with selective localization of nanofillers in specific morphologies to enhance thermal conductivity and mechanical resilience, achieving a balance through optimized polymer composition and morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If higher filler volumes (up to 80%) are used in thermal pads, then thermal conductivity is improved, but mechanical properties deteriorate (embrittlement)
Solution Approach 1:
The patent uses a composite material system consisting of silicone elastomeric matrix combined with thermally conductive fillers (such as aluminum oxide, aluminum nitride, or boron nitride). This composite structure allows the material to simultaneously achieve good thermal conductivity from the fillers and mechanical flexibility from the silicone matrix, resolving the contradiction between thermal performance and mechanical properties.
Solution Approach 2:
The patent optimizes the filler volume percentage within a specific range (40-80% by weight) rather than using maximum filler content. This parameter optimization ensures sufficient thermal conductivity while maintaining adequate mechanical properties. Additionally, the patent adjusts particle size distribution and shape parameters of fillers to balance thermal performance and mechanical flexibility.
2Temperature
If higher filler concentrations are used, then thermal conductivity is improved, but conformability deteriorates (increased surface roughness)
Solution Approach 1:
The patent employs a bimodal or trimodal particle size distribution of fillers, combining fine particles (1-10 micrometers) with coarser particles (10-50 micrometers). The fine particles fill gaps between larger particles, reducing surface roughness and improving conformability, while the larger particles provide the primary thermal conduction pathways. This parameter optimization allows achieving good thermal conductivity without sacrificing conformability.
Solution Approach 2:
The silicone elastomeric matrix acts as a binding phase that holds the filler particles together while maintaining flexibility. This composite structure allows the thermal pad to conform to surface irregularities even with significant filler content, as the elastomeric matrix can deform to match surface contours.
3Ease of manufacture
If conventional silicone matrix is used, then ease of manufacture is improved, but thermal conductivity is insufficient
Solution Approach 1:
The patent enhances the conventional silicone matrix by incorporating thermally conductive fillers such as aluminum oxide, aluminum nitride, or boron nitride particles. This composite approach maintains the ease of manufacturing with silicone while dramatically improving thermal conductivity. The fillers create thermal conduction pathways through the silicone matrix, achieving thermal performance sufficient for high-power electronic devices.
Solution Approach 2:
The patent optimizes the type, size, shape, and distribution parameters of filler particles within the silicone matrix. By selecting appropriate filler materials with high intrinsic thermal conductivity and optimizing their concentration and arrangement, the patent achieves enhanced thermal conductivity while maintaining the processability and manufacturability advantages of silicone-based materials.
4Ease of operation
If thermal pads are made softer for conformability, then ease of operation is improved, but mechanical robustness deteriorates
Solution Approach 1:
The silicone elastomeric matrix provides inherent softness and conformability, while the thermally conductive filler particles (aluminum oxide, aluminum nitride, or boron nitride) provide structural reinforcement. This composite structure allows the thermal pad to be soft enough to conform to surface irregularities while maintaining mechanical robustness to resist deformation under compression and during thermal cycling.
Solution Approach 2:
The patent optimizes the crosslinking density and Shore hardness of the silicone matrix within specific ranges to achieve the right balance between softness and robustness. Additionally, the filler particle concentration, size, and shape are adjusted to provide mechanical reinforcement without excessive hardness, enabling the thermal pad to maintain both conformability and mechanical strength.
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 composition achieves enhanced thermal conductivity and mechanical robustness, preventing tearing or cracking, and maintaining stability under thermo-mechanical cyclic conditions, optimizing both thermal and mechanical performance.
Implementation Method 1
The rubber can absorb strain energy during mechanical loading, preventing the films from tearing or cracking.
Implementation Method 2
Nanofillers can be incorporated into the glassy-rubbery polymer blends or block copolymers to enhance functional properties such as: thermal conductivity
Data Source
AI summary
The thermal interface material (TIM) system of the present disclosure includes a thermal pad having a thermoplastic elastomeric copolymer coupled to a thermally conductive nanoparticle. The thermoplastic elastomeric copolymer may include glassy and rubbery polymers. In a specific example, the thermoplastic elastomeric copolymer may include a pseudo-bicontinuous morphology of polymer blends, such as polystyrene (PS) and/or polyisoprene (PI). In a more specific example, the thermoplastic elastomeric copolymer may include a triblock copolymer of polystyrene-block-polyisoprene-block-polystyrene (SIS). The thermally conductive nanoparticle may be non-electrically conductive. The thermally conductive nanoparticle may include 2D boron nitride (BN). The thermally conductive nanoparticle may include a metallic filler material such as gold (Au).