Thermally Conductive Silicone Composition with Gallium Alloy
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Solution Overview
Problem
Conventional thermally conductive materials, such as sheets and greases, face limitations in achieving sufficient thermal conductivity due to restrictions on the amount of thermally conductive fillers, leading to issues like contamination, leakage, low thermal conductivity, cracking, and voids in cured products, especially when used with heat-generating electronic components like CPUs.
Innovation Solution
A thermally conductive silicone composition is developed by adding gallium or its alloys with low melting points and palladium powder to an addition-curable silicone composition, which allows for uniform dispersion of these materials as fine particles, inhibiting cracks and voids during curing and enhancing thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large amount of thermally conductive filler is added to improve thermal conductivity, then thermal conductivity is improved, but workability and processability deteriorate
Solution Approach 1:
The patent changes the physical state of the thermally conductive filler from solid particles to liquid metal (gallium or gallium alloy) that can be dispersed in the silicone composition. This parameter change allows the liquid metal to flow and distribute uniformly throughout the composition without creating viscosity problems, thereby maintaining high thermal conductivity while preserving excellent workability and processability.
Solution Approach 2:
The patent creates a composite material system combining silicone resin with liquid metal (gallium or gallium alloy). This composite approach allows the liquid metal droplets to be uniformly dispersed throughout the silicone matrix, achieving high thermal conductivity through the thermally conductive liquid metal while the silicone resin maintains the material's flexibility and workability.
2Temperature
If low-melting-point metal is added to improve thermal conductivity, then thermal conductivity is improved, but contamination and leakage occur
Solution Approach 1:
The patent uses silicone resin as an intermediary matrix to contain the liquid metal (gallium or gallium alloy). The silicone resin acts as a binding medium that immobilizes the liquid metal droplets, preventing them from leaking out or causing contamination to surrounding areas, while still allowing the liquid metal to provide its high thermal conductivity function.
Solution Approach 2:
The patent creates localized regions of liquid metal dispersed throughout the silicone composition. The liquid metal exists as discrete droplets or particles distributed locally throughout the matrix, providing thermal conductivity at specific points while the surrounding silicone resin contains and isolates these liquid metal regions, preventing widespread contamination or leakage.
3Temperature
If gallium or gallium alloy is dispersed in addition-curable silicone to improve thermal conductivity, then thermal conductivity is improved, but cracks and voids occur during curing
Solution Approach 1:
The patent performs preliminary dispersion of the liquid metal (gallium or gallium alloy) uniformly throughout the silicone composition before the curing process begins. This preliminary uniform distribution ensures that the liquid metal droplets are evenly spaced and stabilized in the matrix, preventing them from coalescing or creating voids during the subsequent curing process, thereby maintaining the integrity of the cured product.
Solution Approach 2:
The patent controls the physical parameters of the liquid metal dispersion, including droplet size distribution and spacing, to optimize the curing process. By adjusting these parameters, the patent prevents excessive gas evolution or localized stress concentration during curing that would otherwise lead to crack formation or void creation in the final cured product.
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 high heat dissipation performance with improved workability and no interfacial thermal resistance, ensuring efficient heat transfer between electronic components and heat dissipation members without cracks or voids in the cured product.
Implementation Method 1
adding gallium and/or an alloy thereof that have a low melting point
Implementation Method 2
the hydrogens of the Si-H groups derived from the hydrogen polysiloxane will leave such that air bubbles of a hydrogen gas will occur in the system
Implementation Method 3
a thermally conductive sheet with a favorable thermal conductivity or a thermally conductive grease is often interposed or applied between such IC package and a heat dissipation fin-equipped heat dissipation member so that the heat generated from the IC package or the like can be efficiently transmitted to the heat dissipation member
Data Source
AI summary
Provided is a thermally conductive silicone composition whose cured product exhibits no cracks and voids, and has a favorable thermal conductivity. The thermally conductive silicone composition contains: (A) an organopolysiloxane having at least two silicon atom-bonded aliphatic unsaturated hydrocarbon groups per each molecule, and having a kinetic viscosity of 10 to 1,000,000 mm2/s at 25°C; (B) an organohydrogenpolysiloxane; (C) gallium and/or a gallium alloy that have a melting point of -20 to 70°C; (D) a thermally conductive filler having an average particle size of 0.1 to 100 µm; (E) a platinum group metal catalyst; (F) a palladium powder; and (G-1) an organopolysiloxane represented by the following general formula (1): wherein R1 independently represents an aliphatic unsaturated bond-free substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms; R2 independently represents an alkyl group, an alkenyl group or an acyl group.