Silicone Thermal Pastes With Rounded Silicon Fillers for Heat Transfer
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Solution Overview
Problem
Existing thermally conductive silicone compositions face issues such as high weight, cost, flammability, electrical conductivity, and processing difficulties due to the use of ceramic or metallic fillers, and limited thermal conductivity with silicon particles, which are also hazardous and flammable.
Innovation Solution
Non-crosslinkable silicone compositions containing large, predominantly round silicon particles with a specific size distribution and aspect ratio, combined with other thermally conductive fillers, providing improved thermal conductivity and reduced flammability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic fillers such as aluminum oxide are used to increase thermal conductivity, then thermal conductivity is improved, but weight and cost significantly increase
Solution Approach 1:
The patent changes the particle size parameter of silicon fillers to 30-200 μm, which fundamentally alters the relationship between thermal conductivity and weight. This parameter change enables achieving acceptable thermal conductivity (≥0.6 W/mK) without the weight penalty of ceramic fillers, as larger silicon particles provide sufficient thermal pathways while maintaining low density
Solution Approach 2:
The patent replaces expensive ceramic fillers (aluminum oxide, boron nitride, aluminum nitride) with inexpensive silicon particles. Silicon is a abundant, low-cost material that can achieve the required thermal conductivity when used in the specific particle size range of 30-200 μm, eliminating the need for costly ceramic alternatives
2Weight of moving object
If ground silicon particles are used to reduce cost and weight, then cost and weight are reduced, but viscosity increases and processability deteriorates
Solution Approach 1:
The patent changes the particle size parameter from fine ground particles to coarse particles (30-200 μm), which fundamentally improves processability. The larger particle size reduces the total surface area, decreasing polymer binding and maintaining low viscosity even at high filler contents (5-50 vol%), enabling conventional dispensing and processing methods
Solution Approach 2:
The patent applies a size distribution strategy where the filler consists predominantly of particles in the 30-200 μm range. This local quality control ensures that the majority of particles contribute to thermal conductivity while minimizing the surface area that would otherwise increase viscosity and reduce processability
3Temperature
If small silicon particles smaller than 30 μm are used, then thermal conductivity is improved, but flammability increases and safety hazards arise
Solution Approach 1:
The patent changes the particle size parameter to 30-200 μm, which fundamentally reduces flammability. The larger particle size decreases the surface area to volume ratio, raising the minimum ignition energy and reducing dust explosion hazards. This parameter change maintains thermal conductivity while eliminating safety hazards associated with fine particles
Solution Approach 2:
The patent converts the potential harm of fine silicon particles (high flammability, dust explosion risk) into a benefit by using larger particles (30-200 μm). The larger particle size inherently reduces surface area and ignition risk, transforming a hazardous material into a safe one while still achieving the required thermal conductivity of ≥0.6 W/mK
4Temperature
If high filler content is used to increase thermal conductivity, then thermal conductivity is improved, but viscosity increases and composition becomes stiff
Solution Approach 1:
The patent changes the particle size parameter to 30-200 μm, which enables high filler content (5-50 vol%) without excessive viscosity increase. The larger particles have reduced surface area, minimizing polymer binding and maintaining processability even at high filler loadings, thus achieving high thermal conductivity without the composition becoming unprocessable
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 compositions achieve a thermal conductivity of at least 0.6 W/mK with reduced flammability, low density, and improved processability, suitable for applications in electronics and automotive industries.
Implementation Method 1
thermally conductive silicone compositions containing large Si particles with an average particle size of 30 to 200 μm, a predominantly round shape... The disclosed vulcanizates are not elastic and therefore unsuitable for use as gap fillers in lithium-ion batteries
Implementation Method 2
The mounting surfaces of heat sinks and components always contain varying degrees of unevenness and deviations from planarity. Thermal pastes fill these unevenness, thus enabling better heat transfer to the cooling housing or heat sink
Data Source
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AI summary
The present invention relates to a non-crosslinkable, thermally conductive silicone composition (Y) comprising - 5-50 vol.% of at least one non-crosslinkable silicone composition (S) and - 50-95 vol. % of at least one thermally conductive filler (Z) having a thermal conductivity of at least 5 W/mK, with the proviso that the non-crosslinkable, thermally conductive silicone composition (Y) has a thermal conductivity of at least 0.6 W/mK, and that at least 20 vol.% of metallic silicon particles are included as thermally conductive fillers (Z) which satisfy the following features: a) their mean diameter x50 is in the range of 30-200 µm; b) they are predominantly rounded, and characterized in that the width/length ratio (aspect ratio b/l) is at least 0.76; c) their distribution width SPAN ((x90-x10)/x50) is at least 0.28.