Aluminum Thermal Paste with Rounded Fillers for UL94 V-0 Gap Fillers
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Solution Overview
Problem
Existing heat-conducting silicone compositions for gap fillers in lithium ion batteries face challenges with high density, cost, and combustibility due to the use of finely divided aluminum particles, which also pose safety risks and do not meet fire safety standards.
Innovation Solution
The development of crosslinkable heat-conducting silicone compositions using aluminum particles with a median diameter of 20-150 μm and a predominantly rounded surface shape, produced via a melting process, which reduces combustibility and enhances thermal conductivity while maintaining low density and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If very finely divided aluminum particles (below 20 μm) are used to increase thermal conductivity, then the thermal conductivity improves, but the combustibility increases and fire safety standards (UL94 V-0) are not met
Solution Approach 1:
The patent changes the particle size parameter from below 20 μm to 20-150 μm, and modifies the particle shape from irregular to predominantly rounded. This parameter change reduces the surface area to volume ratio, thereby reducing combustibility while maintaining adequate thermal conductivity and achieving UL94 V-0 fire safety classification
Solution Approach 2:
The patent specifies that aluminum particles should have a predominantly rounded surface shape. This spheroidality reduces the sharp edges and corners that facilitate combustion, thereby reducing combustibility while maintaining thermal conductivity performance
2Temperature
If very finely divided aluminum particles are used, then thermal conductivity increases, but the viscosity of the silicone composition increases significantly, making processing difficult
Solution Approach 1:
The patent changes the particle size parameter to 20-150 μm with a predominantly rounded shape. This parameter change reduces the specific surface area, thereby reducing polymer binding and viscosity increase, enabling processing by conventional methods while maintaining thermal conductivity
Solution Approach 2:
The predominantly rounded shape of aluminum particles reduces interparticle friction and improves flow characteristics, thereby reducing viscosity and improving processability compared to irregularly shaped particles of the same size
3Temperature
If very finely divided aluminum particles are used, then thermal conductivity increases, but the cost of safety precautions increases significantly
Solution Approach 1:
The patent changes the particle size to 20-150 μm with predominantly rounded shape, which inherently reduces combustibility. This parameter change eliminates the need for complex and costly safety precautions required for handling very fine aluminum particles, while maintaining adequate thermal conductivity
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, meet the UL94 V-0 fire safety standard, and offer improved processing properties, making them suitable for lithium ion battery gap fillers.
Implementation Method 1
aluminum particles as heat-conducting filler
Implementation Method 2
produced via a melting process
Data Source
AI summary
A crosslinkable, heat-conducting silicone composition along with processes for producing and uses for the same. Where the composition includes 5-50% by volume of a crosslinkable silicone composition (S) and 50-95% by volume of at least one thermally conductive filler (Z) having a thermal conductivity of at least 5 W/mK. Where the crosslinkable heat-conducting silicone composition has a thermal conductivity of at least 0.6 W/mK and at least 20% by volume of metallic aluminum particles present as thermally conductive fillers (Z).