Thermally Conductive Composition With Shear-Dependent Sedimentation Control
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Solution Overview
Problem
Existing thermally conductive compositions face challenges in suppressing sedimentation of fillers while maintaining excellent handling properties, as increasing filler content to improve heat dissipation worsens viscosity and handling, and reducing viscosity leads to filler sedimentation.
Innovation Solution
A thermally conductive composition comprising a liquid polymer, a thermally conductive filler, and a structural viscosity imparting agent, with a viscosity ratio (η1/η3) of more than 10, formed by mixing and adjusting viscosities at specific shear rates to create a loose bond that suppresses filler sedimentation and enhances handling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the content of thermally conductive filler is increased to improve heat dissipation, then thermal conductivity is improved, but viscosity increases and handling properties deteriorate
Solution Approach 1:
The patent changes the rheological parameters of the composition by introducing a viscosity ratio specification (η1/η3 > 10) measured at different shear rates. This parameter change allows the composition to have high viscosity at low shear rates (preventing sedimentation) while maintaining lower viscosity at high shear rates (improving handling), thereby resolving the contradiction between filler content and handling properties
Solution Approach 2:
The patent creates a composite system combining thermally conductive filler with a specifically formulated viscosity-modified matrix. The composite achieves both high thermal conductivity (through filler content) and excellent handling properties (through the viscosity ratio control mechanism), resolving the trade-off between these two properties
2Ease of operation
If the viscosity of thermally conductive composition is reduced to improve handling properties, then dispensing and coating operations are improved, but sedimentation of thermally conductive filler occurs during long term storage
Solution Approach 1:
The patent introduces a dual-viscosity parameter system (η1 at low shear rate and η3 at high shear rate) with a specified ratio > 10. This parameter change enables the composition to exhibit high viscosity under storage conditions (low shear) to prevent sedimentation, while showing reduced viscosity during application (high shear) for improved handling
Solution Approach 2:
The patent makes the viscosity dynamic rather than static by specifying different viscosity values at different shear rates. The composition dynamically adjusts its viscosity based on the applied shear rate: maintaining high viscosity during storage (γ = 0.00252 1/s) to prevent sedimentation, and reducing viscosity during application (γ = 0.05432 1/s) to improve handling properties
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 effectively prevents filler sedimentation during storage and improves handling properties by maintaining high viscosity at low shear rates and reducing viscosity at higher shear rates for improved dispensing and coating, thus enhancing thermal conductivity.
Implementation Method 1
the thermally conductive composition having a viscosity ratio (η1/η3) between a viscosity η1 measured by a rheometer under conditions of a measurement temperature of 25° C. and a shear rate of 0.00252 (1/s) and a viscosity η3 measured by a rheometer under conditions of a measurement temperature of 25° C. and a shear rate of 0.05432 (1/s) of more than 10
Implementation Method 2
a thermally conductive composition comprising a liquid polymer, a thermally conductive filler and a structural viscosity imparting agent
Data Source
AI summary
The thermally conductive composition of the present invention includes a liquid polymer, a thermally conductive filler and a structural viscosity imparting agent, wherein the thermally conductive composition has a viscosity ratio (η1/η3) between a viscosity η1 measured by a rheometer under conditions of a measurement temperature of 25° C. and a shear rate of 0.00252 (1/s) and a viscosity η3 measured by a rheometer under conditions of a measurement temperature of 25° C. and a shear rate of 0.05432 (1/s) of more than 10. The present invention can provide a thermally conductive composition in which sedimentation of the thermally conductive filler is suppressed in storage and which has excellent handling properties in use.