Thermally Conductive Epoxy Composition That Prevents Filler Settling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermally conductive filler settles down during storage and causes quality degradation in thermally conductive compositions containing epoxy compounds, leading to poor handling properties.
Innovation Solution
A thermally conductive composition with a viscosity ratio (η1/η3) of 60 or more, comprising a curable compound, a thermally conductive filler, and a structural viscosity imparting agent, which forms a loose bond due to cohesive force, suppressing settling and enhancing handling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a low viscosity epoxy compound is used to improve workability and handling properties, then the composition becomes easier to dispense and apply, but the thermally conductive filler settles down during storage and the epoxy compound undergoes liquid-phase separation
Solution Approach 1:
The patent applies parameter changes by controlling the viscosity ratio (η1/η3) to be 60 or more, where η1 is the viscosity at shear rate 0.0001 (1/s) and η3 is the viscosity at shear rate 0.0251 (1/s). This parameter control allows the composition to maintain high viscosity at low shear rates (preventing filler settling) while achieving acceptable viscosity at higher shear rates (ensuring workability). The structural viscosity imparting agent is used to achieve this specific viscosity ratio characteristic.
Solution Approach 2:
The patent uses composite materials by combining the epoxy compound, thermally conductive filler, and structural viscosity imparting agent into a unified composition. The structural viscosity imparting agent creates a composite structure that provides both storage stability (preventing filler settling) and workability (allowing easy dispensing). This composite approach integrates multiple functions into a single material system.
2Stability of the object's composition
If the viscosity is increased to prevent filler settling during storage, then storage stability is improved, but the composition becomes difficult to dispense and apply
Solution Approach 1:
The patent applies dynamics by creating a non-Newtonian fluid behavior through the structural viscosity imparting agent. The viscosity of the composition dynamically changes based on the applied shear rate: at low shear rates (storage conditions), the viscosity is high to prevent filler settling; at higher shear rates (during dispensing and application), the viscosity decreases to allow easy flow and application. This dynamic viscosity adjustment resolves the contradiction between storage stability and workability.
Solution Approach 2:
The patent controls the viscosity ratio parameter (η1/η3 ≥ 60) to achieve the desired balance. By setting this specific parameter range, the composition maintains high viscosity at low shear rates for storage stability while ensuring adequate flow characteristics at higher shear rates for workability. This parameter optimization simultaneously addresses both requirements.
3Stability of the object's composition
If a high viscosity composition is used to maintain stability, then filler settling is suppressed, but the composition causes stress when pressed against battery cells
Solution Approach 1:
The patent uses dynamic viscosity adjustment to resolve this contradiction. During installation when the composition is pressed against battery cells, the applied shear stress causes the viscosity to decrease, allowing the material to flow and conform to the gap geometry without generating excessive stress. During storage when no shear is applied, the viscosity remains high to suppress filler settling. This dynamic behavior eliminates the need to choose between high viscosity for stability and low viscosity for stress reduction.
Solution Approach 2:
The patent optimizes the viscosity ratio parameter (η1/η3) to achieve the triple benefit of filler settling suppression, reduced compressive stress, and improved workability. The specific parameter range ensures that the composition has sufficiently high viscosity at low shear rates to prevent settling and reduce compressive stress during installation, while maintaining acceptable viscosity at higher shear rates for ease of dispensing and application.
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 settling during storage and improves handling properties by maintaining high viscosity at low shear rates while reducing viscosity at higher shear rates for improved workability.
Implementation Method 1
a structural viscosity imparting agent, which forms a loose bond due to cohesive force, suppressing settling
Implementation Method 2
Cured products formed by filling a thermally conductive composition including a thermally conductive filler between a heating element and a heat dissipating element are used as a thermally conductive member that transfers the heat generated by the heating element to the heat dissipating element
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The thermally conductive composition of the present invention includes at least one curable compound selected from the group consisting of an epoxy compound or an epoxy curing agent, 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 0.0001 (1/s) and a viscosity η3 measured by a rheometer under conditions of a measurement temperature of 25°C and a shear rate of 0.0251 (1/s) of 60 or more. The present invention can provide a thermally conductive composition in which settling down of the thermally conductive filler is suppressed in storage and which has excellent handling properties in use.