Diamond Particles Purification for Thermal Interface Curability
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Solution Overview
Problem
Heat-dissipating members containing diamond particles face issues with incomplete curing, leading to liquid sagging and contamination of electronic devices due to high ionic impurities on the diamond surface, which affect the polymer matrix and curability over time.
Innovation Solution
The development of diamond particles with reduced ionic conductivity, achieved through purification methods using polar solvents and organic acids, to minimize surface impurities and enhance curing properties in diamond-containing compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diamond particles with high ionic impurities are used in diamond-containing composition, then thermal conductivity is improved, but curability deteriorates and liquid sagging occurs
Solution Approach 1:
The patent applies extraction by removing ionic impurities from the diamond particle surface through acid treatment. The acid treatment process extracts harmful ionic substances (such as metal catalyst residues) from the diamond surface, reducing ionic conductivity to 1.0 mS/m or lower while preserving the diamond's thermal conductivity properties. This resolves the contradiction by eliminating the harmful ionic impurities that prevent curing.
Solution Approach 2:
The patent employs acid treatment (using strong oxidizing acids like nitric acid or a mixture of sulfuric and nitric acids) to oxidize and remove ionic impurities from the diamond surface. This accelerated oxidation process effectively eliminates harmful ionic substances that interfere with curing, while the diamond core maintains its excellent thermal conductivity.
2Temperature
If diamond particles are used to enhance thermal conductivity, then heat dissipativity is improved, but electric insulativity may be compromised due to ionic impurities
Solution Approach 1:
The acid treatment process extracts ionic impurities from the diamond surface, reducing ionic conductivity to 1.0 mS/m or lower. This maintains the diamond's high thermal conductivity for effective heat dissipation while removing the ionic contaminants that would compromise electric insulativity in the cured composition.
3Ease of manufacture
If conventional purification methods are used on diamond particles, then some impurities are removed, but ionic impurities remain and curability is still inhibited
Solution Approach 1:
The patent employs strong acid treatment (nitric acid or sulfuric-nitric acid mixture) as an accelerated oxidation process that effectively removes ionic impurities from diamond surfaces. This stronger purification method overcomes the limitations of conventional gentle purification methods, achieving ionic conductivity of 1.0 mS/m or lower and enabling complete curing of the diamond-containing composition.
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 approach results in improved curability and thermal conductivity of diamond-containing compositions, preventing liquid sagging and maintaining stability even after long-term storage, ensuring effective heat dissipation in electronic devices.
Implementation Method 1
cleaning a raw material diamond particle with a polar solvent which is water at 50°C or higher
Implementation Method 2
cleaning a raw material diamond particle with a liquid containing an organic acid having 2 to 6 carbon atoms in a molecule thereof and the polar solvent
Implementation Method 3
diamond has a higher thermal conductivity than alumina, magnesium oxide, boron nitride and the like usually used as thermally conductive fillers
Data Source
AI summary
The diamond particle according to the present invention has an ionic conductivity Di represented by the following expression of 0.8 mS/m or lower: Di=Ds−Dw wherein Ds represents an ionic conductivity of an aqueous solution obtained by dissolving-out in a pressure cooker test carried out according to IEC68-2-66; and Dw represents an ionic conductivity of distilled water.