Thermally Conductive Adhesive Composition for Thermal Stress Alleviation
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Solution Overview
Problem
Conventional highly thermally conductive adhesive compositions face issues with peeling and cracking during cooling/heating cycles due to increased elastic modulus and thermal stress when used with metals like copper and aluminum, which have different coefficients of thermal expansion.
Innovation Solution
A thermally conductive adhesive composition is developed using an organic-solvent-soluble polyimide, epoxy resin, and thermally conductive filler, with specific diamine residues to control filler dispersibility, reduce elastic modulus, and match the coefficient of thermal expansion of copper or aluminum, enhancing bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If inorganic filler is contained in large quantities to increase thermal conductivity, then thermal conductivity is improved, but elastic modulus increases causing peeling or cracks during cooling/heating cycle
Solution Approach 1:
The patent changes the chemical composition parameters of the resin system by incorporating specific diamine residues (polyoxyethylenediamine, polyoxypropylenediamine, polyoxybutylenediamine) into the polyimide structure. This modifies the resin's physical properties to achieve lower elastic modulus while maintaining thermal stability, allowing the adhesive to withstand thermal stress without cracking or peeling during cooling/heating cycles.
Solution Approach 2:
The patent creates a composite adhesive system combining polyimide resin with specific diamine residues and inorganic fillers. The composite structure allows the resin matrix to provide flexibility and stress absorption while the inorganic fillers provide thermal conductivity, resolving the contradiction between thermal performance and mechanical flexibility.
2Temperature
If inorganic filler is contained in large quantities to increase thermal conductivity, then thermal conductivity is improved, but bonding reliability deteriorates due to thermal stress from coefficient of thermal expansion mismatch
Solution Approach 1:
The patent modifies the resin's coefficient of thermal expansion by incorporating specific diamine residues with flexible molecular structures (polyoxyethylene, polyoxypropylene, polyoxybutylene chains). These structural modifications allow the cured adhesive to have a coefficient of thermal expansion closer to that of copper and aluminum, reducing thermal stress and improving bonding reliability during thermal cycling.
3Strength
If epoxy resin content is increased to improve adhesive strength, then adhesive strength is improved, but manufacturing precision deteriorates due to difficulty in controlling filler dispersibility
Solution Approach 1:
The patent changes the resin system composition by incorporating specific diamine residues that modify the resin's viscosity and surface properties. This improves the wettability and dispersibility of inorganic fillers within the adhesive matrix, allowing for more uniform filler distribution and reducing manufacturing variability while maintaining high adhesive strength.
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 adhesive composition achieves high thermal conductivity while maintaining low elastic modulus and coefficient of thermal expansion, ensuring excellent bonding reliability and stress alleviation during thermal cycles.
Implementation Method 1
a highly thermally conductive adhesive composition... adding inorganic fillers having high thermal conductivity to increase the thermal conductivity of the composition
Implementation Method 2
controlling the dispersibility of a thermally conductive filler... the organic-solvent-soluble polyimide contains specific diamine residues to control filler dispersibility
Implementation Method 3
since copper and aluminum respectively having different coefficients of thermal expansion are bonded to each other... thermal stress exerted on the highly thermally conductive adhesive during the cooling/heating cycle
Data Source
AI summary
The purpose of the present invention is to provide an adhesive composition having high heat conductivity and excellent adhesion, in which the dispersibility of a heat-conductive filler is controlled, and in which thermal stress during cooling/heating cycle testing can be alleviated. An adhesive composition containing a soluble polyimide (A), an epoxy resin (B), and a heat-conductive filler (C), the adhesive composition characterized by containing three types of diamine residues having a specific structure, and in that the content of the epoxy resin (B) is 30-100 parts by weight with respect to 100 parts by weight of the soluble polyimide (A).