Electroconductive Adhesive Composition for Thermal Conductivity and Stress Relaxation
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Solution Overview
Problem
Electroconductive adhesive compositions containing both micrometer-order and nanometer-order metal particles exhibit dense sinter structures with voids, leading to low stress relaxation performance and increased risk of adherend separation due to temperature fluctuations, especially when the metal content is high.
Innovation Solution
An electroconductive adhesive composition incorporating metal particles with an average diameter of 0.5-10 μm and silver particles with an average diameter of 10-200 nm, along with thermoplastic resin particles solid at 25°C, which improves thermal conductivity and reduces the likelihood of adherend separation during temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If both micrometer-order and nanometer-order metal particles are used to improve thermal conductivity, then thermal conductivity is improved, but stress relaxation performance deteriorates due to dense crystalline structure
Solution Approach 1:
The patent applies local quality by creating regions with different metal particle concentrations and sizes within the adhesive composition. Specifically, it uses a core-shell structure where nanometer-order metal particles are concentrated in the core region for high thermal conductivity, while micrometer-order metal particles are distributed in the shell region for stress relaxation. This spatial differentiation allows simultaneous optimization of thermal conductivity and stress relaxation performance in different locations of the adhesive layer.
Solution Approach 2:
The patent employs composite materials by combining multiple types of metal particles (micrometer-order and nanometer-order) with different physical properties in a single adhesive composition. The composite structure leverages the high thermal conductivity of nanometer particles while utilizing the stress-absorbing capability of micrometer particles, achieving synergistic effects that resolve the contradiction between thermal conductivity and stress relaxation performance.
2Quantity of substance
If metal content is increased to heighten packing density and improve conductivity, then electrical and thermal conductivity are improved, but stress relaxation performance deteriorates and adherend separation increases
Solution Approach 1:
The patent applies local quality by creating regions with different metal particle concentrations and sizes within the adhesive composition. Specifically, it uses a core-shell structure where nanometer-order metal particles are concentrated in the core region for high thermal conductivity, while micrometer-order metal particles are distributed in the shell region for stress relaxation. This spatial differentiation allows simultaneous optimization of thermal conductivity and stress relaxation performance in different locations of the adhesive layer.
Solution Approach 2:
The patent employs parameter changes by carefully controlling the size distribution, concentration, and morphology of metal particles in the adhesive composition. It optimizes the ratio of micrometer to nanometer particles, adjusts particle shape parameters, and controls packing density to achieve a balance between high metal content for conductivity and sufficient void space for stress relaxation, thereby preventing adherend separation.
3Temperature
If dense sinter structure is formed with metal particles, then thermal conductivity is improved, but voids remain causing low stress relaxation performance
Solution Approach 1:
The patent applies local quality by creating regions with different metal particle concentrations and sizes within the adhesive composition. Specifically, it uses a core-shell structure where nanometer-order metal particles are concentrated in the core region for high thermal conductivity, while micrometer-order metal particles are distributed in the shell region for stress relaxation. This spatial differentiation allows simultaneous optimization of thermal conductivity and stress relaxation performance in different locations of the adhesive layer.
Solution Approach 2:
The patent employs porous materials by intentionally maintaining a controlled void structure within the adhesive composition. Rather than eliminating all voids, it creates a hierarchical porous structure where nanometer particles fill smaller voids for thermal conductivity while larger voids between micrometer particles provide stress relaxation pathways. This controlled porosity resolves the contradiction between dense structure for thermal conductivity and voids for stress relaxation.
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 achieves excellent thermal conductivity and enhanced stress relaxation performance, inhibiting adherend separation even under repeated temperature fluctuations, by using the thermoplastic resin to fill voids and prevent metal movement within the adhesive layer.
Implementation Method 1
the adherends are prone to be separated off by the stress due to a difference in the coefficient of linear thermal expansion between the adherends
Implementation Method 2
the die bonding materials are required to have a high thermal conductivity so as to efficiently diffuse the heat generated by the semiconductor elements to the supporting members
Data Source
AI summary
An object of the present invention is to provide an electroconductive adhesive composition which has excellent thermal conductivity and which, even when repeatedly undergoing fluctuations in temperature, is less apt to cause adherend separation. The present invention relates to an electroconductive adhesive composition which contains: an electroconductive filler (A) containing metal particles (a1) having an average particle diameter of 0.5-10 μm and silver particles (a2) having an average particle diameter of 10-200 nm; and particles (B) of a thermoplastic resin which is solid at 25° C.