Silver-Tin-Silver Coated Resin Particles for Heat-Cycle Adhesion
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Solution Overview
Problem
Silver coated resin particles used in conductive films face issues with adhesion of the silver coating layer to the resin particles, especially under severe heat cycles, leading to potential peeling off due to thermal stress and reduced electrical conductivity.
Innovation Solution
The development of metal coated resin particles with a specific layered structure, comprising a first silver layer, a tin intermediate layer, and a second silver layer, which enhances adhesion and mitigates thermal stress by halving the thickness of the silver layer and introducing a tin intermediate layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick silver coating layer is used on resin particles, then electrical conductivity is improved, but adhesion deteriorates under thermal stress due to difference in thermal expansion rate
Solution Approach 1:
The silver coating layer is divided into multiple thin layers (first silver layer, tin intermediate layer, second silver layer) instead of a single thick layer. This segmentation reduces the overall thickness of the silver coating while maintaining electrical conductivity, and the intermediate tin layer further mitigates thermal stress by accommodating differential thermal expansion between the resin core and silver coating.
Solution Approach 2:
A tin intermediate layer is introduced between the resin core particles and the silver coating layers. This intermediate layer acts as a buffer that reduces the difference in thermal expansion rate between the resin and silver, thereby preventing peeling of the silver coating under thermal stress while maintaining electrical conductivity through the conductive tin layer.
2Strength
If silver coating layer is made thinner to improve adhesion, then thermal stress mitigation is improved, but electrical conductivity deteriorates
Solution Approach 1:
The coating structure uses a composite material system consisting of silver layers for electrical conductivity and a tin intermediate layer for mechanical adhesion and thermal stress management. This composite structure allows each material to perform its optimal function: silver provides conductivity, while tin provides adhesion and thermal expansion buffering, achieving both good adhesion and electrical conductivity simultaneously.
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
This configuration results in improved adhesion of the metal coated layer to the core resin particles, maintaining high electrical and thermal conductivity even under severe heat cycles, thus enhancing the performance of conductive films.
Implementation Method 1
a step of subjecting spherical resin particles to pretreatment with an aqueous solution of a tin compound; and a step of subjecting the spherical resin particles to electroless silver plating
Implementation Method 2
a step of subjecting the spherical resin particles to electroless silver plating using a reducing agent
Data Source
Figure 1~2(b)
Figure 3~4
AI summary
Metal coated resin particles (10) include: spherical core resin particles (11); and a metal coated layer (12) provided on a surface of each of the core resin particles (11), in which the metal coated layer (12) consists of: a first silver layer (12a) formed on the surface of each of the core resin particles (11); a tin intermediate layer (12b) consisting of one or more of metallic tin and/or tin compounds selected from the group consisting of tin (Sn), tin oxide (SnxOy), and tin hydroxide (Snx(OH)y) formed on a surface of the first silver layer (11a) (where, 0.1 < x < 4, 0.1 < y < 5); and a second silver layer (12c) formed on a surface of the tin intermediate layer (12b).