Terminal Plating Structure for High-Temperature Durability
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Solution Overview
Problem
Noble metal or monometal plating films, such as silver or tin, used in electronic equipment terminals lack durability under high temperature environments.
Innovation Solution
A terminal with a plating layer structure that includes an intermetallic compound crystal of Sn, Cu, and Cr dispersed in a Sn-Cu alloy parent phase, forming an endotaxial joint, which enhances durability by improving mechanical strength and reducing brittleness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If noble metal or monometal plating film is used for terminal, then electric conductivity is improved, but durability under high temperature environment deteriorates
Solution Approach 1:
The invention uses a composite plating layer structure consisting of an intermetallic compound layer (containing Sn, Cu, and Cr) and a Sn-Cu alloy layer. This composite structure combines the benefits of different materials: the intermetallic compound layer provides high temperature stability and oxidation resistance, while the Sn-Cu alloy layer maintains good electric conductivity and mechanical properties, thereby resolving the contradiction between durability and strength.
Solution Approach 2:
The invention optimizes the chemical composition parameters of the plating layer by controlling the content of Sn, Cu, and Cr elements within specific ranges. By adjusting these compositional parameters, the plating layer achieves both high temperature durability and adequate mechanical strength, resolving the contradiction through precise parameter control.
2Reliability
If intermetallic compound is dispersed in plating layer, then durability is improved, but brittleness increases
Solution Approach 1:
The invention creates a plating layer with non-uniform local composition and structure. The intermetallic compound phase is dispersed as discrete particles or regions within the Sn-Cu alloy matrix, creating local variations in properties. This local quality approach allows the intermetallic compounds to provide durability at specific locations while the surrounding alloy matrix maintains ductility and reduces overall brittleness.
Solution Approach 2:
The plating layer is designed as a composite material system where intermetallic compound phases are embedded in a Sn-Cu alloy matrix. This composite structure allows the intermetallic compounds to enhance durability locally while the ductile alloy matrix prevents catastrophic failure, thereby improving durability without excessive brittleness.
Data Source
AI summary
According to this invention, provided is a terminal having a plating layer formed on a surface of a base, the plating layer having a structure in which an intermetallic compound crystal that contains Sn, Cu, Cr and Ni, is dispersed in a parent phase that contains Sn and an Sn—Cu alloy.