Tin-plated Copper Terminal Oxidation Resistance
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Solution Overview
Problem
Existing connector terminals face issues with increased contact resistance when used in high-temperature environments, such as engine bays, due to oxidation of the copper-tin alloy, which affects their reliability and performance over time.
Innovation Solution
A tin-plated copper terminal material is developed with a laminated structure of a nickel-or-nickel-alloy layer, a copper-tin alloy layer, and a tin layer, where the copper-tin alloy layer contains Cu6Sn5 with nickel substitution, and tin solidification parts are formed to appear as islands on the surface, preventing oxidation and maintaining low dynamic friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If copper-tin alloy is exposed on the surface to reduce friction coefficient and insertion force, then insertion/extraction characteristic is improved, but contact resistance increases due to oxidation in high temperature
Solution Approach 1:
The invention applies local quality by creating distinct regions on the terminal surface: tin solidification parts (islands) in specific areas and exposed copper-tin alloy layer in other areas. The tin islands serve as oxidation-resistant anchors maintaining electrical contact, while the exposed alloy regions provide low friction for insertion. This spatial differentiation of surface properties resolves the contradiction between insertion ease and oxidation resistance.
Solution Approach 2:
The tin solidification parts act as intermediary elements between the copper-tin alloy layer and the external environment. These tin islands prevent direct oxidation of the copper-tin alloy while allowing controlled exposure of the alloy layer for friction reduction. The tin mediator thus enables both low friction and oxidation resistance simultaneously.
2Reliability
If tin layer thickness is increased to prevent oxidation, then reliability in high temperature is improved, but insertion force increases due to higher friction coefficient
Solution Approach 1:
Rather than uniformly increasing tin layer thickness, the invention locally concentrates tin in solidification islands while maintaining thinner or exposed regions elsewhere. This localized tin distribution provides oxidation protection only where needed (at contact points) while keeping friction surfaces exposed for low insertion force.
Solution Approach 2:
The invention applies partial action by providing tin protection only in the form of discrete islands rather than complete coverage. This partial tin presence is sufficient to prevent oxidation of the copper-tin alloy while allowing the exposed alloy regions to maintain low friction characteristics.
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 reduces contact resistance and maintains good electric connection and insertion/extraction characteristics while enhancing high-temperature reliability by preventing oxidation of the copper-tin alloy.
Implementation Method 1
tin solidification parts upheaved from the surface of the tin layer exist like islands
Implementation Method 2
copper-tin alloy exposed at the surface is oxidized when left in high temperature for a long time
Data Source
AI summary
A tin-plated copper terminal material in which on a substrate made of copper or copper alloy, a nickel-or-nickel-alloy layer, a copper-tin alloy layer, and a tin layer are laminated in this order; in this material, the tin layer has an average thickness 0.2 μm to 1.2 μm inclusive; the copper-tin alloy layer is a compound alloy layer in which Cu6Sn5 is a main ingredient and part of copper in the Cu6Sn5 is substituted with nickel, and an average crystal grain size is 0.2 μm to 1.5 μm inclusive; part of the copper-tin alloy layer appears on a surface of the tin layer and tin solidification parts exist like islands; and the tin solidification parts have an average diameter 10 μm to 1000 μm inclusive in a direction along the surface of the tin layer and an area ratio to the surface of the tin layer 1% to 90% inclusive.