Multilayer Metallic Plating for Connector Terminals
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Solution Overview
Problem
Conventional metallic materials for electronic components suffer from high insertion force, whisker formation, inadequate gas corrosion resistance, and insufficient durability in terms of heat resistance and solder wettability, which are not adequately addressed by existing technologies.
Innovation Solution
A metallic material structure comprising a base material with a lower layer, an intermediate layer, and an upper layer, where the lower layer is formed from Ni, Cr, Mn, Fe, Co, or Cu, the intermediate layer includes Ag, Au, Pt, Pd, Ru, Rh, Os, and Ir with Sn or In, and the upper layer is composed of Sn and In, with specific thickness and composition ratios to reduce whisker formation and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Sn or Sn alloy plating is applied to reduce contact resistance and improve solder wettability, then electrical conductivity and solderability are improved, but whisker formation occurs causing short circuiting
Solution Approach 1:
The invention uses a composite plating structure with multiple layers: a base plating layer (Ni or Cu) and an intermediate layer containing Ag and Sn in specific proportions (Ag:Sn = 2:8 to 85:15 by mass). This composite structure combines the low contact resistance and good solderability of Sn with the whisker-suppressing properties of Ag, eliminating the harmful whisker effect while maintaining electrical conductivity and solderability.
2Reliability
If conventional plating structures are used to achieve low contact resistance, then electrical conductivity is improved, but gas corrosion resistance remains insufficient
Solution Approach 1:
The invention creates a composite plating system where the intermediate layer (Ag-Sn alloy) provides gas corrosion resistance while the base plating layer maintains electrical conductivity. The specific Ag-Sn ratio and controlled thickness (0.03-0.50 μm) ensure both functions are achieved simultaneously, solving the contradiction between electrical conductivity and corrosion resistance.
3Reliability
If thicker plating layers are applied to improve durability and corrosion resistance, then protection performance is improved, but insertion force increases
Solution Approach 1:
The invention applies local quality by creating an intermediate layer with specific local composition (Ag-Sn alloy with controlled ratios) and controlled thickness (0.03-0.50 μm) only where needed for corrosion protection, rather than uniformly thickening the entire plating layer. This localized approach provides durability and corrosion resistance while keeping the overall plating thickness minimal to maintain low insertion force.
4Object-generated harmful factors
If Ag-Sn alloy layer with high Ag content is used to reduce whisker formation, then whisker suppression is improved, but gas corrosion resistance deteriorates
Solution Approach 1:
The invention changes the compositional parameters of the intermediate layer by precisely controlling the Ag-Sn ratio (2:8 to 85:15 by mass) and thickness (0.03-0.50 μm). This parameter optimization achieves the right balance: enough Ag to suppress whiskers but sufficient Sn to maintain gas corrosion resistance, resolving the contradiction between whisker suppression and corrosion resistance.
Data Source
AI summary
The present invention provides metallic materials for electronic components, having low degree of whisker formation, low adhesive wear property and high durability, and connector terminals, connectors and electronic components using such metallic materials. The metallic material for electronic components includes: a base material; a lower layer formed on the base material, the lower layer being constituted with one or two or more selected from a constituent element group A, namely, the group consisting of Ni, Cr, Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer, the intermediate layer including an alloy constituted with one or two or more selected from a constituent element group B, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, and one or two selected from a constituent element group C, namely, the group consisting of Sn and In; and an upper layer formed on the intermediate layer, the upper layer being constituted with one or two selected from a constituent element group C, namely, the group consisting of Sn and In; wherein the thickness of the lower layer is 0.05 μm or more and less than 5.00 μm; the thickness of the intermediate layer is 0.02 μm or more and less than 0.80 μm; and the thickness of the upper layer is 0.005 μm or more and less than 0.30 μm.