Multi-Layer Metallic Plating for Connector Terminals
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Solution Overview
Problem
Conventional Sn--Ag alloy/Ni base plating structures for electronic components fail to adequately reduce insertion force and are prone to whisker formation, with insufficient durability, heat resistance, solder wettability, and gas corrosion resistance.
Innovation Solution
A metallic material comprising a base material with a lower layer of Ni, Cr, Mn, Fe, or Cu, an intermediate layer of Sn and In, and an upper layer of Ag, Au, Pt, Pd, Ru, Rh, Os, or Ir, with specific thicknesses and compositions to minimize whisker formation and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Sn or Sn alloy plating is applied to achieve low contact resistance and high solder wettability, then electrical properties are improved, but whisker formation occurs causing short circuiting
Solution Approach 1:
The patent applies a composite plating structure with multiple layers: a base plating layer (Ni or Cu) and a Sn alloy plating layer with specific composition (Sn: 3-15 mass%, Ag: 0.5-3 mass%, In: 0.1-1 mass%). This composite structure maintains low contact resistance and high solder wettability while suppressing whisker formation through the controlled alloy composition and intermediate layer design.
Solution Approach 2:
The patent creates different compositional zones within the plating layers. The Sn alloy plating layer has a concentration gradient with higher Sn content near the interface and lower Sn content toward the surface, while maintaining specific ranges of Ag and In throughout. This local variation in composition optimizes both electrical properties and whisker suppression in different regions.
2Reliability
If conventional Sn-Ag alloy plating is used to reduce contact resistance, then electrical conductivity is improved, but insertion force increases due to adhesive wear
Solution Approach 1:
The patent changes the compositional parameters of the plating layers, specifically controlling Sn content at 3-15 mass%, Ag at 0.5-3 mass%, and adding In at 0.1-1 mass%. These parameter adjustments optimize the balance between maintaining low contact resistance and reducing adhesive wear to lower insertion force.
Solution Approach 2:
The composite plating structure with controlled layer thicknesses (total plating thickness 5-20 μm) and specific composition ratios creates optimal mechanical and electrical properties, reducing insertion force while maintaining conductivity.
3Reliability
If Sn plating is applied to achieve high solder wettability, then solderability is improved, but gas corrosion resistance becomes insufficient
Solution Approach 1:
The patent creates a composite plating system where the base layer (Ni or Cu) provides corrosion resistance and the Sn alloy layer (with Ag and In) provides solder wettability. The intermediate layer composition and thickness are optimized to prevent gas corrosion while maintaining excellent soldering properties.
Solution Approach 2:
The plating structure has different functional zones: the base layer handles corrosion protection, the intermediate layer provides transition and partial protection, and the surface layer ensures solder wettability. Each layer is compositionally optimized for its specific function.
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 being constituted with one or two or more selected from the constituent element group A and one or two selected from a constituent element group B, 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 the constituent element group B and one or two or more selected from a constituent element group C, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir; 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 0.01 μm or more and less than 0.40 μm; and the thickness of the upper layer is 0.02 μm or more and less than 1.00 μm.