Multilayer Metal Plating for Electronic Components Whisker Suppression
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Solution Overview
Problem
Conventional metal materials for electronic components face issues with high contact resistance, unsatisfactory insertability/extractability, whisker formation, and durability, particularly in terms of heat resistance and gas corrosion resistance.
Innovation Solution
A metal material with a specific layered structure comprising a surface layer with 50% or more Sn and In, a middle layer with 50% or more Ag, Au, Pt, Pd, Ru, Rh, Os, and an underlayer with Ni, Cr, Mn, Fe, Co, Cu, which are formed using wet plating techniques to achieve low insertability/extractability, low whisker formability, and high durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Sn or Sn alloy plating is carried out on a Ni or Cu base undercoat plating to achieve low contact resistance and high solder wettability, then the electrical properties are improved, but tin whiskers are generated causing short-circuit problems
Solution Approach 1:
The plating structure is divided into multiple functional layers: a barrier layer (Ni, Pd, or Pt) that prevents Sn diffusion and whisker formation, and a surface layer (Sn or Sn alloy) that provides solder wettability. This segmentation isolates the Sn layer from direct contact with the base material, eliminating the diffusion path that causes whiskers while maintaining electrical functionality.
Solution Approach 2:
An intermediate barrier layer composed of Ni, Pd, or Pt is introduced between the Sn surface layer and the Cu or Cu alloy base material. This intermediary layer acts as a diffusion barrier that prevents Sn atoms from migrating into the base material, thereby suppressing whisker formation while allowing the Sn layer to maintain its low contact resistance and solder wettability properties.
2Ease of manufacture
If the plating structure is simplified to reduce manufacturing complexity, then the manufacturing process is easier, but the suppression of tin whiskers and maintenance of durability are compromised
Solution Approach 1:
Different regions of the plating structure are assigned different compositions and functions: the barrier layer is optimized for diffusion prevention (using Ni, Pd, or Pt), while the surface layer is optimized for solder wettability (using Sn or Sn alloy). This local quality differentiation allows each layer to perform its specific function efficiently, achieving both whisker suppression and durability without excessive complexity.
Solution Approach 2:
The invention uses a composite plating structure combining different metal layers with complementary properties. The barrier layer (Ni, Pd, or Pt) provides diffusion resistance, while the Sn or Sn alloy surface layer provides solderability. This composite structure achieves superior performance in both whisker suppression and durability compared to single-layer platings, while remaining manufacturable through conventional electroplating processes.
3Object-generated harmful factors
If a multilayer plating structure with barrier layer and Sn layer is formed to suppress whiskers, then whisker formation is reduced, but the insertability/extractability becomes unsatisfactory
Solution Approach 1:
The invention optimizes critical parameters including the thickness of the barrier layer (0.01-1.0 μm) and Sn layer (0.05-5.0 μm), the composition of the Sn alloy (containing 3-15 mass% In), and the surface roughness (Ra ≤ 0.5 μm). These parameter adjustments ensure that the multilayer structure suppresses whiskers while maintaining satisfactory insertability and extractability by balancing mechanical compliance and electrical contact.
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
The solution provides a metal material with improved insertability/extractability, reduced whisker formation, and enhanced durability, including heat resistance and gas corrosion resistance, through precise control of layer composition and thickness.
Implementation Method 1
formed using wet plating techniques
Data Source
Figure 1~2
Figure 3
AI summary
There are provided a metal material for electronic component which has low insertability/extractability, low whisker formability, and high durability, and a method for manufacturing the metal material. The metal material 10 for electronic components has a base material 11, an A layer 14 constituting a surface layer on the base material 11 and formed of Sn, In or an alloy thereof, and a B layer 13 constituting a middle layer provided between the base material 11 and the A layer 14 and formed of Ag, Au, Pt, Pd, Ru, Rh, Os, Ir or an alloy thereof, wherein the surface layer (A layer) 14 has a thickness of 0.002 to 0.2 µm, and the middle layer (B layer) 13 has a thickness of 0.001 to 0.3 µm.