Precious Metal Plating Structure for Uniform Luster on Metal Members

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Solution Overview

Problem

Existing metal members with precious metal plating layers face issues with luster unevenness, which can lead to false recognition in automatic visual inspections, particularly in electronic component mounting surfaces.

Innovation Solution

A metal member configuration that includes a metal substrate with a surface of multiple crystal grains, a non-oriented first intermediate plating layer containing nickel, a second intermediate plating layer also containing nickel, and a precious metal plating layer, all of which are formed without polishing the substrate surface, thereby reducing luster unevenness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a precious metal plating layer is formed directly on a metal substrate with multiple crystal grains, then the plating process is simplified, but luster unevenness occurs due to growth unevenness reflecting the underlying crystal grain orientations

Engineering Contradiction:

Improveplating process complexityVSAvoidluster uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

A first intermediate plating layer is introduced between the metal substrate and the precious metal plating layer. This intermediate layer acts as a mediator that decouples the crystal grain orientation of the substrate from the precious metal plating, preventing the transmission of orientation-dependent growth patterns that cause luster unevenness.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The plating structure is segmented into multiple distinct layers: a first intermediate plating layer and a second intermediate plating layer, each with specific compositional characteristics. This segmentation allows each layer to perform its specific function in controlling the final surface properties independently.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If surface polishing is performed on the metal substrate before plating, then luster unevenness is reduced, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:

Improveluster uniformityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The first intermediate plating layer serves as an intermediary that compensates for surface irregularities of the metal substrate without requiring mechanical polishing. This layer masks the underlying crystal grain structure and provides a uniform base for subsequent plating operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanical polishing process is replaced by a chemical/electrochemical plating process. Instead of mechanically removing material to achieve surface uniformity, the patent uses controlled deposition of intermediate plating layers to create a uniform surface structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a thick precious metal plating layer is applied to ensure complete coverage, then coverage is improved, but cost increases and luster unevenness is exacerbated

Engineering Contradiction:

Improvecoverage completenessVSAvoidluster uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The plating system is divided into multiple functional layers with the first intermediate plating layer providing the foundation for uniform coverage and the second intermediate plating layer providing the final uniform surface, eliminating the need for excessive precious metal thickness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compositional parameters of the intermediate plating layers are specifically controlled to achieve optimal coverage and uniformity. By adjusting the composition and thickness of the intermediate layers, the system achieves complete coverage with minimal precious metal while maintaining uniform luster.

Inventive Principle:

Principle #35Parameter changes

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 prevents growth unevenness of the precious metal plating layer, reducing luster unevenness and minimizing false recognition in visual inspections, while also simplifying the manufacturing process by eliminating the need for surface polishing.

Implementation Method 1

A first intermediate plating layer is directly formed on the plurality of crystal grains of the metal substrate

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 2

A second intermediate plating layer is directly formed on the first intermediate plating layer

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS12209313B2Metal member and production method therefor

Publication Date: 2025.01.28 NGK ELECTRONICS DEVICES INC

AI summary

A metal member includes a metal substrate, a first intermediate plating layer, a second intermediate plating layer, and a precious metal plating layer. The metal substrate includes a surface constituted of a plurality of crystal grains. The first intermediate plating layer is directly formed on the plurality of crystal grains of the metal substrate, contains a nickel element, and is non-oriented with respect to each crystal orientation of the plurality of crystal grains of the metal substrate. The second intermediate plating layer is directly formed on the first intermediate plating layer. The precious metal plating layer is formed on the second intermediate plating layer.