Tin-Gadolinium Alloy Plating for Oxidation Resistance

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Solution Overview

Problem

Tin-containing alloy plating products face issues with surface oxidation and whisker generation, leading to contact resistance failures and electric short circuits, particularly in lead-free plating solutions, which are more complex to process compared to traditional tin-lead alloys.

Innovation Solution

A tin-containing alloy electroplating bath comprising a tin compound, a gadolinium compound, a complexing agent, and a solvent, with specific concentration ranges for tin and gadolinium, is used to deposit a tin-containing alloy on substrates, providing excellent antioxidation performance and suppressing whisker generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If lead-free tin-containing alloy plating is used, then environmental conservation is improved, but whisker generation and surface oxidation occur

Engineering Contradiction:
Improveenvironmental harm from leadVSAvoidwhisker generation and surface oxidation
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the plating bath by introducing gadolinium compounds and specific complexing agents, adjusting the chemical environment to prevent whisker formation and surface oxidation while maintaining lead-free composition

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite plating system by combining tin with gadolinium and other alloying elements, forming a multi-element alloy that exhibits improved resistance to whisker generation and oxidation compared to simple tin plating

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If complex process methods are used to suppress whiskers (such as multiple plating layers or ultrasonic treatment), then whisker generation is reduced, but device complexity increases

Engineering Contradiction:
Improvewhisker generationVSAvoidprocess complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by incorporating gadolinium and complexing agents into the plating bath composition before plating occurs, preventing whisker formation during the plating process itself rather than requiring subsequent treatment steps

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent modifies the electroplating parameters by adjusting bath composition, temperature, and current density to achieve whisker-free plating in a single-step process, eliminating the need for multiple plating layers or post-treatment operations

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

The method prevents surface oxidation, suppresses whisker formation, maintains wettability similar to tin-lead alloys, and achieves a surface hardness of 20 to 165 Vickers hardness, while avoiding discoloration and corrosion, thus enhancing the reliability of electronic components.

Implementation Method 1

applying a plating bath to deposit a tin-containing alloy on the surface of a substrate

Methodology Applied
Scientific EffectElectroplating: Electroplating

Data Source

PatentUS9080247B2Tin-containing alloy plating bath, electroplating method using same, and substrate with the electroplating deposited thereon
Publication Date: 2015.07.14 DAIWA FINE CHEM

AI summary

Provided are a tin-containing alloy plating bath being capable of manufacturing a tin-containing alloy plated product suitable for electric and electronic members with excellent anti-oxidation performance, and an electroplating method using the bath. Specifically the bath is a plating bath to deposit a tin-containing alloy on the surface of a substrate, which plating bath contains: (a) a tin compound containing 99.9% by mass to 46% by mass of tin based on entire metal mass in the plating bath; (b) a gadolinium compound containing 0.1% by mass to 54% by mass of gadolinium based on entire metal mass in the plating bath; (c) at least one complexing agent; and (d) a solvent, and the electroplating method uses the tin-containing alloy bath, thus can manufacture a tin-containing alloy plated product having excellent anti-oxidation performance.