Disulfide Compound Sealing for Gold Plating Pinhole Corrosion
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Solution Overview
Problem
Existing surface treatment methods for gold or gold alloy plating films are inadequate in preventing corrosion from pinholes, which can lead to substrate corrosion, increased contact resistance, and reduced reliability, while maintaining essential properties like solder wetting spreadability and corrosion resistance.
Innovation Solution
A surface treatment method involving a solution containing at least one disulfide compound, specifically represented by the formula R1—S—S—R2, where R1 and R2 are alkyl, aryl, or N,N-dialkylthiocarbamoyl groups, is used to contact the gold or gold alloy plating film, forming a protective film that enhances anticorrosive properties without compromising other essential characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the gold plating film is thinned to reduce the amount of gold used, then the cost is reduced, but pinholes in the gold plating film increase causing corrosion of the substrate
Solution Approach 1:
The patent applies a sealing film formed by disulfide compound treatment on the gold plating surface. This thin film layer seals the pinholes in the thinned gold plating, preventing corrosive substances from reaching the substrate while maintaining the reduced gold thickness.
Solution Approach 2:
The patent creates a composite structure consisting of the thinned gold plating layer combined with a sealing layer formed by disulfide compound. This composite structure provides both cost benefits from reduced gold usage and corrosion protection from the sealing layer.
2Reliability
If sealing treatment is applied to prevent corrosion from pinholes, then corrosion resistance is improved, but solder wetting spreadability may be harmed
Solution Approach 1:
The sealing treatment is applied locally only where needed - on the gold plating surface with pinholes. The disulfide compound forms a sealing film that targets the corrosion pathways while preserving the solder wetting properties in areas where sealing is not required.
Solution Approach 2:
The patent uses specific disulfide compounds with controlled molecular structures (R1 and R2 groups) to achieve optimal sealing performance. By adjusting the chemical parameters of the disulfide compound, the sealing effectiveness is improved while maintaining solder wetting spreadability.
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 disulfide compound-based surface treatment significantly reduces corrosion from pinholes, maintaining solder wetting spreadability and corrosion resistance, and effectively prevents substrate corrosion, as demonstrated by reduced nitric acid aeration and contact resistance tests.
Implementation Method 1
a surface treatment method for gold or gold alloy plating film formed on a metal wherein the surface treatment method includes a step for bringing the gold or gold alloy plating film into contact with a surface treatment solution containing at least one type of disulfide compound
Data Source
AI summary
To provide a surface treatment solution and treatment method for gold or gold alloy plating that effectively suppresses corrosion of underlying metal or substrate metal from pinholes that develop on the gold or gold alloy plating film.[Solution] A surface treatment solution containing a disulfide compound is brought into contact with a gold or gold alloy plating film. A compound represented by the following formula (2) is preferred as the disulfide compound.X1O3S—R3—S—S—R4—SO3X2 (2)in the formula, R3 and R4 independently represent a linear or branched alkylene group having from 1 to 10 carbon atoms, cyclic alkylene group having from 3 to 10 carbon atoms, or phenylene group, R3 and R4 independently may be substituted by one or more substituents selected from an alkyl group, halogen atom, hydroxyl group, or alkoxy group, and X1 and X2 represent monovalent cations.