Tin-Plated Copper Electrical Connection with Corrosion-Resistant Surface Treating Layer
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Solution Overview
Problem
Existing electrical connection structures face challenges in preventing corrosion between dissimilar metal members, particularly when grease is used as a barrier, as it can lead to stickiness, dripping, and instability of the oil film, especially under high temperature conditions.
Innovation Solution
An electrical connection structure featuring a copper or copper alloy first metal member with a plated tin layer, coated with a surface treating layer containing a base oil and a metal affinity compound with azole and acidic alkyl phosphate ester adducts, which binds stably to both copper and tin, preventing corrosion current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grease or oil component is applied onto connection portion to prevent corrosion, then corrosion prevention is improved, but stickiness and dripping occur impairing workability and contaminating surrounding base materials
Solution Approach 1:
The patent changes the chemical parameters of the protective coating by using silane-based compounds that form cross-linked polymer films. This transforms the physical state from liquid grease (causing stickiness) to a solid-like cured film (eliminating dripping) while maintaining corrosion protection. The cross-linking density and film thickness can be controlled to optimize both protection and non-stick properties.
Solution Approach 2:
The patent replaces traditional grease that requires frequent reapplication (short-lived) with a silane-based coating that forms a durable, long-lasting protective film. The cross-linked structure provides stable corrosion resistance over extended periods, reducing maintenance frequency and improving workability by eliminating the need for frequent reapplication.
2Ease of operation
If oil component is applied thinly to avoid stickiness and dripping, then workability is improved, but it becomes difficult to retain a stable oil film on metal surface for long period of time
Solution Approach 1:
The patent creates a composite protective film combining silane compounds with base oil. The silane forms a cross-linked polymer network that acts as a scaffold, while the base oil fills the network and provides lubrication. This composite structure allows thin application (improving workability) while the cross-linked framework prevents oil migration and maintains film stability over long periods.
Solution Approach 2:
The patent creates different functional zones within the coating: the silane cross-linked network provides structural stability and adhesion to metal surfaces, while the base oil phase provides lubrication and corrosion protection. This local differentiation allows thin overall coating thickness while maintaining both workability and long-term film stability through functional specialization.
3Reliability
If oil component is applied to prevent corrosion, then corrosion prevention is improved, but under high temperature conditions the oil component may be turned into low molecular weight molecules due to oxidation or volatilize, thus making it more difficult to retain a stable oil film
Solution Approach 1:
The patent fundamentally changes the thermal stability parameter by replacing hydrocarbon-based grease with silane-based cross-linked polymers. The Si-O-Si bond strength and cross-linked network structure provide high thermal resistance, preventing decomposition and volatilization at elevated temperatures. This allows the coating to maintain corrosion protection and film stability under high temperature conditions where traditional oils fail.
Solution Approach 2:
The patent converts the potential harm of high temperature (which causes oil degradation) into a benefit by using silane compounds that undergo condensation reactions at elevated temperatures to form even more robust cross-linked networks. The heat that would normally degrade organic oils instead promotes further cross-linking and strengthens the protective film, enhancing corrosion resistance at high temperatures.
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 effectively stabilizes the base oil film on metal surfaces, suppressing corrosion even when water is present, thereby enhancing the reliability of electrical connections between dissimilar metals.
Implementation Method 1
the affinity group of the adduct (a) between an acidic alkyl phosphate ester and an azole compound included in the metal affinity compound preferentially binds to copper included in the first metal member, and the affinity group of the adduct (b) between a metal and/or an organic amine compound and an acidic alkyl phosphate ester preferentially binds to tin contained in the plated tin layer
Implementation Method 2
the oil component does not chemically bond to the metal surface but is in intimate contact with the metal surface due to van der Waals forces
Data Source
AI summary
An electrical connection structure includes: a first metal member including copper or a copper alloy, a plated tin layer being formed on at least a portion of the first metal member; a second metal member that is electrically connected or connectable to the first metal member; and a surface treating layer formed on the surface of the first metal member. The surface treating layer is formed by applying a surface treating agent containing base oil and a metal affinity compound having a lipophilic group and an affinity group that has an affinity for metal. The metal affinity compound contains an adduct between an acidic alkyl phosphate ester and an azole compound and an adduct between an acidic alkyl phosphate ester and a metal and/or an organic amine compound.