Tin Seal Plating for Corrosion-Resistant Electrical Conductors
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Solution Overview
Problem
Conventional nickel-gold plated copper conductors are insufficient in resisting corrosion due to pin holes in the plating layers, leading to pitting corrosion, and thickening the plating layers increases costs.
Innovation Solution
A tin-based seal plating layer is applied between the metal substrate and the nickel and gold plating layers, which forms intermetallic interface layers through solid-state diffusion and reaction, reducing porosity and increasing nobility, thereby sealing pin holes and enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nickel and gold plating layers are thickened to resist corrosion, then corrosion resistance is improved, but manufacturing cost increases
Solution Approach 1:
A seal plating layer is applied as a preliminary layer before the nickel and gold plating layers. This seal layer fills pin holes and defects in the substrate before subsequent plating, preventing corrosion pathways from forming. The preliminary seal layer eliminates the need for excessive thickness in subsequent layers, achieving corrosion resistance at reduced overall plating thickness and lower cost.
Solution Approach 2:
The seal plating layer acts as an intermediary between the substrate and the nickel-gold plating system. It mediates the corrosion resistance function by providing a pin-hole-free barrier that protects the substrate, allowing the nickel and gold layers to be thinner while maintaining overall corrosion protection. This intermediary layer decouples the thickness requirement from the corrosion resistance performance.
2Reliability
If the nickel and gold plating layers are thickened to seal pin holes, then corrosion resistance is improved, but material cost increases
Solution Approach 1:
The seal plating layer is deposited first to fill pin holes and create a continuous barrier surface. By performing this sealing action preliminarily, subsequent nickel and gold plating layers do not need to be thickened to compensate for pin hole defects, significantly reducing the total quantity of expensive plating materials required while maintaining corrosion resistance.
Solution Approach 2:
The seal plating layer provides localized quality improvement by specifically targeting and filling pin hole defects in the substrate. This localized sealing action creates a pin-hole-free surface that allows thin, uniform layers of nickel and gold to provide adequate corrosion protection without requiring excessive material quantity throughout the entire plating structure.
3Reliability
If a pin hole free plating layer is achieved by increasing plating thickness, then corrosion resistance is improved, but the complexity of the plating structure increases
Solution Approach 1:
The seal plating layer performs the pin hole sealing function in a dedicated preliminary step, creating a simple, uniform barrier layer. This separates the pin hole elimination function from the corrosion protection function, allowing subsequent layers to be thin and simple while the overall structure achieves pin-hole-free corrosion resistance through the seal layer's preliminary barrier action.
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 cost-effective corrosion-resistant electrical conductor with reduced pitting corrosion, as the intermetallic interface layers effectively seal the substrate from environmental corrosion, balancing effectiveness with reduced layer thickness and cost.
Implementation Method 1
The intermetallic process creating the intermetallic interface layers may cause a volumetric increase in the seal plating layer thereby sealing pin holes in at least one of the seal plating layer, the nickel plating layer or the metal substrate
Implementation Method 2
The intermetallic process creating the intermetallic interface layers may cause a volumetric increase in the seal plating layer thereby sealing pin holes
Data Source
AI summary
An electrical conductor has a metal substrate. A seal plating layer is provided on and exterior of the metal substrate. A nickel plating layer is provided on and exterior of the seal plating layer. A gold plating layer is provided on and exterior of the nickel plating layer. The seal plating layer is a non-nickel based metal. Optionally, the seal plating layer may be tin based. Optionally, the seal plating layer may create intermetallic interface layers with the nickel plating layer and the metal substrate. Optionally, the electrical conductor may constitute a contact configured for mating with at least one of a printed circuit board or another mating contact.