Copper Alloy Terminal with Laser Welded Crimp for Corrosion Resistance
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Solution Overview
Problem
Existing terminal designs for electric wire connections, particularly in automotive wire harnesses, face issues with oxidation and corrosion due to differences in metal types, leading to increased electrical resistance and reduced product life, and current solutions either compromise on strength, increase production costs, or complicate manufacturing processes.
Innovation Solution
A terminal with a tubular crimp portion formed by laser welding, using a copper or copper alloy base material with a coating layer of tin, nickel, or silver, which suppresses strength and thickness decreases, and prevents cracking during crimping, while maintaining a closed structure to shield the electric wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper terminal is used to prevent oxidation of aluminum wire, then corrosion resistance is improved, but galvanic corrosion occurs between copper terminal and aluminum wire
Solution Approach 1:
The terminal employs a composite structure with a copper base material and an aluminum alloy coating layer. This composite material design allows the terminal to combine the advantages of both materials: the copper base provides excellent electrical conductivity and corrosion resistance, while the aluminum alloy coating prevents galvanic corrosion by creating a compatible interface with the aluminum wire, thus eliminating the harmful galvanic effect while maintaining reliability.
2Object-affected harmful factors
If an aluminum alloy terminal is used to match the wire material, then galvanic corrosion is suppressed, but strength and spring characteristics become insufficient
Solution Approach 1:
The terminal uses a composite material structure where the copper base material provides the necessary mechanical strength and spring characteristics, while the aluminum alloy coating layer suppresses galvanic corrosion by being chemically compatible with the aluminum wire. This composite approach allows both requirements to be satisfied simultaneously without compromising either strength or corrosion resistance.
Solution Approach 2:
The terminal applies different material properties to different parts: the base material (copper) is optimized for mechanical strength and elasticity, while the surface coating (aluminum alloy) is optimized for chemical compatibility and corrosion prevention. This local differentiation of material quality allows the terminal to meet both mechanical and chemical requirements.
3Strength
If a spring made of iron-based material is incorporated to compensate for insufficient strength, then terminal strength is improved, but galvanic corrosion occurs between spring and terminal base material
Solution Approach 1:
The terminal achieves the necessary strength through the copper base material itself rather than incorporating an iron-based spring. The copper alloy base is formulated to provide adequate mechanical properties, eliminating the need for additional spring components that would introduce galvanic corrosion risks. This integrated composite design avoids the harmful effect while maintaining strength.
4Reliability
If a copper cap is attached to protect the connection part, then oxidation is prevented, but crimp portion volume increases and production cost increases
Solution Approach 1:
The protective function previously requiring a separate copper cap is merged into the terminal body itself. The aluminum alloy coating layer is applied directly to the terminal base material, integrating the protection function into the main component. This eliminates the need for an additional cap part, thereby preventing oxidation while avoiding increases in crimp portion volume and production complexity.
Solution Approach 2:
The terminal uses a composite material structure where the aluminum alloy coating serves as both the protective layer and an integral part of the terminal body. This composite design provides oxidation protection without requiring a separate cap component, thus avoiding volume increase and additional manufacturing steps.
5Reliability
If a metal cap is provided to shield the aluminum conductor, then oxidation is prevented, but the process becomes cumbersome and cap breakage occurs during crimping
Solution Approach 1:
The protective function is merged into the terminal structure itself through the aluminum alloy coating layer. This eliminates the separate metal cap component and its associated attachment process. The coating is applied during terminal manufacturing, streamlining the process and eliminating the risk of cap breakage during crimping operations.
Solution Approach 2:
The protective coating is applied in advance during terminal manufacturing, before the crimping process. This preliminary protection eliminates the need for separate protective components and ensures the protection is already in place, avoiding any risk of damage during subsequent assembly operations.
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 strong, corrosion-resistant connection with improved weldability and reduced risk of cracking, enhancing the reliability and longevity of the wire connecting structure without increasing the crimp portion size or production complexity.
Implementation Method 1
the base material being composed of copper or a copper alloy and having a thickness of 0.20 mm to 1.40 mm, the coating layer being composed of one of tin, a tin alloy, nickel, a nickel alloy, silver and a silver alloy
Implementation Method 2
the tubular crimp portion having a weld portion formed by butt welding the metal member
Data Source
AI summary
A terminal includes a connector portion, a tubular crimp portion that crimps/joins with a wire, and a transition portion joining the two portions. The tubular crimp portion is composed of a metal member including a base material of copper or copper alloy with 0.20-1.40 mm thickness and a coating layer of tin, tin alloy, nickel, nickel alloy, silver or silver alloy with 0.2-3.0 μm thickness formed on the base material. The tubular crimp portion has a weld portion formed by butt-welding and having, in its cross-section perpendicular to a terminal longitudinal direction, a phase existing therein of tin, tin alloy, nickel, nickel alloy, silver or silver alloy greater than 0.01 μm2. The tubular crimp portion is a closed tubular body with one end opposite to a wire-insertion-opening being closed.