Fluid Conformal Coating for Sealed Crimp Connections
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Solution Overview
Problem
The existing connections between dissimilar materials in wire conductors and terminals are prone to galvanic corrosion, which degrades the electrical and mechanical performance, especially in automotive applications where lighter weight wire conductors are used, and there is a need for improved protection while maintaining or enhancing these properties.
Innovation Solution
A crimp connection is formed using a fluid conformal coating made from an acrylic urethane material that is applied to the terminal and wire conductor, cured to create a robust seal, reducing exposure to contaminants and enhancing the mechanical and electrical properties, including increased pull force and low crimp resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealant is applied to protect the terminal/wire conductor connection from contaminants, then protection against galvanic corrosion is improved, but crimp resistance increases and electrical performance decreases
Solution Approach 1:
The patent changes the physical state parameter of the sealant material by using a curable composition that transitions from fluid to solid state. In the fluid state, the material has low viscosity allowing it to flow and conform to the crimp interface without increasing crimp resistance. After curing, it becomes a solid protective seal that prevents galvanic corrosion. This parameter change resolves the contradiction by separating the material properties during application versus during protection.
Solution Approach 2:
The patent utilizes phase transition of the sealant composition from liquid to solid through curing. The material is applied in a fluid phase that does not interfere with the crimping process, then undergoes phase transition to a solid phase that provides corrosion protection. This phase transition allows the material to provide protection without adversely affecting crimp resistance or electrical performance.
2Reliability
If a sealant is applied to protect the connection, then protection against contaminants is improved, but the complexity of the connection increases
Solution Approach 1:
The patent merges the sealant application process with the existing crimp connection process. The fluid conformal coating is applied and then cured in-situ within the crimp connection structure, combining the sealing function with the mechanical connection. This integration adds protection without requiring separate sealing components or complex assembly steps, thus minimizing increase in device complexity.
3Reliability
If conventional seal material is used in the crimp connection, then protection is provided, but pull force decreases and crimp resistance increases
Solution Approach 1:
The patent changes the viscosity parameter of the sealant material by using a curable composition that is fluid during application. This low-viscosity fluid state allows the material to be displaced during crimping without creating excessive pressure or reducing pull force. After curing, the material provides protection while maintaining the mechanical strength characteristics of the crimp connection.
Solution Approach 2:
The patent allows the fluid sealant to be rapidly displaced during the crimping process. The low-viscosity material flows and conforms to the crimp interface quickly during formation, then sets to provide protection. This rapid conformance and setting prevents the sealant from interfering with the development of proper crimp strength and pull force characteristics.
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 prevents galvanic corrosion, maintains or improves electrical conductivity, and provides a durable connection with increased pull force and low crimp resistance over time, suitable for the automotive industry's service life expectations.
Implementation Method 1
The fluid conformal coating in, and about the crimp connection is cured to a non-fluid state
Data Source
AI summary
Methods of making a sealed crimp connection attaching a terminal to a wire conductor are provided. A layer of fluid conformal coating is applied to overlie a terminal and underlie at least a lead of the wire conductor upon at least the lead being received into the terminal. The terminal, the fluid layer, and at least the lead of the wire conductor are crimped to form the crimp connection. Fluid conformal coating is displaced where an abutting surface of the terminal makes contact with at least the lead of the wire conductor. The fluid conformal coating is cured to a non-fluid state. The fluid conformal coating may be formed of an acrylated urethane material that may provide an increased pull force and a low crimp resistance in the crimp connection. The crimp connection may be constructed using a manufacturing process on an automated assembly line.