Ultrasonic Wire Terminal Bonding Stress Relief
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Solution Overview
Problem
Conventional electric wires with terminals experience disconnection issues during ultrasonic bonding due to stress concentration caused by the edge of the ultrasonic horn, leading to potential disconnection of the core wire.
Innovation Solution
The use of a protective member with specific dimensions, matching or exceeding the dimensions of the ultrasonic horn's distal end, to sandwich and protect the core wire during ultrasonic bonding, reducing stress concentration and material surplus, thereby preventing disconnection and lowering manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ultrasonic horn directly contacts the core wire during ultrasonic bonding, then the bonding process can be performed, but stress concentration occurs at the edge of the ultrasonic horn causing disconnection of the core wire
Solution Approach 1:
A protective member made of resin is introduced as an intermediary between the ultrasonic horn and the core wire. The protective member has a distal end surface that contacts the core wire during ultrasonic bonding, preventing direct contact between the ultrasonic horn edge and the core wire, thereby eliminating stress concentration and disconnection while maintaining the bonding function
Solution Approach 2:
The protective member is designed with rounded edges and a specific geometry that distributes stress before it reaches the core wire. The distal end surface of the protective member acts as a cushioning element that prevents stress concentration at the ultrasonic horn edge, protecting the core wire from disconnection before the bonding process occurs
2Reliability
If the protective member dimensions are increased to fully protect the core wire, then disconnection is prevented, but material surplus increases and manufacturing cost rises
Solution Approach 1:
The protective member is designed with non-uniform dimensions, being wider at the distal end where protection is needed and tapering towards the base. The width in the wire direction is specifically optimized to be equal to or greater than the ultrasonic horn width minus the core wire diameter, providing precise local protection only where stress concentration occurs, rather than excessive material throughout the entire structure
Solution Approach 2:
The protective member dimensions are precisely controlled within specific ranges: the width in the wire direction is set to ≥(ultrasonic horn width - core wire diameter), and the thickness is set to ≥core wire diameter. These parameter optimizations ensure adequate protection while minimizing material usage, balancing reliability with material efficiency
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 protective member effectively suppresses core wire disconnection and reduces manufacturing costs by distributing stress and optimizing material usage, ensuring reliable bonding and improved productivity.
Implementation Method 1
the core wire is integrally connected to a protective member and the terminal by ultrasonic vibration applied in a pressurized state from the ultrasonic horn via the protective member
Data Source
AI summary
An electric wire with a terminal and manufacturing method thereof is provided. In the electric wire with the terminal, the protective member, the core wire, and the terminal fitting are integrally connected to each other by ultrasonic vibration applied via the protective member from an ultrasonic horn in a state in which the core wire is sandwiched between the protective member and the terminal fitting. Therefore, there is no possibility that the ultrasonic horn directly presses the core wire, and the edge (particularly, the rear edge) of the pressing portion of the ultrasonic horn is direct in contact with the core wire. Thereby, at the time of ultrasonic bonding, stress concentration due to the edge (particularly the rear edge) of the pressing portion of the ultrasonic horn with respect to the core wire can be relaxed, and disconnection of the core wire can be suppressed.