Coil Terminal Electrode Alloy Bonding for Stronger Wire Joints
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Solution Overview
Problem
The bonding strength between the wire and the terminal electrode in existing coil components is insufficient, leading to potential connectivity issues during actual use.
Innovation Solution
A coil component design featuring a core with flange portions, terminal electrodes, and a wire wound around the core, where the wire's end portion is embedded in a metal layer with an alloy layer formed between the metal layer and the wire, and the wire's cross-sectional dimensions are optimized for enhanced bonding through thermal pressure bonding, increasing the visibility and mountability of the wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wire is embedded directly in the terminal electrode without an alloy layer, then the manufacturing process is simpler, but the bonding strength between the wire and terminal electrode is insufficient
Solution Approach 1:
The terminal electrode is constructed as a composite structure with a metal layer and an alloy layer. The alloy layer contains an alloy of a metal element from the wire end portion and a metal element from the metal layer, creating a metallurgical bond that significantly enhances bonding strength between the wire and terminal electrode.
Solution Approach 2:
The invention changes the chemical composition parameters of the terminal electrode by introducing an alloy layer with specific compositional characteristics. This alloy layer has a controlled composition that differs from both the base metal layer and the wire material, optimizing the bonding interface properties.
2Illumination intensity
If the wire end portion is completely covered by the terminal electrode, then the appearance is cleaner, but the visibility for inspection and testing is reduced
Solution Approach 1:
The terminal electrode is designed with non-uniform coverage of the wire end portion. Specifically, the metal layer partially covers the wire end portion while leaving a part exposed. This local differentiation allows the covered region to provide bonding function while the exposed region provides visibility for inspection and testing.
3Strength
If the wire end portion has larger cross-sectional dimensions, then the bonding area is increased, but the heat concentration during thermal pressure bonding is reduced
Solution Approach 1:
The wire end portion is designed with non-uniform cross-sectional dimensions. The first principal surface has a smaller dimension than the second principal surface, creating a tapered or asymmetric structure. This local dimensional variation concentrates heat during thermal pressure bonding at the smaller first principal surface area, improving heating efficiency while the overall larger cross-section provides sufficient bonding area.
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 enhanced bonding strength between the wire and terminal electrodes improves the reliability and mountability of the coil component, addressing the insufficient bonding strength in existing designs.
Implementation Method 1
when the first end portion of the wire is joined to the first terminal electrode by thermal pressure bonding by using a heater in manufacture of the coil component
Implementation Method 2
heat applied to the second principal surface by the heater is transmitted such that the heat is concentrated at the first principal surface because the dimension of the first principal surface in the width direction is less than a dimension of the second principal surface in the width direction. This accelerates alloying at the interface between a part of the first end portion of the wire including the first principal surface and the metal layer of the first terminal electrode
Data Source
AI summary
A coil component includes a core including a winding core portion, and first and second flange portions at first and second ends, respectively, of the winding core portion. The coil component also includes first and second terminal electrodes on the first and second flange portions, respectively, and a wire wound around the winding core portion and including first and second end portions respectively connected to the first and second terminal electrodes. The first terminal electrode is at least on a first surface of the first flange portion. The first end portion of the wire is embedded in the first terminal electrode such that a part of the first end portion is exposed. The first terminal electrode includes a metal layer in which the first end portion is embedded and an alloy layer at least in a portion of a region between the metal layer and the first end portion.