Solid Electrolytic Capacitor Lead Wire Structure for Low-Heat Welding
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Solution Overview
Problem
The use of copper as a base metal for anode terminals in solid electrolytic capacitors leads to high resistance values and abnormal heating during resistance welding due to the melting of copper, which complicates the connection with anode lead wires.
Innovation Solution
A manufacturing method that forms anode lead wires with thicker and thinner portions, allowing for increased contact area during resistance welding by positioning the anode terminal to overlap with the thicker portion and connect with both sections, ensuring effective welding without excessive heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper is used as the base metal of the anode terminal to reduce ESR, then the equivalent series resistance is reduced, but the resistance value of the junction becomes too high due to melting during resistance welding
Solution Approach 1:
The anode lead wire is designed with different thicknesses at different locations: a thicker portion for welding contact and a thinner portion for embedding in the anode body. This local variation in geometry allows the welding portion to have sufficient cross-sectional area to prevent melting and maintain low resistance, while the thinner portion serves the functional requirement of embedding. This resolves the contradiction by making the wire's properties location-dependent rather than uniform throughout.
Solution Approach 2:
The anode lead wire is segmented into functionally distinct portions: a thicker welding portion and a thinner embedding portion. This segmentation allows each portion to be optimized for its specific function - the thicker portion for low-resistance welding connections and the thinner portion for proper embedding in the anode body - thereby resolving the contradiction between reducing ESR and preventing junction overheating.
2Ease of manufacture
If the anode terminal is resistance welded to the anode lead wire, then electrical connection is established, but abnormal heating occurs at the junction due to high resistance from metal melting
Solution Approach 1:
The thicker portion of the anode lead wire is specifically designed for the welding operation, providing sufficient material volume to prevent melting and maintain low resistance during the resistance welding process. This local thickening at the welding location prevents abnormal heating while still allowing the welding operation to be performed, thus resolving the contradiction between ease of manufacture and temperature control.
Solution Approach 2:
The anode lead wire is pre-formed with a thicker portion at the welding location before the resistance welding operation takes place. This preliminary preparation ensures that when welding occurs, the junction has sufficient cross-sectional area to handle the thermal and electrical loads without melting or excessive heating, thereby preventing abnormal temperature rise while maintaining manufacturing simplicity.
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
This method prevents high resistance values at the junction of the anode terminal and lead wire, reducing the risk of overheating and enhancing weldability, thereby ensuring reliable connections and preventing insulation defects.
Implementation Method 1
applying electric current between the upper electrode and the lower electrode with force applied to both of the upper electrode and the lower electrode in the up-down direction to carry out resistance welding of the anode terminal and the anode lead wire to each other
Data Source
AI summary
A solid electrolytic capacitor includes a capacitor element, an anode terminal and a cathode terminal. The capacitor element includes an anode body, a dielectric layer, a solid electrolytic layer, a conductive layer and an anode lead wire. The anode lead wire is partially embedded in the anode body and extends in a horizontal direction from the anode body. The anode lead wire has a thicker portion and a thinner portion. The thinner portion is positioned closer to the anode body than the thicker portion is in the horizontal direction. The anode terminal at least has a first end, a second end and an overlapping portion. The anode terminal is connected to the anode lead wire under a state where the first end of the anode terminal is positioned on the thinner portion while the overlapping portion of the anode terminal overlaps with the thicker portion.