Shunt Resistor Laser Welding Defect Detection
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Solution Overview
Problem
Conventional shunt resistors face challenges in detecting welding defects, such as blowholes, due to their structural design, which makes it difficult to identify defects through external visual inspection.
Innovation Solution
A shunt resistor design featuring a resistive body with obverse and reverse curved surface portions and electrodes bonded to the resistive body using laser welding, with bonded areas subjected to bending stress to facilitate defect detection through visual inspection, and terminal portions that ensure proper contact and prevent electrical shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If electrodes are bonded to the resistive body by welding in a conventional structure, then the connection strength is improved, but the detectability of welding defects deteriorates
Solution Approach 1:
The patent applies inversion by making the electrode thinner than the resistive body, reversing the conventional design where electrodes are thicker. This thin electrode design allows the electrode to bend toward the resistive body when bonding defects occur, making the defects visible from the external surface while maintaining strong bonding through the bending mechanism
Solution Approach 2:
The patent introduces dynamic behavior by allowing the thin electrode to bend elastically toward the resistive body when bonding defects are present. This dynamic response enables defect detection without compromising the static bonding strength, as the electrode maintains strong adhesion while changing shape to reveal defects
2Strength
If the electrode thickness is greater than the resistive body thickness, then the bonding strength is improved, but the visual inspection capability deteriorates
Solution Approach 1:
The patent reverses the conventional thickness relationship by making the electrode thinner than the resistive body. This inversion enables the electrode to bend and conform to the resistive body surface, allowing bonding defects to manifest as visible surface irregularities while maintaining adequate bonding strength through the bending action
3Object-affected harmful factors
If a protective film covers the resistive body, then the protection capability is improved, but the defect detection capability deteriorates
Solution Approach 1:
The patent segments the protective function by applying the protective film only to specific regions of the resistive body that do not interfere with defect detection. This selective protection allows the film to shield vulnerable areas while leaving other areas exposed or transparent for visual inspection of bonding defects
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 design enhances the reliability of shunt resistor bonding by allowing for the detection of defects and improves contact with circuit boards, preventing electrical shorting and ensuring high reliability in current detection systems.
Implementation Method 1
electrodes bonded to the resistive body using laser welding
Data Source
AI summary
A shunt resistor includes a resistive body and a pair of electrodes each bonded to the resistive body. The resistive body has an obverse surface and a reverse surface that face in mutually opposite directions. The two electrodes are separate from each other in a first direction perpendicular to the thickness direction of the resistive body. The resistive body has two ends separate from each other in the first direction. The obverse surface of the resistive body includes a pair of intentionally curved portions that are located at the two ends of the resistive body.