Thermal Fuse Electrode Clad Structure for Cost and Strength
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Solution Overview
Problem
The Ag—CuO-based alloy used in thermal fuse movable electrodes is expensive and prone to softening at high temperatures, making cost reduction through thinning difficult, and its welding resistance makes it challenging to change the material for ensuring device reliability.
Innovation Solution
A five-layer clad structure is adopted, comprising a Cu core material layer, an Ag—Cu-based alloy intermediate layer, and an Ag—CuO-based oxide-dispersed alloy surface layer, with the intermediate layer thickness ratio set between 0.2 and 1.0, to reduce Ag usage, enhance strength, and maintain welding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Ag—CuO-based alloy is thinned to reduce cost, then material cost decreases, but strength and spring property deteriorate
Solution Approach 1:
The patent uses a composite clad structure combining Ag—CuO-based alloy (surface layer) with Cu-based alloy (core layer). The Cu-based alloy core provides mechanical strength and spring properties, while the Ag—CuO surface layer provides welding resistance and conductivity. This composite structure allows cost reduction by replacing expensive Ag with cheaper Cu in the core, while maintaining required performance through the Ag—CuO surface layer.
Solution Approach 2:
The patent applies local quality by giving different regions of the movable electrode different material properties. The surface layer uses Ag—CuO-based alloy for welding resistance and conductivity where it contacts lead wires, while the core layer uses Cu-based alloy for strength and spring property. This localized material assignment optimizes both cost and performance.
2Quantity of substance
If the Ag—CuO-based alloy is thinned to reduce cost, then material cost decreases, but welding resistance may deteriorate
Solution Approach 1:
The clad structure ensures the Ag—CuO-based alloy surface layer maintains adequate thickness for welding resistance while the Cu-based alloy core reduces overall cost. The surface layer specifically contacts lead wires for welding, ensuring welding resistance is preserved where needed.
Solution Approach 2:
The surface layer is specifically designed with Ag—CuO-based alloy to provide welding resistance at the critical welding interface with lead wires, while the core layer uses cheaper Cu-based alloy. This local quality assignment ensures welding resistance is maintained where it matters most.
3Quantity of substance
If a Cu core material layer is added to reduce cost, then material cost decreases, but device complexity increases
Solution Approach 1:
The movable electrode is segmented into two functional layers: Ag—CuO-based alloy surface layer for welding and conductivity, and Cu-based alloy core layer for strength and cost reduction. This segmentation allows each layer to perform its specific function optimally while reducing overall material cost.
Solution Approach 2:
The patent employs a composite clad structure that integrates two different alloys with distinct functions. The manufacturing process involves clad bonding technology to join the Ag—CuO surface layer with the Cu-based core layer, creating a multi-functional material that reduces cost while maintaining performance.
Data Source
AI summary
The present invention is an electrode material constituting a movable electrode of a thermal fuse, having a five-layer clad structure including a core material layer, an intermediate layer formed on the both sides of the core material layer, and a surface layer formed on the intermediate layer, wherein the core material layer includes Cu, the intermediate layer includes an Ag—Cu-based alloy, the surface layer includes an Ag—CuO-based oxide-dispersed strengthened alloy, and the ratio of the thickness of the intermediate layer to the thickness of the surface layer (intermediate layer/surface layer) is 0.2 or more and 1.0 or less. This electrode material can be manufactured by partially internally oxidizing a three-layer clad material in which plate materials made of an Ag—Cu-based alloy are clad-jointed to both sides of the plate material made of Cu.