Indented Fuse Endcaps for Robust Solder Connections
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Solution Overview
Problem
Traditional cartridge fuses experience unreliable electrical connections between endcaps and the fusible element due to insufficient or misshapen solder domes, which can't support the rated current effectively.
Innovation Solution
The implementation of indented surfaces on the endcaps of the fuse, concentrating solder fillets to enhance the electrical connection between the endcaps and the fusible element, thereby improving the robustness of the solder connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional smooth endcaps are used, then the manufacturing process is simple, but the solder connection between endcaps and fusible element is unreliable
Solution Approach 1:
The endcap structure transitions from a uniform smooth surface to a non-uniform surface with localized indentations. The indented regions concentrate solder material specifically at the contact points with the fusible element, creating locally enhanced connection quality without requiring complex structures throughout the entire endcap. This localized modification improves solder connection reliability while maintaining overall structural simplicity.
Solution Approach 2:
The endcap surface is modified by adding a third dimension through indentations that extend into the endcap body. This creates a stepped or multi-level surface topology that allows solder to be trapped and concentrated in specific regions, transforming a two-dimensional flat contact surface into a three-dimensional structure that enhances mechanical and electrical connection reliability.
2Reliability
If insufficient solder is used, then the manufacturing cost and material usage are reduced, but the electrical connection cannot support the rated current
Solution Approach 1:
Instead of uniformly distributing solder across the entire endcap surface, the indentation structure concentrates solder locally at the critical contact regions with the fusible element. This ensures that the solder quantity is optimized precisely where it is needed for reliable electrical connection, rather than wasting material across the entire surface. The localized concentration achieves robust electrical connection with reduced overall solder usage.
Solution Approach 2:
The indentation structure on the endcap automatically guides and traps solder material during the soldering process. The geometric features of the indentation create capillary action and physical containment that self-concentrate the solder fillet into the desired location and volume, eliminating the need for precise manual control of solder quantity. The structure itself serves the function of optimizing solder distribution.
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 indented surfaces on the endcaps increase the volume of solder connecting the endcaps to the fusible element, resulting in a more robust and reliable electrical connection, supporting the rated current of the fuse.
Implementation Method 1
The indented surfaces on the endcaps increase the volume of solder connecting the endcaps to the fusible element
Data Source
AI summary
A fuse including a tubular fuse body, a fusible element extending through the fuse body, a first endcap disposed on a first longitudinal end of the fuse body in electrical communication with the fusible element, the first endcap having a first indentation defining a first indented surface extending into the fuse body, and a second endcap disposed on a second longitudinal end of the fuse body in electrical communication with the fusible element, the second endcap having a second indentation defining a second indented surface extending into the fuse body.