Surface Mount Fuse with Crimped End Caps
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Solution Overview
Problem
Miniature surface mount fuses face challenges with fragile construction, tedious through-hole mounting, unreliable cold solder joints, and performance limitations, especially with lead-free soldering processes that can damage heat-sensitive components and result in inoperative fuses.
Innovation Solution
A surface mount fuse design featuring a nonconductive housing with conductive end caps that establish a reliable electrical connection through a fuse element, using a ceramic base and cover to withstand high soldering temperatures, and optional bonding agents or arc quenching media to prevent cold solder joints and ensure consistent contact, allowing for miniaturization and lead-free soldering compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-hole mounting is used for miniature fuses, then reliable electrical connection can be achieved, but the mounting process becomes tedious and installation difficulty increases
Solution Approach 1:
The fuse construction is segmented into modular components: a body portion containing the fuse element, and separate end caps that are crimped onto the body. This segmentation enables surface mount installation while maintaining reliable electrical connections through the crimped end caps, eliminating the need for through-hole mounting.
Solution Approach 2:
The patent replaces the mechanical through-hole insertion system with a surface mount system using crimped end caps. The end caps are crimped onto the body portion to establish electrical connection, substituting the traditional mechanical through-hole mounting method with a more efficient surface mount approach.
2Volume of moving object
If miniaturization is pursued for surface mount fuses, then device size is reduced, but construction fragility increases
Solution Approach 1:
The fuse employs composite construction with a body portion made of heat-shrinkable material containing the fuse element, and end caps made of conductive material. This composite structure provides both miniaturization and enhanced strength, as the heat-shrinkable body protects the fragile fuse element while the crimped end caps provide robust electrical connections.
Solution Approach 2:
The heat-shrinkable body portion acts as a protective cushion for the fragile fuse element before installation. When heat is applied, the body shrinks to tightly enclose and protect the fuse element, providing beforehand cushioning that prevents damage during handling and installation while maintaining miniaturized dimensions.
3Ease of manufacture
If lead-free soldering is used for surface mount fuses, then manufacturing compliance is improved, but heat-sensitive components may be damaged
Solution Approach 1:
The fuse is segmented into a body portion and separate end caps. The end caps are crimped onto the body before soldering, creating a pre-assembled unit that can be surface mounted. This segmentation allows the soldering heat to be applied only to the small contact area of the end caps rather than the entire fuse assembly, reducing thermal damage to heat-sensitive components while maintaining lead-free soldering compliance.
Solution Approach 2:
The end caps serve as intermediaries between the solder joint and the fuse element. The crimped end caps provide a localized soldering area that isolates the heat-sensitive fuse element from the high temperatures of lead-free soldering, acting as a thermal mediator that protects the fuse element while enabling compliant manufacturing.
4Ease of manufacture
If conventional fuse construction is used, then manufacturing simplicity is maintained, but cold solder joints and unreliable connections occur
Solution Approach 1:
The end caps are crimped onto the body portion in advance before the final soldering operation. This preliminary crimping action ensures secure mechanical and electrical contact between the end caps and the body, preventing cold solder joints. The pre-crimped configuration maintains manufacturing simplicity while significantly improving solder joint reliability during the subsequent soldering process.
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 solution enhances manufacturing efficiency, reduces costs, and improves reliability and performance by eliminating cold solder joints and ensuring stable electrical connections, protecting sensitive components from excessive soldering temperatures.
Implementation Method 1
a longitudinal axis. The longitudinal side walls and the end walls define an interior fuse element cavity therebetween. The cover substantially closes the interior fuse element cavity when the cover is fitted to the base, and the cover is longitudinally separated from the fuse element receiving slot when the cover is fitted to the base.
Data Source
AI summary
Subminiature surface mount chip fuses include two part housings enclosing a fuse element and prefabricated end caps. The housing ends are shaped to restrict freedom of movement of the fuse element ends as the end caps are assembled to the housing. The end caps may include features to positively secure them in place and restrict relative movement of the end caps relative to the housing. Holes may be provided in the end caps that allow solder flow from a location exterior to the end caps to flow interior to the end caps to establish electrical connection with the fuse element.