Fuse Element Protection Layer to Prevent Conductive Carbide
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Solution Overview
Problem
Existing fuse elements, such as chip fuses and FPC fuses, fail to interrupt electrical circuits effectively due to the formation of electrically conductive carbide when a conductor is fused and cut, leading to the re-establishment of electrical conduction paths.
Innovation Solution
A fuse element with an insulating base material, a conductor layer, and an insulating protection layer having a specific heat of 1.1 J·g−1·K−1 or more and a specific gravity of 1.0 g·cm−3 or more, which suppresses the formation of carbide by maintaining a low temperature rise during abnormal current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional protection layer containing organic polymer is used near the conductor, then the conductor is protected during normal operation, but carbide forms when the conductor is fused and cut by abnormal current, creating unwanted electrical conduction paths
Solution Approach 1:
The patent changes the physical parameters of the protection layer by selecting materials with specific heat capacity (≥1.0 J/g·K) and specific gravity (≥1.0 g/cm³) values. This parameter change allows the protection layer to absorb heat more effectively during fuse operation, preventing carbide formation while maintaining protective functions.
Solution Approach 2:
The patent employs composite material selection for the protection layer, using materials that combine appropriate heat capacity, specific gravity, and chemical stability. Examples include silicone resin, polyimide, and epoxy resin, which provide both protective coverage and heat management properties to suppress carbide formation.
2Reliability
If the conductor is designed to fuse and cut easily for circuit protection, then abnormal current interruption is achieved, but excessive heat is generated that causes carbide formation in surrounding materials
Solution Approach 1:
The protection layer acts as an intermediary between the conductor and surrounding materials. It absorbs and dissipates heat generated during conductor fusion, preventing excessive temperature rise in adjacent organic polymer materials that would otherwise form carbide. The layer mediates thermal energy transfer while maintaining chemical stability.
Solution Approach 2:
By selecting materials with specific heat capacity and specific gravity thresholds, the patent changes the thermal response parameters of the protection layer. This allows the system to manage heat more effectively during fuse operation, enabling reliable circuit interruption while controlling temperature rise to prevent carbide formation.
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 fuse element effectively interrupts electrical circuits by preventing the formation of conductive carbide, ensuring reliable circuit disconnection and protection against abnormal currents.
Implementation Method 1
the protection layer having a specific heat of 1.1 J·g−1·K−1 or more and a specific gravity of 1.0 g·cm−3 or more
Implementation Method 2
a specific heat of 1.1 J·g−1·K−1 or more and a specific gravity of 1.0 g·cm−3 or more, which suppresses the formation of carbide by maintaining a low temperature rise
Implementation Method 3
the fusible conductor is fused and cut by the heat generation of the fusible conductor itself or by the heat generation of a heating conductor film provided between the terminal electrodes
Data Source
AI summary
It is aimed to provide a fuse element capable of interrupting an electrical circuit while suppressing the formation of carbide when an abnormal current is generated. A fuse element 10 is provided with an insulating base material 3, a conductor layer 1 provided on a surface of the base material 3 and an insulating protection layer 4 provided on a surface of the conductor layer 1. The protection layer 4 has a specific heat of 1.1 J·g−1·K−1 or more and a specific gravity of 1.0 g·cm−3 or more.