Flexible Printed Wiring Fuse Layout for Short-Circuit Suppression
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Solution Overview
Problem
Flexible printed wiring boards with fuses mounted on them face issues of carbonization and damage to the insulative film or insulator coating when the fuse melts, leading to potential short-circuits due to exposure and moisture adherence.
Innovation Solution
A wiring module design featuring a flexible printed wiring board with a conductive path including a fuse portion of reduced cross-sectional area, covered by a coverlay and protected by a resin portion on the base film and coverlay surfaces, and through holes to discharge gas, preventing exposure and pressure buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is mounted on a flexible printed wiring board, then overcurrent protection is provided, but the number of components and mounting steps increases
Solution Approach 1:
The patent combines the fuse function with the existing conductive pattern of the flexible printed wiring board by reducing the cross-sectional area of a specific portion of the conductive pattern. This integration eliminates the need for separate fuse components and mounting steps while maintaining overcurrent protection functionality.
Solution Approach 2:
The conductive pattern serves dual functions: it acts as both the circuit conductor and the fuse element. By designing the conductive pattern with a reduced cross-sectional area portion, it automatically provides overcurrent protection without requiring dedicated fuse components, thus achieving multi-functionality.
2Reliability
If the cross-sectional area of the conductive pattern is reduced to create a fuse, then overcurrent protection is achieved, but the surrounding region reaches high temperature causing carbonization and damage to insulative film
Solution Approach 1:
The patent introduces an insulator coating as an intermediary layer between the fuse portion and the insulative film. This coating layer absorbs and dissipates the heat generated during fuse operation, preventing direct thermal damage to the insulative film and avoiding carbonization.
Solution Approach 2:
The insulator coating is applied in advance to the flexible printed wiring board before the fuse portion is formed. This pre-applied protective layer acts as a thermal buffer that prevents heat from the fuse portion from damaging the insulative film during overcurrent events.
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
Suppresses short-circuiting by preventing exposure of the melted fuse and managing pressure, ensuring reliable operation even under overcurrent conditions.
Implementation Method 1
a resin portion that includes a synthetic resin with insulating properties is formed on a portion of the second surface of the base film that corresponds to the fuse portion
Implementation Method 2
the conductive path has a fuse portion forming a part of a circuit and having a smaller cross-sectional area than another part of the conductive path
Data Source
AI summary
A wiring module including a flexible printed wiring board to be electrically connected to a plurality of power storage elements, wherein the flexible printed wiring board includes: a base film that has insulating properties and has a first surface and a second surface; an adhesive layer that has adhesive properties and is stacked onto the first surface of the base film; a conductive path that is stacked onto the first surface of the base film using the adhesive layer; and a coverlay that is stacked onto the first surface of the base film using the adhesive layer, and covers the first surface of the base film and the conductive path, the conductive path has a fuse portion forming a part of a circuit and having a smaller cross-sectional area than another part of the conductive path, and a resin portion that includes a synthetic resin with insulating properties.