Pattern Fuse Coating and Opening for Controlled FPC Breakage
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Solution Overview
Problem
Existing flexible printed circuit boards (FPCBs) face challenges in accurately breaking a specific part of the circuit line due to fusing caused by overcurrent, leading to potential fire outbreaks due to heat generation and unpredictable movement of broken fuse lines.
Innovation Solution
A pattern fuse with a flame retardant coating layer and an opening is designed, featuring a first electroconductive line portion within the opening, covered by a coating layer with lower thermal conductivity and higher melting point than the film layer, ensuring precise breakage and preventing fire outbreaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal conductive pattern is used for the fuse pattern, then the melting point is very high (about 1085°C for copper), but very high heat and flames may momentarily occur during operation of the fuse pattern
Solution Approach 1:
A flame retardant coating layer is applied over the metal conductive pattern to act as an intermediary barrier. This coating layer prevents direct contact between the metal pattern and the surrounding environment, suppressing flame propagation and reducing harmful heat effects while allowing the metal to maintain its high melting point for effective fuse operation
Solution Approach 2:
The fuse pattern is constructed as a composite structure combining a metal conductive pattern with a flame retardant coating layer. This composite material approach allows the metal to provide electrical conductivity and fusing function while the coating provides fire suppression, resolving the contradiction between high melting point requirement and flame hazard reduction
2Reliability
If a chip fuse is operated on a flexible printed circuit board, then the fuse element can block overcurrent, but the fuse line is separated from the adhesive layer due to stress caused by vibration or heat
Solution Approach 1:
The fuse pattern is designed as a separate, distinct element on the flexible printed circuit board rather than being integrated into the adhesive layer. This segmentation allows the fuse pattern to independently handle thermal and mechanical stress, preventing separation from the adhesive layer while maintaining its overcurrent protection function
Solution Approach 2:
The fuse pattern is created with specific local properties including appropriate thickness, material composition, and geometric design in the regions subjected to thermal and mechanical stress. This localized optimization ensures the fuse pattern maintains stable bonding and structural integrity under vibration and heat while performing its protective function
3Reliability
If the fuse line breaks due to overcurrent, then the current is blocked, but the broken fuse line may move or the breakage position cannot be predicted, causing fire outbreak
Solution Approach 1:
A predetermined breakage region is designed into the fuse pattern during manufacturing, with reduced thickness or weakened structure in this specific area. This preliminary preparation ensures that when overcurrent occurs, the fuse will break at this predetermined location rather than at an unpredictable position, preventing fire outbreaks from misplaced breakage
Solution Approach 2:
The fuse pattern incorporates a breakage region with modified physical parameters such as reduced thickness, different material composition, or altered geometric dimensions compared to the main fuse line. This parameter change creates a controlled weak point that ensures predictable breakage at the desired location while maintaining the overall reliability of current blocking
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 pattern fuse effectively blocks current at a specific position, preventing heat concentration and fire outbreaks, ensuring reproducible breakage and secure insulation, thus preventing short circuits and movement of broken fuse lines.
Implementation Method 1
a coating layer with lower thermal conductivity and higher melting point than the film layer
Implementation Method 2
configured such that current is blocked through fusing
Data Source
AI summary
The present invention relates to a pattern fuse including a flame retardant coating layer and an opening, the pattern fuse being configured to prevent fire outbreak due to overcurrent generated when a circuit pattern is operated and to designate a breakage position, a flexible printed circuit board including the same, and a battery module including the same, wherein it is possible to prevent fire outbreak even when the pattern fuse is heated to a high temperature as the result of operation of the pattern fuse, and the pattern fuse is broken by fusing at a specific position thereof.