Flexible Circuit Board with Liquid Crystal Polymer Insulation
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Solution Overview
Problem
Conventional flexible circuit boards suffer from wiring layer exfoliation or breakage due to bending stress and thermal expansion differences, leading to electrical connection defects, especially when repeatedly bent or subjected to high-density electronic part mounting and heat dissipation.
Innovation Solution
A flexible circuit board with a thermoplastic resin insulating film and layer, featuring a bent portion with a maintained radius of curvature, allowing elastic deformation and reduced stress on the wiring layer, and using a liquid crystal polymer for the insulating film and layer to prevent exfoliation and breakage, along with a production method involving shaping and heating to set the bent portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the flexible circuit board is repeatedly bent or folded with large curvature, then the flexibility and adaptability are improved, but the wiring layer may exfoliate or break due to bending stress
Solution Approach 1:
The bent portion is formed in advance during the manufacturing process before the product is put into service. By pre-forming the bent portion with an appropriate radius of curvature, the circuit board is prepared to accommodate future bending operations without causing wiring layer damage, thus resolving the contradiction between flexibility and reliability.
2Productivity
If electronic parts are mounted with high density to improve packaging density, then the functionality and space utilization are improved, but heat dissipation issues and wiring layer damage risk increase
Solution Approach 1:
The insulating film exhibits locally different properties: in non-bent regions it maintains high rigidity to provide structural support and heat dissipation pathways, while in the bent portion it becomes more flexible to accommodate deformation. This local differentiation allows high-density mounting without compromising thermal management or causing wiring layer damage from thermal stress.
3Length of moving object
If the wiring layer is made thinner to reduce overall board thickness, then the flexibility and thinness are improved, but the wiring layer becomes more susceptible to breakage
Solution Approach 1:
The bent portion is pre-formed with an optimized radius of curvature that distributes bending stresses away from the wiring layer. This preliminary structural preparation allows the use of thinner wiring layers without increasing breakage risk, as the stress concentration that would normally occur during bending is eliminated by the pre-formed geometry.
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 flexible circuit board maintains high connection reliability by preventing wiring layer exfoliation and breakage during repeated deformation and heat dissipation, while allowing for elastic conformity to electronic equipment shapes and potential recycling of the thermoplastic resin.
Implementation Method 1
allowing elastic deformation and reduced stress on the wiring layer
Implementation Method 2
the cause of the difference in thermal expansion between the insulating material and the wiring layer
Data Source
AI summary
A flexible circuit board with high connection reliability and a manufacturing method thereof, wherein the flexible circuit board has a bent section formed thereon, can be deformed flexibly, and wherein a wiring layer will not be peeled off or ruptured even when deformation is repeated onto the flexible circuit board, heat is radiated from electronic parts, or minute wiring is formed on the flexible circuit board. The flexible circuit board is provided with an insulating film comprised of liquid crystal polymer, a wiring layer formed upon the insulating film, and an insulating layer comprised of liquid crystal polymer formed upon the wiring layer. The flexible circuit board has a bent section with a radius of curvature of R (mm) formed on at least one location thereof, and is made to be deformable in a state with the radius of curvature of the bent section maintained at R (mm).