Single Conductive Layer Flexible PCB for LCD Thickness Reduction
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Solution Overview
Problem
Conventional flexible printed circuit boards (FPCBs) for liquid crystal display devices have a dual conductive layer structure, which increases thickness, reduces flexibility, and raises manufacturing costs due to the unnecessary soldering conductive layer.
Innovation Solution
A single conductive layer FPCB design is implemented, where the conductive layer is formed between cover layers and extends from the body section to the leg section for electrical connectivity, eliminating the need for a separate soldering conductive layer and reducing thickness and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual conductive layer structure is used in FPCB, then electrical connectivity is ensured, but thickness increases and flexibility deteriorates
Solution Approach 1:
The patent extracts and removes the unnecessary soldering conductive layer from the FPCB structure, retaining only the power-supplying conductive layer that is essential for LED operation. This extraction eliminates the thickness contribution of the redundant layer while preserving the essential electrical connectivity function through the remaining conductive layer and adhesive layer with conductive particles.
Solution Approach 2:
The adhesive layer in the patent is designed to serve multiple functions: it provides mechanical bonding between layers and simultaneously provides electrical conductivity through embedded conductive particles. This multi-functionality replaces the need for a separate soldering conductive layer, reducing overall thickness while maintaining electrical connectivity.
2Reliability
If a dual conductive layer structure is used in FPCB, then electrical connectivity is ensured, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the redundant soldering conductive layer from the manufacturing process, reducing material costs and simplifying the manufacturing sequence. The power-supplying conductive layer serves both power delivery and soldering functions, reducing the number of manufacturing steps and associated costs.
Solution Approach 2:
The adhesive layer with conductive particles performs dual functions of bonding and electrical connection, eliminating the need for separate conductive layer manufacturing processes. This multi-functionality reduces manufacturing complexity and cost while ensuring reliable electrical connectivity.
3Length of stationary object
If a single conductive layer is used in FPCB, then thickness is reduced and flexibility is enhanced, but electrical connectivity may be compromised
Solution Approach 1:
The patent changes the electrical conductivity parameter of the adhesive layer by incorporating conductive particles, transforming it from a non-conductive bonding material to a conductive pathway. This parameter change enables the single conductive layer structure to maintain electrical connectivity equivalent to dual-layer designs while achieving reduced thickness and enhanced flexibility.
Data Source
AI summary
A flexible printed circuit board for use in a liquid crystal display device includes: a body section having a light source portion embedded therein; a leg section including a solder pad connected to an external printed circuit board, the leg section being extended from the body section and integrally formed with the body section; and a single conductive layer formed across the body section and the leg section for electrically interconnecting the light source portion and the solder pad.