Flexible PCB Layer Stacking for High-Frequency Signal Integrity
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Solution Overview
Problem
Conventional flexible printed circuit boards (FPCBs) experience increased noise and transmission loss when used in high frequency or ultra-high frequency communication environments due to signal wavelength, affecting power and signal transmission between the FPCB and antenna.
Innovation Solution
The FPCB design includes vertically separated and insulated power and signal wiring layers, with a ground layer for shielding, and surface-mounted IC chips to minimize transmission distance, along with flexible connection parts for easy connection to antennas and main PCBs, utilizing insulating base films and EMI shielding layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power wiring layer and signal wiring layer are formed in one layer, then device complexity is reduced, but noise and transmission loss increase in high frequency environment
Solution Approach 1:
The patent divides the wiring structure into separate power wiring layer and signal wiring layer, stacking them vertically instead of forming them in one layer. This segmentation isolates power and signal paths, reducing electromagnetic interference and transmission loss in high frequency environments while maintaining manageable device complexity through systematic layering.
Solution Approach 2:
The patent transitions from a planar wiring arrangement to a three-dimensional stacked configuration. By stacking the power wiring layer and signal wiring layer vertically in different dimensions, the patent reduces interference between power and signal paths while maintaining compact device complexity, effectively addressing high frequency transmission issues.
2Ease of manufacture
If conventional FPCB structure is used, then ease of manufacture is maintained, but connection reliability decreases due to step difference
Solution Approach 1:
The patent applies a covering layer over the wiring layers to beforehand cushion and eliminate the step difference at connection parts. This pre-compliance approach ensures flat surfaces for reliable connections before assembly, preventing connection reliability issues while maintaining ease of manufacture through a straightforward coating process.
3Adaptability or versatility
If IC chip is mounted on FPCB, then functionality is achieved, but transmission distance between IC chip and antenna increases causing loss
Solution Approach 1:
The patent mounts the IC chip on the upper surface of the FPCB rather than within the layered structure, utilizing the third dimension (vertical space) to minimize the transmission distance between the IC chip and antenna. This spatial arrangement reduces energy loss while maintaining full functionality and adaptability of the device.
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
This configuration minimizes signal loss and noise, enhances flexibility for connections, and reduces transmission distance, effectively addressing the challenges in high frequency communication environments.
Implementation Method 1
a ground layer on the insulating base film
Implementation Method 2
an insulating base film on the lower wiring layer
Data Source
AI summary
A flexible printed circuit board includes a power wiring layer transmitting power and a signal wiring layer insulated and stacked over or under the power wiring layer. The flexible printed circuit board may also include an upper wiring layer and a lower wiring layer insulated and stacked each other, and the power wiring layer and the signal wiring layer are provided between the upper wiring layer and the lower wiring layer.