Flexible PCB Dielectric Layout for Bending Durability and Crosstalk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flexible printed circuit boards in foldable and rollable electronic devices experience reduced lifespan due to stress accumulation in bending portions, leading to potential damage and reduced durability from repeated folding and unfolding.
Innovation Solution
A flexible printed circuit board design featuring a permittivity change area with a different permittivity than the surrounding dielectric layer, formed by removing a portion of the dielectric layer and potentially filled with air, to reduce crosstalk between signal wires while enhancing durability against bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible printed circuit board is used to connect electric elements in foldable/rollable devices, then the ease of operation and space utilization are improved, but the durability and service life are worsened due to stress accumulation in bending portions
Solution Approach 1:
The patent applies local quality by creating a permittivity change area with different dielectric properties at specific locations (where signal wires are disposed) rather than uniformly changing the entire circuit board structure. This localized modification reduces crosstalk and stress concentration at critical bending areas while maintaining the overall flexibility of the FPCB, thus improving durability without sacrificing flexibility.
2Reliability
If the dielectric layer is made thicker to improve insulation, then the electrical insulation is improved, but the flexibility and bendability are worsened
Solution Approach 1:
Instead of uniformly thickening the dielectric layer, the patent locally modifies the dielectric layer's permittivity at specific areas where signal wires are disposed. This creates regions of enhanced electrical insulation and reduced crosstalk only where needed, while other areas maintain thinner dielectric layers that preserve flexibility and bendability of the FPCB.
3Object-affected harmful factors
If ground wires are placed closer to signal wires to reduce crosstalk, then the crosstalk reduction is improved, but the signal interference and electromagnetic coupling are worsened
Solution Approach 1:
The patent changes the dielectric parameter (permittivity) in specific areas between signal wires and ground wires. By creating a permittivity change area with different dielectric constant, the patent reduces crosstalk between adjacent wires while controlling electromagnetic coupling. This parameter modification allows ground wires to be positioned closer to signal wires without causing excessive interference, as the altered permittivity reduces capacitive coupling effects.
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 permittivity change area effectively reduces crosstalk between signal wires and improves the durability of the flexible connecting member, maintaining performance and longevity of the circuit board under repeated bending.
Implementation Method 1
the dielectric layer includes a permittivity change area formed to at least partially overlap the common ground wire, and the permittivity change area has a permittivity different from that of the dielectric layer around the permittivity change area
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Various embodiments may provide a flexible connecting member, wherein the flexible connecting member includes a first protective layer 902, a wiring layer 903 disposed under the first protective layer, and a second protective layer 908 disposed under the wiring layer, wherein the wiring layer includes a support layer 906 configured to support a plurality of wires and a dielectric layer 904 that at least partially covers the plurality of wires, and the plurality of wires include a first ground wire 910 disposed on the support layer, a second ground wire 950 disposed in parallel with the first ground wire, a first signal wire 920 disposed between the first ground wire 910 and the second ground wire 950, a second signal wire 940 disposed between the first ground wire 910 and the second ground wire 940, and a common ground wire 930 disposed between the first signal wire and the second signal wire, and wherein, when viewed from above the flexible connecting member, the dielectric layer includes a permittivity change area 905 formed to at least partially overlap the common ground wire, and the permittivity change area has a permittivity different from that of the dielectric layer around the permittivity change area. Various other embodiments and modifications are possible.