In this configuration, one power layer, one ground layer, and two signal layers are arranged as follows: TOP (signal layer), L2 (ground layer), L3 (power layer), BOT (signal layer).
Option II
Here, one power layer, one ground layer, and two signal layers are arranged as follows: TOP (power layer), L2 (signal layer), L3 (signal layer), BOT (ground layer).
Option III
This arrangement consists of one power layer, one ground layer, and two signal layers, arranged as follows: TOP (signal layer), L2 (power layer), L3 (ground layer), BOT (signal layer).
Option I
The primary laminated design scheme for the 4-layer flexible PCB incorporates a ground plane beneath the component surface, with crucial signals preferably situated on the TOP layer. Regarding layer thickness configuration, the following recommendations are proposed: the core board for impedance control (GND to POWER) should not be excessively thick to mitigate distributed impedance in the power supply and ground plane, thereby ensuring effective decoupling of the power plane.
Option II
These solutions primarily aim to achieve a certain shielding effect by situating the power supply and ground plane on the TOP and BOTTOM layers. However, the following drawbacks may arise if one expects flawless shielding solely through this method. Solution 2’s applicability is confined to a limited range. Nevertheless, for specific boards, Solution 2 stands out as the optimal layer configuration.
Option III
This scheme bears resemblance to Scheme 1 and is suitable for scenarios where the primary components are arranged in the BOTTOM layout or on the bottom layer housing key signals.
