See PCB manufacturer's flexible circuit board copper coating

Copper coating refers to the use of the upper idle space as the datum plane, and then filled with solid copper. These copper areas are also called copper filling. The significance of copper coating is to reduce the ground wire impedance and improve the anti-interference capability; Reduce voltage drop and improve power efficiency; Connecting with the ground wire can also reduce the loop area. In order to keep PCB from deforming as much as possible during welding, most PCB manufacturers also require PCB designers to fill the open area of PCB with copper sheet or grid shaped ground wire. If copper coating is handled improperly, it will be rewarded or lost. Is copper coating "more beneficial than harmful" or "more harmful than beneficial"?

As we all know, the distributed capacitance of the wiring on the printed circuit board will play a role in high frequency. When the length is greater than 1/20 of the corresponding wavelength of the noise frequency, the antenna effect will be generated, and the noise will be emitted through the wiring. If there is a poorly grounded copper coating in the PCB, the copper coating will become a tool to spread the noise. Therefore, in high frequency circuits, do not think that the ground wire is grounded somewhere, This is the "ground wire", which must be less than λ/ 20, make holes on the wiring, and "well grounded" with the ground plane of the multilayer board. If the copper coating is properly treated, it not only increases the current, but also plays a dual role in shielding interference.

Flexible circuit board

There are generally two basic methods for copper coating of flexible circuit boards, namely, large-area copper coating and grid copper. It is often asked whether large-area copper coating or grid copper coating is better. It is not easy to generalize. Why? Large area copper coating has the dual functions of increasing current and shielding. However, if large area copper coating is used for wave soldering, the board may be warped or even blistered. Therefore, for a large area of copper coating, several grooves are usually opened to alleviate the blistering of copper foil. The simple grid copper coating is mainly used for shielding, and the effect of increasing current is reduced. From the perspective of heat dissipation, the grid is beneficial (it reduces the heating surface of copper) and plays a certain role in electromagnetic shielding.

However, it should be pointed out that the grid is composed of lines in staggered directions. We know that for circuits, The width of the wiring has its corresponding "electrical length" for the operating frequency of the circuit board (the actual size is divided by the digital frequency corresponding to the operating frequency, see the relevant books for details) When the working frequency is not very high, perhaps the role of grid lines is not very obvious. Once the electrical length matches the working frequency, it is very bad. You will find that the circuit does not work properly at all, and there are signals everywhere that interfere with the work of the system. Therefore, for colleagues who use grids, my suggestion is to choose according to the working conditions of PCB designed circuit boards. Don't hold on to something. Therefore, high-frequency PCB circuit requires high anti-interference multi-purpose grid, and low-frequency circuit with high current circuit is commonly used to lay copper completely.