Advantages and disadvantages of pcb copper coating

Copper coating, that is, the idle space on the PCB is used as the base level, and then filled with solid copper, these copper areas are also called copper filling. The significance of copper coating is to reduce the ground impedance and improve the anti-interference ability. Reduce voltage drop, improve power efficiency; Connected with the ground wire, the loop area can also be reduced. Also for the purpose of making PCB welding as much as possible without deformation, most PCB manufacturers will also require PCB designers to fill the open area of the PCB with copper or grid-like ground wire, if the copper is improperly treated, it will not be lost, whether the copper is “more good than bad” or “more bad than good”?

We all know that in the case of high frequency, the distributed capacitance of the wiring on the printed circuit board will work, when the length is greater than 1/20 of the corresponding wavelength of the noise frequency, there will be an antenna effect, and the noise will be emitted outward through the wiring, if there is a bad grounded copper coating in the PCB, the copper coating has become a tool to spread noise, therefore, in the high frequency circuit, Do not think that a certain place of the ground wire is connected to the ground, which is the “ground wire”, and must be less than λ/20 spacing, punching holes in the wiring, and the ground plane of the multilayer board is “well grounded”. If the copper coating is properly treated, the copper coating not only increases the current, but also plays the dual role of shielding interference.

There are generally two basic ways of copper coating, that is, large area of copper coating and grid copper, and it is often asked whether large area of copper coating or grid copper coating is good, it is not good to generalize. Why is that? Large-area copper coating has the dual role of increasing current and shielding, but large-area copper coating, if over wave soldering, the board may tilt up, and even foam. Therefore, a large area of copper coating, generally open several slots, alleviate copper foil foaming, simple grid copper coating is mainly shielding effect, increase the role of the current is reduced, from the point of view of heat dissipation, the grid has advantages (it reduces the heating surface of copper) and has played a certain role in electromagnetic shielding.

But it should be pointed out that the grid is composed of staggered direction of the line, we know that for the circuit, the width of the line for the circuit board working frequency is its corresponding “electrical length” (the actual size divided by the working frequency of the corresponding digital frequency can be obtained, specifically see the relevant books), when the working frequency is not very high, Perhaps the role of the grid lines is not very obvious, once the electrical length and the operating frequency match, it is very bad, you will find that the circuit does not work properly, everywhere is emitting signals that interfere with the work of the system. So for colleagues who use the grid, my suggestion is to choose according to the design of the circuit board, and not to hold on to one thing. Therefore, the high frequency circuit against interference requirements of the multi-purpose grid, low frequency circuit with high current circuit and other commonly used complete copper paving.