The so-called copper coating is to take the idle space on the PCB as a reference level, and then fill with solid copper, these copper areas are also called copper filling. The significance of copper coating is to reduce the impedance of ground wire and improve the anti-interference ability. Reduce voltage drop, improve power efficiency; Connecting to the ground also reduces the loop area.

What are the advantages and disadvantages when covering PCB copper

Copper covering is an important part of PCB design. Both domestic Qingyuefeng PCB design software and some foreign Protel and PowerPCB provide intelligent copper covering function. So how to apply copper well, I will share some of my ideas with you, hoping to bring benefits to peers.

The so-called copper coating is to take the idle space on the PCB as a reference level, and then fill with solid copper, these copper areas are also called copper filling. The significance of copper coating is to reduce the impedance of ground wire and improve the anti-interference ability. Reduce voltage drop, improve power efficiency; Connecting to the ground also reduces the loop area. In order to minimize the deformation of PCB welding, most PCB manufacturers also require PCB designers to fill copper skin or grid-like ground wire in the open area of PCB. If copper covering is not handled properly, it will not be rewarded and lost. Is copper covering “more good than harm” or “more harm than good”?

Under the condition of high frequency is known to all, on the printed circuit board wiring capacitance will work, when the length is more than 1/20 of the noise frequency corresponding wavelength, can produce the antenna effect, the noise will launch out through wiring, if there are bad grounding copper clad in the PCB, copper clad became the tool of transmission noise, therefore, in the high frequency circuit, Do not think that the ground somewhere connected with the ground, this is the “ground”, must be less than λ/20 of the spacing, in the wiring hole, and the floor of the multilayer board “good grounding”. Ak je medený povlak správne ošetrený, medený povlak nielen zvyšuje prúd, ale hrá aj dvojitú úlohu pri rušení tienenia.

Copper covering generally has two basic ways, is a large area of copper covering and grid copper, often someone asked, a large area of copper covering or grid copper covering is good, bad generalization. Prečo tomu tak je? Large area copper coating, with increased current and shielding dual role, but large area copper coating, if the wave soldering, the board may become warped, or even bubble. Therefore, a large area of copper coating, generally also open a few slots, alleviate copper foil foaming, pure grid copper coating is mainly shielding, increase the role of the current is reduced, from the perspective of heat dissipation, grid has the advantage (it reduces the heating surface of copper) and has a certain role in electromagnetic shielding. But it should be pointed out that, the grid is made by alternating direction of running, we know for circuit line width for the work frequency of the circuit board has its corresponding “electricity” length of (actual size divided by the working frequency of the corresponding digital frequency, concrete books), when the working frequency is not very high, Maybe the grid lines don’t work very well, but once the length of the power matches the operating frequency, it’s very bad, and you find that the circuit doesn’t work at all, and there are signals going off all over the place that interfere with how the system works. So for those who use grid, my advice is to choose according to the design of the circuit board, do not cling to one thing. So the high-frequency circuit against interference requirements of high multi-purpose grid, low-frequency circuit has a large current circuit and other commonly used complete copper laying.

Having said so much, we need to pay attention to those problems in copper cladding in order to achieve the desired effect of copper cladding:

1. If there are many PCB ground, SGND, AGND, GND, etc., it is necessary to use the most important “ground” as the reference to independently coat copper according to the different PCB surface position. It is not mentioned that digital ground and analog ground are separately coated copper, at the same time, before covering copper, the corresponding power cables should be thickened: 5.0 V, 3.3 V atď. Týmto spôsobom sa vytvoria viacnásobné deformačné štruktúry rôznych tvarov.

2. For the single point connection of different ground, the method is to connect by 0 ohms resistance or magnetic beads or inductance;

3. Copper coating near the crystal oscillator, the crystal oscillator in the circuit is a high frequency emission source, which is copper coating around the crystal oscillator, and then the shell of the crystal oscillator is separately grounded.

4. Island (dead zone) problem, if you think it is too big, then it is not much trouble to define a hole and add it.

5. At the beginning of the wiring, the ground should be treated equally. When the wire is laid, the ground should go well.

6. It is better not to have sharp angles on the board (” =180 degrees “), because from the point of view of electromagnetism, this constitutes a transmitting antenna!

7. Do not cover copper in the open area of the wiring of the middle layer of the multilayer. Because it’s hard to get the copper cladding to be “well grounded.”

8. Ensure that the metals inside the device, such as the metal heat sink and metal reinforcement strip, are well grounded.

9. The heat dissipation metal block of the three-terminal regulator must be well grounded. Uzemňovací izolačný pás v blízkosti kryštálového oscilátora musí byť dobre uzemnený. Stručne povedané: medený povlak na doske plošných spojov, ak je problém s uzemnením dobre vyriešený, je určite „viac dobrý ako zlý“, môže znížiť oblasť spätného toku signálneho vedenia, obmedziť vonkajšie elektromagnetické rušenie signálu.