Introduction to some advantages and disadvantages of PCB copper cladding

 

The so-called copper cladding is to use the idle space on the PCB as the datum plane, and then fill it with solid copper. These copper areas are also called copper filling. The significance of copper cladding is to reduce the earth wire impedance, improve the anti-interference ability, reduce the voltage drop, improve the power efficiency; connect with the ground wire, and also can reduce the loop area. Also for PCB welding as far as possible without deformation, most PCB manufacturers will also require PCB designers filled copper wire or grid in the PCB open area, if the improper processing of copper, it will not reward lost, what is "copper outweigh" or "more harm than good"?


We all know that in case of high frequency, capacitance wiring on printed circuit board will play a role, when the noise frequencies greater than the length of the corresponding wavelength 1/20, will produce the antenna effect and noise will be emitted outside through wiring, if there are bad grounding copper clad in PCB, copper became the spread of noise the tool, therefore, in the high frequency circuit, do not think that, to a place to pick up the ground, this is the "ground", must take the distance is less than lambda /20, played on the wiring hole, ground plane and multilayer board "well grounded". If the copper coating is properly handled, the copper cladding not only increases the current, but also plays a dual role of shielding interference.


There are two basic ways to cover copper, that is, covering large area of copper and grid copper, and some people often ask whether it is good to cover copper in large area or copper covered in grid, which is not good enough to generalize. Why? A large area of copper cladding, with the increase of current and shielding double role, but a large area of copper, if the wave soldering, the board may become warped, and even blistering. The large area of copper, the general will open several slots, alleviate the copper foam, pure copper clad grid mainly shielding effect, increase the effect of electric current is reduced, the heat from the point of view, good grid (it reduces the heating surface of copper) also played a certain role in electromagnetic shielding.


1. if the PCB more, SGND, AGND, GND, etc., will be based on the PCB plate in different position, with the main "place" as reference to independent copper, analog ground and digital ground to separate copper from the few words, while copper before the first power supply line bold corresponding: 5.0V, 3.3V and so on, as a result, on the formation of a number of different shapes of structure deformation.

2. single point connections to different areas are connected by 0 ohm resistors or magnetic beads or inductors;

The 3. crystal oscillator near the copper, the crystal oscillator in the circuit is a high frequency transmitter source, the method is to surround the crystal oscillator copper, and then the crystal shell to be grounded.

4. Island (dead) problem, if you feel very large, it is not too expensive to define a hole through adding.

5. in the beginning of wiring, the ground should be treated equally, the line should be taken when the ground wire is good, can not rely on copper after adding holes through to eliminate the connection to the ground pin, this effect is very bad.

6. it is better not to have sharp corners on the board, because from an electromagnetic point of view, this constitutes a transmitting antenna! There is always an impact on other things, just big or small, and I suggest using the edge of the arc.

7., the middle layer of the multilayer wiring, open area, do not cover copper. Because it's hard for you to make this copper grounding"

8., the metal inside the equipment, such as metal radiator, metal reinforcement, etc., must realize "good grounding"".

9. three terminal regulator metal block, must be good grounding. The earthing isolation belt near the crystal oscillator must be well grounded. In short, the copper covered on the PCB, if the grounding problem is dealt with well, it must be "advantages outweigh the disadvantages", it can reduce the signal line return area, reduce the external electromagnetic interference of the signal.


 

(Source: internal information)

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