PCB copper experience

writer: G May 10, 2019

The significance of copper coating is to reduce the ground impedance, improve the anti-interference ability, reduce the voltage drop, improve the power efficiency, and connect with the ground to reduce the loop area. If the PCB has more ground, there are SGND, AGND, GND, etc. How to cover copper? My approach is to separate the copper by the most important "ground" as the reference reference according to the position of the PCB board. The digital ground and the analog ground are separated by copper. At the same time, before the copper coating, first increase the corresponding power connection: V5.0V, V3.6V, V3.3V, and so on. In this way, a plurality of multi-deformed structures of different shapes are formed.

Copper cladding needs to deal with several problems: First, a single point connection in different places, the method is to connect through 0 ohm resistor or magnetic beads or inductor; second is copper cladding near the crystal oscillator, the crystal oscillator in the circuit is a high frequency emission source, The copper is applied around the crystal, and then the outer casing of the crystal is grounded separately. The third is the problem of an island (dead zone). If you think it is very big, it will not cost much to define a place to add it.

In addition, the large area of copper is good or the grid is copper, it is not easy to generalize. why? Large area of copper, if the wave soldering, the board may be upturned, and even foaming. From this point of view, the heat dissipation of the grid is better. Usually, the high-frequency circuit is used to resist the interference of the multi-purpose grid, and the low-frequency circuit has a large current circuit and the like. However, there is a hero who once told me that when making signals above 1 GHz, the impedance must match, and the reflective surface must be full copper.

Personal experience: When starting the wiring, the ground wire should be treated equally. When the wire is routed, the ground wire should be taken well. You cannot rely on the copper to add the via hole to eliminate the ground pin. This is not good. . Of course, if you choose the grid copper, these ground connections will affect the appearance of beauty, if you are careful, delete it.

Finally, summarize the benefits of copper: improve power efficiency, reduce high frequency interference, and one is beautiful.