PCB News - PCB copper knowledge must know

Copper pour is a common operation, which is to cover the area of the PCB circuit board without wiring with copper film. This can enhance the anti-interference performance of the PCB circuit board. The so-called copper pour is to use the unused space on the PCB as a reference surface and then fill it with solid copper. These copper areas are also called copper filling. Copper coating can reduce ground wire impedance and improve anti-interference ability; reduce voltage drop and improve power supply efficiency; in addition, connect to ground wire to reduce loop area.

There are several issues that need to be dealt with in copper coating:
1. Single-point connection of different grounds: The method is to connect through 0 ohm resistors or magnetic beads or inductance.
2. Copper-clad near the crystal oscillator, the crystal oscillator in the circuit is a high-frequency emission source: the method is to coat copper around the crystal oscillator, and then ground the shell of the crystal oscillator separately.
3. Island (dead zone) problem: If you think it is too big, it will not cost much to define a ground via and add it.
What are the benefits of copper coating?
Improve power efficiency, reduce high-frequency interference, and the other is that it looks beautiful!
Is it better for large area copper pour or grid copper pour?
does not make generalizations. why? If the copper is covered with a large area, if the wave soldering is used, the board may be uplifted or even blistered. From this point of view, the heat dissipation of the grid is better. Usually it is a multi-purpose grid with high anti-interference requirements for high-frequency circuits, and circuits with large currents in low-frequency circuits are commonly used with complete copper.
When wiring starts, the ground wire should be treated the same. When wiring, the ground wire should be routed well. You can't rely on adding via holes to eliminate the ground pin for connection after copper pour. This effect is very bad. Of course, if the grid copper is used, these ground connections will affect the appearance. If you are careful, delete it.
Copper filling is intelligent. This operation will actively judge the network properties of the vias and pads in the copper filling area, which absolutely conforms to the safety distance you set. This is different from drawing copper skin. Drawing copper skin does not This feature.
There are many functions of copper filling. Filling the reverse side of the double-sided board with copper and connecting it to the ground can reduce interference, increase the laying range of the ground wire, reduce low impedance, and so on. Therefore, after the wiring of the PCB circuit board is basically completed, it is often necessary to fill it. copper.
Precautions for copper-clad wiring
1, PCB copper clad safety spacing setting:
The safety distance of copper clad is generally twice the safety distance of wiring. But before there is no copper pour, the safety distance of the wiring is set for the wiring, then in the subsequent copper pour process, the safety distance of the copper pour will also default to the safety distance of the wiring. This is not the same as the expected result.
A stupid way is to double the safety distance after laying out the wires, then pour copper, and then change the safety distance back to the safe distance of the wiring after the copper pour is completed, so that the DRC inspection will not report an error. This method is ok, but if you want to change the copper pour again, you have to repeat the above steps, which is slightly troublesome. The best way is to set a rule for the safety distance of the copper pour separately.
Another way is to add rules. In Rule's Clearance, create a new rule Clearance1 (the name can be customized), and then select Advanced (Query) in the Where the FirstObjectmatches option box, click QueryBuilder, and then the BuildingQueryfromBoard dialog box appears, in the first line of the dialog box, in the drop-down menu Select the default item ShowAllLevels, select ObjectKindis from the drop-down menu under ConditionType/Operator, select Ploy from the drop-down menu under ConditionValue on the right, so IsPolygon will be displayed in QueryPreview, click OK to confirm, the next step is not finished, save completely Will prompt an error:
Next, just change IsPolygon to InPolygon in the FullQuery display box, and finally modify the copper safety gap you need in Constraints. Some people say that the priority of the wiring rules is higher than the priority of the copper pour. If the copper pours, it must also comply with the rules of the safety spacing of the wiring. You need to add the copper pour exception to the safety spacing rules of the wiring. The specific method is in FullQuery Note on notInPolygon inside. In fact, this is completely unnecessary, because the priority can be changed. There is an option priority in the lower left corner of the main page of the rule setting, which increases the priority of the copper-clad safety spacing rule to be higher than the wiring safety spacing rule, so that they can interact with each other. Don't interfere anymore.
2, PCB copper clad line width setting:
Copper When choosing the Hatched and None modes, you will notice that there is a place to set TrackWidth. If you choose the default 8mil, and the minimum line width of the network connected to your copper pour is greater than 8mil when setting the line width range, then an error will be reported during DRC, and you did not notice this at the beginning In detail, there are many errors in DRC after each copper pour.
In the Clearance of Rule, create a new rule Clearance1 (the name can be customized), then select ADVANCED (Query) in the Where theFirstObjectmatches option box, click QueryBuilder, and then the BuildingQueryfromBoard dialog box appears. In this dialog box, the first line of the drop-down menu Select ShowAllLevels (this is the default), then select ObjectKindis from the drop-down menu under ConditionType/Operator, and then select Ploy from the drop-down menu under ConditionVALUE on the right, so IsPolygon will be displayed in the QueryPreview on the right, click OK to confirm Save and exit. The next step is not over. In the FullQuery display box, change IsPolygon to InPolygon. The last step is to modify the spacing you need in Constraints. In this way, it only affects the spacing of copper laying, and does not affect the spacing of each layer of wiring.

The above is the introduction to the knowledge of PCB copper coating. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology