PCB Technical - pcb coating knowledge technology

Copper plating is a common operation, it is to cover the area of the circuit board without wiring with a copper film.

This can improve the anti-interference performance of the circuit board. The so-called copper plating is based on the unused space on the PCB, and then filled with solid copper. The copper plating can reduce the impedance of the ground wire, improve the anti-interference ability, reduce the voltage drop, and improve the power efficiency ; In addition, it is connected to the ground wire to reduce the loop area.

1. Copper plating needs to solve several problems:

1. Single-point connection at different positions: The method is to connect with 0Ω resistors or magnetic beads or inductors.

2. The copper-plated layer near the crystal oscillator is the source of high-frequency emission in the circuit: the method is to coat copper around the crystal, and then separate the crystal vibrating shell.

3. Dead zone problem: If you think you are big, adding a hole to the hole will not cost a lot of money.

What are the benefits of copper coating?

Improve power efficiency, reduce high-frequency interference, one is beautiful!

Large area copper or mesh copper?

You can't generalize, why? Large-area copper plating, if wave soldering, the board may rise up, or even blisters. From this perspective, the heat dissipation effect is better. Usually it is a multi-purpose power grid with high anti-interference requirements for high-frequency circuits, and all copper is commonly used for low-frequency circuits and high-current circuits.

When you start the grounding wire, you should go when the ground wire is routed. You can't add a hole and then wrap the copper plate to connect to the pin. The effect is very poor. Of course, if you choose to use mesh copper, these connections will have some impact on aesthetics. If you are careful, you can delete them.

Copper filling and intelligence, this operation will actively determine the copper pouring area and the pad for the network performance, which is absolutely safe from you. It is different from the extraction of copper sheet, which does not have this feature when extracting copper sheet.

Filling copper has many functions. Filling the opposite double-sided board with copper and connecting it to the clock can reduce interference and increase the range of grounding wire laying, reducing low impedance and so on. Therefore, after the PCB wiring is completed, it is basically inclined to fill copper.

2. Precautions for copper wiring.

1. Set the safety distance of the PCB cladding:

The safety distance of the copper clad laminate is usually twice the safety distance of the circuit, but the safety distance should be set for the circuit before the copper clad laminate is not covered. Therefore, the safety distance of the copper plating layer will also be the safety distance of the wiring in the subsequent copper plating process, which is different from the expected result.

After a line is in good condition, the safety distance is doubled, and then after the safety distance is completed, the copper and copper cladding return to the wiring safety distance. This DRC check is not an error. This can be done, but if you want to re-run the copper, repeat the above steps, which is more tricky, the best way is to make rules for the safe distance of the police.

The other is to add rules. In the clearing rules, create a new rule CLEXANG1 that can be customized (name), then select Advestress (query) in the first object matching option box, click the standard IUBILDER, and then the "From BuffetQueDeFabor" dialog box appears, this dialog box In the first line of the drop-down menu, select the default showallllevels, select objectkindis from the conditiontype/operator in the drop-down menu below, and select a polygon under the right conditionvalue drop-down menu, which will be displayed in querypreview ispolygon, click "OK" to confirm The following operations have not yet been completed, and an error will be prompted when saving completely:

The next step is to change the ispolygon in the fullquery display box to inpolygon, and finally modify the copper safety spacing required in the constraints. Some people say that the priority of the wiring rules is higher than the priority of copper clad, and the copper clad must comply with the rules of the wiring safety spacing, and internal wiring is required The abnormal addition of the safety distance between the regular copper foils, the specific way is in the complete query NoTimeNo.on comment. In fact, this is unnecessary, because the priority can be changed. There is an option priority setting rule in the left corner of the homepage. The safety spacing rule of the copper cladding layer takes precedence over the safety spacing rule of the above wiring. They are just ways to each other.

2. Width setting of copper wire of printed circuit board:

When copper is selected in the selection of the two modes, set a place for the track width. If you choose the default 8 mils, copper and you connect to the network when you set the line width range, and the minimum line width is 8 mils, then when DRC will be an error, you did not notice this detail at the beginning, and every future There are many errors in the copper DRC.

Inside the clearing rule, create a new rule CLEXANS1 that can be customized (name), then select Advestress (Quebug) in the first object matching option box, click SudiiabuILDER, and then the BuffugQueDeFabor dialog box appears. In this dialog box, Select the first line of the drop-down menu showallllevels (default value), then select the objectkindis drop-down menu under conditiontype/operator, and then on the right side of conditionvalue, select plloy, display the polygon in the right QueRePress view, click OK to confirm exit, and then Not finished, the IsPosion In polygon replaces the full query display box, the last step, now you can change the spacing you need in the constraints. This only affects the copper spacing, not the spacing between layers.