There are several considerations when performing copper pouring:
1. **Single-point connection of different grounds**: This can be achieved by connecting the grounds with 0-ohm resistors, ferrite beads, or inductors.
2. **Copper-cladding near the crystal oscillator**: Since the crystal oscillator is a high-frequency noise source, copper should be poured around it and the oscillator’s casing should be grounded separately.
3. **Island (Dead Zone) Problem**: If the island area is too large, defining a ground via and adding it won’t significantly increase the cost.
**What are the benefits of copper coating?**
Copper coating can enhance power efficiency, reduce high-frequency interference, and, of course, improve the appearance of the board.
**Is large-area copper pour or grid copper pour better?**
This is not a one-size-fits-all answer. Why? If the copper pour covers a large area and wave soldering is used, the board may warp or even blister. From this perspective, the heat dissipation of grid copper is superior. Typically, grid copper is used in high-frequency PCBs with strict anti-interference requirements, while low-frequency circuits with high current demands often utilize full copper pours.
At the initial stage of routing, the ground wire should be treated with equal importance. The ground trace should be routed properly; you cannot rely solely on adding via holes to connect the ground pins after the copper pour. This approach will have poor results. Of course, if grid copper is used, these ground connections may affect the appearance—if needed, they can be deleted with care.
Copper filling is an intelligent process. It actively evaluates the network properties of vias and pads within the copper pour area, ensuring compliance with the safety distances you have set. This is different from manually drawing copper, which does not have this functionality.
Copper pouring serves many purposes. For example, applying copper on the reverse side of a double-sided PCB and connecting it to the ground can reduce interference, expand the ground wire coverage, and reduce impedance. Therefore, copper is typically poured after the majority of PCB routing is completed.
### Precautions for Copper-Clad Wiring
**1. PCB Copper Clad Safety Spacing Setting:**
The safety distance for copper-clad areas is typically twice that of the routing safety distance. However, prior to copper pouring, the routing safety distance is set first, and once copper is poured, the copper safety distance will default to the routing safety distance. This may not yield the expected results.
A common workaround is to double the safety distance after completing the routing, then pour copper, and finally return the safety distance to the original routing value after the copper pour is finished. This ensures no DRC errors, but if copper needs to be re-poured later, you will have to repeat this process, which can be cumbersome. The optimal approach is to define a separate safety distance rule specifically for the copper pour.
Alternatively, you can add a custom rule. Under the “Clearance” section of the Rule dialog, create a new rule (e.g., “Clearance1”). Then, in the “Where the FirstObjectmatches” dropdown, select “Advanced (Query),” click “QueryBuilder,” and the “BuildingQueryfromBoard” dialog will appear. In the first line of this dialog, select “ShowAllLevels” from the dropdown, and under “ConditionType/Operator,” choose “ObjectKindis.” Next, from the “ConditionValue” dropdown, select “Ploy” (Polygon), which will display “IsPolygon” in the QueryPreview. Click OK to confirm. Save the changes, but note that an error may prompt you to modify the query.
Next, change “IsPolygon” to “InPolygon” in the FullQuery display, and adjust the copper safety gap in the Constraints section. Some believe that routing rules take precedence over copper pour rules, meaning copper pours must comply with routing safety spacing. To ensure compatibility, add an exception for copper pours in the routing safety spacing rules under “FullQuery.” However, this step is unnecessary because you can adjust priorities directly within the rule settings. In the lower-left corner of the rule settings page, there is a “priority” option. By increasing the priority of the copper-clad safety spacing rule, it will take precedence over the routing safety spacing rule, ensuring smooth interaction between both rules.
**2. PCB Copper-Clad Line Width Setting:**
When selecting either the “Hatched” or “None” modes, you will notice a field for “TrackWidth.” If you select the default 8 mil width and the minimum line width for the network connected to your copper pour exceeds 8 mil, a DRC error will occur. This detail is often overlooked, leading to multiple DRC errors after each copper pour.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
