10 design guidelines for PCB copper layers

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Here are 10 design guidelines for PCB copper layers.

1. When generating output, use “flashes” for pads and avoid “painted” pads (i.e. pads filled with small draws).
2. Avoid filling large copper areas or copper planes with small draws (“painting”). Where possible, use contours or polygons to construct areas or planes. Contourized areas or Polygon Area fill are standard features in Extended Gerber output (RS-274X).
3. When generating output include the board outline in your copper layers.
   It is better to use a small line – e.g. 0.50mm (20mil) wide – where the center of the line is the exact board outline. We will remove this line during the making of the production tools.
4. Remove copper pads from NPTH holes if these pads are not used or connected to other copper. If you require copper pads on NPTH holes then it is advisable to use a minimum Outer Annular Ring (OAR) of 0.30mm (12mil).
5. Check your final design for small areas of unconnected copper or narrow copper webs and slivers which can lead to problems in production.
   
   X: Must meet or larger than minimum Track Width.
   A: Avoid if possible.
   B: Preferred design
6. Minimal clearance between edge of board and pattern.
   For routed boards:
   0.25mm (10mil) on outer layers
   0.40mm (16mil) on inner layers
   For boards with scoring (V-cut):
   0.45mm (18mil) on outer and inner layers
7. If you require a copper area or plane to extend up to the board edge, then clearly indicate this in the mechanical layer. Copper up to the board edge should only be used where absolutely necessary because:
   7.1. There is a risk of a rough board edge as the copper may tear during contour routing (profiling).
   7.2. The copper can create electrical shorts(https://sdy-pcb.com/capabilities/#a-pequ) between layers.
   7.3. Copper up to the board edge is NOT compatible with scoring (V-cut).
8. If you require the board edge or part of it to be plated, then clearly indicate this in the mechanical layer.
9. Any text placed in a copper layer has to comply with the design rules for the given class (see classification table).
   All copper text must be correctly readable. As a PCB is always viewed from top to bottom through the PCB, text on the top layer of your board should be readable and text on the bottom layer should be non-readable or mirrored.
10. Avoid “peelables”. “Peelables” occur during production and are small/narrow pieces of photo resist enclosed by pads, traces and/or planes which may “peel” away during processing and cause short or open circuits. All copper even within the same net must comply with the design rules for the given class.

Above are 10 guidelines for PCB copper layers design. It is able to avoid some confusion on gerber data to take those guidelines into consideration. SDY will check the PCB data pre-production, but it would help the order going smoother if the PCB data is perfect. Kindly please feel free to contact Alex@sdy-pcb.com or our engineer for further questions or PCB projects.