PCB design is based on the circuit schematic diagram to realize the functions required by the circuit designer. PCB design is a very technical work, and it requires many years of experience accumulation. This checklist covers fabrication-file checks for rigid PCBs: pad and drill definitions, copper-layer mapping, silkscreen clearance and mask openings. Map the Protel layer names below to the copper, mechanical and documentation layers in your CAD tool, then inspect the exported CAM files. Flex-specific coverlay, stiffener and bend rules require a separate review.
First. Overlap of Pads
- Pad overlap and drill overlap are separate checks. In a CAM viewer, inspect the exported copper and drill layers for duplicate or intersecting drill hits, unintended pad bridges and insufficient annular rings; resolve intended slots with the fabricator rather than drawing overlapping round holes.
- Two holes in the multi-layer board overlap. For example, one hole is an isolation disk and the other hole is a connection pad (flower pad), so that the film will appear as an isolation disk after drawing the film, resulting in scrap.
Second. The Abuse of the Graphics Layer
- Some useless connections were made on some graphics layers. Originally, it was a four-layer board but designed with more than five layers of wiring, which caused misunderstandings.
- Save trouble during design. Take the Protel software as an example to draw the lines on each layer with the Board layer, and use the Board layer to mark the lines. In this way, when performing light drawing data, because the Board layer is not selected, it is omitted. The connection is broken, or it may be short-circuited due to the selection of the marking line of the Board layer, so the integrity and clarity of the graphics layer is maintained during design.
- Violation of conventional design, such as component surface design in Bottom layer and welding surface design in Top, causing inconvenience.
Third. The Random Placement of Characters
- The SMD soldering pad of the character cover pad brings inconvenience to the continuity test of the printed board and the soldering of the components.
- The character design is too small, resulting in difficulties in screen printing, and too large will cause the characters to overlap each other and be difficult to distinguish.
Fourth. The Setting of the Single-Sided Pad Aperture
- For a surface-mount pad, use a pad definition without a drill and check that no drill hit is exported. For a through-hole pad, specify its real finished-hole requirement and plating status. Do not set a required hole to zero merely to suppress a drill output.
- Identify plated and non-plated holes in the fabrication package, and compare drill locations with pad and mechanical layers in the exported files.
Five. Use Filler Blocks to Draw Pads
Copper regions can form intentional custom pads, but their electrical connectivity, solder-mask opening and paste aperture need explicit definitions. Check the exported copper, mask and paste together in a CAM viewer; a clean CAD DRC alone does not prove that the intended solderable area has been exported.
PHILIFAST has professional PCB engineer team, provides helpful engineering suggestion to optimize your design.