PCB DFM checklist: what to check before you send the files
Ten checks that take minutes and prevent most manufacturing questions: geometry, holes, mask, legend and file set.
What DFM means
DFM (design for manufacturing) means designing the board so that it can be produced reliably and at a fair price. A board that breaks no manufacturing rule is accepted without questions; a board that does leads to calls, changes and lost days. Run through this list before you export the Gerber files.
The checklist
| Check | Why it matters | Rule of thumb |
|---|---|---|
| 1. Board outline | Without a closed outline the shape is unknown | One closed contour, slots and cut-outs on the outline layer |
| 2. Trace width and spacing | Below the process limit traces break or short | Not below the minimum for your copper weight (from 0.15 mm / 0.15 mm on thin copper); see the capabilities page |
| 3. Drill sizes | Very small drills break and cost more | Drill from 0.3 mm with a 0.5 mm pad; holes above 6.4 mm are milled |
| 4. Annular ring | Too little copper around a hole breaks the connection | Give every pad a real margin around its hole |
| 5. Copper to board edge | Copper at the edge is damaged when the board is routed or scored | Keep copper a few tenths of a millimetre from the edge, more for V-cut |
| 6. Solder mask openings | Openings that are off the pad make soldering unreliable | Openings centred on pads, about 0.05 mm larger per side |
| 7. Solder mask bridges | Between fine pads a strip of mask must remain | Check the pad spacing of fine-pitch parts |
| 8. Silkscreen | Legend on pads prevents soldering; tiny text is illegible | Keep text off pads, letters at least about 0.8 mm high |
| 9. Plated and non-plated holes | Mixed holes get the wrong treatment | Separate Excellon files, finished hole sizes, millimetres |
| 10. File set | A missing layer is the most common cause of delay | All copper layers, mask, silkscreen, outline and drill; same origin; checked in a viewer |
Common findings
- Copper pours that touch the board edge.
- Pads whose mask opening is smaller than the pad, so the mask covers the solder surface.
- Text placed over holes or on bare copper.
- Slots drawn on a copper layer instead of the outline layer.
- Different origins in the drill file and the Gerber files.
How to check quickly
Open the complete set in a Gerber viewer and walk through the ten points; the guide how to open and check Gerber files explains how. The price calculator reads your archive, shows a preview and detects layer count and size, and our engineers check every file before production and contact you if something is unclear.
For the limits in detail see vias and hole sizes, trace width and current and the Gerber guide.
Frequently asked questions
What is DFM?
Design for manufacturing: designing a board so that it respects the limits of the production process and can be made reliably at a fair price.
Do you check my files before production?
Yes. Our engineers check every file before production and contact you if something is unclear or outside the manufacturing limits.
What is the most common reason for a delay?
An incomplete file set: a missing layer, a missing outline or a drill file from a different export.
Browse the questions and answers →
See our manufacturing capabilities
Minimum trace and spacing, drill sizes, materials, tolerances and tests for every board type, on one page.
Open the capabilities →Ask an engineer
Not sure what applies to your board? Describe it in a few lines and our engineers will advise you.