PCB design glossary
Silkscreen
The white (or other-color) ink layer on a PCB used for labels, reference designators, and component outlines.
Silkscreen is the printed layer that helps humans assemble and debug the board. Reference designators (R1, C2, U3), polarity marks on diodes and LEDs, pin-1 indicators on ICs, version numbers, and logos all live on silkscreen.
Silkscreen has no electrical function but is essential for usability. Tiny or missing silkscreen is a top cause of assembly errors.
What belongs on the silkscreen
- Reference designators (R1, C2, U3) next to each part.
- Polarity marks for diodes, LEDs and electrolytic capacitors.
- Pin-1 marks for ICs and connectors.
- Connector labels and pin names (GND, 5V, TX, RX).
- Board name, version and date, which save confusion later.
Sizes that stay readable
Low-cost fabs typically need silkscreen lines of at least about 0.15 mm and text at least 0.8 to 1 mm tall to stay legible. Smaller text often prints as a smudge. Check your fab's own minimums before shrinking labels to fit.
Common silkscreen mistakes
- Text over pads: the fab clips it, leaving half-labels.
- Labels hidden under the part once it is assembled.
- Designators placed ambiguously between two parts.
- Polarity marks missing, which is a top cause of backwards diodes and capacitors.
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Labels that survive to the finished board
Reference designators and part outlines come with every footprint in PCBEditor, and the Silk tab is where you check them before export, so no label ends up printed across a pad.
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