PCB Silkscreen Guide for Design and Manufacturing

Introduction

PCB silkscreen is a marking layer that helps people identify key information on a printed circuit board. It does not carry current. It does not affect the circuit directly. However, a clear silkscreen PCB design helps people read, assemble, test, repair, and identify the board.

This guide explains what PCB silkscreen is, why it matters, and how to design it correctly. You will also learn how to choose the best font for PCB silkscreen.

What Is Silkscreen in PCB?

In PCB design and manufacturing, people also call silkscreen the legend layer or component legend.

On our quotation page, “Component Legend” means PCB silkscreen. The options “Component Legend Color” and “Component Legend Side” let you choose the silkscreen color and printing side.

Silkscreen includes component marks, symbols, logos, warning labels, and other useful information printed on the board surface.

Common silkscreen content includes:

Silkscreen can also include general board information.

Examples include:

• Board name
• Part number
• Revision number
• Date code
• Manufacturer logo
• Customer logo
• Warning labels
• QR code
• Serial number
• UL mark

For mass production, board revision and part number are essential. They help prevent mixed versions during assembly and shipment.

PCB silkscreen colors depend on the solder mask color and the options offered by the PCB factory.

The most common silkscreen colors are:

PCB Silkscreen Manufacturing Methods

PCB manufacturers use different methods to print silkscreen. The printing method can affect cost, lead time, and text clarity.

Screen Printing

Screen printing is a traditional silkscreen method. It uses a mesh screen to transfer ink onto the PCB surface.

This method works well for standard PCB production and larger batch orders. It is cost-effective, but it may not be the best choice for very fine text.

LPI

LPI(Liquid Photo Imaging) uses photoimageable ink and exposure process steps. It can produce finer and more accurate markings than traditional screen printing.

LPI is a good choice when the PCB needs clearer text, finer details, and better alignment.

Inkjet Printing

Inkjet printing is a digital printing method. It prints text and symbols directly onto the PCB.

It is suitable for quick-turn production, prototypes, and variable markings such as serial numbers or QR codes.

Different PCB manufacturers may use different silkscreen methods. Designers should always check the manufacturer’s capability before using very small text, fine graphics, or special marks.

PCB Silkscreen Design Guidelines

Good silkscreen design should be clear, useful, and manufacturable.

Keep Text Clear and Readable

Silkscreen text should be large enough to read after manufacturing.

Tiny text may look fine in CAD software, but it may become blurred or broken on the real PCB.

For most standard PCB designs, a safer choice is:

• Font height: 1.0 mm or larger
• Stroke width: 0.15 mm or larger

JLCPCB states that silkscreen text should use at least 1 mm height and no less than 0.15 mm width or spacing between letters. These values are useful references, but you should always confirm the final rule with your PCB manufacturer before production

Avoid Placing Silkscreen on Pads

Do not place silkscreen over solder pads.

Silkscreen on pads may affect soldering. The manufacturer can also remove it automatically during DFM cleanup. If this happens, the final board may lose part of the text or symbol.

For example, if the letter R1 touches a resistor pad, the manufacturer may clip the text. The result may look unclear on the final board.

Keep Enough Clearance from Solder Pads

Silkscreen should keep enough clearance from solder pads, vias, and exposed copper.

A practical rule is to keep silkscreen away from pads by at least the manufacturer’s minimum clearance.

For standard boards, keep about 0.15 mm between silkscreen and solder pads as a general reference. The final rule depends on your PCB factory, so check its DFM rules before production.

Use Consistent Reference Designators

Use standard and consistent designators.

Common examples:

Consistent labels make the PCB easier to compare with the schematic, BOM, and assembly drawing.

Adding Custom Logos and Graphics

Custom logos, icons, and graphics can be added to PCB silkscreen.

They are useful for:

• Brand identity
• Product identification
• Warning symbols
• QR codes
• Serial numbers
• Assembly marks

Minimum Font Height and Stroke Width

The table below gives practical design references for standard PCB silkscreen.

These values are general references. The real limit depends on solder mask color, silkscreen color, board surface, printing method, and manufacturer capability.

Font Size Recommendations by Fab

Each PCB manufacturer may have different silkscreen design rules. The safest approach is to check your chosen manufacturer’s latest guidelines before production.

Best Font for PCB Silkscreen

The best font for PCB silkscreen is simple, clean, and easy to read.

A good silkscreen font should remain clear after printing, solder mask processing, assembly, and inspection.

Good choices include:

• Sans-serif fonts
• Vector fonts
• Simple CAD fonts
• Single-line or stroke fonts supported by your EDA tool

Avoid decorative fonts, very thin fonts, and complex logo-style text.

Conclusion

A good silkscreen design should be clear, accurate, readable, and manufacturable. It should also avoid pads, keep enough clearance, and follow the PCB manufacturer’s design rules.

If your PCB needs special silkscreen requirements, such as logos, QR codes, serial numbers, UL marks, or custom graphics, confirm them with your PCB manufacturer before production.