PCB Silkscreen Guide: Design Rules, Colors, and Common Mistakes to Avoid

If you’ve ever squinted at a circuit board trying to figure out which way a capacitor goes or where pin 1 is located, you already understand why PCB silkscreen matters. After 12 years of designing boards and reviewing thousands of Gerber files, I can tell you that silkscreen is one of the most overlooked aspects of PCB design—until something goes wrong during assembly.

PCB silkscreen (also called the legend layer or nomenclature) is the ink layer printed on your circuit board that contains component designators, polarity markings, logos, and other human-readable information. It’s essentially the user manual printed directly onto your board, and getting it right can mean the difference between smooth production runs and costly assembly errors.

In this guide, I’ll walk you through everything you need to know about PCB silkscreen—from material selection and color choices to design rules and the mistakes I’ve seen derail projects. Whether you’re a hobbyist working on your first board or a seasoned engineer looking to refine your process, you’ll find practical information you can apply immediately.

---

What is PCB Silkscreen and Why Does It Matter?

PCB silkscreen refers to the layer of ink applied to the outer surfaces of a printed circuit board. This layer serves purely informational purposes—it doesn’t affect the electrical characteristics of your board, but it significantly impacts manufacturability, assembly efficiency, and field serviceability.

The term “silkscreen” comes from the traditional printing method where ink was pushed through a silk mesh stencil onto the board surface. While modern PCB manufacturing has largely moved beyond actual silk screens, the name stuck.

Primary Functions of PCB Silkscreen

Your silkscreen layer serves several critical purposes:

Component identification — Reference designators (R1, C5, U3, etc.) help assemblers place components correctly and technicians locate parts during troubleshooting.

Polarity and orientation marking — Indicators for pin 1, cathode stripes, and alignment marks prevent reversed component installation.

Test point labeling — Clearly marked test points speed up debugging and quality control testing.

Branding and documentation — Company logos, part numbers, revision codes, date codes, and certification marks.

Assembly instructions — Jumper settings, configuration notes, and warning symbols.

From a production standpoint, well-designed silkscreen can reduce assembly time by 15-20% and cut down on placement errors significantly. That’s real money when you’re running thousands of boards through an assembly line.

---

PCB Silkscreen Materials and Ink Types

The ink used for PCB silkscreen isn’t just regular paint. It needs to withstand soldering temperatures, resist chemicals used in manufacturing, and adhere properly to the solder mask surface. Here’s what you need to know about the main types.

Types of PCB Silkscreen Ink

Ink Type	Curing Method	Durability	Cost	Best For
Epoxy Ink	Heat cure (150-175°C)	Excellent	Medium	High-reliability applications, automotive, aerospace
Acrylic Ink	UV cure	Good	Low	Consumer electronics, prototypes
Polyester Ink	Heat cure	Very Good	Medium-High	Industrial applications requiring chemical resistance

Epoxy-based inks are the industry standard for most applications. They cure through a thermal process and offer excellent adhesion, chemical resistance, and durability. If you’re not sure what to specify, epoxy ink is usually the safe choice.

Acrylic inks cure under UV light, which speeds up production. They’re less expensive but don’t hold up as well under harsh conditions. Fine for consumer products that won’t see extreme temperatures or chemical exposure.

Polyester inks offer superior chemical resistance, making them suitable for industrial environments where boards might be exposed to solvents or cleaning agents.

Silkscreen Ink Properties to Consider

When specifying your PCB silkscreen requirements, consider these properties:

• Adhesion strength — How well the ink bonds to the solder mask
• Abrasion resistance — Important for boards that will be handled frequently
• Chemical resistance — Crucial if the board will be exposed to solvents or cleaning processes
• Temperature resistance — Must survive reflow soldering (typically 260°C peak)
• Contrast ratio — Readability against the solder mask color

Read more: A Step-by-Step Introduction of PCB Manufacturing :

---

PCB Silkscreen Colors: Making the Right Choice

Color selection for PCB silkscreen isn’t just aesthetic—it’s a legibility issue. The goal is maximum contrast against your solder mask color for easy reading under various lighting conditions.

Standard PCB Silkscreen Color Combinations

Solder Mask Color	Recommended Silkscreen	Alternative Options	Avoid
Green	White	Yellow	Green, Black
Blue	White	Yellow	Blue
Black	White	Yellow	Black, Dark colors
Red	White	Yellow, Black	Red
White	Black	Blue, Red	White, Yellow
Yellow	Black	Blue, Red	Yellow, White
Purple	White	Yellow	Purple
Matte Black	White	Yellow (high contrast)	Any dark color

White silkscreen is the industry default and works well with green, blue, red, black, and purple solder masks. It’s the safest choice for most applications.

Black silkscreen is necessary when using white or yellow solder masks. Some designers also use it on green boards for a distinctive look, though contrast is reduced.

Yellow silkscreen provides excellent visibility on darker boards and can be a good alternative to white, particularly for boards that will be inspected under low-light conditions.

Special Color Considerations

Some industries have specific requirements:

• Automotive often specifies white on green for standardization
• Medical devices may require specific colors for compliance or identification
• Military/aerospace typically follows IPC standards with white on green

I generally recommend sticking with white on green unless you have a specific reason to deviate. It’s the most widely used combination, which means suppliers have the most experience with it and problems are less likely.

---

PCB Silkscreen Printing Methods

How your silkscreen gets applied affects resolution, cost, and durability. Understanding the options helps you make informed decisions and communicate effectively with your fabricator.

Manual Screen Printing (Traditional Method)

The original method uses an actual mesh screen with a stencil of your artwork. Ink is pushed through the mesh onto the board surface.

Pros:

• Low setup cost for high volumes
• Works well for simple designs
• Familiar process at most fab houses

Cons:

• Lower resolution (8 mil minimum line width typical)
• Registration accuracy limited
• Screen wear affects consistency

Liquid Photo Imaging (LPI)

LPI uses a photosensitive ink that’s applied to the entire board, then exposed to UV light through a photomask. Unexposed areas are washed away.

Pros:

• Better resolution than manual screening (4-5 mil lines possible)
• More consistent results
• Good for fine-pitch components

Cons:

• Higher cost than manual screening
• More complex process
• Not available at all fabricators

Direct Legend Printing (DLP) / Inkjet

The newest method uses industrial inkjet technology to print directly onto the board surface. No screens or masks required.

Pros:

• Highest resolution (down to 3 mil lines)
• No tooling costs
• Easy to change designs
• Excellent registration
• Cost-effective for prototypes and small runs

Cons:

• Ink adhesion can be slightly lower
• Not all fab houses have the equipment
• May have color limitations

For most modern designs, DLP/inkjet is becoming the preferred method. The resolution and flexibility benefits outweigh the minor adhesion trade-off, especially for boards with fine-pitch components where accurate silkscreen placement matters most.

---

PCB Silkscreen Design Rules and Guidelines

This is where many designers get into trouble. Following proper design rules prevents manufacturing issues and ensures your silkscreen actually serves its purpose.

Critical PCB Silkscreen Design Specifications

Parameter	Minimum Value	Recommended Value	Notes
Text height	0.8 mm (32 mil)	1.0 mm (40 mil)	Smaller text may be illegible
Line width	0.15 mm (6 mil)	0.2 mm (8 mil)	Thinner lines may not print
Text stroke width	0.1 mm (4 mil)	0.15 mm (6 mil)	Varies by font
Clearance from pads	0.1 mm (4 mil)	0.2 mm (8 mil)	Prevents solder contamination
Clearance from vias	0.1 mm (4 mil)	0.15 mm (6 mil)	Unless tented
Clearance from board edge	0.25 mm (10 mil)	0.5 mm (20 mil)	Prevents cutting issues

Font Selection for PCB Silkscreen

Not all fonts work well for silkscreen printing. Here’s what I’ve learned works best:

Recommended fonts:

• Vector fonts — Scale cleanly and produce consistent results
• Sans-serif fonts — Better legibility at small sizes
• Monospace fonts — Useful for aligned data like serial numbers

Fonts to avoid:

• Serif fonts (fine details get lost)
• Script or decorative fonts
• Fonts with very thin strokes
• TrueType fonts that don’t convert well to vectors

Most EDA tools have built-in stroke fonts designed specifically for PCB silkscreen. Use them. They’re optimized for this application.

Reference Designator Placement Guidelines

Proper placement of component designators is an art form. Here are the rules I follow:

1. Place designators adjacent to their component, not on top of it
2. Maintain consistent orientation — I prefer all text readable from the bottom or right edge
3. Group related designators — Keep them close but not overlapping
4. Prioritize readability — If space is tight, prioritize key components
5. Consider assembly process — Place designators where they’ll be visible after component placement

For dense boards, you may need to make hard choices about what gets labeled. In these cases, prioritize:

• Polarized components (ICs, diodes, electrolytics)
• Adjustment components (potentiometers, switches)
• Test points
• Connectors

---

What to Include on Your PCB Silkscreen

Every board is different, but there are standard elements that should appear on most designs.

Essential PCB Silkscreen Elements

Component reference designators — R1, C5, U3, etc. Follow the schematic naming convention.

Polarity indicators:

• Pin 1 dots or notches for ICs
• Plus/minus symbols for polarized capacitors
• Cathode bars for diodes
• Key markings for connectors

Board identification:

• Part number
• Revision number (REV A, REV B, etc.)
• Date code placeholder
• Serial number area (if applicable)

Regulatory markings:

• CE mark (for European compliance)
• FCC ID (for US RF devices)
• UL recognition mark
• RoHS compliance indicator

Company information:

• Company name or logo
• Website URL (optional)
• Country of origin (required for some markets)

Optional but Useful PCB Silkscreen Elements

Test point labels — TP1, TP2, etc., or signal names like VCC, GND, CLK

Jumper settings — Configuration tables showing jumper positions

Version information — Hardware version, firmware compatibility notes

Assembly notes — “NO CLEAN” indicators, special instructions

Functional labels — INPUT, OUTPUT, POWER, USB, etc. on connectors

---

Common PCB Silkscreen Mistakes to Avoid

I’ve reviewed thousands of designs over the years. These are the mistakes I see most often.

Mistake #1: Silkscreen Over Pads

This is the cardinal sin of silkscreen design. When silkscreen ink gets on exposed copper pads, it can:

• Prevent proper solder wetting
• Cause intermittent connections
• Lead to solder joint failures

The fix: Set up your DRC (Design Rule Check) to catch silkscreen-to-pad violations. Most EDA tools can do this automatically. Use a minimum clearance of 4 mil, preferably 8 mil.

Mistake #2: Text Too Small to Read

Designers often try to label every component on a dense board, resulting in text so small it’s useless.

The fix: If text must be smaller than 32 mil height, consider:

• Using abbreviations
• Labeling only critical components
• Creating a separate assembly drawing with full designators

Mistake #3: Missing Polarity Indicators

Nothing ruins your day like finding 500 boards with reversed electrolytics because there was no polarity marking.

The fix: Always include polarity indicators for:

• All polarized capacitors
• Diodes (show cathode)
• ICs (pin 1 indicator)
• Connectors with key orientation
• LEDs

Mistake #4: Silkscreen Over Vias

Unless your vias are tented (covered with solder mask), silkscreen ink can flow into via holes during printing, causing:

• Incomplete ink coverage
• Messy appearance
• Potential contamination issues

The fix: Maintain clearance from exposed vias, or specify tented vias in your fab notes.

Mistake #5: Inconsistent Text Orientation

Boards where some text reads left-to-right, some bottom-to-top, and some upside-down are frustrating to work with during assembly and debugging.

The fix: Establish a convention and stick to it. My preference is all text readable from the bottom or right edge of the board.

Mistake #6: Forgetting the Second Side

Many designers focus on the top silkscreen and forget the bottom layer entirely. If you have bottom-side components, they need proper labeling too.

The fix: Review both silkscreen layers before releasing your design.

Mistake #7: Non-Manufacturing-Ready Artwork

Silkscreen that looks great on screen may not translate to production. Common issues include:

• Lines thinner than the fab house can produce
• Text converted to fills instead of strokes
• Missing clearances at board edges

The fix: Always generate Gerber files and review them with a Gerber viewer before sending to manufacturing.

---

PCB Silkscreen Design Rules by Manufacturer

Different fabricators have different capabilities. Here’s a comparison of typical silkscreen specifications from major PCB manufacturers:

Manufacturer	Min Line Width	Min Text Height	Min Clearance to Pad
JLCPCB	0.15 mm (6 mil)	0.8 mm (32 mil)	0.1 mm (4 mil)
PCBWay	0.15 mm (6 mil)	0.8 mm (32 mil)	0.15 mm (6 mil)
OSH Park	0.15 mm (6 mil)	1.0 mm (40 mil)	0.15 mm (6 mil)
Eurocircuits	0.12 mm (5 mil)	0.8 mm (32 mil)	0.1 mm (4 mil)
Advanced Circuits	0.15 mm (6 mil)	0.8 mm (32 mil)	0.1 mm (4 mil)

Always check your specific fabricator’s design rules before finalizing your layout. Capabilities vary, and what works at one shop may cause problems at another.

---

PCB Silkscreen and IPC Standards

If you’re working on professional or certified products, you’ll need to follow IPC standards for silkscreen quality and marking requirements.

Relevant IPC Standards for PCB Silkscreen

IPC-A-610 — Acceptability of Electronic Assemblies Defines acceptance criteria for silkscreen quality including:

• Legibility requirements
• Adhesion standards
• Acceptable defects

IPC-2221 — Generic Standard on Printed Board Design Provides guidance on:

• Marking content requirements
• Text sizing recommendations
• Placement guidelines

IPC-6012 — Qualification and Performance Specification for Rigid PCBs Specifies:

• Class 1/2/3 requirements for legend quality
• Testing methods
• Acceptance criteria

For Class 3 (high-reliability) boards, silkscreen requirements are more stringent, with tighter tolerances for legibility, adhesion, and registration accuracy.

---

Useful PCB Silkscreen Resources and Tools

Here are resources I’ve found valuable over the years:

Design Guidelines and Standards

• IPC Designer Certification Program — www.ipc.org — Training and certification for PCB design
• PCB Design Guidelines — Most EDA vendors provide application notes on silkscreen best practices
• Manufacturer Design Rules — Always download and review your fab house’s specific capabilities

Gerber Viewers (Free)

Tool	Platform	Features
Gerbv	Linux, Windows	Open source, lightweight
KiCad Gerber Viewer	Cross-platform	Part of KiCad suite
ZofzPCB	Windows	3D visualization
Ucamco Reference Gerber Viewer	Web-based	Official Gerber format viewer
JLCPCB Gerber Viewer	Web-based	Quick online checking

EDA Software with Silkscreen DRC

• KiCad — Free, open-source, excellent DRC capabilities
• Altium Designer — Professional tool with comprehensive rule checking
• Eagle — Popular mid-range option
• OrCAD/Allegro — Industry standard for complex designs

Additional Reference Materials

• Saturn PCB Design Toolkit — Free calculator for various PCB parameters
• PCB Libraries — Component footprint libraries with proper silkscreen
• IPC-7351 — Land pattern standard that includes silkscreen guidelines

---

PCB Silkscreen for Different Applications

Different industries have different requirements. Here’s what to consider for specific applications.

Consumer Electronics

• Cost optimization often means minimal silkscreen
• Focus on regulatory markings and essential polarity indicators
• White on green is standard
• DLP/inkjet printing common for cost efficiency

Medical Devices

• Full traceability required (UDI compliance)
• Must include lot codes and serial numbers
• Higher legibility standards
• May require specific material certifications

Automotive

• Must survive extreme temperatures (-40°C to +125°C typical)
• Higher adhesion requirements
• IATF 16949 compliance considerations
• AEC-Q standards may apply

Aerospace and Defense

• MIL-spec requirements (MIL-PRF-55110, MIL-PRF-31032)
• Full documentation of materials and processes
• Class 3 IPC standards minimum
• May require conformal coating compatibility

---

Frequently Asked Questions About PCB Silkscreen

Can PCB silkscreen be removed or modified after manufacturing?

Technically, silkscreen can be removed using abrasive methods or chemical solvents, but I don’t recommend it. Removal attempts typically damage the solder mask underneath or leave visible marks. If you need to correct silkscreen errors, it’s almost always better to respin the board. For prototypes where cost is a major concern, you can sometimes mask over incorrect markings with additional silkscreen ink, but this is a band-aid solution at best.

Does PCB silkscreen affect electrical performance?

No, silkscreen is electrically inert and has no direct effect on your circuit’s performance. The ink is non-conductive and is applied only to the solder mask surface, never on exposed copper. However, silkscreen problems can cause indirect issues—for example, if ink contaminates solder pads during printing, you may experience solder joint failures. This is why maintaining proper clearances is critical.

What’s the minimum feature size for PCB silkscreen?

Most manufacturers can reliably produce 6 mil (0.15 mm) line widths and 32 mil (0.8 mm) text height using standard processes. With DLP/inkjet printing, some fabs can go down to 4 mil lines and 25 mil text, but I recommend designing to 8 mil lines and 40 mil text unless space constraints force otherwise. Remember: just because a fab can produce smaller features doesn’t mean you should specify them.

Should I put silkscreen on both sides of the PCB?

Yes, if you have components on both sides. Bottom-side silkscreen is often neglected, leading to assembly difficulties and increased error rates. Even if your bottom side only has a few passives, having reference designators visible makes hand assembly easier and helps during debugging. The cost difference for adding bottom silkscreen is minimal at most fabricators.

How do I specify silkscreen color in my fabrication notes?

In your fab drawing or order notes, specify both the solder mask color and silkscreen color explicitly. For example: “Solder mask: Green (both sides), Silkscreen: White (both sides).” Don’t assume the fabricator will choose appropriate colors—I’ve seen boards come back with green silkscreen on green solder mask because the color wasn’t specified. When ordering through online PCB services, there’s usually a dropdown menu for these options.

---

Conclusion

PCB silkscreen might not be the most glamorous aspect of board design, but getting it right pays dividends throughout your product’s lifecycle. From reducing assembly errors to simplifying field repairs, good silkscreen design is a hallmark of professional PCB work.

The key takeaways:

• Choose appropriate ink and color combinations for your application and solder mask
• Follow design rules — minimum sizes, clearances, and placement guidelines exist for good reasons
• Include all necessary information — designators, polarity, identification, and regulatory marks
• Avoid common mistakes — especially silkscreen over pads and illegible text
• Verify before manufacturing — review Gerbers carefully, including both top and bottom silkscreen layers

Your silkscreen layer is the communication channel between you and everyone who will ever handle your board—assemblers, test technicians, field service engineers, and future designers working on revisions. Make that communication clear, and you’ll avoid countless headaches down the road.

Have questions about a specific silkscreen challenge? Drop them in the comments below—I’m happy to help troubleshoot.