How to Add Unique Serial and QR Codes to Your PCBs with Laser Engraving
As the demand for smart electronics and secure traceability grows, integrating unique serial numbers and QR codes into PCB designs has become essential. Whether for inventory tracking, anti-counterfeiting, or quality assurance, laser engraving offers a precise, efficient, and permanent method to mark PCBs.
In this guide, we’ll explore the process, benefits, tools, and best practices for adding serialized and QR code engravings to your PCBs using laser technology.
Why Add Serial Numbers and QR Codes to PCBs?
1. Traceability
Each PCB can be uniquely identified, making it easier to trace back to its production batch, test results, or version.
2. Quality Control
Tracking PCBs through their manufacturing lifecycle improves quality assurance and defect diagnostics.
3. Anti-Counterfeiting
Serialized QR codes provide a tamper-proof mechanism to verify product authenticity.
4. Automation and Inventory
Scannable codes streamline inventory management and integration with ERP/MES systems.
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What Is Laser Engraving for PCBs?
Laser engraving is a non-contact process where a high-powered laser ablates the surface of the PCB’s solder mask or silkscreen to expose markings. It’s often used to inscribe serial numbers, barcodes, or QR codes without affecting the board’s electrical performance.
Tools and Technologies Required
1. Laser Engraving Machine
- CO₂ lasers (for silkscreen marking)
- Fiber lasers (for metal surfaces like copper or aluminum)
- UV lasers (best for high-resolution QR code marking on PCBs)
2. Code Generation Software
Software to generate unique serial numbers and QR codes, often integrated with your manufacturing data system.
3. Engraving Control System
Used to control laser intensity, focus, and path—either standalone or integrated into the pick-and-place or AOI line.
4. Vision Alignment System
Ensures precise placement of the engraving, especially for double-sided or small PCBs.
Step-by-Step Process to Add Serial and QR Codes with Laser Engraving
Step 1: Generate Serial and QR Codes
Use a data management system or scripting tool to auto-generate unique identifiers. Codes can contain:
- Batch IDs
- Date/time stamps
- Product numbers
- URLs for verification
Step 2: Design Placement Area
In your PCB design software (e.g., Altium, KiCad), reserve a specific area (usually 4–8mm²) for marking. Keep it free of components and copper traces.
Step 3: Pre-Process Alignment
Align the board using fiducial markers or machine vision to ensure the engraving lands in the exact location.
Step 4: Laser Engraving Execution
Configure the laser:
- Power settings: Low enough to avoid damaging the PCB layers
- Speed: Adjust for optimal resolution
- Depth: Typically shallow, just removing the top solder mask or silkscreen
Trigger the laser process for each PCB—serial or code is dynamically read from a database or code generator.
Step 5: Verification
Use a barcode scanner or vision system to verify the readability of the code immediately post-engraving.
Types of Codes You Can Engrave
| Code Type | Use Case | Readability |
|---|---|---|
| Serial Number | Unique identifier for traceability | Human/machine readable |
| 1D Barcode | Inventory tracking | Fast scanning |
| QR Code | URLs, data storage | High-density information |
| Data Matrix | Industrial automation systems | Space-efficient |
Best Practices for Laser Code Marking on PCBs
- Use contrasting backgrounds: Ensure the engraved area is visually distinct for better readability.
- Avoid copper layers underneath marking zones: Prevent interference or unintended circuit exposure.
- Maintain adequate clearance: Leave at least 1–2mm around the code area to avoid overlapping components.
- Test different laser settings: Optimize for mask type, color, and substrate material.
- Use version control: Embed firmware version or build ID into the QR for fast diagnostics.
Common Mistakes to Avoid
- Engraving too deep and damaging the underlying copper or board.
- Placing the code where it might be covered by components or solder paste.
- Not verifying code readability under different lighting or after reflow.
- Skipping alignment checks, leading to misplacement.
Advantages of Laser Engraving Over Other Methods
| Method | Durability | Speed | Resolution | Cost | Use Case |
|---|---|---|---|---|---|
| Laser Engraving | Permanent | Fast | High | Medium | Industrial & commercial |
| Inkjet Printing | Low | Very Fast | Medium | Low | Prototyping |
| Sticker Labels | Low | Fast | Variable | Low | Manual handling |
| Etching (chemical) | High | Slow | High | High | HDI/semiconductor |
Laser engraving provides the best balance of durability, automation, and precision for serialized PCB identification.
Real-World Applications
- Consumer Electronics: Trace device back to production line.
- Medical Devices: Compliance with FDA/EMC traceability requirements.
- Automotive: Track performance or recall data by QR code.
- Defense Systems: Secure tracking and anti-counterfeiting.
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Conclusion
Laser engraving of serial numbers and QR codes onto PCBs is a critical feature for modern electronic manufacturing. It provides permanent, readable, and scalable markings that improve traceability, quality control, and logistics automation. With proper planning, laser marking becomes a seamless part of the PCB production workflow—boosting both operational efficiency and product security.
