Designing a circuit board is only half the battle. Even the most innovative electronics design can fall short in production if it isn’t optimized for Printed Circuit Board Assembly (PCBA). That’s where Design for Assembly (DFA) comes in.
At Poly Electronics, we’ve seen firsthand how small oversights in design can create major headaches during assembly—from misaligned components to sourcing delays. Whether you’re building 10 prototypes or scaling to 10,000 units, here are the top DFA mistakes to avoid in your PCBA projects:
Poor Component Placement and Orientation
Automated assembly relies on consistency. Components that are misaligned, inconsistently rotated, or placed too close together increase the risk of misplacement, solder bridging, and rework.
Why it matters:
Pick-and-place machines operate best when components are uniformly oriented and evenly spaced. Non-standard orientations slow down programming and raise the likelihood of placement errors.
Best Practice:
Use standard 0°/90° orientation wherever possible and maintain at least 0.5mm spacing between parts to support accurate, efficient placement.
Ignoring Assembly and Rework Clearances
Designers often pack components too tightly to save board space—but this can backfire during rework or inspection. Components placed near connectors, test points, or board edges may block soldering tools or AOI (Automated Optical Inspection) visibility.
Why it matters:
Technicians need access for rework, and inspection systems require visibility of solder joints.
Best Practice:
Leave sufficient clearance around larger components, connectors, and heat sources to allow for airflow, testing, and manual rework.
Overlooking Fiducials and Tooling Features
Fiducials are reference marks that help machines align and place components accurately. Omitting them—or placing them incorrectly—can result in alignment issues during surface-mount assembly.
Why it matters:
Without fiducials, machines may misplace components, especially on dense or double-sided PCBs.
Best Practice:
Include at least three global fiducials on the board or panel, and local fiducials near fine-pitch and BGA components.
Unverified or Obsolete BOM Components
Even a perfect PCB layout can be held up if your Bill of Materials (BOM) includes parts that are out of stock or obsolete. Designers sometimes spec uncommon or discontinued parts without checking availability.
Why it matters:
Unavailable parts delay production—or worse, force a redesign around alternate components.
Best Practice:
Work with your PCBA partner early to vet BOM parts for availability and cost. At Poly Electronics, we perform BOM audits during quoting to catch issues before they disrupt productionDesigning Without
Manufacturing Feedback
Skipping a Design for Manufacturability (DFM) review is like building a house without consulting the contractor. Small decisions—like poor thermal relief or incorrect pad sizing—can lead to issues like tombstoning, cold joints, or solder bridging.
Why it matters:
These problems aren’t always obvious in design tools, but they can cause field failures or costly rework in production.
Best Practice:
Submit your Gerber files, BOM, and assembly drawings for a DFM review before production. Many manufacturers, including Poly Electronics, offer this as a value-added service to prevent surprises later.
Final Thoughts
Designing for assembly isn’t just about how your board looks on a screen—it’s about making sure your product can be built accurately, efficiently, and at scale. The earlier you involve your PCBA partner in the process, the fewer delays and surprises you’ll encounter.
At Poly Electronics, we help customers move seamlessly from concept to full production, with a strong focus on speed, quality, and reliability. If you’re unsure whether your design is ready for production, we’re here to help.
