Summary of HOW TO PREVENT MISTAKES THAT DELAY YOUR PCB ASSEMBLY (AND COULD COST YOU)
Summary (under 100 words): Focus on five practical steps to avoid delays and extra cost when sending PCB designs to contract manufacturers: panelize PCBs correctly, ensure legible silkscreen, indicate component polarity, include fabrication and assembly drawings, and provide a complete BOM with manufacturer part numbers. Proper panelization (or leaving it to the PCB fab), readable silkscreen (about 0.2 mm line width), and complete documentation help ensure smooth, on-time, on-budget PCB assembly.
Parts used in the PCB Assembly Best Practices Project:
- PCB panels (multi-board arrays)
- Silkscreen ink/layer
- Overhanging components
- Component reference designators
- Component polarity markings
- Test points
- PCB fabrication drawing
- PCB assembly drawing
- Bill of Materials including Manufacturers’ Part Numbers
Many designers can’t get their board fast enough after sending their PCB design files to their PCB assembly vendors.
But the surprising thing is some customers do not provide sufficient and necessary information to their contract manufacturers (CM) – causing problems, delays, and increased cost.
By focusing on 5 simple steps, you can ensure a smooth PCB assembly process and help your CM deliver your boards to you on-time and on-budget.
Let’s walk through these action items:
- Panelize your PCBs Correctly
- Make Sure Silkscreen is Legible
- Indicate Component Polarity
- Include PCB Fabrication and PCB Assembly Drawings
- Send a Complete BOM that includes Manufacturers’ Part Numbers
1. Panelize Your PCBs Correctly
Panelization is the placement of smaller boards into multi-board arrays to gain manufacturing efficiency.Panelization plays a vital role in the PCB assembly process. And to progress through the PCB assembly process without complications requires using correctly panelized PCBs.
Generally, it is best to leave the PCB panel design to your PCB manufacturer since they know all the requirements and how to implement them. However, should you decide to do the PCB panelization yourself, make sure you follow the design guidelines. Particularly, if your PCB has overhanging components, there needs to be enough spacing between the individual PCBs in the panel so that overhanging components do not overlap adjacent PCBs.
2. Make Sure Your PCB Silkscreen Is Legible
The silkscreen resides on the top layer of a PCB, and it displays useful and necessary information for anyone assembling, testing, or troubleshooting a circuit board. Silkscreen markings are used to indicate component placement locations, component values, reference designators, warning symbols, component polarity, test points, board name & revision, and more. It follows that the non-readability of the silkscreen could create bumps in the assembly process and sabotage the completion date. So, what is a good size for the silkscreen text? In many cases, a line width of about 0.2 mm works well.
Read more: HOW TO PREVENT MISTAKES THAT DELAY YOUR PCB ASSEMBLY (AND COULD COST YOU)
- How should I panelize my PCBs?
Panelize to place smaller boards into multi-board arrays for manufacturing efficiency, follow your PCB manufacturer's guidelines, or leave panel design to the PCB manufacturer. - Can I panelize PCBs myself?
Yes, but follow design guidelines and ensure sufficient spacing for overhanging components so they do not overlap adjacent PCBs. - What is important about silkscreen on a PCB?
Silkscreen provides component placement, values, reference designators, polarity, test points, board name and revision; legibility is essential to avoid assembly issues. - What is a good silkscreen text size?
A line width of about 0.2 mm works well in many cases. - Why indicate component polarity?
Component polarity markings on silkscreen help ensure correct component placement and prevent assembly errors. - What drawings should I include with my PCB files?
Include PCB fabrication and PCB assembly drawings. - What should a complete BOM contain?
A complete BOM should include manufacturers' part numbers. - How does poor documentation affect PCB assembly?
Insufficient documentation can cause problems, delays, and increased cost in the assembly process.
