How to Set PCB Via Tenting in PCB Design Software
4 min
- Introduction
- Gerber Output and Via Tenting
- Why Via Tenting is Important
- Via Tenting in Altium Designer (AD)
- Via Tenting in Protel 99
- Conclusion
- FAQ
Introduction
Via tenting refers to covering the via pads and holes with solder mask ink (also known as solder resist), preventing solder from adhering to the pads. This is a process widely used in most circuit boards.
It's a critical part of PCB design, protecting the vias and enhancing the board’s durability and performance. In this guide, we'll show you how to configure PCB via tenting in commonly used software such as Altium Designer (AD) and Protel 99 to ensure your Gerber files meet the required manufacturing standards.
Inspection standard: Solder should not adhere to the via pads, whether through reflow soldering or manual soldering.
Gerber Output and Via Tenting
For PCBs ordered with Gerber output, although JLCPCB provides a “Via Covering” option on the ordering platform (with Tented as the most common/default choice), the Gerber file ultimately determines the final via properties. The “Via Tenting” or “Via Expose” options selected on the platform are secondary and not a substitute for correct Gerber configuration, so it’s crucial to configure your files correctly before submission.
Why Via Tenting is Important
According to JLCPCB’s manufacturing standards, tented vias are the default and most commonly used option. They prevent solder wicking into via holes during reflow or wave soldering. For reliable full coverage, via holes should ideally be 0.4 mm or less in diameter and no larger than 0.5 mm (if permitted by routing and current-carrying requirements). Larger vias are not guaranteed to be fully covered, and no complaints are accepted for such defects. By default, AD and Protel 99 export vias as exposed, so you’ll need to adjust the settings to apply tenting before generating Gerber files. Here’s how you can do it.
Via Tenting in Altium Designer (AD)
1. Open your PCB design in Altium Designer. Double-click on any via to open the properties. Check the boxes in front of "Force complete tenting on top" and "Force complete tenting on bottom".
- "Force complete tenting on top " means the vias will be covered on the top layer.
- "Force complete tenting on bottom " means the vias will be covered on the bottom layer.
2. Right-click the via you just edited and choose "Find Similar Objects" from the context menu.In the dialogue box, check both boxes next to "Solder Mask Tenting - Top/Bottom" and click OK to apply the changes.
By completing these steps, your Gerber file will contain tented vias when exported.
Via Tenting in Protel 99
1. Open your PCB design in Protel 99 and go to Design → Rules.In the rules menu, select "Solder Mask Expansion" and double-click to open the settings.
Configure Tenting Settings:
2.In the Solder Mask Expansion Rule menu, set the expansion mode to “Manual” and enter a negative expansion value (e.g., -0.1 mm or a value greater than or equal to the via radius) for vias. This forces the solder mask to fully cover the vias for complete tenting.
Click OK to save the settings, and proceed to export the Gerber file.
Following these steps will ensure that the vias are tented in your Protel 99 design, aligning with manufacturing requirements.
Conclusion
Mastering via tenting is key to producing high-quality, reliable PCBs. By setting up via tenting in Altium Designer or Protel 99, you can ensure your Gerber files are correctly configured for manufacturing. Properly tented vias will enhance the lifespan and performance of your PCB, protecting it from environmental factors.
For the best results, always review your via tenting settings before submitting your Gerber files to manufacturers like JLCPCB. It is also recommended to verify the final Gerber files using JLCPCB’s online Gerber viewer to confirm that all vias are properly tented.
FAQ
Q: Do I still need to set via tenting in the design software if I select “Via Covering” on the JLCPCB ordering platform?
Yes. The Gerber file ultimately determines the via properties; the platform option is secondary.
Q: What via diameter ensures reliable full tenting at JLCPCB?
≤0.4 mm is ideal for full coverage; up to 0.5 mm is allowed but not guaranteed.
Q: Can I apply tenting to only one side of the PCB?
Yes. In Altium Designer, check only “Force complete tenting on top” or “on bottom”.
Q: How do I verify tenting after exporting Gerber files?
Upload the Gerber files to JLCPCB’s online Gerber viewer and confirm solder mask fully covers the vias.
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