# Soldermask on Hole (Via) Without Opening

_Published: 2016-10-06_

Soldermask opening always is a very important thing for [various PCB](http://www.bestpcbs.com/), esp. for rigid [FR4 PCB](http://www.bestpcbs.com/products/FR4-pcb.htm). In previous article, we already discussed [why soldermask opening & tented was not the same like original gerber file](https://www.bestpcbs.com/blog/2016/08/why-sldermask-opening-or-tented-was-not-the-same-like-the-original-gerber-file/).

If you really want soldermask opening for hole (Via) less than 0.60mm, you should added special notice when placing order.

At the same time, there’s another method you can use: To increase the soldermask opening diameter, that means add an “Annular Ring”. Normally you will need to increase 0.10mm (4mil) on each side, so that there’ll be a 0.1mm “Annular Ring” around the hole/Via, that Annual ring will stop soldermask into the hole/via of [PCB](http://www.bestpcbs.com/).

Because in a lot of design, if there’s Via/Hole, there’ll no opening in its soldermask file, maybe engineer think the drill will remove the soldermask and then there’ll no soldermask on these Via/hole of board. As mentioned before, if Via/Hole in Printed circuit board was less than 0.6mm, or around 0.65mm then it’ll be a problem.

See from bellowing pictures of [PCB board](http://www.bestpcbs.com/products/FR4-pcb.htm):

![0.635mm Drill hole (Via)](https://www.bestpcbs.com/blogimages/2016/10/0.635mm-Via.jpg)0.635mm Drill hole (Via)

(0.635mm Drill hole (Via)

This is the original PCB [Gerber file](https://www.bestpcbs.com/blog/2016/08/what-is-pcb-gerber-file/), the diameter of drill hole was 0.635mm and there’s no soldermask opening on GTS (top soldermask) Gerber file. (Purple color was GTS, Yellow: GTL (top layer); Blue: Drill (PTH) file), and no Annular Ring.

So final circuit boards will be like belowing:

![0.635mm Via covered/tented by soldermask](https://www.bestpcbs.com/blogimages/2016/10/hole-covered-by-soldermask.jpg)0.635mm Via covered/tented by soldermask

 

 

 

 

 

 

 

 

 

 

 

So you need to add at least 0.10mm (4mil) soldermask opening on each side of hole, so that there’ll be a 0.1mm Annular Ring, like bellowing:

![Add 4mil Annular Ring on PCB Via](https://www.bestpcbs.com/blogimages/2016/10/4mil-annular-ring.jpg)Add 4mil Annular Ring on PCB Via

 

 

 

 

 

 

 

 

 

 

Then that hole will become like bellowing:

![Hole/Via without soldermask (soldermask opened)](https://www.bestpcbs.com/blogimages/2016/10/hole-without-soldermask.jpg)Hole/Via without soldermask (soldermask opened)

 

 

 

 

 

 

 

 

 

 

We believe there’re a lot of other handling method about that soldermask opening, please leave your comments, or [contact us](http://www.bestpcbs.com/contact/) to discuss more about that, and believe you will be happy to receive with the [PCB](http://www.bestpcbs.com) with correct soldermask opening!