Is there a way to have the soldermask cover all vias and leave the pads for components uncovered? My assembly house is having problems with shorts between vias on the backside of the board. The solder migrates through the via hole and is bridging some of the vias that are only 10 mils apart. All the surface mount parts are on the top of the board. The problem occurs when the vias are next to a component solder pad. Apparently the solder paste is migrating over to the via and then down through the hole.
You can get vias 'tented' which means they are covered with solder resist. In the Gerber output menu on the resist & paste plots, there are options on the left which deal with this.
On the resist plot I have ticked the Inculde Drilled Pads & Include Undrilled Pads, and on the paste plot I have just Include Undrilled Pads ticked.
This seems to work just fine for me! Hope this helps :)
If you have created separate layers in your layer stack (on the Design Technology dialog) for solder mask, you can control what appears on those layers by the settings in the associated Layer Type. This allows you to separate SMT and PTH free and component pads, and vias.
By the way rbuck I have had the same issue in the past with via's/pads 10 mils apart and your solution has worked for us. The way I do it is to make separate solder mask layers and just create a pad where I want it and leave it blank where I don't.
soldermask on vias
Posted - 08 Dec 2009 : 02:04:06
