Screaming Circuits: Icky Via Near Pad


Icky Via Near Pad

Here's a case where the board house didn't do an engineer any favors. There are issues with soldermask opening size, registration and masking between the via and the pad.

The pads are non-soldermask defined as we like them, however, the mask openings are much larger than we would like or than most manufacturers would recommend. Check the component datasheet for the actual number you need to use.


Then, the registration is way off. That alone wouldn't make the board unusable, but it does speak to the suitability of the fab process to this level of technology. Either it was a bad batch or this fab house shouldn't be making boards for BGAs or other fine pitch components.

The worst part is the direct solder path from many of the pads to their vias. It's quite likely that in reflow, the capillary action from the via will suck the solder paste and the solder ball off of the BGA leaving a complete open. Check out this post for a little more information.

Make sure your board house is capable of building to the technology you need. It's not worth the discount you might recieve. And, always give your boards a good look over before sending them out for assembly.

Duane Benson
In this case, BGA = Bad Green Area


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