Electronics Forum | Thu Sep 04 10:43:44 EDT 2008 | mrmaint
Surface wiping will not clean your board. Look under a scope and you will see paste in the vias.
Electronics Forum | Wed Jul 03 09:47:39 EDT 2019 | SMTA-Pat
We have seen that vias included in the PCB under the thermal pad will give less voiding.
Electronics Forum | Sun Jun 04 08:49:58 EDT 2000 | Roni Haviv
Hi C.K. , You can ask your PCB manufacturer to cover all vias with solder mask from CS (It called "pluged" vias). It's done from one side to prevent any close area that can cause "eraption" of solder because of pressure under reflow. All our boards
Electronics Forum | Fri Apr 15 11:16:03 EDT 2005 | HOSS
It's a longshot but.....I have seen low-standoff parts move caused by via's under the part erupting from within internal layers (outgassing). If this is a multilayer PCB and vias are not well plated or pourus, they can and will expand when heated.
Electronics Forum | Wed Mar 23 22:29:21 EDT 2011 | nkinar
I have a few prototype circuit boards with BGA footprints where some (but not all) of the vias have been placed too close to the pads. During reflow, some of the solder from the balls flowed into the holes. Only one of the pads under the BGA is not
Electronics Forum | Thu Jun 30 13:49:36 EDT 2005 | John
I had the same incident before, and like GS pointed out, the degassing from the via under the component was responsible. The via was covered with solder mask, but it burst open during the reflow.
Electronics Forum | Thu Jul 26 22:52:56 EDT 2007 | davef
Choices are: * Respin the board to move the via so that it is no longer under the pad. * Have the board fabricator plug and plate over the via. Search the fine SMTnet Archives for background.
Electronics Forum | Thu Feb 21 17:19:08 EST 2008 | davemn
if you are not using them for test points or want them filled with solder for current carrying capability then tent them puppies. i was able to move our company away from exposed vias many years ago and this eliminated lots of hairline shorts between
Electronics Forum | Thu Mar 29 15:50:35 EST 2001 | tomgervascio
We've think that with seen solder shorts under BGAs after wave soldering the boards. In addition, it seems to be related to a certain soldermask configuration over the topside BGA vias.. THere is one vendor,A, that is applying soldermask after HASL,
Electronics Forum | Mon Sep 28 09:35:28 EDT 1998 | Clive Heke
I have had some field failures returned recently, the boards had flux contamination under the components in a sensitive area, Nothing really visible until the component was removed, and the board had no evidence of rework of any type. Is it possib
