Electronics Forum | Thu Aug 15 15:58:12 EDT 2002 | robertnguyen
To whom this may concern, I recently ran into the problem with vias on pads of BGA when place BGA and reflow gas trap on vias escape and result in ball having void greater than 50% of BGA diameter. The BGA pad is measured at 20 mils and the vias mea
Electronics Forum | Fri Aug 16 10:00:03 EDT 2002 | davef
You have a very bad situation. It�s tough for the gas, flux material, er whatever to escape when the BGA is sitting on top of it and the blind via is blocking it from the other side. Obviously the vias should have been: * Placed on the edge of the
Electronics Forum | Thu Oct 05 11:37:15 EDT 2006 | russ
with this design you will have voids, you cannot trap the gas inside of via it has to go somewhere. These vias should be relieved from pad to prevent the scavenging of the paste during reflow. You may try a thicker stencil if you can to allow for t
Electronics Forum | Fri Dec 01 13:30:08 EST 2017 | kojotssss
Stencil thickness is 4 mil. Via's are plugging from bottom. Gas may be developed under the component? Take Reflow Ovens Thermal Profiling changes? In your opinion?
Electronics Forum | Sun Jan 09 19:37:15 EST 2005 | Bob R.
I'm just thinking out loud here with no experience to back it up, but I could see where you're trapping air or solvent filled voids inside the via by tenting from both sides. When you go through a heat cycle like reflow or wave solder you could be e
Electronics Forum | Thu Dec 21 13:33:46 EST 2006 | ppcbs
The problem with super glue is that is has a cyanide base that turns into a toxic gas and evaporates when heated. See IPC-7095. Via's should be fully plugged with solder mask at the fab house. If your PCB designers are not up to speed on IPC requi
Electronics Forum | Tue Jul 28 02:28:48 EDT 1998 | Bob Willis
The causes for solder on gold are: Paste wash offs Dirty stencils Dirty under stencil cleaning cloths/no solvent Poor handling The most common reason is wash offs when there is a couple of balls left on the tabs and they reflow. With correct profile
Electronics Forum | Thu Aug 05 13:51:18 EDT 2004 | davef
You need to have 1 thou of copper. If don't moisture absorbed by the board will out-gas through the plating.
Electronics Forum | Thu May 30 09:33:15 EDT 2019 | emeto
Contributors in order of importance: 1. PCB design - if you have large thermal pads, a grid of via holes should be created. Components with low profile will not let the gas to escape from the joint. The only way is going down. 2. Reduce paste volum
Electronics Forum | Mon Apr 12 08:10:17 EDT 2004 | wgaffubar
We are sometimes, not always, seeing very large voids in the solder joints of BGA's with Via in Pad. Some lots of PCB will have the voids and other lots of boards will not. I feel the via's are outgassing during reflow, due to the PCB not having been
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