Electronics Forum | Tue Mar 31 08:11:51 EDT 2009 | davef
Solder ball formation can be a significant problem if the balls get trapped in the smaller spaces between ceramic chip carriers and substrates or possibly between the leads of small pitch leaded ICs. The solder balls also reduce the solder volume ava
Electronics Forum | Tue Aug 25 08:04:26 EDT 2009 | davef
Trapped moisture can be a problem, and one standard recommends baking a PCB for a minimum of 4 hours at 93+/- 5.5ºC before conformally coating. [NASA-STD-8739.1, “Workmanship Standard for Staking and Conformal Coating of Printed Wiring Boards and Ele
Electronics Forum | Thu Aug 27 11:35:07 EDT 2009 | davef
There are many possibilities: * Conformal coat is incompatible with surface residue on the board * Conformal coat is incompatible with solder mask on the board * Moisture is out-gassing from the board * Conformal coat is too thick and does not allow
Electronics Forum | Wed Oct 21 10:18:00 EDT 2009 | stepheniii
Make sure the ground pad is reduced on the stencil and window paned. The solder on the thermal pad can lift the part up, especially if it traps gas. 360-380C does sound insane. I would believe a manufacturer saying 360-380F before I could believe
Electronics Forum | Mon May 24 19:43:46 EDT 2010 | jry74
Can anyone share some good practices to reduce FOD in the conformal coat area? I am new and trying to get my hands around a serious FOD issue. We get red, black, blue, and white fibers that gets trapped in our conformal coat, causing a lot of scopi
Electronics Forum | Wed Oct 03 09:23:21 EDT 2012 | kkay
Well what we have seen so far is that the voiding occurs on nearly every part, but only underneath the terminations. When we run a board with no parts we do not see any voiding as there are no terminations to trap the out-gassing from the pads. Next
Electronics Forum | Sat Mar 14 15:48:40 EDT 2015 | horchak
The white haze is definitely an indication of moisture being trapped in uncured or improperly applied solder mask. You can verify this by heating up the board using a heat gun on an area of the board with the white haze, and if it clears up that is t
Electronics Forum | Fri Nov 02 17:23:52 EDT 2018 | cbart
are these requirements outlined by your company or the manufacture of the part? if its your company is the product tested? if so the test guys don't usually like to power things up with water trapped in them or under them as it can cause some problem
Electronics Forum | Mon Nov 26 09:33:49 EST 2018 | charliedci
The problem you create by soldering from solder destination side (presuming you have already soldered from other side) is that you will trap air in PTH so you have virtually no continuous solder in PTH from one side to other. This will not meet IPC-A
Electronics Forum | Tue May 21 16:18:57 EDT 2019 | edhare
Interesting problem. I've seen this before on SMT device leads (see Gold Embrittlement paper at http://www.semlab.com). The AuSn4 IMC is solid at typical reflow temperatures and traps volatiles in the solder joint. One usually cannot crank the ref
