Electronics Forum | Fri Jan 16 06:53:33 EST 2009 | stevewilde
I am using Humiseal 1B31 conformal coating and xylene mix on a PVA coating machine. Bubbles are appearing between the pins of LCCs mainly and bubbling is worse when put through the IR oven. Does anyone have any suggestions or tips to elliminate this
Electronics Forum | Fri Jan 16 08:36:40 EST 2009 | davef
That the bubbling gets worse when you run the board through the oven indicates the issue is with the balance between releasing volatiles and cure. Try one of these ideas: * Adjust the atomization pressure, nozzle size, temperature or viscosity of th
Electronics Forum | Tue Feb 03 11:42:54 EST 2009 | lmartenson
We use PVA and I have had bubbles that came from the pressure in the pressure pot being to high. Also the material filter was slightly clogged. I'm not sure of your setup hope this helps.
Electronics Forum | Fri Oct 09 16:07:30 EDT 2009 | dlabelle
We use Dow 2620 silicone conformal coat applied with PVA1000 sprayer machine. If used on a daily bases, we have no problem. If we let the machine sit idle for over a week, we will get bubbles in the conformal coating. Sometimes, purging the line w
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 | Thu Sep 10 15:01:28 EDT 2009 | mefloump
I currently spray DOW 2620 with my PVA650 without any problems. I do not thin it but I do have a distance between the coating machine and IR oven to provide a flash off period. I notice bubbles only when the flash off time is too short and the coatin
Electronics Forum | Tue Aug 26 11:15:47 EDT 2003 | blnorman
We use HTN (high temperature nylon - Zytel) connectors in our reflow ovens with no warping, bubbling, or cracking. You can also use PPA (Amodel).
Electronics Forum | Fri Jan 16 10:54:21 EST 2009 | realchunks
Hi Steve, Make sure your spray head is all the way down. If so, try slowing your rate of speed over the part. Which head are you using to coat this part?
Electronics Forum | Mon Jan 19 09:10:17 EST 2009 | stevewilde
Thank you for all of the advice. I am using the extended spray for these cards. Humiseal have recommended using their own thinners 600 instead, so will run some trials with this and also the humiseal pre-mixed material (at the moment we mix our ow
Electronics Forum | Tue Feb 03 13:47:59 EST 2009 | grics
I would also suggest looking at your ramp rate in the cure oven. We noticed that accelerated heating increased the "gas out" of the solvent. We run 1A33 and and do not exceed a .5/degC ramp rate.
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