Sorry I'm late on this, and I haven't read all of the thread, but Sounds like the variation may be in the environment (temp, RH, barometric pressure and such), or the can is almost empty/almost full/not shaken enough/too much. Are these parameters being followed as well? Devil's always lurking in those itty-itty details. If already checked, then pardon this ole' geezer... Roger (BTW, back to work doing board design again! Woo-hoo!) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Sunday, August 23, 2009 3:07 PM To: [log in to unmask] Subject: Re: [TN] Manual spraying Yes, variations with same cans. OK, will try baking. Yes, from same fabricator. Mystery. One of our old foxes, experienced process engineer, you've met him, made a try, At first, the wet coating was crystal clear, but successively throughout room drying, the coating changed character, and became matte. Will let you know. Inge ----- Original Message ----- From: "Graham Naisbitt" <[log in to unmask]> To: <[log in to unmask]> Sent: Sunday, August 23, 2009 6:35 PM Subject: Re: [TN] Manual spraying > Inge > > All from the same can? > > If no, then I suspect some incomplete curing or "residual board > contaminants" might be the problem. > > Try baking the problem boards for around 8 hours at 80C, leave them to > revert to room temp and try again. If problem persists, then there you > probably need to run FTIR to figure what is there causing the problem. > > Also, are they from the same board fabricator? If not, check ROSE to see > if there is a difference. > > If yes, then have the batch checked - it is possible that there has been > a labelling issue. > > Let me know > > Regards > > Graham Naisbitt > > Email: [log in to unmask] > Phone: +44 (0)12 5252 1500 > Web: www.gen3systems.com > > On 21 Aug 2009, at 12:48, Hernefjord Ingemar wrote: > >> Nick, >> we have done tests today, same operator, same boards, same cans, same >> everything. Most boards get a clear, deep and nice look, but suddenly we >> get a greyish coating, quite matte! >> >> Q1: what spray angle do you recommend? >> Q2: what spray pattern do you recommend? Zig-zag, up-and-down, side- >> to-side or what? >> Q3: is the room RH of importance? >> Q4: is the process sensitive to laminar flow and if so, what level is >> critical? >> >> Inge >> >> >> >> >> -----Original Message----- >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Nicholas >> Redgrave-Plumb >> Sent: fredag 21 augusti 2009 12:31 >> To: [log in to unmask] >> Subject: Re: [TN] Manual spraying >> >> The only way I can see for the propellant causing this kind of problem >> is if the nozzle of the spray can is too close to the substrate whilst >> spraying. I note several suggestions in the posted responses of >> expensive elevated IR curing ovens etc. for IB31 but these are really >> not necessary as this material is dry to the touch/"tack" dry in only >> minutes, dry in 24 hours and cured/fully optimised in 7 days. This would >> undoubtedly be accelerated by an elevated cure but it shouldn't really >> be necessary. So all you should really need is simple drying cabinet at >> ambient temperature just to take the solvent vapours away. >> >> Otherwise, it could be "champagning" or "solvent-popping" which are >> terms to describe a condition where the surface of the coating material >> partially cures leaving solvent still trapped inside the wet- film. The >> solvent has to go somewhere so it finds it's way out through the surface >> and in doing so makes multiple small holes. >> >> To avoid this problem should be a matter of going back to basics. >> Review the coating procedure, make sure the operators are properly >> trained (and not getting the spray nozzle too close to the substrate). >> If the volumes justify the use of a purpose-built spray booth for >> conformal coating with intrinsic safety features and laminar air- flow/ >> extraction then it might be worth going in that direction. >> >> But there should be a simple solution to this problem because the usage >> of HumiSeal 1B31 globally, in both liquid and aerosol cans is massive. >> >> Nick Plumb >> Gen3 Systems Limited >> Farnborough, United Kingdom >> >> _________________________________ >> >> >> On 20 Aug 2009, at 19:17, Inge wrote: >> >>> Good Evening, >>> we use small cans filled with 1B1 conformal coating for handspraying >>> boards. The guys are not satisfied with the result, because sometimes >>> the result is matte. Microscope photos show thousands of microscopic >>> bubbles in the coating. I suspect that it's included driving gas. Or >>> wrong handling the spray can.Anyone out there with experience? How do >>> you avoid this problem? >>> /Inge >>> --------------------------------------------------- >>> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To >>> unsubscribe, send a message to [log in to unmask] with following text in >>> the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt >>> or (re-start) delivery of Technet send e-mail to [log in to unmask] >>> : SET Technet NOMAIL or (MAIL) >>> To receive ONE mailing per day of all the posts: send e-mail to >>> [log in to unmask] >>> : SET Technet Digest >>> Search the archives of previous posts at: >>> http://listserv.ipc.org/archives Please visit IPC web site >>> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 >>> for additional information, or contact Keach Sasamori at >>> [log in to unmask] or 847-615-7100 ext.2815 >>> ----------------------------------------------------- >> >> --------------------------------------------------- >> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To >> unsubscribe, send a message to [log in to unmask] with following text in >> the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or >> (re-start) delivery of Technet send e-mail to [log in to unmask] : SET >> Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the >> posts: send e-mail to [log in to unmask]: SET Technet Digest Search the >> archives of previous posts at: http://listserv.ipc.org/archives Please >> visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for >> additional information, or contact Keach Sasamori at [log in to unmask] or >> 847-615-7100 ext.2815 >> ----------------------------------------------------- >> >> --------------------------------------------------- >> Technet Mail List provided as a service by IPC using LISTSERV 15.0 >> To unsubscribe, send a message to [log in to unmask] with following text >> in >> the BODY (NOT the subject field): SIGNOFF Technet >> To temporarily halt or (re-start) delivery of Technet send e-mail to >> [log in to unmask] : SET Technet NOMAIL or (MAIL) >> To receive ONE mailing per day of all the posts: send e-mail to >> [log in to unmask] : SET Technet Digest >> Search the archives of previous posts at: >> http://listserv.ipc.org/archives >> Please visit IPC web site >> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >> information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 >> ext.2815 >> ----------------------------------------------------- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------