Bill, Well Done!! Certainly seems like you found a smoking gun. Maybe try to fully outgass the material with a bake, then plasma clean (there are places you can have this done and recommend an appropriate plasma if you don't have in-house capability), before epoxy die attach. Bruce > ---------- > From: Bill Christoffel[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum. > Sent: Thursday, September 06, 2001 3:05 PM > To: [log in to unmask] > Subject: Re: [TN] Outgassing of LPI's and Legend Inks > > Never Assume !!! However in this case, Yes we are seeing a dramatic > drop off in bond pull strengths and interfacial failure modes. Our tests > we performed with controls on board lots, epoxy lot (down to syringe > level) and all epoxy stamping done on same machine, same run etc. > > As a follow on we ran some down and dirty "wettability" tests using > glass slides and measuring contact angle vs. oven atmosphere (loaded/not > loaded), definitely a difference when boards with previously cured > legend ink on them we in the oven. I think we found the source, now how > to eliminate it ? > > Bill C. > > -----Original Message----- > From: Misner, Bruce [mailto:[log in to unmask]] > Sent: Thursday, September 06, 2001 1:46 PM > To: [log in to unmask] > Subject: Re: [TN] Outgassing of LPI's and Legend Inks > > > Bill, > > My experience with the type ovens you describe have shown them to do an > excellent job of exhausting outgassed material and precluding redeposit > on a > board or substrate surface. If it is outgassing, I would tend to believe > that you would see a difference in wire bond pull strengths as well. > Especially when comparing before/after accelerated bakes. Is this the > case? > Please forgive me, but are you absolutely sure the same lot and even > same > syringe/application of epoxy was used on both board types? > > Bruce Misner > > > ---------- > > From: Bill Christoffel[SMTP:[log in to unmask]] > > Reply To: TechNet E-Mail Forum. > > Sent: Thursday, September 06, 2001 9:03 AM > > To: [log in to unmask] > > Subject: [TN] Outgassing of LPI's and Legend Inks > > > > Technetters, > > > > We are experiencing what appears to be the result of some type of > > outgassing of white legend ink. > > Details: Board design uses a white legend ink as an overcoat. > > Subsequent processing includes die attach (COB) using electrically > > conductive epoxy. Testing shows that the die attach epoxy strength > (die > > shear) is greatly reduced on boards that use the white legend ink. I > do > > not believe this to be a surface contaminant issue since the epoxy > > failure mode is cohesive. Epoxy cure temperature is 150C in a air > > circulating oven with a high exhaust rate. Questions - Is outgassing > > of legend inks and LPI's a probable cause? Is any information > > available regarding this ? > > > > Bill C. > > > > > ------------------------------------------------------------------------ > -- > > ------- > > Technet Mail List provided as a free service by IPC using LISTSERV > 1.8d > > 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 delivery of Technet send the following message: > SET > > Technet NOMAIL > > Search previous postings at: www.ipc.org > On-Line Resources & > Databases > > > E-mail Archives > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > > additional > > information, or contact Keach Sasamori at [log in to unmask] or > 847-509-9700 > > ext.5315 > > > ------------------------------------------------------------------------ > -- > > ------- > > > > ------------------------------------------------------------------------ > --------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > ------------------------------------------------------------------------ > --------- > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > ------- > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------