Madhu Please Inspect after UV and then again after the 150 c cure to isolate the source You may need to lower the temp to around 140 C Try to cure them laying flat or support the board during the cure cycle You could be working with a low Tg material which will soften at these temp and as the other respondant said an unbalanced cu board will cause warpage You may need to balance the cu area -----Original Message----- From: S.R. Madhuchandra [mailto:[log in to unmask]] Sent: Wednesday, October 22, 2003 2:22 AM To: [log in to unmask] Subject: Re: [TN] Warpage after PLSM Afri In thermal curing, boards are baked at 150 deg C for 30 min with horizontal stacking We do UV curing to reduce cycle time for some selective jobs only In UV curing, the boards are subjected to 3.1 joules at 160 deg C for approx 1 min Thanx in advance Madhu |---------+----------------------------> | | "Afri Singh" | | | <[log in to unmask]> | | | | | | 10/21/2003 03:25 | | | AM | | | | |---------+----------------------------> >------------------------------------------------------------------------------------------------------------------------------| | | | To: "TechNet E-Mail Forum." <[log in to unmask]>, "S.R. Madhuchandra" <[log in to unmask]> | | cc: | | Subject: RE: [TN] Warpage after PLSM | >------------------------------------------------------------------------------------------------------------------------------| Madhu What temp are you baking the boards at and how do you rack them ? Also why do you do UV ? Most shops only thermal cure peelables at 150 C for 5-15 minutes You could try curing it at 140 C . On the UV .How many joules and what does temp do these boards see afri -----Original Message----- From: S.R. Madhuchandra [mailto:[log in to unmask]] Sent: Monday, October 20, 2003 2:12 AM To: [log in to unmask] Subject: [TN] Warpage after PLSM fellow technetters In some of the part numbers, we are facing a strange phenomenon The boards will be flat till the process of PLSM(peelable solder mask) but after the PLSM, there will be severe warpage & wobbling In PLSM, we are doing both UV & thermal curing Can some one throw some light on this Thanks in advance Madhu Scan by AT&S virus protection --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 ----------------------------------------------------- Scan by AT&S virus protection --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 -----------------------------------------------------