We have done some underfill here, very limited quantities will no clean fluxs. These were 5 mil parts with 2 mil balls. It depends who you talk to there are advantages to cleaning but there are also problems. We had reasonable success with the no-clean process. IMHO, Even if you get the semi-aqueous solvent under the part, how can you rinse it out? We use Vigon A200 in out inline cleaner and Kyzen Ionox I3330 in our batch cleaner. I have seen residue under large BGAs after cleaning. Both are excellent but the water rinse just won't go into tight places. If I was going to try this I think I would experiment with the HFE in a co-solvent process. But it's expensive, requires modern equipment and good process monitoring. Guy Ramsey Senior Lab Technician / Instructor E-Mail: [log in to unmask] <mailto:[log in to unmask]> Ph: (610) 362-1200 x107 Fax: (610) 362-1290 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Lambert, Katherine A. Sent: Thursday, August 23, 2001 12:00 PM To: [log in to unmask] Subject: [TN] Cleaning under BGAs Hi folks, We're embarking on something new. We will be assembling boards with BGAs. Some are small and fine pitch, others are regular pitch but quite large (40mm square). We will be underfilling them with adhesive. Because we're underfilling, we have to clean the flux from underneath the parts. We're using an RMA flux based solder paste. Now for the question - how should I clean the flux from under these parts? Any clues as to which solvent to use? Any ideas on what type of equipment to use? I have at my disposal an in-line semi-aqueous cleaner and a vapor degreaser. Thanks for any insight. Kathie Lambert Process Engineer Northrop Grumman Baltimore, MD 410-765-9746 ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------------