Ingemar, I may be barking up the wrong tree but, I recall IVF in Gothenburg had some pictures they took of Adipic Acid "Roses". In fact I may still have copies around here somewhere..... Try calling Per-Erik Tegehall - if he can't remember, ask Bill Brox. Eureka - and SPOOKY! As I am writing this, I just had a customer walk in with EXACTLY the same problem! - Yikes. Anyhow, I found the pictures, will scan them and have them available electronically for anyone who is interested. Let me know off line. Examining the pictures, the "problems" were: EITHER - Trapped colophane particles in the solder resist - OR - Sodium Carbonate - OR - Adipic Acid dendrites/flakes - OR - Zinc Oxide (or Hydroxide). All at micron levels. Furthermore, GEC Hirst Research Group (before they were closed down!) established 16 different forms of "White powder residue". The gentleman who was in charge at that time is Dr Brian Richards at the NPL - got your TechNet ears on? If any fellow Techie want more info, let me know. Regards, Graham Naisbitt [log in to unmask] WEB: http://www.concoat.co.uk CONCOAT Ltd Alasan House, Albany Park CAMBERLEY GU15 2PL UK Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227 ----- Original Message ----- From: <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, August 25, 1999 11:29 AM Subject: [TN] BGA solder residues Oumphf! You can't pronounce that? Like me not being able to see what strange roses we find between the balls after BGA on FR4 after 10 minutes in a REHM heat conveyour oven. Top temp is +230 / 1 minute. Preheat is included in the 10 minutes. Kester 229D is used (if a Kester man reads this, please give a line or two in response. The residues grow to something that reminds of roses or cabbage! Colour in daylight is white, but the residues do not seem to belong to the ordinary white residues (Tin Abiate, polymerized rosin and lead salts). Flakes are <<1micron thick and up to 50microns in diameter. EDAX gives 99%Lead and bal is some Tin and Carbon and other random elements. Not soluble in the usual solvents like Ethylene, Perclorethylene, Acetone etc. And that is natural, as the residues are inorganic. Kester 229D is not QPL'd. Paste Sn62Pb36Ag2 is screenprinted on traditional Cu/Ni/Sn-pads. We have used this Kester formula for years for other products without seeing cabbage nor roses. BGA is ceramic C4 from Mota, number of balls (bumps) approx. 25x25 matrix. Can it be PbCO3? The flux is RMA and contains clorides. The line is stopped, nothing will be delivered until the cabbage growth is eliminated. Special question to SIRguru labs: can we send this job to you if our qualification does not cover the need? Regards Ingemar Hernefjord Ericsson Microwave Systems ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################