Rick, Plastic BGAs as you describe are classified as moisture-sensitive components. The main concern has to do with potential internal defects if the parts have absorbed too much moisture from the ambient air prior to reflow (rapid vaporization of entrapped moisture will create high stress causing cracks and delaminations inside the package). Another moisture-related phenomena that is unique to PBGAs is that they also have a tendency to warp due to moisture absorption, even prior to any temperature cycle like reflow. This is because moisture tends to swell the different materials at different rates (i.e. the BTU laminate and the plastic overmold). In most cases however, the corners tend to warp up, not down as you explain. Try to bake the components prior to reflow to see if the problem goes away. If it works this means that your components have absorbed too much moisture and you should also be concerned about potential reliability damage due to internal cracks and delaminations. Francois Monette Cogiscan Inc. 50 De Gaspe, Suite A5 Bromont, Quebec, Canada, J2L 2N8 Tel : (450)534-2644 Fax: (450)534-0092 www.cogiscan.com Date: Wed, 23 May 2001 09:19:18 -0700 From: Rick Thompson <[log in to unmask]> Subject: Altera BGA Reflow Problem Hi, We have an Altera fine pitch BGA that I'm having difficulty placing & soldering. I'm hoping someone may have experience with this particular part or can offer some suggestions. The part in question is an EP20K300 series in a 'thermally enhanced' 672 ball package. Pitch is 1mm. The package looks like an FR4 substrate with a layer of some sort of bonding material on top. I think it's probably the same as the 'glob-top' material except it covers the entire area of the part. The problem we're having it that the part appears to be 'cupping' down at the corners, causing shorts at the corners. Complicating this is the fact we're placing this on .018" thick PCB's. I've looked at our profiles on top and bottom and don't believe that the top is heating too much but we still get the cupping effect. Any experience with this chip or suggestions in general would be greatly appreciated. Thanks, Rick Thompson Ventura Electronics Assembly 2655 Park Center Dr. Simi Valley, CA 93065 +1 (805) 584-9858 x-304 voice +1 (805) 584-1529 fax [log in to unmask] --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------