Either solder paste or paste flux offers compliance and reduced problems with coplanarity - especially with super BGA's or as otherwise known - perimeter BGA's. Fewer or no voids, as would be expected, with paste flux. Makes me wonder about reliability when some voiding is supposed to be good - but how to control it? Not possible. Don't forget how reliable CCGA solder joints are because of the cast or clasp columns providing good flexibility and solder joint characteristics more common to us all. Also, again, you can come close to columns by using hard balls in the corners or placing an adhesive dot in the center of the device pattern, if opening available, thus rendering semi-columns, etc. etc. Earl Moon Proof Of Design --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------