Hi Rick, I am sure that you will get an avalanche of feedback on this question. Nevertheless, although there are a number of factors that are involved with the long-term reliability of CBGA's, the answer to your question highly depends upon the maximum physical size and the number of solder balls the CBGA's have when they are mounted onto the FR4 PWB, and then exposed to a specific number of temperature cycling regimes that have the extremes that you stated. However, there is a goodly amount of published data available on this subject. I suggest you contact Mr. Werner Engelmaier, who is an expert in this area. best regards, faz ____________________Reply Separator____________________ Subject: [TN] Ceramic BGA's on FR4,any thermal coefficient problems Author: Rick Summers <[log in to unmask]> Date: 7/26/2001 12:54 PM Has there been any studies completed to prove or disprove thermal coefficient problems between ceramic BGA's mounted on FR4 causing long term reliability problems of the BGA balls (solder ball separating from PWB) over commercial and industrial temperature ranges? Commercial temp range: 0O C to +70 O C. Industrial temp range: -40 O C to + 80 O C. -------------------------------------------------------------------------------- ********************************************************************** This e-mail and any files transmitted with it are confidential and may be legally privileged or otherwise exempt from disclosure under applicable law. This e-mail and its files are intended solely for the individual or entity to whom they are addressed and their content is the property of Smiths Aerospace. If you are not the intended recipient, please do not read, copy, use or disclose this communication. If you have received this e-mail in error please notify the e-mail administrator at [log in to unmask] and then delete this e-mail, its files and any copies. This footnote also confirms that this e-mail message has been scanned for the presence of known computer viruses. *********************************************************************** --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------