Hi Wei, What you and I have said is the same thing. Werner In a message dated 09/24/2003 16:39:21, [log in to unmask] writes: >Hi, >I think the other important reason to use high-temp solder sphere on CBGA >is because of the big CTE difference between FR-4 and ceramic. It provide >more flexible joint. Same >reason as IBM CCGA packages which use high-temp solder column. >Wei Wang > >Werner Engelmaier wrote: >> Hi Victor, >> The reason for high-melt solder balls is the same as for solder >> columns--thicker solder connections (higher stand-off heights) provide >higher reliability >> roughly by the square of the heights. This is well documented--just take >one of >> my workshops. >> >> Regards, >> Werner Engelmaier --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------