Ed- Ceramic package BGAs (CBGA) typically use a combination of eutectic solder attach with high temperature solder (90Pb/10Sn) columns (non-reflowing) because... "This hierarchical structure creates a consistent and reproducable gap or standoff between the ceramic package and the card. This standoff accomodates the mechanical strains geenerated during normal machine power cycling, caused by the thermal mismatch between the ceramic carrieer and the card...": This is taken from text "Ball Grid Array Technology," McGraw-Hill (1995), John Lau, Ed., pg.133 of Chapter 5, "An Overview of Ceramic Ball and Column Grid Array Packaging", by T. Caulfield, M. Cole, F. Cappo, J. Zitz and J. Benenati. High Tg FR-4 and BT epoxy laminate based PBGAs are a near perfect CTE match to typical PWBs they are attached to, and thus get away with eutectic solder spheres. -Michael Alderete ------------------------------ Date: Tue, 15 Sep 1998 10:10:23 -0400 From: Ed Holton <[log in to unmask]> Subject: Re: X-ray for open joints on BGA's ? I am curious, why are the ceramic BGA solder balls not eutectic and made with the 90/10 Pb/Sn solder? ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################