I'm wondering if totally reflowing the whole board during rework isn't detatching the solder balls from the Nickel pad that attaches them to the BGA body. This might not show up on X-ray and additional pressure on the component could be enough to re-establish contact. Try micro-sectioning a failed device/board and look for hairline cracks at the solder ball/ BGA pad interface. Pete Duncan Tamir Ben Shoshan To: [log in to unmask] <[log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) OM> Subject: [TN] BGA's failure during rework process. Sent by: TechNet <[log in to unmask] ORG> 05/30/01 10:21 PM Please respond to "TechNet E-Mail Forum."; Please respond to Tamir Ben Shoshan Hi, The board's type I am dealing with is 3.8 mm thick with 28 layers made of GETEK raw material. The BGA's rework process had been defined as followed: Baking the boards for 24 hours at 125C, remove the defected component with the BGA's rework station, clean the component's area, paste printing, locate the component on the pads and pass it through the reflow oven under the same profile definition as the first assembly (because of a big board size- 17" X 18" and thickness we found out that this process is better then local profile). On each board 6 BGAs should be replaced (version upgrade). After replacing the BGAs with the above process few other BGAs components were fail in away that implementing force on the component makes it work properly. The X ray inspection didn't show anything wrong with any of the solder joint. After replacing the suspected components the boards pass all the functional test. The failed components were plastic BGA. Does any one familiar with that phenomena, I appreciate any help or advise. Best Regards, Tamir. --------------------------------------------------------------------------------- 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------