Hi Bob Yes we did a cross section of that row on several RMA boards, the grain structure of that cracked ball looks just as pretty as the others next to it. The I/O is an address line and is not connected to the ground plane. The failure rate acutally is 0.02% . So most of our products we built through the the same process do not see this problem. Thanks for replying my email Rudolph ------Original Message------ From: Bob Perkins <[log in to unmask]> To: [log in to unmask] Sent: March 28, 2001 6:09:57 PM GMT Subject: Re: [TN] BGA crack- major headache Hi Have you had a look under the BGA of the reflow quality on that perticular ball, does it look nasty on the microscope; too much heat, or maybe this ball has not enough heat. If the reflow on the bga is not even I would sugest slowing down the profile and reducing the slope at spike. Give the bga a better chance to reflow evenly. It is quite possible to have a ball close or attached to ground sucking up the heat, or the opposite, a ball that has a thermal stress on it. Bob Perkins SMT Manufacturing Process / Automation Technician Aimtronics-Delta -----Original Message----- From: Rudolph Yu [mailto:[log in to unmask]] Sent: Wednesday, March 28, 2001 8:48 AM To: [log in to unmask] Subject: [TN] BGA crack- major headache Here are the facts: PBGA-272 balls FR4 with HASL finishes 8 layers The failure point always happens at the same I/O which is the 2nd last ball of the top outmost row of the package. It is not located near the edge of the board or any breakaway point. Failure mode Micro fracture found near the intermetallic layer between the BGA package and the solder ball attached to it. Around 0.001% of the products we built failed in the field because of this. None of these were caught during the ICT or Functional test. The same ASIC is also used on several other Products and have never seen an issue like this. Somehow this failure mode with this ASIC only occurs in one particular product /design. The ASIC / fab lot-related , ICT pin interference, stress by the breakaway tab, and stencil cleanliness assumptions had already ruled out after a controlled lot was built few weeks back. All boards passed the tests. But now some boards started failing in the field. Why the crack always happen to one single location(ball) with the same product we built?? We have run out all the possibilities that we can think of. I hope all the experts in TechNet can share their opinions on this. Customer kept asking for the root cause analysis. Right now we just cannot came up with a reasonable one. Thanks Rudolph Yu ---------------------------------------------------------------------------- ----- 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------