Bill, That is a lot of warp. I guess I would try to get the vendor involved. With that much warp over temperature there may be a temp cycle reliability issue. Many suppliers buy standard carriers and attach their custom die. Maybe there is a die attachment problem. If you have to use those parts, maybe a 'hershey kiss' paste shape on the pads (obtained from a dispensor) may be more forgiving than a flat shape from a stencil printer. Just a few thoughts, Jim Kittel -----Original Message----- From: Bill Raymond [mailto:[log in to unmask]] Sent: Thursday, September 06, 2001 7:21 AM To: [log in to unmask] Subject: Re: [TN] BGA Warp Jim, thanks I'll start looking into this today! However, it appears from testing we are doing that the warp occurs during ramp up - we have heated some of these chips in an oven to 125 deg C, allowing them to stabilize, and we measure warp upwards of 6 to 8 mil ... at this point, the solder balls of the BGA are not even touching the solder paste. Bill... At 06:48 AM 09/06/2001 -0600, you wrote: >Bill, >If you have not already, look at the cooling rate on your reflow oven. I >solved a similar similar warpage problem by reducing the solder cooling rate >to 1 deg C/second. I had to modify the blowers in the cool down section to >achieve that rate. I found my oven was designed to blast the top of the BGA >with cold air while the solder was still liquidus. It provided for high >speed production, but was warping some of the BGA's. > >Jim Kittel ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------------