Please check you design first. If this design have an uneven copper pattern / stack-up/ soldermask thickness, the warpage is very hard to avoid. My suggestion is use a fixture to force the board come back to flat in assembly. But, please take care about the potential tension strength after fixture removal, for tension will cause BGA solder joint crack. Good Luck! Ben -----Original Message----- From: <Peter George Duncan> [mailto:[log in to unmask]] Sent: Friday, November 16, 2001 10:11 To: [log in to unmask] Subject: [TN] Board Warp Hi, All, We have received a number of 12 layer ENIG-finished MLB's with blind via hole groups, and which are destined to have BGA's (1.27mm pitch) populated onto them. The boards measure 8.2" x 5.7" and they are warped to the extent of one corner being raised by between 1.5mm and about 3mm. The axis of the warp is the long side of a triangle whose other two sides measure about 5.7 x 5.7. In this age of sensitive boards, does a technology or technique exist for straightening the boards back into spec - they are class 3 boards - or is this an area where angels still fear to tread? The boards are desperately urgent, which is why I'm asking this rather than simply rejecting them and having them re-made (which takes about a month). TIA for any help. Peter Duncan [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------------