Bob, What kind of pick and place machine are you using? Bill -----Original Message----- From: bbarr [SMTP:[log in to unmask]] Sent: Thursday, May 10, 2001 10:31 AM To: [log in to unmask] Subject: Re: [TN] Dumb question I have never had a problem not using local fiducials for 1.27mm and 1.0mm pitch BGAs. I have not yet done .8mm pitch BGAs, but I think I would tend to want to use locals for them. Of course, the usual caveat applies, you need to know the capability of your placement machine. I have not even seen a compelling need for locals with .5mm pitch leaded devices. I normally have the machine find three panel fiducials and go with that. Bob Robert Barr Manufacturing Engineering Formation, Inc. Voice: 856-234-5020 x3035 Fax: 856-234-6679 email: [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Jason Gregory Sent: Thursday, May 10, 2001 9:00 AM To: [log in to unmask] Subject: [TN] Dumb question OK, guys, here's one. Why is it so important for local fiducials to be placed near diagonal corners of BGA's. The keyword here is "SO". I've performed studies in the past detailing the natural tendency of BGA's to self-align during reflow. It's even lead to me to work on a patent concerning a BGA rework preform. What I'm wondering is....ssop's, tssops, qfp's, etc. have greater impact on placement quality when misplaced. And they do not self-align!!! I do, however, understand that BGA's balls are not easily seen once placed (you can only see the edges). But my point that I'm getting to is.....wouldn't you want local fiducials more at the parts that will not "self-correct" themselves during reflow than at the parts are more forgiving? Just wondering. Jason Gregory Software Specialist - NPI Group SCI Systems/Plant 2 13000 S. Memorial Pkwy. Huntsville, AL. 35803 (256) 882-4107 x3728 [log in to unmask] ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------------