When we receive warped boards and there isn't time to return to vendor we can put the boards on the mesh chain and run them through the oven, this help flatten them out for assembly. A careful review of available copper throughout the PWB is in order as even cooling is critical to PWB flatness even in small boards. Dave C. -----Original Message----- From: Dale Ritzen [mailto:[log in to unmask]] Sent: Tuesday, April 20, 2004 4:14 PM To: [log in to unmask] Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance Victor, This is derived from a measurement of the diameter D, length L and width W of the board (or palletized board) in question, using a calibrated roll pin of known value. Page to the back of your IPC-A-600 book. The TM-650 section shows how to make this measurement and what the measurements are based on. Just be sure you use a calibrated flat granite stone when you do the roll pin measurements for the calculations. The flatness of the measuring device can make a difference. We do this all the time in our incoming inspection area and have caught quite a few badly bowed boards recently. Just remember, they can sometimes be annealed back to correct flatness by the supplier. Dale Ritzen, CQA Quality Manager Austin Manufacturing Services -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Victor G. Hernandez Sent: Tuesday, April 20, 2004 4:00 PM To: [log in to unmask] Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance Ramon, I have seen the 1.5% and 0.75% criteria before. What I am not sure is % of what base number. Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon Sent: Tuesday, April 20, 2004 1:07 PM To: [log in to unmask] Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance Hi Victor: It should definitely be less than 1.5% for THT and less than 0.75% for SMT, which that is what it is for a board after it has been soldered. JStd.001B 9.2.3 Regards, Ramon > -----Original Message----- > From: Victor G. Hernandez [SMTP:[log in to unmask]] > Sent: Tuesday, April 20, 2004 1:02 PM > To: [log in to unmask] > Subject: [TN] PCB Raw card Boe & Twist Tolerance > > Steve, > > What has been your experience with measuring Bow & Twist on a raw > card. Is there a RULE Of Thumb that can apply generically. > > Victor, > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 > or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET > Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the > posts: send e-mail to [log in to unmask]: SET Technet Digest Search the > archives of previous posts at: http://listserv.ipc.org/archives Please > visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------