Electronics Forum | Mon Apr 23 14:03:18 EDT 2001 | Ryan Jennens
Dougie- We,too, have the IPC-A-600F, and the spec. refers to IPC-TM-650 test method in the back of the book. Look on page Number 2.4.22 of the test methods appendix. This outlines the procedure for determining the percentage of bow and twist,
Electronics Forum | Fri Apr 20 13:55:09 EDT 2001 | kawiederhold
Hey Dougie, If you go to IPC.ORG and click on the on-line resources and databases, then on the "free downloads" link, the second or third document "for free" is the IPC-TM-650 in its entirety. It does discuss the test you are looking for! Have fun
Electronics Forum | Fri Apr 20 05:32:39 EDT 2001 | dougie
Hi, I've just splashed out �60 on IPC-A-600F trying to find out the formula for measuring the bow and twist of raw PCB's. Much to my dismay there are 10 lines on the subject in the whole standard. Worse still is that it tells me nothing I don't alre
Electronics Forum | Fri Apr 20 07:30:14 EDT 2001 | wbu
In short: the measured deviation / the length this deviation occurs * 100% = % of deviation Actually we encounter mostly "twist" so we put the board on a flat surface, hold it down at the corners to see if any of the corners lifts, measure the heig
Electronics Forum | Thu Dec 12 15:34:59 EST 2002 | msimkin
Has anyone had any expereince with FR4 boards under the std 0.5% warpage for Bow & twist with CSP & uBGA devices on them that have caused failures. Are there any revised percentages for boards loaded with these devices that anyone knows of, istead of
Electronics Forum | Fri May 07 20:08:39 EDT 2004 | Ken
...um also, don't forget that ther are planarity issues associated with BGA devices AND bow-and-twist issues with PCB materials. An example I have one BGA device that has a ball planarity of 7 mils!!! Ant that's the OEM specification! THis will re
Electronics Forum | Wed Oct 04 09:55:51 EDT 2006 | borgie
Hi. I have product in lead containing process that consist lead free BGAs and also big ceramic BGAs with high temperature bumbs. Pcb tends to bow in a reflow profile, since I need long preheating times and relatively high peak temperature to melt BG
Electronics Forum | Mon Mar 03 11:07:40 EST 2003 | MA/NY DDave
Hi In addition to what DaveF gave you which you should look at first Search the archives for warp bow twist warpage etc. A Lot of treads exist. Many of the larger OEM's and even the Mil have historically created their own documents for acceptable
Electronics Forum | Thu Oct 14 20:42:07 EDT 1999 | Jeff Ferry
Grace, As deifned in IPC 7721 Procedure 3.2 Bow and Twist Repair "Bow and twist after soldering shall not exceed 1.5% for through hole PC boards and .75% for surface mount PC boards. The bow and twist shall not be sufficient to cause difficulties d
Electronics Forum | Thu Aug 09 07:53:16 EDT 2012 | davef
Allowable bow & twist: Together, both IPC-A-600G and IPC-6012B represent the core IPC documents for describing the acceptable and nonconforming conditions that are either externally or internally visible on finished printed boards. IPC-A-600G relies
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