Electronics Forum | Thu May 18 20:47:14 EDT 2000 | Dave F
Ed: It might be possible, never tried tho, but if an engineer wandered in, talking about it ... Printing: Makes me pretty nervous, because punched boards are not planar, don�t stay planar, and are inconsistently not planar. If I could work-out th
Electronics Forum | Mon Oct 29 18:21:43 EST 2001 | slthomas
We recently have received a lot of warped (bowed and/or twisted behond IPC 600 specs.) bare boards (some our fabricator's fault, some ours by design) and I can't help but figure that long term reliability will suffer when building product with them.
Electronics Forum | Fri May 19 10:39:19 EDT 2000 | Boca
Ed, I workded with punch and replace fabs yeeeeears ago, major pain! Dave's right, planarity is the biggest problem, then inconsistent retention in the panel, then ANY retention in the panel. If you can get paste on them, you may be able to place
Electronics Forum | Fri May 19 10:41:06 EDT 2000 | Boca
Ed, I workded with punch and replace fabs yeeeeears ago, major pain! Dave's right, planarity is the biggest problem, then inconsistent retention in the panel, then ANY retention in the panel. If you can get paste on them, you may be able to place
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 Sep 30 10:13:54 EDT 2005 | Cmiller
We are having a random problem with boards bowing significantly. Its a large through hole board with only one QFP on it. The bowing occurs during the SMT reflow. The only conclusion I can come to is a problem at the board house that made it. I just w
Electronics Forum | Thu Apr 30 12:50:07 EDT 2009 | realchunks
Could be board support. Breakaway boards are a little more flimzy than boards without. A bowed board will cause miss placements - again can be overcome with proper supports (depending on the machine) I would bet that the boards with breakaways h
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 | Mon Oct 03 22:07:33 EDT 2005 | davef
If the PTH plating thickness is proper, your customer probably won't see the effects of moisture during soldering processes.
Electronics Forum | Fri Dec 27 16:26:30 EST 2013 | davef
I expect to find the specification and measurement method for the bow & twist of an assembly to be on the assembly drawing. Comments are: * Expecting that an industry committee to write a bow & twist spec for an assembly they know nothing about is n
