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
Electronics Forum | Thu Dec 26 12:12:55 EST 2013 | igorfo
Dear Friends, I need your help to understand requirements and measurement methods for bow and twist of assembled PCB (PCBA have and SMT and TH components). I already check all posts on the site but didn't found any related to my question answers.
Electronics Forum | Tue Oct 10 12:56:15 EDT 2000 | Ken Van ZIll
I agree that homplate is a good design, but also this could be caused by the stencil thickness and aperture size, if you are at 7-9 mils thick stencil and a 1:1 ratio on aperture size then 2 things i know of will happen, one a squishing out of past o
Electronics Forum | Mon Jan 09 17:35:32 EST 2006 | russ
How are people getting BGAs reworked on boards that are 15"x15" at .06" thick? The BGAs are pretty much in the center of these assemblies. We have just received these and I cannot keep from warping/bowing as much as 1/2" at the heated area. Our bot
Electronics Forum | Mon Oct 28 18:59:25 EST 2002 | tkenny007
Specs for Bow and Twist for PCBs (IPC-A-610C, 10.6. There may be an update by now). I also have a note in our quality guide referencing (IPC-TM-650, 2.4.22) and (MIL-STD-105D). In summary, a PCB should not bow more than 0.040" with all four corner
Electronics Forum | Wed Dec 19 09:23:47 EST 2001 | davef
Bow & twist for bare boards and panels: IPC-A-610 1.5% for PTH only and 0.75% for SMT
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 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 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 Nov 01 15:35:25 EST 2004 | Ken
Agreed. You will find different part manufacturers have different coplanarity specs. In fact I have on supplier that calls out 7 mil max coplanarity. Then factor in board bow and twist and it becomes a real joy.
