Electronics Forum | Sat May 27 12:50:21 EDT 2000 | Micah Newcomb
Steve, I use homebase apertures as a standard for all chip parts and have no complaints, no solder beading, no issues. I have had to replace almost all stencils ordered previous to my arrival as they all caused defects (7-9mil thickness and 1:1
Electronics Forum | Sun May 28 08:21:52 EDT 2000 | Sal
Can't agree more than moving over to Homebase apertures, But ensure that the cut back angle is correct,to acute of and angle will leave you with an inadequate contact area fot the terminations on the chip components and you will start seeing insuffic
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 | 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 | Mon Apr 23 11:44:55 EDT 2001 | CAL
650 Standards are also located in the back of IPC JSTD-001. I am currently looking at 4 pages on bow and twist. Percent bow = R1-R2/L x 100 (R1= Highest point; R2=lowest or resting point; l= length) Percent twist=(R1-R2)/(2xL)x 100 Sorry if this is
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 | Fri Aug 22 09:50:20 EDT 2003 | Mike Snider
I am placing a plastic Cypress, 256 pin BGA on a small assembly, and I cannot stop the corners from bowing. I've moved my profile up and down with no results. Any suggestions?
Electronics Forum | Fri Jun 25 22:30:47 EDT 2010 | smthexi
i think you need to use a PCB central support. do you know that part ? it specializes in preventing PCB board from bowing during wave soldering.
Electronics Forum | Tue Jul 20 16:02:12 EDT 2010 | mikesewell
You may want to look at IPC 7721 Method 3.2 Bow and Twist Repair. In extreme cases you may need clamp or weight the pcb with bow in the other direction to yield a "flat" pcb in the unrestrained state. You will have to take the PCB up to or slightly
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
