Electronics Forum | Thu Aug 21 09:10:27 EDT 2003 | MK
go to http://www.sipad.com/SIPADBGA.htm mk
Electronics Forum | Thu Aug 21 20:43:21 EDT 2003 | davef
We just plant BGA in the paste when we place them with a standard flex machine. You know, just set your placement force to get the balls into the paste. Justin is correct about collapse.
Electronics Forum | Thu Aug 21 15:50:12 EDT 2003 | davef
Couple of points are: * You're technically correct that ball height has the potential to vary by 8 thou, but we never see that much variation. Ball heights within a lot of components vary just about nil. * When we place BGA, we smush them into the p
Electronics Forum | Thu Aug 21 18:36:32 EDT 2003 | paulm
Hi Dave and Justin, Thanks for the advice. Dave you mentioned you "smush" your bga's. What type of machine are you placing then with it? Is the additional pressure to smush them machine or manually applied? Also, the 0.004" variance we are being
Electronics Forum | Thu Jul 20 14:36:57 EDT 2000 | Bob Willis
Yes there will be higher process temperatures on the currently preferred alloys of tin/silver. There are not that many companies highlighting they have the solutions although many parts will be fine. If all components meet the requirements of the IP
Electronics Forum | Wed Aug 20 21:30:56 EDT 2003 | paulm
Our company if currently reviewing our BGA Screen Printing Process. The problem we are trying to eliminate has to do with BGA Ball Size Variance. Some of our vendors are allowing a +/- of 0.004" in ball size. This would allow for the possibility of a
Electronics Forum | Thu Aug 21 09:34:57 EDT 2003 | davef
Woa. The more paste that you put a a BGA ball, the more likely that you'll bridge between balls. Why do you need to compensate for the size variance in BGA balls? How does using a 8 thou thick stencil to compensate for ball size variance? Fine pi
Electronics Forum | Thu Aug 21 15:10:59 EDT 2003 | paulm
Such balls (=/- 0.004)size variance can occur in a single part. If I have a ball in a part that could be (according to vendor specs) 0.008 larger than another ball the only way I can insure that the smaller ball makes contact with the paste is to hav
Electronics Forum | Thu Aug 21 16:58:25 EDT 2003 | justin
With a eutectic ball, you'll see about a 50% collapse. This negates that .008" issue you're referring to. With a high temp ball, you don't enjoy the same freedom regarding ball collapse. Dave is correct, though. We recently got IBM to sign up to
Electronics Forum | Fri Aug 22 10:20:26 EDT 2003 | Stephen
I hate being persnickity, I just am sometimes. You are not being told you "should expect" that variance. You are being told you can't sue them for manufacturing defects if the balls are within that range. That range is way bigger than what they wil
