Electronics Forum | Sun Oct 10 15:07:04 EDT 2004 | GIO
sorry..it s 40 mils...pitch,...but stencil aperture is square...ANY COMMENTS.. THANKS RUSS...
Electronics Forum | Thu Sep 30 17:36:17 EDT 2004 | GIO
i have a 0.5 pitch(19x19 pbga array) ..with a pad of 20 mils (thou) , solder mask is same...(20th..)..and an stenCil aperture of rectangular 22 X 22.1 thou...WHICH SHOWS..I AM HAVING AN OVERPRINT..MY PASTE IS A NO-CLEAN.. COMMENTS PLS...
Electronics Forum | Thu Sep 30 18:23:00 EDT 2004 | russ
Comment: A 20 mil pad for a .5mm pitch BGA? That seems like an awful large pad for this device. If my math is right the pads will be basically touching each other. .5mm = .020". I would think that you have something else. You cannot have a 22mil
Electronics Forum | Mon Oct 11 15:21:20 EDT 2004 | russ
I have heard of making square apertures for round pads to aid in Xray and possibly allow for better release in some applications. The square aperture in your case would be for Xray inspection and not release. Usually a 20 mil square would be used f
Electronics Forum | Tue Jun 28 11:31:23 EDT 2005 | kennyg
Anyone know of a maximum solder overprint formula? I need to overprint a 0.011" wide aperture but want to go out to 0.050" overprint. This seems extreme, but necessary as I can't go out in width due to numerous issues. It seems like one could come
Electronics Forum | Wed Dec 06 07:24:22 EST 2006 | davef
Successful solder paste overprint is a function of the solder paste rheology, solder mask and through hole component stand off. * Solder mask with a high surface energy will permit a larger overprint than a solder mask with a lower surface energy. In
Electronics Forum | Wed Jun 20 08:14:36 EDT 2007 | pavel_murtishev
Good afternoon, You should use overprint technique if you have any problems with paste volume (PIH technology and mixed designs, for instance). Otherwise, it is useless. Overprint has to be made in such way so that paste would have an ability to flo
Electronics Forum | Tue Dec 05 03:39:39 EST 2006 | pavel_murtishev
Good afternoon, Due to problems with power connector soldering I have to overprint paste on pads for this connector. Stencil thickness is 125um and I cannot make it thicker. Area ratio of chip resistor assemblies limits stencil thickness to 125um. R
Electronics Forum | Tue Jun 28 21:54:44 EDT 2005 | davef
Fabricators take different approaches in developing paste that is more or less prone to solder balling. That being said, you should be able to overprint 250 thou, no problem. Prove this to be correct by printing paste on a scrap board with an obsol
Electronics Forum | Tue Dec 05 08:23:14 EST 2006 | davef
How about a stepped stencil? Not ideal but ... As far as overprinting goes, try: http://www4.uic.com/wcms/WCMS2.nsf/index/Resources_44.html
