Electronics Forum | Thu May 18 11:16:16 EDT 2006 | russ
Go 5 or 6 mil thick with stencil, i am not familiar with that pitch but I would recoomnd a 5mil. Was the thickness in this post before and i missed it? Russ
Electronics Forum | Mon Nov 13 04:57:27 EST 2000 | Wolfgang Busko
Hi Richard, I assume that you deal with a component that has 20mil pitch. In this case depending on your pad design you get from 8 to 10mil spacing for your apertures. With a slight reduction of the aperture (10 to 15% for avoiding shorts)and a 6mil
Electronics Forum | Wed Nov 15 11:00:35 EST 2000 | Finepitch Services
"depending on your pad design"... To me, Wolfgang gave you the biggest secret... I guess he meant the real pad width you get on your board is the start point. Get the average measurement in mils and then cut it from the sides at the percentages he h
Electronics Forum | Mon Nov 13 08:24:03 EST 2000 | G. English
Richard, From your description of the IC, as Wolfgang indicates it sounds like a 20mil pitch device, the aperture design really depends upon your solder paste particle size, we use a type 3 solder paste with a mesh size of �325 / +500microns. This is
Electronics Forum | Thu May 18 09:18:33 EDT 2006 | Chunks
Hi dwelch123, 8 mils seems a bit thick to me. I would normally go 6 or 5 mil for fine pitch such as this. One other area to check is the the snap off. Are you using the slow snap off or just lowering the board right after print? If so you should
Electronics Forum | Thu Jun 16 09:13:46 EDT 2005 | russ
We use a 5 mil for 16mil pitch QFPs, Make sure that the stencil has been polished. Type 3 paste. We have used lead free no-clean, lead no-clean, and water soluble lead pastes for these packages. We set the printer for a slow stroke .7 in/min. wi
Electronics Forum | Thu May 18 10:20:55 EDT 2006 | slthomas
Russ asks good questions and I think Chunks pretty much nailed it. Aspect ratio (aperture width/stencil thickness) s/b 1.2 minimum (I like 1.5 if I can get it). If your aperture width = lead width (.008"), yours is 1. Tough to get consistent paste r
Electronics Forum | Tue Mar 02 10:24:06 EST 2004 | russ
I have done this before, We print with a 5-6mil stencil and have had no problems with any underneath solder. If you are still nervous instead of removing from stencil use some 3 mil kapton tape or equivelant and tape off the BGA pads. This way the
Electronics Forum | Tue Feb 22 12:03:32 EST 2005 | russ
You may to reduce a little bit more with HASL. for .4mm pitch and such I would maybe go to a 5 mil with your standards.
Electronics Forum | Mon Oct 06 04:03:39 EDT 2003 | iman
Does the EIA standard recommend any standard PCB pad sizes (LxB)? and pitch-to-pitch (Pad) distances? Thanks for the advise.
