Electronics Forum | Mon Dec 16 10:23:42 EST 2002 | Grant Petty
Hi, I have checked the archives, but need some advise. We have a 256 pin 1 mm pitch BGA part of our boards, and we have having problems with paste release our of the holes for the BGA. We just cannot seem to get it right, and we have to keep the st
Electronics Forum | Wed Dec 18 01:37:39 EST 2002 | Steve
I dont know what kind of screener you use but my 1st impression is that the board and stencil are separating too fast,the paste doesn't have enough surface tension to stay on the board, you're tearing the paste off the board. If you can, slow down th
Electronics Forum | Thu Dec 19 13:23:11 EST 2002 | gramsey
Now, this is good solid advice. If following this advice does not help there is something wrong with 1. the paste (reology failure) 2. the stencil (rough walls) 3. the board (bad design or fab) (in order of likelyhood)
Electronics Forum | Tue Feb 12 14:00:53 EST 2013 | dyoungquist
We have a board with a 1.0mm pitch BGA. The stencil apertures are 0.0177 inch diameter. We used an electroform stencil with good results.
Electronics Forum | Tue Dec 17 08:46:59 EST 2002 | Randy Villeneuve
Personaly I would try a different solder paste. Give Indium a call and get a sample of their SMQ92J No clean. You will be impressed. Alpha and Kester also have good products but we have a long history with this paste and we have printed millions of b
Electronics Forum | Wed Dec 18 15:38:59 EST 2002 | swagner
I have had a similar problem in the past, since I have never worked with a semiautomatic printer there could be a few things I recommend that will not work for you. 1. Make absolutly sure that you have proper support under all of the BGA's. 2. Print
Electronics Forum | Sun Dec 22 06:00:54 EST 2002 | Mark
Hi: Your stencil specs are good; Did you check the stencil thickness? It would be worth a ck since there may be an error from the stencil mfr If the paste is not releasing with good stencil specs, these are possible causes: 1 The paste isn't tou
Electronics Forum | Sun Nov 07 10:54:21 EST 1999 | Steve Thomas
We're looking at redesigning our stencils to facilitate better (well, it's pretty much non-existant, so any improvement is a big leap) release from fine pitch apertures. Currently we have perpendicular walled laser cut apertures. We'll be having
Electronics Forum | Fri Nov 19 22:48:26 EST 1999 | mark
Steve, your comments from your stencil vendor are very interesting. Any decent laser cutter automatically cuts a trapezoidal aperture. This is just the nature of the cutting. We have a bunch of lasers (and chem-etch). You have to polish your laser cu
Electronics Forum | Tue Nov 09 17:12:38 EST 1999 | Dave F
Steve: Addressing your points: 1 FINE PITCH APERTURES Electropolishing Laser Cut Stencils: Laser cut should not requiring polishing. Geesh, how much money do you have for stencils? ;-) Oval Shaped Apertures: Pass. What do you expect to gain f
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