Electronics Forum | Tue Jun 17 08:52:39 EDT 2003 | russ
Aspect ratio = width of aperture divided by height. E.G. 6 mil stencil at 9 mil wide = aspect ratio of 1.5. Value should be 1.5 min. Area ratio - use when length and width of pad are roughly same dimension like for BGAs and 0805 and smaller R-nets
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 | Tue Jan 16 09:23:26 EST 2001 | P.Gerits
Hello, Standard way to calculate stencil design can be done as follows: A normal ratio of aperture width/stencil thickness = 1.5 for pitches below 650u A normal ratio of stencil aperture width against pad width = 0.8-0.9 (or stencil aperture 10%-20
Electronics Forum | Tue Aug 17 10:41:13 EDT 1999 | Steve A
Wayne, Sounds like a gasketing problem. When the horizontal apertures are bleeding but not the vertical apertures. Could be poor underside support, HASL miniscus issues, masking or plugging issues, but what many people do not account for is that t
Electronics Forum | Fri Sep 21 14:03:45 EDT 2001 | jschake
I have observed solder balling for all aperture sizes tested. Solder balling levels appear to be better correlated against the amount of solder paste that is underneath the 0201 component terminations after placement rather than comparing this to th
Electronics Forum | Tue Sep 21 13:17:29 EDT 1999 | Dave F
snip | I've often been tempted to try something a little different when specifying QFP apertures. Like, for example, using long, tapered triangular apertures arranged in alternating directions. The objective being, get the maximum amount of paste do
Electronics Forum | Tue Nov 09 13:12:26 EST 1999 | Dave F
Steve: Sure, but let's figure it out for you!!! ;-) Here�s some sample calculations. Your results may vary, void where prohibited, etc 20 PITCH: Pinched aperture volume: 0.010"X0.050"X0.005" = 2.5 uin^3 Zippered aperture volume: (0.015"X~0.5)
Electronics Forum | Wed Nov 15 12:52:21 EST 2017 | georgetruitt
IMO – Look into nano-coatings for your stencil and radius all square apertures This should help out with solder paste releasing from the stencil helping with insufficient solder QFN LGA aperture design, try a stencil cut with a few different apertur
Electronics Forum | Sat Sep 30 12:14:32 EDT 2000 | jarnopy
Hi Maybe you have too small apertures in stencil. Good apertures size is 90% from pad. And one thing what you can try is that you cut your stencils(blades) aperture corners round (i mean like a oval). I hope that these advices can help you.
Electronics Forum | Thu Jun 29 11:52:23 EDT 2000 | JAX
sree, There is no Definite. You have to make the call. If you think the previous info was on target, use the info provided to find out the appropriate percentage relation between ball diameter, pad diameter, and aperture size. If you already run BGA,
