Electronics Forum | Thu Feb 23 23:24:14 EST 2006 | KEN
Depends what is adjacent to the step. 1206 chips could reside closer than say a 16 mil fine pitch. Larger apertures are more forgiving to height variations than small apertures.
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 | Fri Oct 18 22:32:20 EDT 2002 | mdm4ua
If you have room try putting a small piece of tape on the bottom of the stencil right next the aperture that is giving you the problem. The added height of the tape (Kapton tape is usually about 3 mils thick) will likely give you a heavy enough depo
Electronics Forum | Wed Jan 22 13:17:48 EST 2003 | slthomas
We're considering stenciling SMT adhesive to increase throughput. This is an as-of-yet unproven process and for that matter pcb design (we've never done anything with more than about 50 SMT parts on the bottom, this board has in excess of 1200, but
Electronics Forum | Mon Sep 21 22:25:05 EDT 2009 | davef
What babies!!!! Sure, give it a try. * Stencil material: metal or plastic, no difference in print, metal is easier to clean, no static problem, available * Stencil thickness: Chips 0.006", SOIC 0.010" [print height equals 1/3 thickness] * For 0603, a
Electronics Forum | Fri Oct 09 06:32:38 EDT 2009 | davef
Here's what is on that post referred to, not sure what you need more than ... "* Stencil material: metal or plastic, no difference in print, metal is easier to clean, no static problem, available * Stencil thickness: Chips 0.006", SOIC 0.010" [print
Electronics Forum | Tue Nov 03 11:46:52 EST 2009 | davef
Search the finee SMTnet Archives for previous posts on the topic. Here's a clip from on of those posts that may get you started. [snip] * Stencil material: metal or plastic, no difference in print, metal is easier to clean, no static problem, availa
Electronics Forum | Tue Sep 24 12:49:43 EDT 2002 | dragonslayr
Aperture reduction @ 5 mils thickness is your best bet. It may take several attempts to get just the right paste volume. What aperture reduction was specified to the stencil house for these specific LEDS? or was the stencil blindly produced using a
Electronics Forum | Mon Apr 11 15:37:29 EDT 2005 | GS
For 1,27 mm Column Pitch, we set our process like this: - Stencil 0,20 mm If allowed also for other SMDs otherways some time 0,150 with step up stencil used only for CCGA area. - paste height min 0,175 mm - aperture 0,75 to 0,8 mm - paste volum
Electronics Forum | Fri Sep 25 16:47:57 EDT 2009 | esoderberg
0.5mm pitch QFP's are typically mixed with large components on all of my boards. I usually use a 6 mil stencil with a minimum aperture width of 10 mils. Normal aperture size is 10 x 50 which causes shorts about 20% of the time. A recent purchase of
