Electronics Forum | Wed Apr 24 21:34:01 EDT 2002 | davef
Search the fine SMTnet Archives. Guidelines * Control: Flux specific gravity, preheater temp, conveyer speed, solder temperature. * Two most important parameters are: solder temperature & dwell time * Contact time. The optimum contact (dwell) time
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 | Mon Feb 19 13:04:17 EST 2001 | billschreiber
The ultrasonic frequency used in today�s stencil cleaners is usually a 40 kHz �sweep� frequency (also used on semiconductors and other sensitive cleaning applications). This frequency is not low enough to cause stencil damage (the lower the frequen
Electronics Forum | Wed Sep 18 10:06:30 EDT 2002 | Bob M
I place 15-20 mil a lot. You need to look at your pad to apature reduction. Your stencil thickness. The type of paste your using. We use 2-5 mil reduction on each side as a general rule on fine pitch. This varies depending on pad width. We also use 5
Electronics Forum | Wed Jan 16 08:56:50 EST 2008 | sigmaprint
The ideal and most cost effective solution to this problem is to purchase the FineFoil/CustomFoil retrofit kit that we have designed and can supply. http://www.sigmaprint.co.uk/customfoil.htm
Electronics Forum | Thu Dec 08 12:24:11 EST 2005 | cyber_wolf
Any good stencil house should be able to recommend the proper configuration on a fine pitch aperture design. They can also advise you as to which foil thickness works best. The norm foil thickness is .005" - .006". There are always special instances
Electronics Forum | Thu Oct 05 17:05:36 EDT 2000 | JAX
These types of foil kits work just fine as long as they are used before expiration. Scraping off the epoxy coat gets a little tough on fine pitch pads and etches. I have always like to use a solder sample board to retrieve my bits & pieces from whene
Electronics Forum | Thu Mar 29 12:05:38 EDT 2007 | cecil
OK, just finished our prototype build. PWB 7.5" x 10" 16 layers smallest pitch 17mil smallest BGA pitch 30mil (round apertures) smallest component 0402 total of 1492 placements 5 mil stencil foil (invar) Had numerous PQFN packages that always gave
Electronics Forum | Thu Sep 02 07:22:03 EDT 1999 | Earl Moon
| I'd like to know the advantages and disadvantages between the two. | | Thanks and regards, | | Both have their place. When using less fine pitch (.025" +) with fine pitch (.020" or less and BGA's) a .007" thick stencil may be used. This would re
Electronics Forum | Thu Dec 08 09:47:46 EST 2005 | slthomas
I'm with Grant on the .005" foil thickness. The key is to keep your aspect ratio (aperture width/foil thickness) over 1.5, laser cut, and I like trapezoidal aps. too.
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