Electronics Forum | Tue Aug 01 10:09:52 EDT 2006 | cyber_wolf
Chunks, Make sure your aspect ratio is OK. Normally for an application like this, I would use a .005 foil. The foil material would be invar.The invar has better release characteristics. Crappy solder paste can also cause release issues. I am not sur
Electronics Forum | Tue Aug 01 10:29:43 EDT 2006 | slthomas
It's been a while since I've built with 16 mil pitch, but I have to second the recommendation to go to 5 mil stencils. Night and day as far as release characteristics. The increase in aspect ratio opens up the window a lot. (read = covers up a mult
Electronics Forum | Tue May 22 12:27:04 EDT 2007 | cyber_wolf
I would consider calling Kester and telling them they need to send their people out. I could not really see mesh size being an issue on anything 20mil and above. There are several other issues that can cause aperture clogging as well...: Incorrect
Electronics Forum | Mon Feb 25 12:21:16 EST 2008 | stevek
Rather than having the artwork cover the via as with tenting dry film, and letting the mask do what it will, the preferred way is to do a second op silk screen with something like SR1000 just in the vias themselves to plug them. This doesn't always
Electronics Forum | Wed Apr 14 14:51:10 EDT 2010 | jgalarza
After checking some of our stencil data for the correct aspect ratio I found that a few are wrong. I would like to change them from 5mil thk to 4mil thk but do not know how much paste volume I need to keep. We are using 0201,0402, and BGA with 0.80 p
Electronics Forum | Mon May 24 13:11:12 EDT 2010 | deanm
A guideline that I use agrees with MikeS: For 20mil pitch, apertures should be 9-10mil with a stencil thickness of 5-6mils to achieve an acceptable aspect ratio of 1.7. Just be sure you are using a mesh Type 3 or 4 solder paste. Otherwise, larger par
Electronics Forum | Wed Feb 17 13:02:03 EST 2016 | comatose
The layer count itself isn't going to be what drives yields. What is the trace/space? How much annular ring for vias did you give them to play with? Class 2 or class 3? What's the worst hole aspect ratio? Controlled impedance? The closer you run to y
Electronics Forum | Wed Jun 14 09:34:25 EDT 2017 | cyber_wolf
In my experience there is no need for wet wiping stencils. We run 0201'and micro BGA's daily with no issues. If you are having paste release issues, I would be looking at other things. Aperture area aspect ratio, aperture design, land design, sold
Electronics Forum | Tue Dec 17 18:16:18 EST 2002 | davef
Square apertures can have a larger area within the same space than a round aperture. You can buy IPC 7525 from IPC. The theory you are missing has to do with: * Aspect ratio * Area ratio Search the fine SMTnet Archives for background on these rati
Electronics Forum | Mon Nov 15 12:13:41 EST 1999 | Dave F
Steve: There are guidelines for determining if your aperture has the correct proportions to the foil thickness. Maybe that�s what you�re looking for: 1 Aspect ratio = aperture width/foil thickness Chemically etched SB GT 1.5 Laser cut SB GT 1.2
