Electronics Forum | Fri Sep 17 13:24:27 EDT 2004 | Bob R.
I also agree with Russ - we use step stencils when we have to but generally try to avoid them because the print isn't as consistent as with a single thickness stencil. Many of our products are for harsh environments so we do a lot of thermal cycle a
Electronics Forum | Wed Aug 18 21:10:23 EDT 1999 | se
| | | Hi, | | | I'd like to ask some tips about the merits and shortcomings o | | | of both screen printer and stencil printer. For small quantity and highly mixed usage, which type of printer is suitable to our | | | application? | | | The board
Electronics Forum | Wed Feb 22 08:02:56 EST 2006 | dj44
I was looking for an stencil design for a 0.5mm pitch uBGA. Pad size is 0.38mm in diameter. We have been using 5mil stencil with type 3 no clean paste. What size aperture should we be using? Any suggestions?
Electronics Forum | Mon Feb 18 11:31:02 EST 2008 | davef
Print paste through the new stencil with a piece of mylar [or other clear plastic sheet about the thickness of paper] between the board and the stencil. Dispose of the mylar according to local practice after confirming proper aperturation of the sten
Electronics Forum | Thu Jul 21 09:43:10 EDT 2005 | davef
We agree with Russ. The solderballs are probably the result of printing too much paste on the board. In designing your 5 thou thick stencil: * Aperatures for the pads should be identical to a IPC-7351 - SO8 [or worst case http://www.vishay.com/docs
Electronics Forum | Mon May 15 15:42:29 EDT 2000 | Doug Smith
Can anyone tell me a recomended stencil apt. design for PBGA's and Ceramic BGA's when using a no clean (UP78) paste?
Electronics Forum | Mon Nov 25 12:32:20 EST 2002 | davef
Now that is a BIG step. Stencil type: * A metal squeegee is fine with stepped stencils. * A rubber squeegee is fine with stepped stencils. Comments on step stencil "keepouts" are: * Use an ample space around the stepped down component pads that is
Electronics Forum | Thu Feb 08 08:28:11 EST 2007 | mzaboogie
Good Morning Everyone, We have an application coming up with several BGA's on a RoHS assembly. One is a 25 mil ball on a 40 mil pitch, another is a 15 mil ball on a 40 mil pitch. In the past for leaded assemblies, we have used square apertures for 1
Electronics Forum | Thu May 03 18:40:34 EDT 2001 | pzohbon
We produce a board right now with a QFP that has 20 mil pitch and we are seeing problems with the solder deposition. I believe it to be a cleaning issue which we are addressing. Soon we will be pasting for bga's. Is there a problem with using inter
Electronics Forum | Fri Sep 17 09:31:17 EDT 2004 | russ
Step stencils are used but only when necessary. One reason to use one would be a PCB with 12 mil pitch and very large coils or something of that nature. The 12 mil pitch part would require a 4 mil thick stencil to ensure release while it would caus
