Electronics Forum | Wed Jul 18 17:09:45 EDT 2018 | slthomas
Update - next run started out horribly so went to another stencil design. Reduced thermal pad coverage by about 40% with 4 panes, with cutouts to avoid the vias. Worked like a charm for 10 boards (90 parts). I think we're finally on to something.
Electronics Forum | Tue Apr 10 08:37:36 EDT 2018 | davef
Hi Steve ... I found nothing in the manufacturers "paper" to help. Comments are: * I agree. No blobs. Solder on the thermal pad should me minimized. Too much solder will float the component. Old timers used to talk about 50-80% coverage. * If you'
Electronics Forum | Mon Apr 16 16:24:20 EDT 2018 | slthomas
Amazingly enough, every one of these held fast where we placed them with a paste brick sized 1:1 with the thermal pad, no sectioning. Yes, there were voids, but we can live with that in this application.
Electronics Forum | Mon Apr 09 12:52:00 EDT 2018 | slthomas
We are about to do a second iteration of something we struggled mightily with last time and I'm hoping to at least make a step in the right direction. There are 12 of these parts on the board and virtually all of them required removal and replacemen
Electronics Forum | Tue Feb 04 17:24:07 EST 2003 | jonfox
we have some pretty tight 0402 placements and our best fix was to reduce the pad (vertically speaking) from .030x.022 to .020x.022. Fewer tombstones and the paste flows out to the edge of the pads nicely. Only difference is that we have a 6mil sten
Electronics Forum | Wed Feb 05 14:20:45 EST 2003 | Stephen
One thing that worked for me was simply rounding off the pads, making square pads into circlesfor the stencil. It worked but did seem a little strange turning squares into circles for 0603's and 0402's and turning cirlces for BGA's into squares, (bu
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 Apr 09 13:53:45 EDT 2018 | dleeper
I've never placed one of these before, but it looks like a poorly designed part. It has pads scattered asymmetrically around the body of the part. when it reflows this is going to apply uneven forces to the component, causing it to skew. I guess hav
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 | Wed May 22 12:32:49 EDT 2002 | pwrgroup
which stencil vendor can deliver aspect ratio and area ratio and the statistical information to the user?It's difficult if the pad is modified.
