Electronics Forum | Thu Mar 19 20:12:32 EDT 2020 | slthomas
Stephen, you are spot on with your description. Here's a .jpg with paste layer, copper, and solder mask.
Electronics Forum | Mon Mar 23 16:38:09 EDT 2020 | emeto
Steve, On 16mil pitch I would try 12mil diameter on 5mil stencil, unless the BGA ball size is something unexpectedly huge.
Electronics Forum | Fri Mar 27 03:42:17 EDT 2020 | sssamw
Did you try 0.12 or 0.1mm nano coated stencil @ 10 mil aperture? A soak time type profile with long reflow time could help.
Electronics Forum | Wed Mar 18 11:27:24 EDT 2020 | slthomas
I am about to order a stencil and I can already see that I'm going to have issues. I'm hoping someone has a recipe for this scenario that we haven't tried yet. The parts are 16 mil pitch bga's, the pads are NSMD (10 mil dia. with 12.6 mil mask open
Electronics Forum | Mon May 28 17:43:33 EDT 2001 | davef
Does this device have a integral heat sink / metal slug on top, like a TI TM320C6XXX er a Altera EP20K4XX? Compare the size of the pads on the interposer and the board. Compare the type solder mask [NSMD vs SMD] on the interposer and the board. Wh
Electronics Forum | Mon Aug 09 17:02:32 EDT 2004 | arminski
Hi Shean, Thanks for the analysis. "Your product looks like it may have non-solder-mask-defined pads." Yes. It is a NSMD PCB. "Does there appear to be any residues on the bare boards, and/or, BGA components prior to applying the solder paste?"
Electronics Forum | Thu Jun 04 20:06:30 EDT 2009 | davef
Since posting the above comment extolling the virtues of NSMD pads and disparaging SMD pads, we've learned that the points apply to all array devices, but in spite of that some designers of fine pitch [eg, 0.4, 0.5mm pitch] array devices choose SMD w
Electronics Forum | Thu Jul 31 09:30:01 EDT 2014 | emeto
I know that some board houses have better capability than others. Some can do down to 4mils mask in between the leads I think. I know that it also depends on the type of the mask they are using - for some types you can't go down to the 4mil. Regards,
Electronics Forum | Thu Mar 19 16:06:29 EDT 2020 | stephendo
Imagine a circle. Now imagine a line attached to that circle. A line almost as wide as the circle. Or look at a regular BGA pattern now imagine if the traces were almost as wide as the pads. I have not seen any quite as bad as he describes but I have
Electronics Forum | Tue Mar 24 10:34:03 EDT 2020 | slthomas
My experience with our process is that those parameters would result in a big bridging problem. I'm working with a stencil designer at our fabricator on an asymmetrical aperture design that hopefully balances forces enough to keep the parts centered.
