Electronics Forum | Tue Apr 10 10:21:06 EDT 2018 | slthomas
Dave, that's a cool idea and sounds like something that would actually work. I'd be tempted to go with oversized pads to increase the holding force. Unfortunately as an EMS we would have to work that through the customer approval system and as usual
Electronics Forum | Tue Apr 10 10:33:08 EDT 2018 | davef
Oh, I just remembered the other thing that I wanted to mention ... Do the pads match the component leads?
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 | Thu Apr 23 07:34:15 EDT 2020 | stephendo
Stencil editing is something that you have to do to do well. And you have to look at the boards after the screen printer and after the oven. Reading white papers ain't gonna cut it. And then there will always be part pad combos that will introduce s
Electronics Forum | Wed Feb 22 10:00:58 EST 2006 | dougs
We've just set up a couple of products with 0.5mm pitch uBGA devices on them, i went for 5thou thick, laser cut nickel (to aid paste release) square pads same size as the diameter of the uBGA pads. Or you could go to a 4 thou nickel stencil, better
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 | Mon Mar 20 10:54:36 EST 2000 | Glenn Robertson
Jack - The last time I checked IBM was specifying a minimum of 4800 cubic mils of paste for each pad. This is required for acceptable reliability, not just to make the connection. There is no way you are getting that volume with a 5 mil stencil
Electronics Forum | Thu Nov 01 13:08:33 EST 2001 | dave231
I am just starting to get into sub 50mil pitch, but from what I can see you are correct. But I can help with solder stencil. I cut the width only half of what the pad is, but the keep the length the same. This has helped but does not fix always. Stil
Electronics Forum | Thu Mar 19 16:13:28 EDT 2020 | stephendo
I tend to go by extending it by a distance rather than a per centage. For example 10 thou over. Does anyone else give a distance rather than a per centage? For long pads on connectors where I need more solder, a per cent doesn't make sense to me.
Electronics Forum | Fri Oct 18 09:50:02 EDT 2002 | russ
Steve, I am not aware of any standards so to speak. But IPC 782 and 770 have some useful info regarding mounting and pad geometries for wave etc... Since I do not know what type of components you will be wave soldering I will just give you some
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