Electronics Forum: thermal stencil (Page 1 of 16)

Solder short-BGA with thermal pad

Electronics Forum | Fri Dec 27 14:11:18 EST 2002 | cnotebaert

We have placed these parts. I have not had problems with them but when I designed the stencil we reduced the app for the large thermal by 20% to reduce the chance of problems like your having. If the balls are close (.040-.050" or

Nordic aQFN73 stencil design

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.

Nordic aQFN73 stencil design

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.

Nordic aQFN73 stencil design

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'

Step stencil troubles

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

Nordic aQFN73 stencil design

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

omit stencil apertures to hand solder or paste, reflow then solder.

Electronics Forum | Thu Feb 27 08:59:15 EST 2020 | spoiltforchoice

In both cases, it will depend on storage conditions, unless you do something horrible to them (or as previously mentioned, wash them) months & months. For boards we put through SMT and then stash for THT loading in smaller qty's I don't think we've e

QFNs (LCCs)

Electronics Forum | Thu Dec 21 15:34:48 EST 2006 | russ

we are reducing the thermal pad stencil apertures by 40% on these with great results Russ

LLP Device

Electronics Forum | Thu Mar 09 04:04:48 EST 2006 | dougs

one point to remember is to have a large stencil reduction on the thermal pad, you need to reduce the solder volume by about 35%, if you don't you risk the solder from the thermal pad shorting out the other leads or the solder volume causing the comp

Solder balls under LLP

Electronics Forum | Thu Sep 01 09:05:47 EDT 2005 | russ

Thermal pads located underneath leadless devices require a 50% reduction in the stencil aperture.

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