Electronics Forum | Thu Oct 26 10:29:03 EDT 2006 | Mike
First, Voiding under thermal pad is unavoidable(pardon the pun), unless you can find a way to add sufficient amount of solder paste to cover the area, and match that solder volume on your terminal leads. I build HVM qty's of "QFN" components w/ therm
Electronics Forum | Thu Nov 10 10:45:32 EST 2011 | aqueous
The use of IPA in automated defluxing systems is nearly extinct for the following reasons: 1. IPA is flammable. In a spray-in-air environment, the already low flashpoint is even lower. 2. IPA is not a great solvent. There are specific containme
Electronics Forum | Wed Nov 28 16:08:38 EST 2007 | jmelson
I've been using Xilinx TQFP's in the 44 and 144 lead sizes with no trouble. I don't even bake them before reflow and have never had any problem. The Xilinx parts are certainly NOT sensitive, I could not break one with my bare hands if I tried (I ha
Electronics Forum | Wed Jul 16 18:46:46 EDT 2008 | mariss
emti, Thank you for the reply but I'm looking for a reasonable quality pcb mfg. We do SMT and thru-hole in house (3 Juki KE-750L machines) of our product. My problem is with the bare boards: holes poorly registered with top copper, solder masks mis
Electronics Forum | Wed Jun 16 07:35:28 EDT 2010 | scottp
Rather than tent the thermal vias, we use a small annular ring of soldermask around them and only print paste in the areas between the vias. Any way you go you're going to have voids under QFNs, so we just try to make it repeatable so our designers
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 | Thu Mar 28 13:19:14 EDT 2019 | davef
There is no industry standard for BTC stand-off height. "IPC-7093A Design and Assembly Process Implementation for Bottom Termination SMT (BTC) Components" just finished "Final Draft for Industry Review" in December 2018. It mentions stand-off height
Electronics Forum | Mon Apr 29 12:45:00 EDT 2019 | slthomas
When you say "....is there a way to easily (or at all) reference parts with the same specs..." do you mean when ordering stencils, or are you trying to drive your designers to choose a package that you already have in play when they have package opti
Electronics Forum | Fri Mar 11 13:03:08 EST 2022 | poly
I've just bought the pick and place machines (universal Genesis GX11 and GC30) and oven (RO300fc-c) but I am confused about printers. I've put in an offer for an MPM Accela (2006 or 2008) but I'm not sure if it's a good idea / deal. It's being sold i
Electronics Forum | Mon Mar 25 21:50:10 EST 2002 | davef
Some of this was copped from Fred. There are numerous package types that now fall under the rubric of land grid array [LGA]. Land grid devices [ie, Bumped Chip Carrier� [BCC], LGA, Quad Flat-pack No-lead [QFN], MicroLeadFrame�, etc] are essentially
