Electronics Forum | Tue May 19 15:06:36 EDT 2009 | c111
we had many problems with this. there is no standard that I could ever find. we came up with our own after weeks of headaches. we use 25% as our guide line we use window pain only for the center paid to allow for out gassing and reduce 15-20% globaly
Electronics Forum | Fri Jun 29 15:35:32 EDT 2012 | gnus
The stencil doesn't seem to match the pcb. On the pcb there seems to be pads that are wider than others whereas the openings in the stencil seems to be uniform. As Phil mentioned, make sure the gerbers match the stencil. As for no fiducials, that sho
Electronics Forum | Fri Mar 06 10:32:34 EST 2009 | fountain42
Yes, We've already experienced this same problem. 1) What kind of flux are you using? No Clean? Rosin? OA? 2) If it's OA, What kind of water wash do you do? Do you use DI water? How Hot? Who's machine? What are the pressures? 3) Have you performed a
Electronics Forum | Fri Apr 06 10:43:57 EDT 2007 | flipit
Hi, Anyone seeing difficulty is soldering MLFs or QFN with lead free solder? I have an MLF with 3 rows of pads on each of the 4 sides of the part and then the large center ground plane in the middle. The part is 20 mil pitch. Had good luck with l
Electronics Forum | Fri Jun 20 18:32:55 EDT 2008 | hegemon
Back when I used to do a lot of these style devices we ran into the same problem you are describing. Use a pattern for the center pad area and keep the total coverage to about 68% of the pad area. Diagonal Stripes, tic tac toe, cloverleaf, dot array
Electronics Forum | Tue May 26 14:39:40 EDT 2009 | boloxis
QFN or MLFs are mainstream now, QFNs already evloved to much more complex versions now like matrix pins, stacked dice and flipchip versions. IPC 610D already includes them, just make sure the pins have solder plating, the PWB pads have soldermask in
Electronics Forum | Tue Sep 14 17:06:25 EDT 2010 | asksmt
Hi All, I have designed 4 Layer PCB with one 28 pin QFN PKG. I have got complaint from Production that the pads which connected to thermal pads (gnd) thru trace is bridging with solder and because of this bridge, pins are not getting soldered prope
Electronics Forum | Fri Feb 25 10:52:59 EST 2005 | russ
Would these be the parts that have just pads located on the bottom of the part? If so, we place these every day in decent volumes and have never had any manufacturing problems with them. I cannot comment on the reliability since we are a contract M
Electronics Forum | Sat Apr 07 01:15:45 EDT 2007 | Haris
Hi I dont think there is a stencil problem or a printing one but i think you should check you paste specification regarding 20 mil pitch i.e. its ball size in microns so that you know Is that paste can be use for this type of components or not. Secon
Electronics Forum | Fri May 23 16:38:28 EDT 2008 | wayne123
Well if you are getting bridges under, one thing that we used to do was flood the part with flux and then run it back through the reflow. Keep in mind we were not a High reliability manufacturer. This practice didn't hurt OUR boards, and most of the
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