Electronics Forum | Thu Apr 15 16:07:37 EDT 2004 | barry
Hi there all, we are having problems with 2 qfp devices. grainy poorly reflowed solder joints. One 100 pin .5mm pitch, and one 64 pin .5 mm pitch . Both of these devices have a thermo pad on the back of them (pad area soldered to back of device)which
Electronics Forum | Tue Aug 17 10:41:13 EDT 1999 | Steve A
Wayne, Sounds like a gasketing problem. When the horizontal apertures are bleeding but not the vertical apertures. Could be poor underside support, HASL miniscus issues, masking or plugging issues, but what many people do not account for is that t
Electronics Forum | Thu Aug 12 22:38:44 EDT 1999 | Dave F
| Hello | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | 100 durometer blade. Getting "tails" on deposi
Electronics Forum | Mon Apr 17 19:30:27 EDT 2000 | Boca
All of the above is good stuff. To add, I have seen this several times if the assembly is wavesoldered. Heat from the wave can partially reflow the top side SM solder joints and weaken them. To test, check joint strength before wave and then after
Electronics Forum | Tue Apr 11 16:42:56 EDT 2000 | Chad Notebaert
I�m thinking �Poor intermatallic� It could be a few things. Lets start at the beginning. -Is your paste a 63/37 mixture? -Have you monitored you screen printing, Verify Solder deposition, Are you getting enough paste? -You say the solder looks like i
Electronics Forum | Tue Jun 13 16:45:30 EDT 2006 | adlsmt
If the only difference is the layer count, check the profile as stated above. If you dont have a profiler you can probably get the local Kic or Mole rep to do a demo on that board. I believe I was the one who stated in an old post that prying the lea
Electronics Forum | Fri Jan 08 21:34:44 EST 2010 | isd_jwendell
Not specific to QFP, but I had a run of poorly etched boards. I could see the short using 75X magnification with back lighting, but only some of the time. Nasty little shorts on ~25% of the boards that cost us a boat-load of cash.
Electronics Forum | Wed Sep 05 08:10:45 EDT 2007 | davef
Questions are: * Do not judge the quality of a solder connection by the shineyness or color of the solder connection. Do you have smooth and unform flow, no pitting, and good wetting to the lead and the pad? * What is the temperature of the leads of
Electronics Forum | Sat Dec 11 12:15:21 EST 1999 | Steve Thomas
We have a pretty challenging board (2-up panel, 15"x20", 48 20mil pitch QFP 100's and 2 25mil QFP128) that gives us LOTS of lead bridging on the 20 mil parts. There is typically very poor wetting on these parts also, and some joints just flat aren't
Electronics Forum | Wed Sep 05 07:07:25 EDT 2007 | mun4o
hi, I have a big problem with soldering uP QFP144 package.All components in PCB are small, only this chip is big and I can't make good temperature profile.Solder joints of other components are shining and with good wetting, but in QFP leads solder j
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