Electronics Forum | Wed Dec 13 19:40:38 EST 2000 | Jerry Wetzel, SME, EM/SME
Your profile must be precise, your stencil aperture sizes and shapes are very important, and the size of the pads on the boards should be very close to what the part manufacturer recommends. We had some trouble with hi-temp paste, and discovered tha
Electronics Forum | Tue Jul 04 16:13:09 EDT 2000 | TOOLMANTIM
HELLO BILL I HAVE SOME QUESTIONS FOR YOU 1:HOW ARE YOU CLEANING YOUR STENCIL 2:ARE YOU SINGLE OR DOUBLE PRINTING. 3:ARE YOU USEING VACUUM FIXTURES OR NOT? HERE ARE SOME OTHER THINGS TO TRY. IF YOU ARE CLEANING YOUR STENCIL OFTEN BECAREFUL OF USEING
Electronics Forum | Fri Nov 30 08:53:17 EST 2007 | jaimebc
Shy, Our 5 and 6 mils stencils have home plate apertures and reduced by 10% and using SMT adhesive. Never had a problem with components non wetting like you have. I do believe that you are not screening enough paste, something about the dog bone ape
Electronics Forum | Wed Nov 06 16:31:59 EST 2002 | slthomas
I would also consider paste control (don't take it personally...I always have to get after people about this one), time on the stencil, time between print and reflow, solderability of the component leads, paste volume (that one really got us once....
Electronics Forum | Fri Mar 06 10:46:35 EST 2009 | davef
First, we agree with Loco that your QFP is nonwetting, rather than dewetting. Your sceen-shots look like ol' timey SnPb paste recipes. Turn-up the heaterometer dial. Second, on nitrogen: * We kinda think your O2 needs to be around 100ppm with 99.99%
Electronics Forum | Tue Nov 20 20:56:23 EST 2001 | davef
You�re correct. The release characteristics of epoxy differ from solder paste. Consider: * Using print/flood stroke, on-contact print cycle. * Printing slow enough to fill the hole with adhesive. * Overcoming the thixotropic [The viscosity of thixo
Electronics Forum | Mon May 18 21:29:38 EDT 1998 | D.Lange
| I've tried every thing I can think of. Do you have any | Ideas? | What I have is micro balls on the gold fingers of | panelize boards. These balls only appear on the gold | finger. Or at least I can only find them on the gold | fingers. | What I
Electronics Forum | Thu Mar 05 11:53:09 EST 2009 | dcell_1t
Hello to all. for certain time, we have been struggling with some issues on a PCB where have tombstoning on 0402 components (due to pad design) and dewetting in qfp256 0.5 mil pitch (discussed on another threads on this forum) component, we have pro
Electronics Forum | Mon Apr 19 17:33:17 EDT 1999 | Tuffty
25 PPM)! | | | | 1. Is there a better process to solder the leads of QFP's with lifted "minute" lifted leads still having a realiable solder joints? | | | | 2. Or has anybody tried modifying solder pads and use thicker solder paste deposit to compe
Electronics Forum | Tue Dec 04 10:30:16 EST 2007 | slthomas
Q: The question I have is do they wet in wave solder, and if they do, why does it matter what happens to them in reflow? A: Yes, but somebody here don't agree with me that the glued part need help from wave to get the good wetting. They are wrong
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