Electronics Forum | Wed Sep 18 12:35:56 EDT 2002 | stepheno
Fourth - > back to design of PCB. Are there solder dams of > mask between the pads? If yes, that helps. If > not, pay close attention to stencil aperture > width and be sure that the aperture deposits less > paste by 1-2 mils per pad, centered o
Electronics Forum | Wed Sep 18 12:31:16 EDT 2002 | dragonslayr
My suggestion is to conduct a Design For Manufacturing (DFM)study on the assembly in question. Pay particular attention to the pad sizes, component lead dimensions and satisfy yourself that those two factors are correct. Given that pads match compone
Electronics Forum | Thu Nov 07 12:35:38 EST 2002 | slthomas
Sounds like you're talking about the "heel" of the lead not being soldered, in other words, no heel fillet, which IS necessary. That problem, for us, was attributed primarily to poor layout (insufficient length of pad extension to provide room for
Electronics Forum | Wed Sep 18 18:41:17 EDT 2002 | davef
People have made good comments. Additional points are: * Your bridging is probably being caused by one or more of the following: [1] printing too much paste, [2] smearing the paste during placement or subsequent handling, or [3] paste slump during t
Electronics Forum | Wed May 17 14:02:06 EDT 2006 | russ
So, what is the pitch of the part and the pad size, also tell us the thickness of stencil. Russ
Electronics Forum | Mon Oct 14 14:35:51 EDT 2013 | garym4569
Thanks for the replies. I have just ordered the IPC Stencil Design Guidelines manual.
Electronics Forum | Mon Dec 20 07:58:02 EST 1999 | pascal MATHIEU
hello guys ; we are using a fine pitch component(0.65mm) on a thick copper PCB (Cu = 90�m) ; in this case we notice that we are in the process'limits , because the different supplier of the PCB are not able to ensure a good stability of it's process
Electronics Forum | Wed Sep 18 19:43:12 EDT 2002 | dragonslayr
One more variable I've remembered - pad height with respect to solder mask height. Pads being too low can cause stencil "gasketing" problems that in turn allow more paste to be deposited than needed. Are your fabs HASL or some other media?
Electronics Forum | Tue Sep 17 15:47:42 EDT 2002 | stepheno
Where I worked previously we had some boards with a couple 15 mil pitch parts. The first batch we got all had undersized pads. We had lots of bridging. We had less bridging with bigger pads. The ball size in the paste makes a bigger diffence regar
Electronics Forum | Wed Sep 18 10:06:30 EDT 2002 | Bob M
I place 15-20 mil a lot. You need to look at your pad to apature reduction. Your stencil thickness. The type of paste your using. We use 2-5 mil reduction on each side as a general rule on fine pitch. This varies depending on pad width. We also use 5
