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 | Tue Sep 17 15:03:33 EDT 2002 | ccross
I am working with fine pitch components (15-20 mil) and having soldering problems and would appreciate some opinions. 1) How much of an effect does pad size have on bridging? 2) How much of an effect does solder paste grain size have? What is the re
Electronics Forum | Thu Sep 19 11:14:45 EDT 2002 | Jim M.
We had lots of problems with bridging on 15.8mm pitch, QFP17-160 at the start.The board was .032 thick, double sided-six boards to a panel. Here is the problems (not neccessarily in the biggest to little but as i remember them) and solutions that he
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 | Tue Jan 08 09:23:18 EST 2013 | lock_2002
This is a question regarding soldermask between pins of fine pitch devices. The majority of our production designs end up with at least 2-3 mils of copper thickness on the external layers due to blind vias, wrap plating requirements, etc. Our curre
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 | Tue Jan 15 10:53:18 EST 2013 | boriskilk
We wouldn't advocate extending the soldermask beyond the component body but yes to ganging for fine pitch. To ensure we don't run into issues with flaking our preference is not to add solder mask when the space between pins is less than 6 mil.
Electronics Forum | Wed Sep 18 18:48:33 EDT 2002 | davef
Fabs can produce a solder mask web between 20 pitch leads, but I've never seen a web for 16 pitch leads. Although, I would like know a supplier that can lay-down a fine web. Minimum solder mask web width is about 0.004 thou. An absolute mininum o
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
