Todd: You say: "... solder masking between the lands of fine pitch components can cause stenciling problems and or manufacturing problems."
I say: Fine pitch components without solder masking between the lands can cause stenciling problems and or manufacturing problems.
You say: "� If the solder mask height is greater than the height of the plating on the SMT lands then you may have a stencil gasketing problem."
I say: If the webbing between the fine pitch component land is higher than the plating on the land, why wouldn�t the mask be higher than all pads? ... regardless of pitch and regardless if there is webbing between pads or not.
Furthermore on a board with pads that are higher than the mask, without webbing, the stencil will not gasket well, partitions between the fine pitch pad openings on the stencil will bow downward under squeegee pressure, and deposit reduced amounts of solder.
Yano, opinions about solder resist-dams vary from "absolutely necessary" to "has no advantage at all". Board fabricators normally start complaining when lead pitches are at 20 mils or below.
I prefer webbing. Beyond the earlier points, boards with webbing between pads are: � Easier to "clean-up" after rework � Prevent "dross bridges" during hand soldering and rework.
What I really believe (no proof mind you) is that the benefit of solder resist-dams depends on the situation, it�s a function of: � Solder mask � Pad lay-out � Solder paste � Some combination of the above
So, that makes me want to do a DOE on new product lay-outs to determine the proper approach.
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