Hello, TechNetters!
Some questions about electrolessNi/Au plated circuits:
What is the cause of shadow plating between the pad and the surrounding
solder mask?
Is it acceptable by IPC standards for Class2,3 if it extends to 30% of
the distance between the
fine pitch lands separated by ~4mil solder mask?
It seems that the presence of the solder mask near the plating area
enhances the occurrence of
the phenomenon.
Also, we see differences in the appearance of the fine pitch area
between two different manufacturers.
One of them gives us very clearly defined pads without any shadowing ,
the other-shadow plating
along the long edges of the pads, for the same artwork.
We are concerned about violating the IPC requirements ,about the
necessity of solder mask
between the pads with less than 20mil pitch and about shorts after
reflow soldering.
Please answer me as soon as possible.
Thank you in advance for your help,
Gaby

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