.0035 - .004 is within the capabilities of most shops, even on .5mm pitch
devices.  Occasionally, this is an issue when small via holes in high aspect
ratio boards must remain open after developing. It requires a slightly
overdeveloped condition to clear all mask residue from the holes.  Otherwise
it is consistently achievable.

-----Original Message-----
From: Ed Cosper [mailto:[log in to unmask]]
Sent: Wednesday, October 13, 1999 5:16 AM
To: [log in to unmask]
Subject: [TN] Fab: Mask dams between fine pitch smt pads


Hi all,

Just a quick industry capability questions. Are board manufactures still
having trouble holding mask dams between fine pitch (19mil) SMT pads. As
recent as a year or so ago I was under the impression that board shops would
ask the remove these small dams when they got them on the Gerber data. Is
this still common. I am interested in what most people think is feasible
regarding mask dams that are 4 mils wide and smaller. All responses are
appreciated.

Ed Cosper
ABC

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