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Date: | Thu, 21 Jun 2012 20:03:11 +0000 |
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Hi Shawn,
Just curious what is the application? It seems that etch factor does not come up unless there is something very critical driving the concern.
Best Regards,
Rick
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Upton, Shawn
Sent: Wednesday, June 20, 2012 11:52 AM
To: [log in to unmask]
Subject: [TN] Etch Factor
Ok, got my specifications, looking at IPC-2221A Figure 10-3, for conductor width (see section 10.1.1 also, pages 77&79); and IPC-A-600H 3.2.1 (see page 86). It looks like "etch factor" drives how much of a trapezoid one has on any given trace, although outer layers (since they are plated) may have overhang.
What I don't see is any qualitative numbers: ie, an etch factor of y +/-z is typical for outer layers, vs w for inner layers. Are these numbers variable from vendor to vendor; and have to be called out on any given FAB drawing, since there isn't a generic number to be pointed at?
Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
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603.626.2429/fax: 603.641.5336
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