[PCB_FORUM] Re: Tooling holes

 
 
Jim S. Wages
SR PCB Layout Designer
H) 919-237-3915 C) 919-484-2963
 
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Mark Salberg
Sent: Tuesday, March 24, 2009 10:53 AM
To: Cadence User Group
Subject: [PCB_FORUM] Tooling holes
 
Hello Group,
This is regarding tooling holes.

We are required add 2, 3 or 4 .125 NP "tooling" holes.
NP normally used for tighter hole size tol (+/-.002")
Also tooling hole to tooling hole location tol =+/- .003".
At our internal assembly, these are only used in assembly on an "old"
stencil screener.

Questions:
1. Do fab vendors use these for fab tooling or do they use their own from
the fab panel.
(i.e.) stack-up, registration, test during fab, etc...
 
Fab vendor's typically use their own tooling holes in the fab panel

2. Is it necessary to have a NP hole as a dimension datum?
We normally do, but if I have a board (ex) all PTH with plated mounting
holes...should I add a NP hole just for a dimension datum? 
No. A plated hole location is as accurate as a non-plated hole.
I believe that the center of a plated hole is as close in tol location as a
NP hole. but the finished hole size is tighter on a NP hole.

Regards,
Mark

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