Phil,

I can only give you a partial answer (because I can't find it in any IPC
docs either!)
The way you are specifying it is fine, except you must allow
+/-10% tolerance
(I know it is 10%, but I searched every relevant doc I have for "10%", can't
find it)

The reason it is most often measured to include the plated metal,
is because in the past it most often mattered for edge connectors.
The edge connector had to include the distance from the gold finish
on one side to the gold finish on the other

Jack

p.s. Final thickness is never measured to include the mask.
p.s.s. I can post your question over on the IPC Designer's Council if you
want me to?


>
> Phil Nutting <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 25.04.2008 21:52
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> Phil Nutting <[log in to unmask]>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> [TN] Specifying board thickness
>
>
>
>
>
>
> Hi Technetters,
>
> We are reviewing how we specify finished circuit board thickness to make
> sure we get what we think we specified.  Recent events have placed what we
> specify under scrutiny.  I've looked through IPC-2221, IPC-2222, IPC-
> 4101B, IPC-6012B and IPC-7351A with no luck.
>
> Currently our documentation calls for 0.059" finished board thickness
> without measuring the thickness of the copper.  Presumably when the copper
> is added we get to 0.062" finished thickness which is important when we
> start stacking circuit boards on standoffs.
>
> How do others specify circuit board thickness?
>
> Is there an IPC spec I can quote chapter and verse?
>
> Thanks in advance.
>
> Phil Nutting
> Design for Manufacturing Engineer
> Kaiser Systems, Inc.
> 126 Sohier Road
> Beverly, MA 01915
> voice: 978-922-9300 x1310
> fax: 978-922-8374
> e-mail: [log in to unmask]
> www.kaisersystems.com
>
>

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