Tom,

You seem to be putting in a lot of unnecessary effort to accomplish your
desired result. I would recommend simply stating on the drawing your overall
finished requirements.

i.e.: Finished boards to be .062 +/- 005 overall after processing.

If you do this there can be no misinterpretation as the drawing takes
precedence over everything but the PO, and I doubt you address thickness on
your PO.  If you supplier has a problem meeting this I'm certain they will
let you know.

Ed Cosper

----- Original Message -----
From: Tom Reilly <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 06, 1999 12:21 PM
Subject: [TN] Plating Thickness


>    We need some expert assistance using the IPC-4101 specification for
> fabricating bare boards. The group seems to have very knowledgeable
fabricators
> and designers. Please take some time and help a new member to the group
help us
> fabricate board more reliably.
>    We recently had problems with bare boards coming in too thick (.070 -
.072).
> I would like to know what the minimum and maximum thickness the card
should be
> using the following specification. (Specification used "MATERIAL: GFN 0620
C1/C1
> A2A per MIL - P - 13949F"). To ensure we receive boards that are .062 +/-
.005
> how should the specification read and why. (Others have suggested GFN 0590
C1/C1
> A2A).
>
> Current specification used:
>        GFN 0620 C1/C1 A2A spec is as follows:
>    0.0000  GFN = FR4 material with no color added.
>    0.0620  0602 = .062 thick base material without copper
>    0.0030  C1/C1 = 1oz. copper each side
>    0.0000  A2A = Quality issues not effecting thickness
>    0.0030  60/40 Tin Lead
>    0.0020  Solder masking (LPI)
>    ----------
>    0.0700 Total thickness Max.
>
>
>    We would like to start using IPC-4101 specification in our fabrication
> control drawings. To accomplish the preferred result of .067 +/- .005 here
are
> the specification we derived from the 4101. Please your recommendations on
how
> we can get yields with our preferred PCB thickness (IPC-4101 K21 0620
C1/C1 KA),
> (IPC-4101 L21 0590 C1/C1 AA) or other.
>
> Maximum dimension specified:
>    IPC-4101 K21 0620 C1/C1 KA  spec is as follows:
>    0.0000  K21 = FR4 material with no color added.
>    0.0620  0620 = .062 thick base material with copper
>    0.0000  C1/C1 = 1oz. copper each side
>    0.0000  A2A = Quality issues not effecting thickness
>    0.0030  60/40 Tin Lead
>    0.0020  Solder masking (LPI)
>    ----------
>    0.0670 Total thickness Max.
>
>    IPC-4101 L21 0590 C1/C1 AA spec is as follows:
>    0.0000  L21 = FR4 material with no color added.
>    0.0590  0590 = .059 thick base material without copper
>    0.0030  C1/C1 = 1oz. copper each side
>    0.0000  A2A = Quality issues not effecting thickness
>    0.0030  60/40 Tin Lead
>    0.0020  Solder masking (LPI)
>    ----------
>    0.0670 Total thickness Max.
>
>    How do you build multi-layer cards using IPC-4101 specification. Our
intent
> is to build boards with the same thickness as the double sided by using
the
> IPC-4101 specification with one ounce copper on external layers and one or
half
> ounce internal layers. We have difficulty extracted this information from
the
> IPC-4101 document. Please enlighten me with your expert knowledge by
sending
> build-up of the specification similar to the specification s shown above.
Thanks
> in advance for your much needed help.
>
>
>    Thanks,
>    Tom
>    Document Services Manager / CAD Manager
>    Inter-Tel Integrated Systems, Inc.
>    7300 W. Boston Street
>    Chandler AZ. 85226
>
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847-509-9700 ext.5365
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