John, From an OEM perspective, I think it's always good to have a default
value. That's what the industry standard is about.  Jih

-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
John Perry
Sent: Wednesday, September 20, 2000 5:37 PM
To: [log in to unmask]
Subject: [IPC-600-6012] End Product Requirements for Board Thickness
Tolerances


Hello Everyone,

IPCWorks 2000 has come and gone.  Ready for Expo in Anaheim?  Sheez, are you
kidding?

As participants in the IPC-6012 and IPC-A-600 groups, many of you have also
been involved with the IPC-2220 design series, and many of you may recall
the ancient IPC-D-300G Printed Board Dimensions and Tolerances document.
This old dinosaur was recently replaced by the IPC-2615, thankfully without
the outdated end-product requirements such as bow and twist and annular
ring, all of which have been updated through the years where they belong -
in the design and performance specs.

One, however, hasn't been transferred to the appropriate requirements
documents, and I wanted to make sure that it was an intentional exclusion.
IPC-D-300G used to provide tolerances for board thicknesses.  We don't have
any applicable tolerances for this in any of the other spec.  Sure, IPC-4101
does provide tolerances for laminate materials (Table 7) , and IPC-6012 and
IPC-A-600 provide thicknesses for foil plus plating (under review now as we
speak!), but did we intentional avoid the transfer of nominal thickness
tolerances for finished rigid boards to the design and performance series of
documents that we currently use for boards?  Should we point people to the
use of IPC-4101 in conjunction with the IPC-6012?  As always, your input is
much appreciated.

Best Regards,



John Perry
Technical Project Manager
IPC
2215 Sanders Road
Northbrook, Il 60062
1-847-790-5318 (P)
1-847-509-9798 (F)
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