The drawing revision description block shall identify the specific
changes
made. It is not acceptable to just reference to the Engineering Change
Proposal
(ECP)or other engineering document that initiated the change
This is ridiculous. Some changes I've seen require multiple pages in the
ECN or EO (Notice or Order) for the schematic, fab and/or assembly.  The
path should be ECP or ECR (Engineering Change Request) and then an
approved ECN or EO, with effectivity serial numbers and effectivity
dates, detailed changes and reasons for change.  How the heck does that
fit in a revision block?


The initial release of a design will be given a (-) revision. Subsequent
Revisions will be assigned A,B,C,etc, leaving out I,O,Q,X,S,Z
This is not a 'shall'-it is company philosophy.  I've seen this all over
the map.  Revisions 1, 2, 3 or X1, X2, X3 for prototypes and A. B, C for
released...with no "-" in a rev block.

Whenever the drawing, or computer transferrable media, requires a
revision,
The description shall identify whether the revision impacts form, fit,
function
When would a change not affect form fit or function?  A spelling error
correction, maybe?

Three fiducials (or registration targets) shall be located on grid and
on
each layer of data pattern. Each additional layer or data pattern shall
have fiducials
located at the same points which, shall register with each other, layer
to layer.
First I've heard of each layer.  If I can fit them, maybe.

The method of excising individual boards shall be included in the
assembly
Pallet description.
We leave that up to the buyers.  Some CM assemblers prefer routed out
boards some prefer paneled either rat bites or v-score.

Unplated through hole patterns, especially tooling and mounting holes
(board
mounting holes, interface connector mounting holes, board top
plate/mounting
bracket mounting holes, etc.) are generally drilled in separate drilling
operations as one of the last fabrication operations. They shall be
explicitly
dimensioned and toleranced, even if they occur on grid.
I agree only insofar as required for inspection.  As designers we don't
dictate the fabrication method or what's first or last. (Although it
helps if you know how they might approach it).  If I tell them I want a
hole at X, Y dimension XX diameter with YY tolerance, I don't care if
they use a laser or a sharpened stick.

The fabrication drawing shall specifically indicate the location for the
date code, fabricator's I.D. and UL marking, user's cage code, ESD
symbol and all other
required traceability markings.
This is also ridiculous.  They know what they're doing.  Maybe specify
that markings must be visible after components are loaded.

A note on the fabrication data set shall specify the acceptable bow and
Twist requirements
Agreed

Anyone who writes back can say they helped a standards development
committee!
See how easy this stuff is?

If you are lucky enough to attend APEX/EXPO, wander into a real meeting.
Here are the choices:
http://www.ipcapexexpo.org/Std.aspx

Just trying to hang on to my job.  They'd throw me out if I asked to go
to APEX.

Jack (aka "the new guy")

Bob Wilson
E/M Designer, CID+
SpectraSensors, Inc.
11027 Arrow Route
Rancho Cucamonga, CA 91730
(909) 948-4110
www.spectrasensors.com
www.ipc.org
 


---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------