See Comments next to statements
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, March 12, 2009 11:01 AM
To: [log in to unmask]
Subject: [TN] Future SHALLs (IPC-2610)
Last week I pointed your attention towards a set of "SHALL"s in the new
IPC-2610 series on Electronic Documentation
http://frontdoor.biz/PCBportal/ThouShaltDocument.pdf
Then, in a follow-up email "To Grid Or Not To Grid" several people
responded
to the requirements in 6.4.7 and 6.5 about documenting grids.
To summarize
(I think this is a fair statement based on the contents of my mailbox),
many people provided good reasons for using grids DURING DESIGN,
but no one advocated DOCUMENTING the grid.
Now, in this email, I would just point out a few more shalls, give you a
chance
to respond, and then I'm done.
(I say I'm done because these comments have to get back to the group
before
the committee meetings in Las Vegas)
-=-=-=-
What Do You Think Of These Requirements?
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
##### I have not seen this done in almost 30+ years in the business,
The only place I have heard of it being done is Military. All commercial
Co I have worked for only state "Per ECN XXXXXXX" in Rev Block.
ECN is usually provided to vendors needing it.#######
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 really is up to the Company period, again it maybe a Military
issue to use only
Letters for revs however if letters are used leaving out I,O,Q,X,S,Z is
good idea######
Whenever the drawing, or computer transferrable media, requires a
revision,
the
description shall identify whether the revision impacts form, fit,
function
### If form fit or function changes we always make it a new part
number#####
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.
###### No Comment ######
The method of excising individual boards shall be included in the
assembly
pallet
description
###### No Comment #############
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.
####### Plated or not, if any feature requires a different tolerance
than in
notes , it's Dimension and tolerance need to be in field of drawing, if
more than
one tolerance range is specified in notes, there would still be a need
to identify
in field of dwg which dimensions get which tolerance so the dimensions
would need to be there
anyway. ########
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
######it can't hurt to always specify a place rather than forget to if
your
Design has any special Electrical Clearances required ##########
A note on the fabrication data set shall specify the acceptable bow and
twist
requirements
#### Could just ref it per IPC Spec ###
-=-=-=-
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
Jack (aka "the new guy")
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