Are there any IPC Certified designers who can confirm or deny the need for a
fab dwg?
        What is the current IPC comment on the issue, come on guys I know
you're out there! Is the fab dwg not just part of the "complete" fabrication
information, what is the IPC training telling you guys to do about fab dwgs
these days? This is a test, are you a IPC man/woman or a mouse?

        here is the best example that I can give. Contrary to some very
opinionated individuals, not all PCB inspectors have computers, nor CAD
software, nor the training to operate CAD software, in a 'LOT' of PCB
fabrication shops. Trust me, I have been in and out of many PCB shops in 3
States and one Province for over 20 years. We aren't talking about the
Merixs, Tycos or Praegitzers here, just normal small - med size fab shops.
How does this inspector check drill sizes or locations? From manually
reading the numeric information? Is the fabricator CAM shop supposed to make
a drill drawing for him? Do you trust the fab shop to generate this drawing,
if they make a mistake who's fault is it, you didn't supply the required
information so they were forced to generate their own? They are not perfect,
neither are you but you didn't even have a chance to check/inspect their
handiwork! What can they use for even their trained CAM operators to confirm
the correctness of the information which they are viewing on their computer

        When the PCB is received at your company's (or your assembly shop's)
loading dock, who checks it for valid hole sizes, dimensions or other
details? Is this a fully trained CAD operator, with system software to deal
with all forms of CAD data or a simple minimally trained inspector with some
pin gauges, calipers and the ability to read a technical drawing? If you
don't supply them with a Fab dwg, do you get called to the loading dock to
check the boards upon arrival because you are the only one in your company
who can access and use the electronic data files?

        Here some other very good examples for you Georg. Where do your
drill files locate themselves within you board outline? Where are any of the
holes with respect to the board outline? What are the dimensions of your
board outline? Does everybody go into the CAM files again and again to
generate their own measures of these items? Isn't that lost repetitive
operations that could be done just once, checked, verified and appropriately
tolerance by the individuals who understand the design? What tolerances
would be allowed by differing individuals who take their own absolute
measures of the CAD data in the file? The CAD data is absolute isn't it? Are
the fabricated parts absolute without tolerance? I wish.

Brad Velander.

Lead PCB Designer
Norsat International Inc.
Microwave Products
Tel   (604) 292-9089 (direct line)
Fax  (604) 292-9010

Visit us at Booth 2G2-09 at CommunicAsia 2002 in Singapore June 18-21.

> -----Original Message-----
> From: Georg Beckmann [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, May 16, 2002 10:17 PM
> To: 'Protel EDA Forum'
> Subject: Re: [PEDA] Too many hole sizes
> I do not understand, what a drill drawing is good for. I only 
> use the drill
> file and the
> board shop read this to the drill machine.
> Since I have a computer and CAD program, I'm happy
> not to fill out a drill drawing sheet with any hole marked 
> with a secret
> label and wether I or
> the man in the board shop makes one or more mistakes when 
> programming the '
> punchhole - tape for
> the drill machine '.
> Georg

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