ARRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGH!!!!!!!!!!!!!
(Very Long and Loud Primal Scream)
Fine Matthew, do it any way you want to . . .
Just don't call it standardized . . .
Just don't call it IPC-7351 compliant . . .
Just don't cry when someone else works on a revision to one of your
Design(s) in the future, and calls you a "stupid moron and a ****ing idiot"
and the worst Designer that they have ever run into because you "did it
backwards" for some stupid personal reason, and caused untold screwups on
some future production run.
You are going to do whatever the hell you want, in spite of what anyone
else, or what any standards, are going to say, so just go ahead and do it,
and stop trying to convince anyone else here in the forum that your are
right, because you are not - you are wrong - so go ahead and make your
boards the way that you want too, but mark my word, they will come back and
bite you in the a** a few years down the road, and all you will be
remembered as is the stupid Designer that screwed things up because he was
too stubborn and wanted to do it his way and wouldn't play according to
Hoyle.
And by the way, your successor, who will inherit your Designs after you
retire or move to another company, >>>>WILL<<<< "use [your] CAD package
(Cadstar) to create the pick & place file." - which will of course be all
****ed up, but he or she will not realize that until after a production run
has been made with your ****ed up Cadstar Pick and Place file because you
were to stubborn to do it right the first time.
You could have started a new Footprint Library and Schematic Symbol Library
and fixed the rotation of all of the components involved and redefined pin
numbers, etc., in one tenth of the time you have already spent writing about
it here in the forum. We are really only talking abour a couple of
components here now (you could add and fix others as you go).
Quit bitching about it here and just do what you are going to do.
I can't leave off here without specifically responding to part of what you
said below:
> IMO it is incapable of generating an accurate P&P file that includes all
> the data. (panel size, fiducials etc). Also component rotations change
> depending upon the supplier as it seems that not all suppliers follow the
> same standard.
If you would CORRECTLY DESIGN your components FOR the P&P file,
you WOULD have all of the CORRECT data in the P&P file. Panel size has
absolutly nothing to do with individual components or their footprints, as a
panel is usually built up as a "step and repeat" of individual boards, and
any "pick and place" machine out there today can compensate for "step and
repeat", including any necessary "rotation". Fiducials are not necessaruly a
problem, since they are generally seperately placed from the component, and
if they are critical to the component and it's rotation, then they can be
made
part of the component footprint itself.
As for the last sentance above, respecting changing rotations or
non-standard component rotation. THIS IS THE EXACT REASON WHY YOU
SHOULD FOLLOW THE COMPONENT ROTATION ADOPTED BY
IPC-7351, SO THAT COMPONENT ROTATION IN THE DESIGN WILL BE
STANDARDIZED, AND SO THAT >>>ANY<<< MANUFACTURING
ENGINEER CAN ADAPT >>>ANY NON-STANDARD<<< COMPONENT
ROTATION TO >>>ANY DESIGN<<< .
Sorry if it seems as if I am yelling at you - because I am !
JaMi
PS. Yes, it is true that some manufacturers do not follow ANSI/EIA-481 when
it comes to packaging components in "tape and reel" for "pick and place"
machines, but more and more are, and month by month the component
manufacturing industry is conforming and coming into line with the existing
standards, which is all the more reason why you should.
=====================================================
=====================================================
----- Original Message -----
From: "Matthew Lamkin" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, March 21, 2007 7:23 AM
Subject: Re: [DC] Footprint standards for Polarized components (Diodes)
Thanks for that Jack, the reasons in that document are exactly why I do NOT
use my CAD
package (Cadstar) to create the pick & place file.
IMO it is incapable of generating an accurate P&P file that includes all the
data.
(panel size, fiducials etc). Also component rotations change depending upon
the supplier
as it seems that not all suppliers follow the same standard.
I prefer to use GC-Place, using the panel data returned (for approval) from
my board manufacturer
prior to plotting, using the pads & an assembly drawing layer & a BOM file
makes it far more accurate & gets the rotations correct regardless of
whatever pin 1
is within Cadstar.
However, as said - I am using a legacy library and cannot go changing all
polarized components
to use pin 1 as Cathode etc as it will then affect future mods to older
boards.
So like I said, pin 1 is not that much of an issue with me.
Thank you,
Matthew Lamkin
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