You are right Jack in that we need to create our libraries and use
design rules to suit the end process.
We changed our component orientation, years ago, to pin 1 - top right in
order to comply with our European technology partners.
There are many Jedec standards at URL http://www.jedec.org I thought
the issue in question was covered in the EIA-JED-95 standard?
Cheers,
Barry Olney
Olson, Jack C wrote:
>
> Well, SOMEONE is missing the point.... <grin>
>
> Yes, you can create stuff any way you like, but since he has a CHOICE what
> orientation to build them, and since it doesn't matter to the CAD operator
> what orientation they are, it seems logical and intelligent to wonder if the
> ASSEMBLER might have a preference, eh?
>
> If you build a library component and plop it into your design, and don't
> rotate it, at the end of the design cycle when you create your pick and
> place files for the assembler, that component will be listed as zero degrees
> rotation, right? If you build a SMT resistor vertically, no matter how you
> rotate it in the database, the rotation in the data file will be useless
> because SMT resistors are packaged horizontally on a reel. The operators
> know this, so they check rotations before they start, but wouldn't it be
> nice if we could get MOST OF THEM right in the library? Sometimes you can't
> because some ICs come on reels horizontally, and some come packaged in
> sticks and come out vertically, so you have to modify some rotations no
> matter what. But all I am saying is that if you know what your vendor is
> using, why not make it easy for him and TRY to supply good data?
>
> Still, you can never win... here at Intel we are asked NOT to place
> components in the same orientation as they come on the reel, because the
> type of pick-and-place machine we use rotates the head 180 degrees as it is
> moving from the reel to the board, and then will have to rotate another 180
> to get back to the same orientation, which wastes a whole tenth of a second
> (perish the thought!). So, you can never learn enough in this business,
> right?
>
> Onward thru the fog, Jack
>
> -----Original Message-----
> From: Uptain, George [SMTP:[log in to unmask]]
> Sent: Tuesday, September 22, 1998 12:29 PM
> To: [log in to unmask]
> Subject: Re: [DC] PCB Footprint standard for smt polarised
> components?
>
> I think you are is missing the point (although
> [log in to unmask] is the only one that can say) To me he seems to be
> asking how he should create the library part. The answer to that is, IT
> DON'T MATTER. It can be rotated any which way in most every CAD system I
> know of when it's placed on the board. THEN assembly and fabrication rules
> apply. But not in library part creation.
>
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__________________________________________________________________
Barry Olney http://www.icd.com.au
Managing Director
In-Circuit Design Pty Ltd
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