Hey Al,

I agree.  (PADS layout tool has a default alphanumeric for the diode decals
that has 'A' and 'K' for the anode and cathode.

Not too long ago I used some surface mount LEDs on a board that had an
indicator for the anode.

Caused a bunch of grief.

"Standards!  We don't need no stinking standards!"

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

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Al Onderick
Sent: Wednesday, March 28, 2007 1:28 PM
To: [log in to unmask]
Subject: Re: [TN] Footprint standards for Polarized components (Diodes)

Hi Gary,
        Diodes and transistors have been an issue for years. My 
recommendation for diodes and transistors is to use alpha pin numbers in 
place of the numerics. It's much easier to map a part to A and C as 
opposed to 1 and 2 ( or EBC, rather than 1,2,3). This can cause extra 
parts in the library but it typically solves the pinout issue.

-Al Onderick
***********************

Steve

Please post this picture on your web site. The Diode D116 pin 1 is 
represented by a white dot which is also the anode. I tried to tell the 
designers that the bar on the silk screen represents the cathode they 
would 
not listen so I wound up with major rework to correct all the misplaced 
(reversed) components. I was just call to the production line for yet 
another problem with F31 again footprint problems. This is why I asked the 

question if there exist a standard for creation of component foot prints. 
I 
do appreaciate all of your replies some have been most enlightening and 
will 
be passing this information along to the boards designers.

Gary Bremer
Manufacturing Engineer CIT - CID

------

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