Gary,
See IPC 7351.
It does help to use a standard. That way all of the groups in the
food chain of data will be getting what they expect.
It also helps to have one group control this like
CAD librarian & Component Eng. To enforce a standard.
A word of caution though, if by switching to a standard you need to
change things, make sure all groups inside & outside company
are aware of what you are doing. An inside or outside assy group may
have placement machine libraries set up with orientations, etc. They
should be checking
their work but with no warning to now see parts 180 deg from anything
you previously sent them might cause a few problems.
Like others have stated not only the chip type parts but the
sot-23/to-92
type parts too where diff vendors have diff ideas of what the pinout
number wise should be.
Again as long as a standard is picked and everyone is on board with it.
Even with everyone on board I have had a few discussions with Engineers
firmly convinced the library was wrong for a particular part because
it did not match the vendor spec sheet for the part and that was why the
board did not work. Bottom line all schematic symbols just need to match
that standard footprint period.
But like all have stated what ever makes the most sense within your
company.
Just keep everyone informed.
Bob Wolfe
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Gary
Bremer
Sent: Monday, March 19, 2007 9:25 PM
To: [log in to unmask]
Subject: [DC] Footprint standards for Polarized components (Diodes)
Hi,
I have been asked if there is a standard for creation of footprints
espicially for diodes. One of the designers reversed the cathode and
anode
causing all the diodes to be placed backwards. The rational was the pin
1
was the anode for this device for other diodes pin 1 is the cathode.
Gary Bremer CID
Manufacturing Engineer
_________________________________________________________________
Exercise your brain! Try Flexicon.
http://games.msn.com/en/flexicon/default.htm?icid=flexicon_hmemailtaglin
emarch07
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