Ian,
I can see your points; but here's why I take the other approach of having
the IC w/pins & pads, and the socket having just an overlay:
- Sometimes we only have the socket for prototype, then remove it; our
method makes it a simple change to remove the socket.
- We can have a single library component for a particular socket (e.g.,
DIP-8) and use it for any matching IC.
- I'd rather not have multiple part-ids referring to the same manufacturer's
part -- our rather simplistic parts-management system (Access and various
macros/reports) wouldn't handle that nicely & it'd probably confuse our
parts purchaser (she's new at this -- we ALL are!).

I think the choice of method in any particular instance may depend as much
on existing BOM/parts management scheme as anything else; or on the specific
situation (e.g., a 'temporary' socket vs. a permanent one).

Good idea about creating the union -- something I usually forget to do.

Dwight Harm
Trax Softworks, Inc.

-----Original Message-----
From: Ian Wilson [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, September 04, 2001 3:57 PM
<snip>
We take the view that any socketed items are actually part of a higher
level assembly than the PWA (printed wiring assembly).  The PWA includes
just the items that are run through the soldering process.  Any extra
things like ROMs or socketed protection components appear on the next
higher level assy parts list.  We use the Sch as the primary source for the
PWA parts list but this has extra bits added, like the PCB.  We usually do
not try to include all PWA bits in the Sch, but I am aware that some people
do.  Doing this would certainly be easier if we had Sch symbol and PCB
footprint attributes to prevent them being involved in synchronization and
to be ignored during netlist import - as has been discussed recently.

(There may need to be two attributes for a Sch symbol.  One to prevent it
being included in the netlist and internal netlist produced during
synchronization.  The other, included with the netlist, to prevent the part
being included on the PCB if that netlist is imported to a PCB design.)

As for the original question, what about:
1) Create socket footprint with all the pins/pads, but a minimum of overlay
2) Create IC footprint which is just overlay/silkscreen (no pins/pads)
3) Position together on PCB carefully
4) Create a union to ensure they move together
5) Pressure Protel to allow correct handling of negative component
clearances to allow for overlapping components, I have an yone else want to
add a voice....

Ian Wilson

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