Very interesting reading. Creating the part list really takes a 
lot of time for me. My company is a medium-sized company and the 
schematics and layout package (P-CAD 2002) is not linked to the
ERP (Movex on IBM AS400). It is a headache to look into the
system to see the availability of part in the store and the
cost since you need to remmeber those cryptic command on the
Movex system. Just hope they could link this together. You
know we have 6-digit part numbers and they just start
to standize on nameing of the component. And they are going 
to upgrade the ERP system to be web based. But it is much
slower than the old terminal based program. :(

When we want to get a new part, we need to request the part
samples, the quotations through the help of the purchasing
department. We need to creat the datasheet, ask the layouter
to create the EDA library. All need to be stored in the 
engineering document manage system (EDM) and need at least
two levels of approval.

So it is true in effect, all the processes are driven from the 
designers schematic (and the part list from the schematics).
But I just think this takes too much time and should put too
much administrative efforts to the design engineer. Can it
be handled at least partially by the "product engineering 
department". Does someone else have a better approach?

Xiaofan

> -----Original Message-----
> From: Kenneth Lumia [mailto:klumia@adelphia.net]
> Sent: Saturday, February 26, 2005 1:58 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Pull-up/down resistors
> 
> --- short reply ---
> It's not really a question of the amount of business.  Most schematic
> software allows you to add text (such as internal part numbers) that
> can be hidden on the actual schematic, but is picked up by other
> software to automate tasks further down the chain.
> 
> ---long reply----:)
> It must be the design engineer's responsibility to generate the parts
> list as only the designer knows exactly what is needed.  This is
> generally done indirectly and automated as far as possible.  For
> example, at a previous employer, all of the systems were linked
> together.  As the designer, I would create a schematic on a Sun
> Workstation using Mentor graphics schematic capture.  The
> schematic software was linked to a database that held all the
> parts that the company used, so in effect, I couldn't add a new part
> with unknown vendors to a schematic.  If a new part was needed,
> I would generate a new parts request that got every one involved,
> from purchasing, production, safety, layout, etc. to verify that the
> new part was acceptable.  Once approved, it could be added.
> When the schematic was complete, it would be sent to the layout
> people.  They would layout the board (after several go-arounds with
> me for placement and general routing instructions).  Once complete,
> the software would magically create a BOM with reference designators,
> parts quantities, etc.  This would get sent to purchasing to
> "load requirements" into the purchasing system based on projected
> demand and production ramp-up.  Unless the company is really small,
> purchasing is automated with the vendos/distributors.  This used to be
> called EDA purchasing, now I think its under the heading B2B.  The
> net effect is that the parts are automatically ordered based on lead
> times for each part and humans really only need to be involved if
> there is a problem (such as parts shortages). This used to be called
> JIT (or JTL if you liked to complain).  As far as production goes, the
> layout people send the files to production.  Production runs another
> software application that generates XY coordinates and rotations
> for each part.  They don't use the reference designators at all. Most
> boards are too tightly packed to fit them on the silkscreen. Similar
> files are sent to test engineering to build test heads for 
> electrical test.
> Even the production techs fixing the ocassional error don't 
> normally use
> the ref des.  They run on xy coordinates that feed back into 
> a database.
> 
> Automating and using good processes goes a long way to avoiding
> errors.  Then, when an error does occur, it happens on all 
> units of that
> build.  Much easier to correct than an occasional "hand 
> stuffed" board 
> error.
> 
> In effect, all the above processes are driven from the 
> designers schematic.
> 
> Ken
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist