>> As for the rest of the input, it sounds like most of you are in the same
>> frame of mind I was- I have one part (the assembled board) that I buy
>> from my CM. =A0They manage a list of parts that they are allowed to use
>> (for instance, multiple manufacturers of *3904 transistors) to fill a
>> given order.

> We allow our CM even more freedom: we don't give them a list of parts that
> they are allowed to use, we only tell them which parts they must use as
> specified. Most of the time it's OK to assume that a jellybean 3904 will
> behave like a 3904, and that a generic 1k 0402 will have a resistance in =
the
> 950-1050 ohm range.

Where is your CM located?
Where / who do they buy from or are allowed to buy from.
I'd be "scared" of doing that in China OR am scared of doing it in
China depending on the factory :-).

Carbon / metal.
Known good vendor eg resistor quality can be very variable.
Known non-supplier of out of spec /  reject parts.
Guaranteed performance PV wafers (not an issue for you).
Guaranteed ROHS parts (discovery only at or after point of foreign
im[port can be vvvv costly)
ESR guaranteed on caps.
Temperature / hours at specd temp on ecaps.
Height of caps (some may vary).
Voltage of ecaps too high (depolarising).
Ceramic cap composition.
LED brands utterly crucial (maybe not as indicators only).
Battery brands.
Bipolar beta.

More.

Any disagreement with any of the above?
If so, may indicate relative trust you can put in market or CM.


          Russell





>
>> We used to do it in a far more complex manner, involving an individual
>> part number under ECO control for every component (down to resistors)
>> on every circuit board (of course, parts may be used on multiple boards).
>> Having to do an ECO to add a new vendor to the list of approved 1%
>> 0402 1k resistors seems like a REALLY big waste of money to me, and
>> fortunately we've moved away from that.
>
> That does sound like overkill. The notes at the bottom of our BOM read:
>
> - OK to substitute equivalent parts, unless marked with "No" in Sub colum=
n.
> - Resistors:
> =A0 =A0- If power dissipation (W) is not specified, assume it's not criti=
cal.
> =A0 =A0- If tolerance (%) is not specified, assume 5%. OK to substitute 1%
> parts as long as value remains within range.
> - Capacitors:
> =A0 =A0- If minimum voltage rating (V) is not specified, assume 6V.
> =A0 =A0- If tolerance (%) is not specified, assume 20%.
>
> We also get FAs so worst case, if a component does not behave as expected,
> we can tell the CM to substitute it before starting production.
>
> Vitaliy
>
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