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From: john larkin <jl@glen--canyon.com>
Newsgroups: sci.electronics.design
Subject: Re: PCB version control
Date: Mon, 24 Mar 2025 16:39:41 -0700
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On Mon, 24 Mar 2025 15:48:58 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 3/24/2025 3:01 PM, Joe Gwinn wrote:
>>> I’m with you—it’s good for stuff to be human-manageable.
>> 
>> Below some size, this can be done.
>
>For most non-trivial businesses, that size is quickly exceeded.
>
>How many part numbers does Bourns assign to resistors?  JUST
>resistors? Surely, unless you declare on Day 1 that you will
>never use a particular power rating, physical size, value,
>tolerance, etc., then YOUR numbering system must be able to uniquely
>accommodate ALL of their parts!  (and, some way of accepting "identical"
>parts made by some other manufacturer -- with undoubtedly different
>part numbers!)

Our stocked parts are identified by a 7-digit MAX number, like
133-2000 for a 1 ohm 1206 1% resistor. It can have up to 5 different
acceptable manufacturer's part numbers that purchasing can buy.

The MAX numbers appear on the BOM associated with an assembly drawing.

MAX is our material control software.



>
>Repeat for chokes, BJTs, FETs, caps, etc.
>
>And, when a new packaging (or fabrication) technology comes
>along, you'll be ready to REVISE your numbering scheme to
>accommodate *that*!
>
>Will you ever know if a particular identifier maps to a *real*
>device?  I.e., are there HOLES in your numbering system??
>
>> I've run into problems trying to code the sub-fields of small
>> addresses (used within some hardware gadget).  It took only two or
>> three implementations of such gadgets before one ran out of code
>> space.  The solution was to make each kind of gadget have its own
>> subfield coding, because these devices were bespoke anyway.
>
>You end up with every type of device needing its own "system".
>In which case, why not just adopt a system of using
>    (manufacturer, manufacturer's-part-number)
>instead of wasting your time trying to create another system that
>MIMICs those on which you will rely?

We often qualify several different manufacturers and their (often
weird) part numbers for a given MAX part. And sometimes we change
them, but we don't want to change our BOMs. Lots of manufacturing
control software doesn't understand that concept, having multiple
vendors qualified for one part.

Full Traceability is a different ballgame. We don't do that.

>
>If I depopulate the diagnostic/test connector from a board
>"effective serial number XYZ", is that a new revision?  A new
>board?  If I *repurpose* said connector at a higher level
>in the assembly hierarchy, is THAT a different board?
>
>If I install entirely different firmware (effectively changing
>the high level function of the board), is THAT a new assembly?

If it's functionally different but runs on the same hardware, the
assembly becomes a new dash number. The BOM for the new dash number
variant calls out the new firmware. If the hardware didn't change, its
rev letter doesn't change if we change the code that runs on it.

>
>If I replace the search algorithm in a piece of code with a
>different algorithm, is this a new revision?  

If one line of code changes, the software rev letter rolls. We treat
software just like any other drawing; it has a drawing number and a
rev letter.

Some software naming schemes are nightmares. Version 14.571.03b and
such.