# Help with part number levels and system structure

#### FunkyMunky

Joined Jan 17, 2018
2
Hi,
I've set up a new electronics department in my company, where we will now design parts and have ownership of that where as before we'd subcontract designing out. I don't have experience of working elsewhere so I'm looking for help in the best way to structure my part numbers and document control.
so the finial assembly is fine, but below that i have my schematic that I'll document in drawing and part number, but what do people do with the gerber plots? do you stick them in a drawing boarder to have a record of them? to by that finial assembly I may have to have the board configuration this way to fit the housing so is that another level or linked into the schematic.
Any help on how I should best structure this would be great or experiences others have had.

Thanks

#### ericgibbs

Joined Jan 29, 2010
8,744
hi FM,
The level of control and tracking of technical documentation will depend very much on your end users.
Is the end product for Commercial, Industrial, Consumer or Military use.?

This PDF may have some helpful pointers.

E

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#### FunkyMunky

Joined Jan 17, 2018
2
hi FM,
The level of control and tracking of technical documentation will depend very much on your end users.
Is the end product for Commercial, Industrial, Consumer or Military use.?

This PDF may have some helpful pointers.

E
Hi, we supply alsorts OEM's in on and off road applications but aftermarket as well. We have a full PLM system and document control revison levels etc and ISO we have looked at TS but its not a requirement for most of our customers.
But as a company we've only dealt with metal work before, so that's why I'm asking about how the schematic and gerber mainly data would mainly be controlled and stored.
Thanks

#### RichardO

Joined May 4, 2013
2,273
The schematic and Gerber's are computer files just like any others you have. How do you deal with files for mechanical designs? Do the same for your electronic designs.

#### AnalogKid

Joined Aug 1, 2013
8,109
Treat electronic information as if it is a physical component. Give schematics, native pc board layout files, Gerber files, rework orders, ECO's, etc. individual part numbers with base, configuration, and revision fields.

The schematic is T.H.E. control document for an electronic design. If it is on the board, it is on the schematic. This includes mounting holes, registration marks, etc. If a serial number sticker is put on a board after it passes final test, there should be a symbol on the schematic for it. If some traces mus have a minimum width or spacing for compliance, or tight dimensions for impedance control, or length-matched differential pairs, build that into the net properties in the schematic and let them flow down to the pc board layout software.

Schematics, layout, and Gerber files should appear on the assembly BOM as zero-quantity items. In this way the exact design documents for any particular configuration or revision are frozen in time. It is entirely possible for one pc board layout to support multiple configurations and revisions (two separate things). Have a part number and BOM systems that can handle that.

Designate a place on the in-house LAN for the native design file folders, have a specific set of sub folders for each assembly (even if they all are not used for every assembly). Control access to those folders so not just anyone can read, revise, or delete stuff.

Have a separate LAN location for PDF files of the things non-secure people might need, such as pc board assembly layers for production or test.

No one likes iron-fisted control; it is hard to maintain and seriously inconvenient. BUT, it also means that 10 years from now you can bring up the correct docs for anything in under a minute without question about whether or not they are the right ones. That is gold.

ak

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#### AnalogKid

Joined Aug 1, 2013
8,109
The goal of any part number system is to give a unique identifier to each unique thing. However, unique is a relative term. We had a 15 character part number system that evolved from four separate number systems over the years, some internal and some by acquisition. One of the major goals was being able to search for similar parts in the inventory computer system, given that the system at the time (1997) was fairly stupid and could search a field only alphabetically. It took over two months of once-a-week meetings to design all categories and sub categories, and a standardized part description field (again, dumb computer) and document everything into a user manual. When we were done, you could find all 10K resistors, sorted by tolerance, package, and power rating, in a single search of almost 8000 part numbers.
Here are the basics: www-xxxx-Cyy-Rz

The "phone number" was the first seven digits and two dashes:
123-4567-

The prefix was the part category:
0xx - electrical/electromechanical/connectors
1xx - hardware
2xx-electronic components and asemblies
subcategories:
20x - assemblies
22x - capacitors
23x - resistors
4xx - wire harnesses
5xx - top level assembly numbers
510 - complete systems
540 - customer specific categories

The body was 4 digits assigned in next available sequence, no "intelligence" built into this number field.

Next, Configuratiion:
Cxx- (00 through 99)
A configuration is a changeable variation of the original design. It is a way for there to be multiple versions of the same product active simultaneously. For example, if the Navy wants a widget in flight line yellow for a carrier, and the army wants the exact same widget in desert camo, those would be configurations.

Next, Revision (or version):
Rx (0-9, A-Z)
A revision is a non-reversible change that obsoletes all previous versions of the part. It is last so that when a list of part numbers is sorted, the previous revisions are listed in order. For any particular base part number, it is possible for different configurations to have different rev levels. For example, the navy might have been happy with the shade of yellow (C00-R0), but the army configuration needed three tries to get the camo colors just right (C01-R2). Some people prefer letters for revs to prevent confusion with the config field.

The final system was detailed, but very usable. There were over 200 of the 999 possible prefixes defined. 20 years later it has never needed any kind of adjustment or overhaul, other than rarely defining a new prefix.

ak

#### wayneh

Joined Sep 9, 2010
16,102
No one likes iron-fisted control...
...when they first encounter it and have not yet learned the advantages.

I lived through my company going ISO 9000 without any previous system in place. The wailing, moaning and gnashing of teeth of was everywhere. A year or so later, everyone was happy to work within the system. It eliminated endless BS and dramatically streamlined many daily activities.

#### AnalogKid

Joined Aug 1, 2013
8,109
We jumped on ISO9001 in the late 80's. Single best marketing plus ever.

#### BobaMosfet

Joined Jul 1, 2009
806
The company I work at was faced with this problem 4 years ago. Since it sources tens of thousands of parts from over a hundred countries, components/sub-assemblies/assemblies/tertiary parts. We examined all the number methods we could think of, including an adaptation of the Dewey Decimal system, like libraries use. I would like to say I wish we'd seen the scheme that AK mentioned above, but in the end I'm glad we didn't because we wound up with a tool more suited to our needs.

There are actually two approaches to this problem. Using a part number that contains information within itself is a valid way to do things, but it exists because it was developed historically in an era where relational databases did not really exist or were so expensive they were unfeasible. In the end, we found that containing information in the part number, which is simply an index, was not nearly as useful as simply recording all necessary information about each part and it's lifecycle from procurement to customer (whether it ended up in an assembly or sub-assembly, kit, or individual component), and maintaining that in a database. The database allowed us to keep everything organized, available, and usable, without being tied to an encrypted partnumber. Along with every aspect of a component, this includes images, datasheets, gerber-files, schematics, and unique graphical marking information for each item. We can search for parts that work within certain thermal limits, or within certain tolerances, or are within certain price-ranges. We can see if a part is obsolete, has an alternate, or is paired with something else normally. And there is much more. It integrates vendor, customer, and marketing information as well for full lifecycle management. It can be accessed on the company intranet as a web-page, so is very convenient, and accessible.

Whichever method you choose is valid, so long as you make sure you understand what it is you're ultimately after. For us, flexibility in information management was the most important.

#### AnalogKid

Joined Aug 1, 2013
8,109
And - there is no such thing as a numbering system that pleases everyone, so get over it. Come up with something that is rational and has legs for expansion, and people will adapt.

I worked through school working nights and weekends in a TV station videotape room. We had over 1000 video tapes, back when they were huge. The VCR hadn't been invented yet; a 1-hour tape was over a foot in diameter and weighed 7 pounds. As the inventory grew we needed a new numbering system. Scheduling and management spent weeks debating it. What finally happened: the head scheduler came in on a Saturday and Sunday afternoon when it was just the two of us, and we renumbered everything.

Monday morning there was a lot of yelling and threatening.

Two weeks later no one could remember the old system.

ak

#### wayneh

Joined Sep 9, 2010
16,102
And - there is no such thing as a numbering system that pleases everyone, so get over it. Come up with something that is rational and has legs for expansion, and people will adapt.
So true. And the primary failing of all database projects can never be avoided: $hit in,$hit out. Accept it, plan for it, program for it, teach it, punish it, whatever. It'll still be the main problem.

#### BobaMosfet

Joined Jul 1, 2009
806
So true. And the primary failing of all database projects can never be avoided: $hit in,$hit out. Accept it, plan for it, program for it, teach it, punish it, whatever. It'll still be the main problem.
This is a problem with all data-related problems, not just database projects.