Out of curiosity. I'd like to know what your conventions for naming PCB's vs schematics are. I'm aware that disziplin! is key to properly manage projects, just like consistent naming conventions are key in software development. Here are a few of my points of questioning. Note: I'm using the term "revision" but you could use what suits your habits, so just describe what you're doing in general. Here are a few of my questioning points:
- Do you use anything else than a "revision" marking? In software development, for instance, we often use major + minor + build version numbers, though not limited to that set.
- Do you use numerals or alphabetic revisions? or a mix of both? Or something else?
First I will say that the PCB and the schematic get separate part numbers and can have different revision levels.
Part numbers are just an incrementing numeral, assigned by the person who has the keys to the MRP system.
Revisions are letters, with the exception of the initial release which is simply '-' (dash). They indicate the release level of the item. Our rule is that a PCB must be released in our system if it will be fabricated. Actually the rule is that anything that goes out of house to a customer must be released entirely.
For other things, especially firmware (firmware gets a part number in our system), we have this notion of "prelease" revisions, indicated by +1, +2, etc. Prerelease is not "official." It basically corresponds to "OK, I think this is good, so let me give it to someone else for testing." The code for this prerelease is of course a tag in the source-code control repository. But it's not official. When the code is ready for release to customers, then it gets a proper revision number and again a tag in the repo.
- When do you change that revision?
For released product, if there is a change to the design, then ECOs are written and when that is all handled, the revision is bumped, say from - to A or B to C.
Now say we build a first-article board and the schematic calls out resistor values. During test we decide we need to change a couple of resistors. The schematic (and the resulting BOM) are marked up with the new value, and the new schematic gets its pre-release bumped up, so now it's rev +1. When it's final, again an ECO is written and when finished the schematic will get a new revision say rev A.
Do note that all old versions (and pre-release versions) are archived. Nothing is thrown away.
- Do you keep separate/distinct revisions for PCB and schematics?
Absolutely. It's very common for schematics and PCBs to get out of sync with regards to part values. A PCB may be on rev - but the schematic and BOM have advanced to rev B because of changes. The point is that the new parts can get put on the old board.
- If a schematics is edited, what about the related PCB revision?
If the physical board layout does not change, then its revision does not change. The board doesn't care that a resistor value went from 10k to 12k.
- Do you change the revision only of the schematics that was edited or are all related schematics bumped to that revision as well?
If you are referring to multiple pages in the same schematic, all of the pages get a revision bump. The pages are not separate as such. The top-level sheet will have the change log with the revision, and the page or pages changed will to have their change log section updated.
- How about multiple PCB's for a project?
A higher-level assembly document (which itself gets its own part number and revision history) calls out each PCB in the product, as well as everything necessary to actually build it.