Special-purpose pad name convention

[fruchti]

There are some parts with exposed pads currently in the pool (QFN, …). Their exposed pads are all named PAD, which I'd like to keep, but extend to other “pad types”.

IMO, there should be a list of allowed pad names. These come to my mind:

• PAD for exposed pads
• TAB for horizontally mounted power transistors (TO220, etc.)
• SHIELD for cable or connector shields
• CASE for modules or where they serve a mainly mechanical purpose (with no electrical connection)

I'm a bit unsure whether SHIELD/CASE are good names resp. whether they make the distinction clear. Maybe MECH would be an option?

[atoav]

I like MECH for mechanical pins, CASE sounds more like something that you have to manually solder on (e.g. like a cable onto the back of a potentiometer).

The rest is okay.

[fruchti]

An edge case to consider: What name should a TO-3 BJT's collector (which is connected to the package's metal case) get? IMHO, CASE would be the most logical option. I'd propose the following rules:

• CASE for mechanically and electrically important (i.e. not just a regular pin that is fused to the metal case like with a TO-18) connections to a part's or module's metal case.
• TAB for horizontally mounted power transistors/ICs.
• MECH for mechanical stabilisation without an important electrical connection.
• SHIELD only for connectors and cables where it is connected to a cable shield.

That does leave a few unclarities, e.g. if a crystal should have a CASE or MECH, but I can't think of a better solution.