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Battery contacts - which library? #2149

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mibe opened this issue Mar 16, 2020 · 4 comments
Open

Battery contacts - which library? #2149

mibe opened this issue Mar 16, 2020 · 4 comments

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@mibe
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mibe commented Mar 16, 2020

Hey guys,

I have two new footprints ready, they are the 9 volt battery contacts Keystone 269 & 261. My question now is, which is the most fitting library for them?

Of course the Battery library with the BatteryHolder footprints first comes to mind. But on a second thought, these parts are contacts, not holders. They have (beside the actual contact) no mechanical support for holding a battery. You'd also need both to connect a battery to and you'd as a designer also need to get the distance of both parts on your PCB right.
My next idea was to maybe put them in the generic Connector library? They are mating contacts after all, so a designer could use them for whatever they like, as a fancy board-to-board interconnect for example.

What's your opinion on this?

@evanshultz
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They're specifically for batteries, so put them in the Battery repo. Instead of BatteryHolder_ as a prefix, which I still think might be reasonable, you could use Contact_ or some other term you think might fit better.

@mibe
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mibe commented Mar 21, 2020

Alright, the Battery library it is. I'd prefer the prefix named BatteryContact_ actually.

@ghost
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ghost commented Apr 9, 2020

I assume the contacts always get used in pairs? I see some benefit in having them as seperate symbols+footprints as it makes the BOM creation easier.

Question: How does the designer know how much distance needs to be between the contacts?
Related: How does the designer know how big the battery will actually be? There is no keepout or courtyard associated with those contacts.

The first solution that comes to mind is to add some kind of marker in F.Fab for the 2nd contact into each footprint (maker example here #1394). Perhaps also add the outline of the battery into each footprint. On the board they should perfectly overlap.
That leaves the courtyard. No clue on how to fix that :/

@mibe
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mibe commented Apr 12, 2020

Question: How does the designer know how much distance needs to be between the contacts?

The designer would have to look up the distance in the specification / battery datasheet. It is half an inch. Maybe it'd good to have the distance in the footprint description?

Related: How does the designer know how big the battery will actually be? There is no keepout or courtyard associated with those contacts.

The first solution that comes to mind is to add some kind of marker in F.Fab for the 2nd contact into each footprint (maker example here #1394). Perhaps also add the outline of the battery into each footprint. On the board they should perfectly overlap.
That leaves the courtyard. No clue on how to fix that :/

Indeed that's a problem. How about having an X drawn on Fab or Cmts in both footprints, which have to overlap to match the correct distance?
The courtyard could be made half the battery, so that the lines of both footprints have to overlap to match, like in the screenshot below. But how does the DRC react to having a CrtYrt line on another?
On the other hand there's so much space between the contacts and in the Z direction to the battery itself, you could easily fit standard 1206 components between the contacts. My quick measurements yielded at least 3 mm clearance in Z. So, I dunno, is a clearance including the battery itself needed? Depends on the design of the PCB I guess...

Unbenannt

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