Author Topic: unpopulated footprints on PCB?  (Read 6218 times)

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Offline oliver602

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unpopulated footprints on PCB?
« on: November 23, 2011, 07:38:27 am »
Often see PCB's with unpopulated footprints so the same PCB can be used for variations of the same product or perhaps even different products.  Is there a a common way to do this in PCB design software? For exampe, I'd like to make a PCB with footprints for either a coin cell holder or AAA battery holder and be able to change resistor values for LED's.
 

Offline hacklordsniper

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Re: unpopulated footprints on PCB?
« Reply #1 on: November 23, 2011, 07:42:29 am »
Often see PCB's with unpopulated footprints so the same PCB can be used for variations of the same product or perhaps even different products.  Is there a a common way to do this in PCB design software? For exampe, I'd like to make a PCB with footprints for either a coin cell holder or AAA battery holder and be able to change resistor values for LED's.

Often manufacturers make single pcb for more models to save costs and/or remove components from exsisting design later in production to save costs. Additional components could also be used only in testing/prototyping stage and are not needed in final producsts.
Oh, the joy of sending various electronics to silicon heaven
 

Offline armandas

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Re: unpopulated footprints on PCB?
« Reply #2 on: November 23, 2011, 08:13:42 am »
Often see PCB's with unpopulated footprints so the same PCB can be used for variations of the same product or perhaps even different products.  Is there a a common way to do this in PCB design software? For exampe, I'd like to make a PCB with footprints for either a coin cell holder or AAA battery holder and be able to change resistor values for LED's.

It depends on what software you are using. Altium has variants, for example, but if your software does not have such feature, you can do this yourself by having multiple BOMs.

 

Offline Neilm

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Re: unpopulated footprints on PCB?
« Reply #3 on: November 23, 2011, 07:01:06 pm »
The other reason manufacturers might have empty footprints would be for "just in case" scenarios. These would generally be for EMC scenarios where having footprints on the board in the area you might need something would save the expense of re-laying out the PCB if later testing revealed that they were needed.

Sods law being what it is, I have yet to find one in exactly the right place (or correct footprint type)

Neil
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Offline oliver602

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Re: unpopulated footprints on PCB?
« Reply #4 on: November 24, 2011, 09:22:43 pm »
Thanks for the replies. I'm using KiCad and after a quick inspection I can't find anything that would allow for variants. Anybody have tips on how to achieve something like this in KiCad?
 

Offline ElektroQuark

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Re: unpopulated footprints on PCB?
« Reply #5 on: November 25, 2011, 09:12:46 am »
Try the KiCad user mailing list at Yahoo:

http://tech.groups.yahoo.com/group/kicad-users/

There are very experienced KiCad users there.

Offline Jon Chandler

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Re: unpopulated footprints on PCB?
« Reply #6 on: November 25, 2011, 03:23:41 pm »
There's no reason not to just include the extra footprints on the board with a note in the BOM about using one location or another, or to use different parts values in different situations.

If you'd like, include the different parts on the schematic (2 batteries for example) with a note to use one or the other.
 

Offline Greg J

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Re: unpopulated footprints on PCB?
« Reply #7 on: January 08, 2012, 04:03:44 pm »
Good stuff armbands , +1 (not the google shite one :P).
 
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