Different component, same footprint, different stencil - best approach?
logictom , 04-07-2017, 12:15 AM
I am working on a board that will be fitted with a Telit module (LE910C1), we would also like to fit another module (HE910) if selling into different markets - this may or may not happen.
The LE910 is a newer device with additional pads but the older HE910 can be fitted to the same footprint but we would use another stencil so that the pads that don't exist on the HE910 don't have solder applied.
What would be the best approach for keeping this all tied into the sch/PCB within Altium?
I was thinking of using a variant and switching the LE910 with the HE910 sch this would fix the BOM but then won't it want to switch the footprint in the PCB?
I was also thinking of just creating a duplicate layer of the solder paste but altering it for the HE910 but this seems bodgy and we will be using the idea on another project so it would be nice if it was included in the other design without these manual steps as it just adds another point where something may go wrong.
Does anyone have any suggestions?
robertferanec , 04-07-2017, 03:13 PM
In assembly house, when they make the stencil, just tell them which pads you do not want to cover with solder. I know, that for small quantities they may just use a tape to cover the openings.
I would probably just make a document where I would mark the pads and described the situation. Based on the document they would know how to create the stencil (or two stencils).
PS: I am not exactly sure how it is in Altium with variants and different footprints. It was not possible in past, but who knows, maybe having two different footprints in different variants is possible now.
KingVita89 , 04-07-2017, 07:51 PM
robertferanec , 04-07-2017, 10:06 PM
Looks like it is possible to use different footprints. From the link @KingVita89 attached:
Alternate Parts and the PCB Design Process
There is only one type of variation that affects component placement in the PCB design process; when an Alternate Part is specified, and that Alternate Part uses a different footprint from the base design. In this situation you must place 2 footprints on the board ........
logictom , 04-10-2017, 10:36 PM
Thank you both for your feedback.
It looks like the Alternate Parts path is the correct one to use. The only issue I foresee is I would like the footprints to be placed over one another and I am not sure whether this is going to cause DRC issues and whether the stencil layer will be generated correctly.
I am going to have a play about with this and will post my findings.
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