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pointhi / kicad-footprint-generator

creating kicad footprints using python scripts
GNU General Public License v3.0
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Add Microchip_FCVG484_19x19mm_Layout22x22_P0.8mm and #644

Open pthomas opened 3 years ago

pthomas commented 3 years ago

Microchip_FCG1152_35x35mm_Layout34x34_P1.0mm

These packages are defined for the PolarFire SoC's in ug0902 here: https://www.microsemi.com/document-portal/doc_download/1244577-ug0902-polarfire-soc-fpga-packaging-and-pin-descriptions-user-guide

I wasn't sure about the names, should the Microchip prefix be there? Should FCG & FCVG be there? Here's the Microchip_FCVG484_19x19mm_Layout22x22_P0.8mm: Screenshot_20200928_211917

And the Microchip_FCG1152_35x35mm_Layout34x34_P1.0mm: image

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myfreescalewebpage commented 3 years ago

@pthomas comment about the script (I'm not 100% confident so if you have a reason why this is like that tell me):

Microchip_FCVG484_19x19mm_Layout22x22_P0.8mm

Microchip_FCG1152_35x35mm_Layout34x34_P1.0mm

@chschlue if you can have a look to : mask_margin: 0.015 => this one is not clear for me and we find various values in the script for BGA packages. Is it computed from something else ? paste_margin: 0.000001 => probably it should not be 0 ? Other BGA have the same value. Probably Ok even if I'm not sure what is the purpose of this field.

Joel

chschlue commented 3 years ago

0.000001 is a workaround addressing a limitation of the footprint format (0 in the file means "inherit from board setup" so if you actually want zero, you need to use a very small value instead.) Other than that, I believe @cpresser is more knowledgeable WRT the BGA generator.

ghost commented 3 years ago

First, it needs to be decided if this is going to be a IPC-compliant footprint, or should it be build according to vendor spec. O even mix both (which I think is horrible). In this case, I don't see why it should be vendor specific. Its does not have any special properties, and the pitch is rather coarse.

Thus, I would suggest to

To answer the original question. @chschlue is correct. The mask_margin will directly be applied to the footprint. It is not set on a per-pad-level.

pthomas commented 3 years ago

Thanks for looking at this everyone.

On Thu, Oct 1, 2020 at 6:45 AM cp-aquila notifications@github.com wrote:

First, it needs to be decided if this is going to be a IPC-compliant footprint, or should it be build according to vendor spec. O even mix both (which I think is horrible). In this case, I don't see why it should be vendor specific. Its does not have any special properties, and the pitch is rather coarse.

Thus, I would suggest to

  • specify ball_diameter instead of pad_diameter.
  • keep all margins at 0 to use board defaults
  • that will generate a NSMD footprint, as recommened by the manufacturer

So if we do IPC-compliant and specify ball diameter what will the pad diameter end up being? The tables lists the ball diameter as TBD, but I do see in the drawing it shows it, so it would end up looking like this for the 484: description: "FCVG484" ... body_size_x: 19.0 body_size_y: 19.0 overall_height: 2.92 pitch: 0.8 ball_diameter: 0.5 mask_margin: 0 paste_margin: 0 layout_x: 22 layout_y: 22

-Paul

ghost commented 3 years ago

You can omit the mask_margin and paste_margin parameters. Which is the same as having them at zero.