Brian Roth

Kicad edge finger footprints for 500/51X?
« on: November 16, 2018, 08:18:03 PM »
I've just started down this Rabbit Hole and haven't come up with a solution.

The existing libraries I've found all seem to be oriented towards small-sized footprints as used for computer add-on cards and not the Olde School  0.156" center fingers.   I imagine that I could spend a week trying to doodle a footprint, but perhaps this has already been done.

Thanks!

Bri
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com


john12ax7

Re: Kicad edge finger footprints for 500/51X?
« Reply #1 on: November 18, 2018, 09:12:06 PM »
I don't use kicad,  but do have some drawings can provide if you decide to make your own footprint.

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #2 on: November 19, 2018, 08:34:39 PM »
I don't use kicad,  but do have some drawings can provide if you decide to make your own footprint.

After trying a variety of Google search terms, I ran across this website:

http://kicad.rohrbacher.net/quickmod.php

I've doodled with it, and oddly enough, the SIL footprint seemed to yield better results for this application vs. the various edge connector choices.  Shrug.  At least the previews look valid, but I will need to try the actual footprint in Kicad.

Squarewave, how wide and long are the fingers in your drawings?  Perhaps I could find that same info from the Edac or Sullins websites, but maybe not.

Thanks!

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

pahstah

Re: Kicad edge finger footprints for 500/51X?
« Reply #3 on: November 20, 2018, 05:48:11 AM »
This is my Kicad edac 15 pin module design.


https://drive.google.com/open?id=1rEoktfi90OD5llLIwRlNnDsoAGGVoJ5i

Paolo

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #4 on: November 20, 2018, 03:24:00 PM »
Thanks!  I'll give it a look.

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

john12ax7

Re: Kicad edge finger footprints for 500/51X?
« Reply #5 on: November 20, 2018, 03:48:52 PM »
You can get a lot of info from this thread,  just ignore the extra pins for 500 series instead of 51x.

https://groupdiy.com/index.php?topic=39897.60

What I've realized is there really is no standard, everyone does it slightly different.  .156" pitch is the only consistent part.  Finger widths can range from. 090-.114" and lengths .315-.400"

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #6 on: November 20, 2018, 06:09:30 PM »
Indeed, lots of useful info in that thread.  Thanks for that, and for the range of finger widths/lengths.

Bri
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #7 on: November 28, 2018, 08:49:13 PM »
Here's what I ended up with (which included manually hacking the .MOD file with Wordpad).  I had to study the Kicad file format docs to comprehend what all of the various fields represented.

I added through holes to tie the "fingers" on both sides of the PCB together.  One thing I need to tweak...the hole diameters do NOT match any of the standard "number size" drill bits.

I've attached a screen shot from Kicad of the footprint.  After comments/further tweaking, I will post the .MOD file here at GDIY.

Thanks for everyone's help/comments!

Bri



Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

pahstah

Re: Kicad edge finger footprints for 500/51X?
« Reply #8 on: November 29, 2018, 03:21:00 AM »
Brian,
I know that many 500 series modules have fingers on top and bottom layer of the board BUT api's modules fingers are only on the bottom layer.

Paolo

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #9 on: November 29, 2018, 12:17:46 PM »
Brian,
I know that many 500 series modules have fingers on top and bottom layer of the board BUT api's modules fingers are only on the bottom layer.

Paolo

Thanks, Paolo.

Yes, I am guessing that the "classic" API modules had only bottom side fingers (and pads) since they were single-sided cards, which were less expensive to manufacture.

Since modern PC board manufacturers routinely offer two-sided boards as the "low end", I figured it was a good idea to duplicate the fingers on both sides and then tie each pair together to provide contact redundancy.

Bri
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com


john12ax7

Re: Kicad edge finger footprints for 500/51X?
« Reply #10 on: November 29, 2018, 09:31:20 PM »
Usually for production the fingers get plated with hard gold for wear resistance. This adds significant cost to the pcb, so it can make some sense to do single sided only, but there is no firm rule for this.

Generally soldermask is not applied where the fingers are, so it's good to define a keepout area for this.

[silent:arts]

Re: Kicad edge finger footprints for 500/51X?
« Reply #11 on: November 30, 2018, 12:06:16 AM »
There was at least one cheap Rack with the card edge connectors only connected on the wrong side.
Modules with double sided gold fingers worked, single sided didn't ...

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #12 on: November 30, 2018, 12:48:49 AM »
There was at least one cheap Rack with the card edge connectors only connected on the wrong side.
Modules with double sided gold fingers worked, single sided didn't ...

Egads!  <g>  The EDAC and Sullins female connectors I've seen have contacts on both sides.

Point also noted from John12ax7 about costs for plating hard gold on both sides of the connector fingers.

Bri
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #13 on: November 30, 2018, 12:52:01 AM »
Besides this useful discussion, does anyone have any comments on the footprint design I posted earlier in the thread?

Thanks!

bRI
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

john12ax7

Re: Kicad edge finger footprints for 500/51X?
« Reply #14 on: November 30, 2018, 03:15:17 AM »
Besides this useful discussion, does anyone have any comments on the footprint design I posted earlier in the thread?

Thanks!

bRI

The size is fine imo.  You want some clearance to the board edge, at least .010" (more if you bevel the edge), either something to remember,  or incorporate it into the footprint directly. And also the previously mentioned soldermask keepout.

Personally I wouldn't put vias on the pads, but I have seen some designs that do.   So will let others decide on that one.
« Last Edit: November 30, 2018, 03:20:13 AM by john12ax7 »

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #15 on: November 30, 2018, 12:59:06 PM »
Any particular reason(s) to avoid putting vias on the fingers?  Thanks!

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

john12ax7

Re: Kicad edge finger footprints for 500/51X?
« Reply #16 on: November 30, 2018, 06:26:55 PM »
Vias tend to be mechanical weak points.  So if used you need to make sure they are a sufficient distance from the point of stress.

Perhaps look at the Great River units and do it similar.

Brian Roth

Re: Kicad edge finger footprints for 500/51X?
« Reply #17 on: November 30, 2018, 06:57:39 PM »
Excellent point which I hadn't considered.

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com


 

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