footprint with a rectangle cutout

[m4vrick99]

Hello 🙂

I'm trying to create library with for a bottom view led, this means the led is designed to shine through a cutout in the PCB between the two pads.

Here is the datasheet : https://www.mouser.fr/datasheet/2/239/Lite-On-LTST-C230KRKT-1175237.pdf

I dont know on which layer I should put the cutout, I tried several but there is always issues:

- The cutout is not 'viewed' by the design rules, I can totally put a trace over it and the polygon (like a ground plane) can go over it

- I dont see it in the 3D PCB except if it's on the Milling layer, but still not used by the design rules

When pushing the design for manufacturing at JLCPCB the cutout appears on the outline but it's not on the 3D view so I'm not sure if I'll have it or not.

What is the right way to create the footprint for this library ?
I guess it's possible, like there is jack connectors with holes in the PCB for the tip of the jack.

Thanks for your help

[Evert_2N3055]

You should place the cutout on the milling layer. Keep in mind that the pcb manufactures can't make an square hole, the hole has always rounded corners due the radius of the milling bit.

My experience is that if you place the cutout in the milling layer is also used by the design rules. If not you can also place the cutout shape in both restrict layers.

Don't trust the online viewer from Jlcpcb. Use another online gerber viewer to see if you layers and then special the milling layer is looking fine.

Btw, for those kind of led's I'm always using just a round hole.

[m4vrick99]

Thanks for your help.

Initially I've put it on the milling layer, and you're right it's good when using several online gerber viewer.

I know for the rounded corner, it's already taken in account with the final manufacturer (JLCPCB is only for the prototypes).

My main concern is about the design rules and the limits between holes, traces ... I'll try with the restrict layer maybe it'll improve the result. Actually my main ground, which is a polygon pour from outlines, is overring a very small part of the cutouts, and as I said I can totally route a trace over the cutout without any warning from the design rules check.

you can see an example of the result on the image, traces over the cutout and top and bottom polygon pour going over the cutout too.

[jorge_garcia]

Hi @m4vrick99,

Historically, the milling layer has best been used for specialized slots in pads. For something like this, the board outline layer is probably a better fit since the routing engine will respect it. I would urge you to give it a try.

Let me know if there's anything else I can do for you.

Best Regards, 

[m4vrick99]

Thanks @jorge_garcia 😄

Using the Board Outline layer is the right solution, I dont know why I didn't see it before.

[fusion360-1KPVQK]

Hi,

I tried same, a cutout on milling layer, but I dont see it in 3D PCB. In footprint editor I could not find a outline layer. If I

use Laye 20 (document called in footprint) it also makes no cutout in 3D PCB

BR

Gerhard

[jorge_garcia]

Hello @fusion360-1KPVQK ,

Would you be able to post a few pictures of what you are seeing? Assuming closed contours on the BoardOutline layer (20) you should see something, however there are circumstances where the 3D PCB can't accurately reflect the cutouts.

Let me know if there's anything else I can do for you.

Best Regards,

[fusion360-1KPVQK]

Hi,

I have done a demo project.

I attach f3d file from 3DPCB and the lbr from this revers photodiode







hope this help for understanding this problem

BR

Gerhard

[jorge_garcia]

Hello @fusion360-1KPVQK ,

For some reason the project did not attach, would you be able to try again? If not I'm sure images would give me the insight I need. 

Best Regards,

[fusion360-1KPVQK]

Hi

have you got the .lbr file?

[fusion360-1KPVQK]

Hi Jorge

Silvester solved this Problem

There are only circle and line for cutouts on Layer 46 possible,

I had used and tried rectangle and polygon, this is not allowed for cutouts ?

Don’t understand it, but with line it is solved,

half live is determined from software ☹

Thanks for your effort

BR

Gerhard