Try it out in a demo layout and then run and check your Gerbers using a locally installed (i.e. s/w running on your machine) gerber viewer.

It is shown in the gerber viewer on the JLCPCB website too but as far as I understand the fabrication steps multi-layer pad-slots and vias are machined and then the whole panel gets plated way before the board outlines are cut in the end. The outlines are  probably milled with a 1mm bit. I'don't think they can exclude holes from getting plated if they are milled before electroless copper stage. This means I can ether have a plated slot and reduce the size of the pads to increase the distance to the slot or increase the slot to 1mm which results in a less precise alignement of the B2B connector. [https://www.raypcb.com/pcb-board-manufacturing/](https://www.raypcb.com/pcb-board-manufacturing/)

I had the slot with a 0.6mm with in the board outline for my first prototype and the slot was not cut.

It might be worth asking JLCPCB Support about this directly by email.

Thanks I asked directly

@bitterandreal Hello and thank you for sharing your topic here Considering the ST-link drawing for the B2B connection it says that the pad to pad spacing is required to be 1mm and the minimum slot size is 1mm for non plated slots and 0.5mm for plated slots which is drawn in your ECAD designer as a multi-layer pad. Considering the screen-shot of your first posted comment, it seems okay since you already draw the slot as oval multi-layer pad but do not hesitate to check your GERBER files with the support team before proceed to production ([support@jlcpcb.com](mailto:support@jlcpcb.com)), this way you ensure a well produced boards, you can select the "Review Before Payment" option to check your files before proceeding to production, check the 10th point of the following guide: [https://jlcpcb.com/help/article/54-How-do-I-place-an-order](https://jlcpcb.com/help/article/54-How-do-I-place-an-order)<br> <br>