When your gerber is for just one design and need JLCPCB to help you to duplicate many copies onto one panel, you can use this option.
You can drag across the rectangles to select then click on the panel to set how many rows and columns as shown in the image below:
For this image, we will merge 10 small PCBs to 1 big panel. If you order 5 pcs, then we will send 5 big panels to you, each with 10 PCBs on it so you will end up with 50 small PCBs.
If you select the Edge Rails, we will add a 5mm board edge as shown in the image below:
This is 2 rows and 5 cols panel PCB.
1. Make sure the one single PCB's size bigger than 2cm*2cm, small PCB is hard to v-cut.
2. Make sure the board outline is simply, for complex board outline, you need to panelized by your self.