Jumping SMD buttons from one PCB to another

Question

I have two PCBs: one is from a Lutron Pico, while another is from a a generic 2.4GHz wireless controller for some LED lights. I'd like to use the form factor of the Lutron Pico, but keep the functionality of the LED controller, so I figured I could just map the buttons on the Pico PCB to the other PCB.

Here's an image of the PCBs (from the front - Pico on right, LED controller on left):

And back:

My plan is to use the Pico PCB as a power source for the LED controller; I would also want to disconnect the Pico's antenna so it doesn't transmit anything. I'm currently stuck at trying to figure out how to actually jump the buttons. The Pico PCB's buttons are basically a small bit of metal that is taped over the contact point. Since the faceplate makes contact with the buttons, I can't really solder from the front.

My knowledge of dealing with SMD is limited, so I was hoping for some suggestions for approaching this.

Thanks!

Answer 1

You can start by figuring out whether the pushbuttons work in a pull-up or a pull-down circuit. This can be done relatively easily by simply observing the circuit or by powering up the circuit and testing the voltage at the outputs of the pushbuttons when they are pressed and when they are released. From what I have seen, pushbuttons in most circuits work in a pull-up configuration.

Once that is done, you can move forward and trace the pads of the buttons on the Lutron Pico board to the vias they are connected to. Since you cannot solder to the pads from the front, you can solder wires to these vias from the back side of the board. You can then solder these wires to the pads of the pushbuttons on the LED controller board.

You'll also need to make sure that both of these circuits share a common ground.

Note: This will only work if pushbuttons on both of these circuits share the same configuration. Otherwise, the circuit will act like the buttons are pressed when they are not.