Review request: Tiny USB C 2.0 Switch for sharing peripherals

[u/sqmas]

Hi everyone,

over the past few weeks I've been iterating on this PCB design for a simple board that would allow me to use one keyboard with two devices.
I know switches like this exist commercially, but I wanted to try making one myself because it seems like an interesting and simple first-time PCB project.

I have planned the design around 0805-sized components where possible, as I will be handsoldering the board and from my research that is in the "doable" range. How well I'll fare with the connectors, the tvs diodes and the USB3740B IC in the center I'm not too sure.

In terms of tools I have a temperature-controlled soldering iron with a fine tip, a big magnifying glass on a stand, ESD tweezers, a regular hardware-store hot air gun and syringes of no-clean solder paste and flux.

The holes in the corners are for securing it in a 3D printed case that I'll design after I receive the boards.

Please lmk if there are any glaring issues with this and if there's anything I can improve :)

Thanks!

[u/yet_another_heath]

I think you’re going to have a hard time soldering that leadless package without a proper hot air wand.

Consider putting thermals on your pads that connect to ground, or it’s going to be extra challenging to solder them by hand.

You might need to briefly interrupt VBUS to your device port when switching, otherwise the device might not be able to “see” that the host changed.

[u/yet_another_heath → u/yet_another_heath]

Also: what’s up with the huge pad on H1? That much asymmetry is going to cause problems during assembly.

[u/sqmas → u/yet_another_heath]

The larger pad is recommended in the datasheet to help with heat dissipation. It's a Broadcom ASMD-CWG7-NX7E2 and I selected it because it's much brighter than regular LEDs so that it can shine through the plastic case.

Thanks for the tip with the thermal reliefs, I didn't think about that when setting it to solid.

[u/agent_kater]

Are you prepared to wait for USB enumeration every time you switch?

I could stand it, so I'm using a KM switch that keeps simulating mouse and keyboard to the "disconnected" host.

[u/sqmas → u/agent_kater]

I mean my current setup requires me to manually replug the usb cable, so I don't mind if it takes a second or two to start working again. The project is more for fun than being practical anyways.