While placing the 0603 components is not that hard if you have SMD skills soldering the LEDs is quite difficult! Mostly due to the VIAs to give the pads more rigidity. I'm still experimenting a way to easily solder the LEDs, probably using a stencil and low temp solder with hot air is the best solution.

Right now I'm soldering the second tree.

For now my assembly procedure (without hot plate soldering and solder paste) is:

1. Solder all the 0603 excpet the one near the USB C contacts.
2. Solder the USB C
3. Solder the 5.1K resistor skipped on step 1.
4. Solder the ICs.
5. Solder the LEDs, make sure that they are firmly soldered.
6. Solder the ESP module.
7. Check for shorts and program the ESP. Test if first 6 leds are working.
8. Snap the boards and solder them together
9. Check again for shorts and enjoy!

Probably with hot air and a low melting point solder paste step 1-6 can be done in a single jump. Right now I only have flux, and 60/40 solder.

I managed to find a old solder paste, and yes, it makes the assemply a lot easier. I don't have a stencil and in anyu case soldering the LEDs would require manual reworks due to vias under the pads.

To solder the LEDS with this metod i proceed as:

1. Fill the LED pads with the solder paste proceed with the reflow WITHOUT the LEDs.
2. The solder would be wiked into the vias, apply again the solder paster and properly reflow the LEDs.

With my cheap hot air station I use 360°C to solder all the components and 220°C for the LEDs.

I'm a noob with LED soldering I've melted 8 of them on assempling 4 tree. So be careful. (Four on the first board, one fell on the fold and was lost. One had RED color not working. The others 2 has been melted on second and third board)

The touch button is connected to the BOOT0 pin, so you have to press that while you start the sketch upload process. A FTDI 3.3V module with RESET is required, I didnt had one so I temporary connected a wire to ground while also pressing the TOUCH button.

The FW can be found under the WLED repository, I'm using a ESP12, so d1_mini is the right platform to choose.

The pinout from bottom to top is:

• GND
• RESET
• TX (ESP8266 TX)
• RX (ESP8266 RX)
• 3V3