AZ-Delivery ESP8266-12E Manual page 6

Now we remove the ESP-8266 again and we heat up our soldering iron. Depending on
the solder used, the temperature should be between 300 - 330°C (solder containing
lead) or 350 - 370°C (solder containing no lead). If the soldering iron is too hot, the flux
might evaporate too quickly and the component (ESP8266-Chip) might overheat,
leading to its death. Even at the correct or lower temperature, it is advised to solder in
a quick manner!
When our soldering iron reaches the perfect working temperature, we tin one of the
16 soldering pads on the board, by slightly heating the pad and then adding some
solder.
Subsequently, we place the ESP8266 chip on the board and again we briefly heat up
the tinned pad. With a light press on the top of the chip, we fix its position and leave
the ESP8266 to rest on the board.
The result should look similar to this
picture: