Most of the passive components for this project are 0805 surface mount devices measuring 2.0 mm × 1.25 mm, anyone who has dealt with surface mount devices knows that they can be a real pain to solder, especially if you don’t have a variable temp iron with a small diameter tip, So for this project I decided to forgo that mess and purchase a slightly used toaster oven from a second hand store, unfortunately it is missing a knob but besides that its in pretty good shape.

The basic process goes something like this:
1) Tin all your pads.
2) Apply flux to your tinned pads.
3) Stick the components where they go using tweezers / forceps using the flux as a sort of tacky glue.
4) Heat the entire board until the solder “re-flows” and binds the components to the board.
5)Immediately remove the board from the oven to prevent heat damage.

The key to toaster oven reflow is the temperature, basically you want to get to 180-190 Degrees Celsius without getting any higher than ~210 Degrees Celsius. At 180 Celsius most solder will begin to melt, by 190 it will all have become liquid, By 210 Many components will begin to burn, By 230 the entire board and copper substrate will begin to burn.

In the photo’s below you can see the toaster oven I used as well as a multimeter connected to a thermocouple device for monitoring the temperature inside the toaster oven. There are also a couple images of the final board minus some headers attached to a pic-kit 3 for programming.