The oven I used for this is a value range mini-oven sold at Argos for €38.99. It is a 1000 watt oven with two elements ( one upper one lower ) and a temperature range of 100-230 degrees.
Here is a picture of the aforementioned toaster oven:
From looking at how other people on the internet have gone about using toaster ovens for pcb manufacture, it seems that it is not really neccessary to have a PID controller in place that can set the temperature to the nearest degree. Using a thermometer and manually turning the oven on and off to get the desired temperatures seems to work just fine. In my case I used a multimeter that has a temperature function and a k-type thermocouple capable of measuring a range from -20 to +2000 degrees. More than enough for this purpose.
First step in getting everthing ready is to know the reflow profile of the solder paste you are using. This information is normally provided in a datasheet and looks something like this:
I’m not really sure why there are two lines but its not all the important because once you are roughly in the right ballpark temperature everything seems to turn out ok. So for this reflow profile I would do the following:
1. put the board in the oven cold
2. Turn on oven until temperature reaches around 150 Degrees
3. Wait at this temperature for about 2.5 minutes
4. Increase temperature to 200 Degrees. Once this temperature is reached turn of the oven and let it slowly cool down
The next step is applying the solder paste to the board. This is fairly simple to do although it is time consuming if you have a lot of pads on the board. I made a complete shambles of applying the paste to my board as seen below:
Next step is to place all of the parts on the board. This step requires a steady hand and some patience with lining everything up correctly. The end result looked like this:
Now just gently place the board in the oven and follow the reflow profile of the solder paste, keeping an eye on the temperature and elapsed time. Here is a picture of the finished product:
It works! Despite making a balls of the solder paste it turned out all right so its a fairly rugged and reliable method for applying solder.