One of SMD soldering techniques is using a reflow soldering oven. Reflow soldering technique is used when it is impossible to solder components by hand. These may include ball grid arrays (BGA), small pitch quad flat packs. Or simply solder any SMD element to make board look professional and smooth.
Special care has to be taken when soldering with oven. Specialized ovens have controllers built in that control overall soldering process by adjusting temperatures, but if you are using regular oven that is much cheaper than specialized soldering ovens, you need to build a controller. Controller has to adjust soldering oven temperature according to chart that is stored in memory. Together with keypad this gives great interactivity.
Soldering oven controller is based on ATmega32 microcontroller that uses ADC input to read NTC temperature sensor. Current temperature is displayed on graphical LCD as chart. As authors state – system works OK, maybe additional blower could be added for cooling speed controlling as without fan it is to slow. [via]
Reflow Soldering Oven controller with graphical LCD Display - [Link]