Controlling the cooling rate of soldering processes with PIC microcontroller

This paper focuses on the cooling rate of soldering process. Our target was to create a well-controlled equipment that is used to set the adjustable slope of the cooling curve with three special sections. The three sections are: near the melting point, above and below the melting point. The unit uses cooling fans to create a forced convection air flow. K-type thermocouple is used for the temperature measurement in the temperature feedback loop. The cooling rate is adjustable in a wide range, between 0.25 K/s and 10 K/s. To understand the effect of different cooling rates, the undercooling mechanism near the solidus point of the solder has to be investigated. Experiments showed that there is a flat section in the temperature profile when the solder reaches the solidus point during cooling. With the control unit this phenomenon and the effect of various cooling rates can also be investigated.