To keep the electric industry constantly developing, it is very important, to know the physical, and chemical processes behind the technology. My thesis will join to an experiment, which examine the interrelations between the cooling speed and the solidification of the solder's structure. During the semester I designed, and materialized a controller, which can cool with fans a solder sample with an adjusted cooling speed. To understand the essence of the experiment, I made bibliographic searching in the topic of reflow soldering, and cooling processes. During the experiment the cooling was provided by fans, so I dealt with direct current motors and fans in the semester.
To design the controller, I had to learn about microcontrollers and different peripheries. For the project I used PIC microcontroller. To use the PIC as a controller, I used the CCP (capture/compare/PWM) module to generate PWM (pulse with modulation) signals with different duty cycles for the fans. In addition it was necessary to measure the temperature, which was performed by a special IC called MAX 6675. The MAX 6675 used a built-in analog-to-digital converter, to create a 12 bit resolution data from the signal made by K-type temperature sensor. This data was transferred to the PIC microcontroller through an SPI bus. In order to create the controller’s interface, it was required an LCD display as well, which had a compatibleinstruction set with the Hitachi HD44780 controller. After the circuit was done, I tested the proper working of the controller with experiments. During the design process I aspired to create a controller, which can be further developed, and the software of the microcontroller can be easily updated and burned into the microcontroller. The circuit has an ICSP (in-circuit serial port), through which the microcontroller can be programmed.