The design of a heater controller for a thermal evaporation system

A compatible heater system is vital for the successful operation of an evaporator for material fabrication process. This thesis describes the method of designing a heater system well suit for evaporation and deposition of amorphous silicon thin film. Several factors must be taken into consideration in the design of the heater to match the use. Analysis of the system before developing the actual heater system is Boat. Before this actual circuit is assemble, the simulation by using PSim and PSpice were conduct to get the parameters and the expected result in order to compare with the actual result by experiment. By designing the circuit, the resistances of the boat were obtain, and then the whole parameters were regarded to this value in order to get the expected value of current to used in heating system to evaporated process. The calculation of current supply for heater required at 0.295 A for the duration of I hour or 3600 s for evaporation of silicon to take place. An air-cored inductor has been used in this circuit to ripple less the wave­form of DC current. By using the Wheeler's formula, the suitable value of inductor at 1.1 mH was used in the circuit design to filter or ripple less the wave form current from sinusoidal to constant increase. This is because, the constantly increase current are easy to control, difference to the sinusoidal current wave form.