Reflow soldering is a way to solder all surface mount components onto a circuit board simultaneously. I would find this very useful, and as I don't want to buy an industrial reflow soldering system, I considered a DIY approach.
The first step was to choose a mini electric convection oven to provide the necessary heat. A new Adler model AD6003, 1000 watt, 9 litre oven was purchased for only $35.
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| Adler AD6003 "toaster-oven", cover removed |
The guarantee was immediately invalidated by removing its cover to expose the thermostat and mechanical 60min timer/bell, and then disabling both of them. The next task was to check that the temperature would at least reach the solder reflow point of about 217C for Pb/Sn solder. With the oven switched to maximum power, ( upper and lower heating elements ), this temperature could be exceeded by a sufficient margin. To obtain accurate measurements a thermocouple, temperature data logger and a laptop running a control program written in Visual Basic were used.
After adding some electronics to operate a solid state relay connected to the heating elements, several plots of temperature versus time during heating up at different power duty cycles were obtained. Ultimately, the aim is to achieve, to a close approximation, the idealised heating and cooling profile shown below.
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| Idealised thermal profile |
This project is still a 'work-in-progress'. A Part (2) will be posted later.
