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Reflow Toaster

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This is a toaster modified to work as a reflow oven. The toaster itself is largely unchanged except that its electrical system has been reduced to a few wires. The heater elements are now controlled by an ATmega16 microcontroller via a solid state relay. A thermocouple measures the temperature of the board. A MAX6675 reports the temperature of the thermocouple to the microcontroller.

The user interface allows up to four reflow profiles to be defined and edited using only the encoder/button directly below the display. There is also a test mode for testing the heater elements, thermocouple, and some software components.

I have done a few test runs with this toaster, including "deflowing" a populated board which include some BGA devices and large components. The toaster can definitely reach the necessary temperatures although the rate of temperature rise is not a high as I would like. I am considering adding a circulating fan, but I won't do that until I see how well it works in more cases.

The wire connecting the control box to the toaster is 16/3 SJOOW, which is very flexible and can handle temperatures at least as high as what the original power cord was rated for. The wire connected directly to the heating elements is the original wire, which appears to be nickel-plated iron with silicone rubber insulation, spot-welded to the elements.

Complete setup

Wiring

Control box

Inside the control box