Cheap, quick and dirty reflow oven

I got this cheap toaster in a “crap shop” for 11 Euros. It’s perfect for reflowing PCBs and small enough to fit in my lab:

Reflow-ToasterI tried to use only components I had at hand, including:

  • a DIP PIC 18F2450 (total overkill to control a heater, I know)
  • a relay from a timer AC socket
  • a small USB iPhone charger for the +5V supply
  • a K-thermocouple and a MAX6675 for the conversion (quite expensive chip, but very simple to use and I had it in a drawer)
  • a small LCD screen, two buttons and two LEDs

The PIC is running from the internal RC oscillator. Very slow, but enough for what it’s used for.

The relay comes from this timer I bought some time ago at Conrad:

It’s rated for 2000W, the PCB is easy to re-use and fuse protected. I added an opto-coupler, so the PIC and user interface are fully isolated from the 220V mains (also convenient for debugging). I thought about re-using the timer’s LCD and microcontroller, but it’s directly bonded on the upper PCB and difficult to hack.

I managed to squeeze everything into the toaster’s plastic flange. (Unfortunately the temperature can increase a lot inside, so I think I’ll move the electronics into a box, outside the toaster)

For now, I just have two functions:

Drying – keeps the oven at 100°C

Reflow – follows the standard leaded solder paste curve (2 minutes@150°C – 2minutes@200°C – 1minute@250°C)

The LEDs also act as switches to select between the two functions. I’m still looking for a good method to cut plastic in a clean way. It’s not so easy with my Dremel.

It took me more or less one day to build everything (I wasted some time for the LCD display control).

I’m only using the heating elements from the upper “toast hole”. The bottom stays cool enough for the toaster to sit on a table without the need of extra feet or thermal protection.

And of course, the oven works just fine for the small PCBs I have to solder!

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3 thoughts on “Cheap, quick and dirty reflow oven

  1. Hi, I just found this, very nice hack! I’d be interested in replicating this.

    Are you regularly using this? Is the temperature distribution sufficiently even? Have you measured the temperature profiles, and if the temperature change is sufficiently fast?

    Thanks for any information!

    • If you do it, be careful, the heating is done by those resistive wires and they are directly connected to the 230V (or 120V)!
      Yes, the temperature change is quick enough. Actually, it can be VERY quick if you have an incorrect on/off cycle. The heated volume is small, it helps to distribute the heat, but I ramp it up slow, because the PCBs are on a metal plate that heats slower.
      I moved the control electronics into a box where I connect the toaster, because it was too hot inside the plastic enclosure.
      I didn’t measure the temp. profiles, because I don’t use the toaster so often, sorry.
      Good luck!

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