Target has a Black & Decker toaster oven on sale for $19 for their 2 day black friday sale. I decided to pick one up and try it out as a reflow oven.
I just did my first test.
Preheated the oven to 450 degrees (F). I thought I was pre-heating to about 200 degrees but misread the dial, so this first test isn't exactly what I wanted to do. The oven is set to the bake setting. This brings on the top and bottom heating elements at the same time.
While the oven was pre-heating I threw some solder paste on a bare MegaMini and placed an Atmega2560 and some other surface mount components including 2 LED's.
I then placed the board on the rack which is set at the top position. This is where I realized it was set at 450 degrees instead of 200, so I just turned it down to about 420. After about 30 - 45 seconds, the solder paste melted. I let it cook for about another 30 seconds then turned the over off. After turning it off I let it cool for about a minute before opening the door. Then opened the door to let it cool enough to touch.
Results were very good. The Atmea2560 has better alignment than I was ever able to get with a hot air station and only a few solder bridges that can easily be fixed with some solder wick. The solder bridges are probably a result of me not using a stencil for the solder paste.
So if you are looking for a cheap toaster oven to use as a reflow oven, it is probably a good time to go get one from Target.
I will do some more tests today and post my results. This board requires an FT232 and a USB connector on the bottom side, so I think I will see how it handles being baked upside-down with components already attached.
I also picked up a Black & Decker flat griddle (hot plate), also on sale for $19. I might experiment with that this weekend also. Unless I decide to use it for pancakes instead
Very neat...I wonder if anyone has stuck a thermocouple in a toaster oven to see how the "reflow profile" compares to that of a professional reflow oven.
I'm going to guess you won't have any trouble with reflowing the top side even with components on the bottom. Except for the heaviest components, the surface tension of solder should be enough to keep the parts on the bottom in place.
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The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected
I wonder if anyone has stuck a thermocouple in a toaster oven to see how the "reflow profile" compares
I have a bunch of type J thermocouples on their way. Hopefully will have them by the end of next week. I'll run some datalogging tests then to see how it compares.
the surface tension of solder should be enough to keep the parts on the bottom in place.
Seemed to work without a problem.
For the second run the board was flipped over. So the Atmega2560 and some other misc components were on the bottom. The other components I had on what is now the top... Surface mount crystal in a standard low profile size, Mini USB connector, the FT232 and some other misc components. For this run I had the oven at 200 degrees (F) when the board was inserted, cranked it up to 420 after about 30 seconds. After 90 seconds in, the solder began to reflow. I held that for 30 seconds then started the cool-down process.
This run ended up darkening the board slightly. It would probably not be noticed by your average user, but it is there. The darkening happened on the side of the board that has no components, so it probably heated up a little quicker than the rest.
Everything else seemed to go ok. I had no issues with melting plastic on the USB connector and the crystal.
I was able to load the bootloader on the Atmega2560 without issue, but did have issues programing it from the USB. After resoldering a few pins that didn't look right, it all worked as it should.
I know a lot of people have covered this before, but so far I have learned 2 things.
A solder paste stencil seems a lot more necessary with an oven than when using a hot air station.
I think I was ramping the temperature up too quick in the second run. I should probably bring the temperature up in at least 3 stages. While the first run of one temperature worked, it probably causes too much stress on the components.
I also picked up a Black & Decker flat griddle (hot plate), also on sale for $19. I might experiment with that this weekend also. Unless I decide to use it for pancakes instead
Nice, I picked up a 900W pancake maker for free which needs a new thermal fuse (~£2.50 for 5) and I'm gonna fit it with a thermocouple and see how that goes for SMD work.
I'm thinking of using a servo to turn the thermal switch on it so I can turn it on and off (to control the max temp and heating curves) without touching the 230V.
Just had to go and look up what a black Friday sale was. Alien concept to a land without thanksgiving.......
Yes it is a rather cryptic and ominous name for what should just mean the first 'official' day to start shopping for Christmas presents. I always associated the 'black' to mean large crowds, hard to find parking, sold out sales, etc. Pretty much a retailers driven thing these days, time to milk the money from the consumers by making them buy stuff they don't really need, but hey it's on sale.
.I wonder if anyone has stuck a thermocouple in a toaster oven to see how the "reflow profile" compares to that of a professional reflow oven.
I'm currently in the process of tuning the PID controller on my toaster oven. It tracks the temp fairly well (within 0.5 deg C) of setpoint as long as the profile slope during heating doesn't exceed about 0.8 degC/second.
