IR Heat Diistribution In An Oven

[dknguyen]

I am thinking about fitting a toaster oven to do reflow work. It seems that getting a infrared convection oven would be the best way to go, but I am having a really hard time choosing between just one thermocouple or distributed thermocouples. It's about $25 for each thermocouple and cold-junction comp IC. The main problem is I am not sure how uneven the distribution of infrared heat is. Can anyone provide some insight into this?

THe oven would typically use IR as the primary heat source but also have a convection fan to try and more uniformly distribute the heat, but I am not sure how effective this is...

Can anyone provide more insight into the heating properties of a IR+convection oven? Master chefs welcome!

 

[Russlk]

I don't think you need a fan. I bought a toaster oven for reflow but have not tried it yet. My oven has two heaters on top and two below. A thermocouple won't be much use, you have to watch the solder paste and when it is all melted, shut off the oven. To avoid temperature shock, don't take the parts out immediatly, let them cool a bit.
I have used infra-red reflow in industry, but we had a moving belt and controlled temperature rise and fall.

 

[dknguyen]

I think a fan is more crucial if you have PCBs that take up more area...and the only reason I want to use one (and make a project out of it along the way by automating it with electronics and a thermocouple) is because I have to do of the same 20 boards...bleck.