First Run of Toaster Reflow Oven: Fail

I have been working on building up a Toaster Oven based reflow oven. Tonight was the first time I combined my thermocouple and SSR. I wanted to see what the ramp rate of the oven was as well as its maximum temperature. So I taped my thermocouple to a board with kapton and got cooking.

At about 450F I was wondering if anything in the oven would cause it to shut down. At 500F (my target) I thought I heard bubbling and realized the soldermask was starting to melt. So I shutdown the oven down, but it was too late...

Soldermask Failure by JamesC4S, on Flickr

So... I think I will be running without a PCB until I get my temperature curve figured out. :wink:

its not really your temperature in the oven, its the fact you have at least two coils blasting out heat, sure your oven temp at board may only be 270C in the middle but those coils are mini suns just broiling your board

its the same reason I like cooking my pizza's in toaster ovens, the middle says soft, but my cheese is stupid toasty in a much shorter amount of time, heck I have totally roasted boards before the solder even becomes plastic, and some sheet metal to help take the brunt of the abuse did help, though I want some like quater inch thick aluminum plate.

if your going to do it without blowtorch sheilds your going to have to to it slowly

Hey, what do you know... when you control the heat a little bit better you get good results:

Solder Flux Cleaned Off. by JamesC4S, on Flickr

Full Write Up:

Hi James,
Very Very nice...
This is better than any other "oven" I have seen so far!!!!
I have seen the "Hot Plates" on the Spark Fun site, Yours is
very good. Please keep us posted....
I just moved into a new place, I want to start making PCB's soon
and have never done SMT before. After seeing this, I have to
re think SMT, this looks very do-able....
Can you post a step by step on what you did ????
YouTube video would be great...
Thanks !!!!!