[quote author="jrychter"]If you place the PCB on top of the SSR like that, won't you have a problem with heat? The Maxim temperature-reading chip should be kept away from heat sources, and it should have the same temperature as the cold junction of the thermocouple. With this kind of arrangement, I'd be worried about precision.[/quote]
I think that the picture of the SSR with the board on top is just to compare the size !
But you're right concerning the max6675. During my test I have to be careful with the position of the max6675 board. If it was too close of the oven I got strange results. Moreover if you're reading the max6675 too fast, you loose precision.
Ok . Another day, another tests :) I tried PID , but I'm not happy with it , and finally it seems useless. I have to try with autoadaptative, because it's a real pain to find good value pour Kp,Ki,Kd ... Moreover , the PWM is no really compliant with my SSR (non zero crossing). I choosed a slow frequency (120Kz , for an AC frequency of 50 Hz) , but you can see the bulb flashing at 3Hz ...
So I tried with a simple ON/OFF system and this is what I get with a sample profile :
I'm really happy with the dynamic of the oven. I have to implement a linear interpolation to control the slope between setpoint , but I really think this oven is a good solution for reflowing.
Now, I'll waiting for my solderpaste and my next PCB ! :)
I received my oven 2 days ago and modified it in order to get temperature over time with an arduino board, a thermocouple, and a bluetooth module for transmission to my android phone. You can already view the first results on my blog : http://www.tronique.fr It's in french but I guess google trad could do the job :) I'll post some pictures, charts, and results here later this day, not have enough time now :)
[quote author="Sleepwalker3"]Hi SadE, I happened to be in the store this morning and saw one of those IR cooking ovens for $35 Australian. Looking at them, I really don't think they would be as useful or simple as the plain old frypan/skillet or even toaster oven. Sparkfun went through all the mucking about with controllers and all the rest and in the end they found that just putting it on a frypan/skillet and turning it on till it was soldered worked fine. My frypan cost me $17 at the local supermarket and works fine - pretty hard to beat that! I'd save my money if I were you - just my two cents worth.[/quote]
You're probably right. But after some research , I never found such a type of oven modified for reflow. You can see this as a proof of concept :) But if the temperature ramp is fast enough , and if you can switch off the bulb without the fan in order to decrease quickly the temperature, I'm convinced it could be a great tool that could follow some temperature profiles needed for some chips.
Ok , So I'll wait some days before ordering one ;-) For my other oven I used high temp aluminium tape in all the oven wall and door. It helped a lot for the temperature. With this , oven it's partially radiated heat , so I guess the aluminium tape could be ok ! Maybe put a good insulation in the bowl and classic aluminium tape over ?
Nice Rubu !! :) You're lucky , my own order has been cancelled , I have to find another one :-/ You're right the most important thing is the monitored ramp test . What is the volume of your oven ?
[quote author="Sleepwalker3"]Those types of ovens blow the air around quite a lot, as is shown on the infomercials. It's very easy to blow SMD components off the board and my guess is you would be struggling to keep any components on the board. I'd suggest the usual frying pan/skillet method or toaster oven.[/quote]
Yes , the fan has to be regulated too ... It's probably an AC fan , so an optotriac seems OK.
[quote author="JuKu"]Btw, your links are broken. Anyway, sounds like a plan. For ideas, here is a commercial kit: http://http://www.reflow-kit.com/rkuk/index.html. Reding the material might get you some ideas how to do your own. Let us know how it went![/quote]
The controller looks cool , but not really chip :/ , particularly if you've already got the thermocouple, a max6675, an Omron SSR and an arduino ready :)
I alread have a controller for a more classic mini oven with a PID regulation and an K thermocouple. I'm pretty sure the halogen bulb is more adapted for PID than a slow resistor heater. And the forced convection is a real plus Some thoughts before I bought one for 25€ ? :)
I got a little 20L oven with a temp controller in order to reflow PCB but the temp does not increase enough fast :-/ I found this type of infrared (halogen) forced convection 'oven' : http://www.nuwaveoven.com/nuwave-infrar ... ssic.asp#1 There's a lot of similar oven for $35 on the web : http://www.rueducommerce.fr/m/ps/mpid:M ... 0BM7028933 The volume is low , 1500W power, and it seems to cook pretty fast. I like the idea of the glass material in order ton control the process. And the form factor is cool :lol: Do you think it's possible to hack it for reflowing ?
