Dangerous Prototypes

Hi,

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 (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 (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 ?

I have seen those ovens in discount shops. It is convection so the air should circulate. It would also be so easy to keep an eye on. It doesn't have to preheat either, which might be a down side. I don't have a lot of experience, so I'd like to hear what other people think too. New home reflow trend? :D

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€ ? :)

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!

Here's a picture of the 25€ oven :


I think I will try this :)

[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 :)

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 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.

I bought an oven exactly like that locally (second hand) for 13 euros. Already have a controller PCB fabricated and all the parts except the PIC lying around. Not sure what to do with the fan yet. Haven't done any (monitored) ramping tests to see how fast it can ramp though. I think it's 1200W so we'll see how it goes.
I'll probably get on it this week and I'll report progress in here.

Specs of the controller:
-PIC 16F690
-K-type thermocouple
-FT232R for USB communication
-Powered over USB
-SSR for switching the oven on and off

Did some prelim tests without a controller and that went fine. No QFN of big QFP's just some resistors, regulators. The fan didn't prove to be a big problem, but like I said, only minor tests.

I'll snap some pics of the PCB, SSR and oven when I get home later tonight.

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 ?

Concerning the fan , I guess it's metal made. It could be possible to alter the wings angle to minimize the total flow.

[quote author="SadE"]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]

http://http://www.amazon.de/HLO-3322-Glas-1300-Watt/dp/B002UXQJZA That's the one, 1300W, 12 Liters. Pretty big, so who knows. I'm afraid it won't be fast enough. Already looked into decreasing the volume by filling up the bottom with something, not sure if that would make it better though. Ah well.

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 ?

from limor i picked up one of the http://www.orangeonions.com/product/FC3 ... aign=FC300 (http://www.orangeonions.com/product/FC300/Black-Decker-InfraWave-Countertop-Oven.html?meta=google&metacpg=FC300&utm_source=google&utm_medium=CPC&utm_campaign=FC300) these are great, and they cook pizza really well too ;)

I wouldn't suggest orange onions though, they shipped me 6 george foreman skillets instead of two ovens, which were useless for anything but making food.
 
I've got that same glass IR oven too, it did pretty well  for baking soldermask, but typically we've ended up sticking with the hotplate.  The oven is just a bit akward to use i've found

@charliex : I  tried to get a similar oven , but it's impossible to find one in my country :-/

@SadE yeah it took me a while to find one too,  after orange onions screwed up, i ended up searching around local stores and the like.. took me a couple of months to track one.

I think a hard density rockwool disc and a aluminium foil over it could help greatly to reduce the volume

[attachment=1]
The PCB sitting on top of an SSR. It's nice and small, I'll cut up a power cable and put the SSR in there. I intend to make as little mods to the oven as possible, just a hole for the thermocouple.

Still waiting for PIC MCU, but did solder up the thermocouple part. It's a max6675 so used the BP to verify operation. Temps were looking fine so that's positive. Ill see if i can run a ramping test tomorrow to see if i need to decrease the volume or something.
[attachment=0]

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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 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.

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 (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 :)

Before posting additional comments, I'll try to get a functional regulation today with Arduino and the new PID library ! :)

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 :

http://http://img705.imageshack.us/img705/5183/profiledi.png


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 !  :)

Nice work SadE, I'm really glad you're following up on this concept. Maybe it will be the next hot thing :) Please let us know when you have a test board, I'll post up your results on the blog.

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 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.