Reflow:comparisation convection 900W vs 1800W skillet

[Spikee]

Today i tested what is better for a reflow oven convection or a skillet type.

Personally i have been using the Skilled for quite a while (without a proper controller) and i'm pretty happy with it.
But for more sensitive components like a high precision pressure sensor (MS5611 / MPL3115A2) it didn't end that well.

The convection oven is : Samsung CE100V-W 900W 28L
http://www.samsung.com/nl/consumer/home-appliances/microwaves/archive/CE100V-W/XEN

The 1800W skillet is: Tristar Bakplaat BP-2984
http://www.bol.com/nl/p/tristar-bakplaat-bp-2984/9200000008832310/

I measured using a K-Type thermoucouple and a Olimex MOD-TC (MAX6775) interface board.
Thermocouple used:


These measurement were done full power , the convection oven was set to 220 degrees C. the max it would go to was 190 degrees C. .
My cheap chinese non contact IR temp gun measured max 245 degrees C. on the skillet and 210 degrees C. on the pcb that was in the oven.
So i'm not sure why the thermocouple only measured 180 degrees C. .

[X axis is seconds]
[Model number of convection oven is wrong in the picture]

So... my conclusion is that a convection oven would be great for equal heat distribution and for a fast cool-down because you can drive the fan in the opposite direction.
But you would need a 1200/1400/1600/1800/2000 W convection oven capability to achieve the faster ramp-up required to follow the reflow curve nicely.

[MatCat]

I use a 1500W convection oven and get a fantastic warm-up that is almost as good as recommended profile:

[Spikee]

I use a 1500W convection oven and get a fantastic warm-up that is almost as good as recommended profile:
...

Could you post which model and brand your oven is , that curve looks really good.

[Lurch]

Could you post which model and brand your oven is , that curve looks really good.

https://www.eevblog.com/forum/projects/another-diy-reflow-controller/

[MatCat]

To be very specific: http://www.walmart.com/ip/Black-Decker-Convection-Toaster-Oven/15806194

[Spikee]

My oven was running on only 500W because the top door latch wasn't closed properly.
I have added a arduino reflow controller now and run it at full power 1780W now.

The initial pre-heat does take quite a while (a lot of empty space to warm up 20-150 deg C). But when the preheat is done it follows the reflow curve perfectly.

I'm in the process of building some prototypes now , I will record some footage and post it on my YouTube channel tonight.

Stay tuned ...

[MatCat]

One thing I found in mine was a half bridge of diodes on the top elements to cut them down to 50% power, removing those made a heck of a difference in warm up time!

[thm_w]

How is that thermocouple attached to the skillet? I could see it being a bit lower in temperature due to the large metal mass attached, if not coupled well to the skillet. But would expect more of a linear offset.

Funny, the first google image I see for MS5611 is one thats been melted: http://www.varesano.net/blog/fabio/first-soldering-experiment-ms5611-01ba-huge-fail

[Spikee]

How is that thermocouple attached to the skillet? I could see it being a bit lower in temperature due to the large metal mass attached, if not coupled well to the skillet. But would expect more of a linear offset.

Funny, the first google image I see for MS5611 is one thats been melted: http://www.varesano.net/blog/fabio/first-soldering-experiment-ms5611-01ba-huge-fail

Those mems devices are pretty specific with the heat they will allow.

I just put the thermocouple on the skilled and put some weight on it using a few pcb's. But it isn't perfect as the thermocouple is a bit bulky.... I have ordered a few new ones.
But i must say the Convection oven reflow is going perfectly.

[Spikee]

YouTube video is uploaded:
http://youtu.be/xIuSq8NOSWQ

[Spikee]

The Vacuum pen i use is very good and only costs 26 USD:
http://www.goodluckbuy.com/qs-2008-pick-and-place-vacuum-pen-for-smt-smd-high-low-speed.html

I recorded my reflow curve:


I baked 3 boards today which have smd parts on both sides and it went perfectly.
First applky solderpaste to the bottom layer -> populate it -> reflow -> do top side . I put a old pcb under the it so the components didn't fall off @ 230 deg C.
I just turn the oven on via the serial terminal and look again at it when its done.



(the gray parts are things that i cannot show)

The micro will be soldered on tomorrow when the farnell shipment arrives.
The reverse mounted 2pin header is because i forgot to remove the tenting on the bottom layer. This is the only way to get it on securely.
I cut out the panels using a sheet metal shear as it works good.

[jopiek]

What do you guys think about this oven?

http://www.redcoon.nl/B307440-Tristar-OV-1415_Mini-ovens

Temp max: 250 degrees C
Only 10 liter and then 650 Watt so 65 watts per liter (that is pretty good I think)

It has two RVS heating elements. Not sure about that.