Reflow oven

For my DAB+ project, I had to solder pcb's with SMD-parts. With a good quality solderstation it is possible but with a reflowoven it would be better (in my mind it was...). So how to build your own reflowoven.

This is not exact science since not every oven is the same.

First you need an oven with a lot of power. This power is necessary to allow the temperature in the oven to rise quickly.

I have searched for a 'cheap' oven. So I found this one:

For €20 you have an oven that can reach up to 230°C!!

But, with the first test of this oven,.... It took a while to reach 100°C so to get the themperature of 230°C I think it needed more then 30 minutes. I have not tested that because of another thing: the housing is not insulated! So the housing was becoming very hot itself. So these things are very dangerous.

And I did not had the place to place some extra heaters in it.

I'm using this oven as a dryer when I have cleaned electronics with water.

In search of better oven, a colleague of mine stated that he had oven at home that he had used in his college days. He hadn't used that oven for a long time and was willing to give it to me. Great!

Meanwhile I needed some electronics to control the temperature in the oven. First I was thinking of building my own PID-controller with an Arduino but then I found the X-toaster (www.x-toaster.com).

So I have an oven and a controller, it is time to build the oven. But also with this oven, the time for reaching the desired temperature of 250°C was taking to long, I needed more power in the oven.

Fortunately I am someone who keeps track of a lot of material. Many people sometimes call it rubbish, but it is indeed 'material'. So I went searching in 'my stock' for the next thing, a heating element from a convection oven:

In total I have around 3000W of heating power.

Time to strip the oven.

Remove the back and al the electrical parts (also the heating elements).

In the backpanel I installed an Euroconnector for the main power of the oven.

Remember the problem with the not insulated oven, the cover becomes very hot and it takes a lot of time to heat up the oven. This oven has the same problem, there is no insulation. So I have modified the housing to provide space for insulation.

I have place a aluminium plate in the top of the oven with mineral wool between it.

This I have done also at the back of the oven. So I have modified the sidepanels to fit a back aluminium plate so mineral wool could be placed in the back of the oven.

With these modifications, the original place of the heating elements was not OK anymore, I had to modify the positions of these elements.

In the original oven, two elements where on the botom and two in top part of the oven.

In my configuration, there is the heating element with fan (from a convection oven) on the bottom with one heating element of the original oven.

In the top, I have placed the three other elements of the original oven.

For the I had to modify the panels so the heatingelements would fit in the new position.

On top and bottom of this side panel, you see the original holes for the heating elements. In the middle you see the 4 new holes. Look also on the right of this panel. Here you can see the modification for an extra panel in the back of the oven.

Already 3 heating elements installed.

For that I needed to modify some heating elements in lenght.

I used a pipecutter to shorten the heating element. But handle with care!

Connecting the elements with original wire and insulationcaps.

After installing and connecting the elements, time for more mineral wool:

The extra heating element of the convection oven, that was not easy. First I was thinking of mounting it at the back of the oven (as it is done in a convection oven) but at the end I did placed it on the bottom of the oven.

For that I needed to cut a hole in the botom (and side panel for the contacts of the heating elements). One problem now, you have to raise the oven because the motor is higher the the feet of the oven.

Meanwhile I had received the X-toaster. I have build it into a housing that was in 'my stock'. It is perhaps a little big but than you have lot of space for placing the parts.

I had ordered the X-toaster as compleet package, so with the solidstate relais and heatsink.

The parts of the X-toaster are the panel on the front (left in the picture) and the solidstate relais with heatsink (on the top right of the picture). Above in the middle that is a powersupply for the X-toaster and I have also used a solid state relais (from my stock ;-)) for running the fan.

The power cables I have used are 2, 5mm² cables.

One important thing is the thermocouple. I had ordered the one with metal sealing, but it not usable with the oven. The metal sealing must not come into contact with the metal casing. I have tried this thermocouple, but it was not easy to insulate the complete wire with material that could resist higher tempetures, so I have ordered one with same specification but without a metal shield.

AND FINALY using the oven....

NO, sorry, before you could use the oven, you need to tuning the controller so its parameters have the correct settings for you oven.

And this took some time. I have done multiple testing for finding at last the most suitable settings for my oven. But you find on the website of X-toaster a very good manual. The only thing you have to do is reading it and trying to find the correct settings.

Now I have a realy good working oven AND with the isolation the cover is not heating up so it is save to place it in a 'normal' environment. With the extra isolation and extra power, the rise-time for reaching the solder temperature is acceptably short.

I have tried to make a good video of the use of the oven, but I did not manage. So please look at het X-toaster website where you can find a lot of info about the user interface of the control unit.

However, I have some pictures of the result: