Reflow Oven or IR Preheater

[luky315]

I need to solder a few small to mid-sized PCBs (<100x160mm) with lead-free solder and quite expensive analog ICs on it. At the moment I'm using a modified pizza oven but the controller is unstable and the temperature profile is not as it should be. The heating is to slow and the cooling down is problematic (opening the door etc).
With a budget arround 1000€ (so everything it should be availabe in europe ;-) ) what would be the better option?
Getting a T-962A with the usual modifications? There is also the "new" T-962A+ model, but not much informations about possible or necessary modifications of this model.
The T-937 seems to have the worst possible software, so this is not really an option, or has this improved?
Or would it be an option to get a decent IR preheater (which one?) in combination with some hot air from above to solder the PCBs?

[meshtron]

I've got a T937 and have successfully created and run my own reflow profiles.

Your description of "the worst possible software" isn't far off the mark.    That said, I've got the software (downloaded from where another user here posted it) and it's a bit wonky, but functional. And, once you've built your profile and uploaded it to the oven, you don't need the software anymore until you're making new profiles.  I'd be happy to not only share the files you need but add a few pointers on how to get from zero to the profile you want as well.  I'm far from an expert, but the steepest early part of the learning curve is still vividly etched in my brain!

And, for me, getting the reflow profile set to match the recommended profile for the (GC10) paste I was using made a big difference in getting good boards out of the oven consistently.

I'm also on the Unexpected Maker Discord, and there are quite a few folks there having (apparently) good success with his Reflow Master Pro controller attached to various types of toaster ovens.  But, for me, the "active cooling" part of a "real" oven was important for consistent cycling, etc.  And, I wanted my oven to just work, not be a(nother) project.

[MR]

I would rather get a small toaster oven and some PID controller for it than one of those chinese reflow ovens.

The reason behind that is that the toaster oven usually will have a heating module below the PCB.
That said I also have a 4k reflow oven for prototypes but I still prefer my 8-9L PID controlled toaster oven which cost a fraction of the professional one (but the professional one was just unpack it and it worked out of the box, while the 8-9L toaster oven needed some sourcing and assembly).
Also 8-9L is suitable for many smaller PCBs and won't require as much energy as a bigger one, you can easily get away even with a 700W toaster oven, 1000W can be considered upper class for small (again 8-9L) toaster ovens.

The chinese cash register reflow ovens do not have any bottom heating, they purely rely on transferring the heat from the top to the bottom, if you have big masses on your PCB that might turn out to a problem.

I had a chinese cash register reflow oven that worked to some extent but I dumped it relatively quick because it was also very sensitive to the ambient temperature. Any other oven worked better for me than those chinese reflow ovens.

I'm using PB-free solder only.

[wrickert]

A replacement controller would be my first thought. Keep your modified pizza oven but go further with your own controller.
I built a very simple one for my first reflow oven. This is the code I used https://github.com/wrickert/ReflowOvenController. All it takes is an ESP32 and a couple adafruit boards.
It is not the safest route but I'm also not sure how much I would trust the code on Chinese reflow ovens either and at least this way you get to see the code thats running.

[asmi]

If you want to go for an off-the-shelf solution, I highly recommend taking a look at ZB25xxHL family of reflow ovens. They are the best in their price range, work well out of box with no tinkering required. I've got a ZB2520HL oven and I'm very happy with it, it does what I needed it to do, had no problems reflowing anything from super-tiny 0.6x0.2 mm ESD diodes to large-ish 27x27 mm 676 ball BGAs, large SMT connectors like ERM-5 and ERM-8, or SODIMM connectors.

[luky315]

I heard from the ZB25 reflow ovens, but I havent found much informations on the "western" internet about them. Is the software usable? Is it even available in english?

[asmi]

I heard from the ZB25 reflow ovens, but I havent found much informations on the "western" internet about them. Is the software usable? Is it even available in english?

There were a bunch of threads about them here just recently. Software (I assume you mean PC software) is available and usable, but you don't really need it as everything you can do through software you can do using controls on the oven itself.

[MR]

You really not only need to have luck with IR heating ovens but also good thermal sensors inside.

Take care that the IR modules are a bit shielded otherwise they might damage the PCBs.

I still prefer resistive heating modules over IR modules because resistive heating modules are more predictable and K-type probes will also work better/more reliable with them.

When using K-type probes with IR ovens I'm 99% sure that the temperature readout is off (ranging from several 10s of degrees to 100s of degrees). That is my experience with unshielded IR modules. Also some elements are heated up differently than other ones.
K-type probes are good for measuring the ambient temperature. For IR probably something else would be better.

I have had cases eg. unsoldered shielded large inductors vs burned small inductors reflowed with IR heating modules on one and the same PCB. This can possibly be avoided by shielding the IR modules (or using resistive heating modules which I prefer)

[law]

Hiya, Do you know of any examples of ovens (modified or new) with the resistive modules you speak of?
I'm wrestling with a batch oven that has IR elements (and a convection fan) and components melting. So far I've made an aluminium shield from an upside down BBQ tray. I cut the sides out of the tray, but left the top covered.
This has effectively turned the IR/convection oven into a convection only oven. It's kind of working ok..

[MR]

A local company nearby can make customized resistive heating modules, and they're not even expensive like 10-15$ per module (for my 8-9L oven). Lead time was 1 week. I put in 3 modules into mine.
If you can give me the size & photos of your modules I can ask for resistive replacements for them. They're rather light and made of stainless steel, magnesium oxide and some heating wire inside.

[sinned6915]

If you can give me the size & photos of your modules I can ask for resistive replacements for them. They're rather light and made of stainless steel, magnesium oxide and some heating wire inside.

I am curious about these elements too.
This video shows some pretty good shots of the inside of the 962A unit.


If we are paying to have custom elements made, it stands to reason to make them flat plates instead of cylinders for the reasons the video explains.

Thoughts?  Comments?

Where generally speaking is said fabricator for idea on shipping etc...

thanks

sinneD

[MR]

Why easy if you can do it complicated too ;-)
Those are all IR heating modules, the problem is that it takes more effort to measure the real temperature of the PCB than just put a k-type temperature probe there.
And there's a difference between small and large PCBs.

The price of resistive heating modules isn't expensive at all, because there's not much technology behind that either (IR modules aren't expensive either of course).

[Doctorandus_P]

I would much rather have an old toaster oven then a new T-962A.

You can buy some spare heating tubes to upgrade the power of your oven, combine it with a better temperature measurement and PID controller (there are plenty of projects around). For cooling, you can either add a servo to open the door, or make something with a fan that blows  in a controlled amount of cold air, but be careful so hot air can't leak out the oven and reach the fan.

One reason I prefer a toaster oven above a T-962 is the glass front so you can see what is happening. Once everything is tuned in this is not very important, but during setting things up this is a useful addition. It also helps if you have parts you are not sure are capable of withstanding the soldering heat (such as some plastic connectors).

But mostly, the Idea of buying a soldering oven and having to modify it before it even works somewhat as it is intended just offends me, while tinkering with a toaster oven to make it do something it was never made for is kinda fun, and if it's done properly, you can make a good working soldering oven out of it.

Modifying a toaster oven is also appealing because there simply are not many good complete solutions for an affordable price.

[jmelson]

I use a GE toaster oven I got at WalMart about 16 years ago.  I got a ramp and soak temperature controller and connected it to a solid state relay wire in series with the internal thermostat.  I poke a TINY thermocouple wire into a through hole in the board to measure actual temperature.  I have done over 2000 boards this way.  The ramp and soak controller allows you to program the ramp-hold-ramp-and ramp down profile all as one cycle. 

This oven has two horizontal heating elements on top and two below the rack.  I don't think an oven with just two elements would work as well.  I bent some 1/8" stainless rod to act as a spacer to hold the boards up off the rack.  I can put 6-8 small boards in the oven for one cycle, but fewer if the boards are bigger.  I always use lead-free solder.  My favorite now is GC10.
Jon

[law]

> But mostly, the Idea of buying a soldering oven and having to modify it before it even works somewhat as it is intended just offends me
Haha! I bought my oven used. The manufacturer claims that it was a lead free oven, and it will actually reflow my lead free boards pretty well, it just melts my connectors.
I dont think I could have known this before I bought it, short of taking all my parts to the seller and testing it out. But it was $500, so I took a chance.
I'm in a pretty committed relationship with my connectors, so it will be the oven that has to change.
I've already changed the oven controller to a Controleo3. The factory controller was horrific.

My oven has 6 elements:
Metal end to end length = 405mm
Metal can dia = 15.7mm
Glass dia = 12mm

Thanks,
Laurence

[Pinkus]

Some connectors (especially if taller or with some large open space such as RJ45 connectors) are pretty sensitive. As the heating elements are just approx. 40mm away, a connector with 10mm height will have problems. It helps, to add (wrap) some aluminium foils to the top of the connector. It can be done quickly and removes any hassle with melted connector housings.

[law]

Hey, I've seen some other posts where people are wrapping the connectors in a shield. Its not so practical for me - My boards have anywhere up to 12-13 connectors on them.
I'll probably stick with the large shield approach until I sort something better out.
Thanks

[coppercone2]

get a punch to make little aluminum disks you can put over connectors. or a perforated shield. its layout planning work but it might just make your project viable  i feel like this might be the japanese solution that requires some 'paperwork'