recommendations for prototyping Reflow Oven

[Electrons]

Hi ,
I am in the market for a reflow oven , my main application is for prototyping maximum of 20-50 pcb per month . I mostly solder by hand but now i am working with IMS (aluminum board) and would like to buy an appropriate oven . I am willing to spend 1500$-3000$ max. Used is out of question , So only interested in New 230v units (single or 3 phase). Mainly I use Leaded Solder. I am not a PCb assembler shop So i am not an expert on running ovens and fix profiles etc.. so i prefer if something works out of the box.

After reading on this forum I found that I have 3 choices:

1. Benchtop convection oven (T937M is best of Chinese products) and Affordable. European versions are upward of 3000$. people say all benchtop ovens suck in-terms of heat and conveyer are better.
2. Conveyer conversion ovens (T961 or T980) affordable but many people hate them especially new version where LCD is on the Top of the oven. IN6 also has negative reviews. European versions are very expensive. Also as I read they donot work out of the box and they need testing and dialing. maybe the negatives are for huge quantities but Ok for prototyping ??
3. Vapor Phase oven , mixed opinions , no china version , only European which is nice and within budget (ex:
Vaporflow 480) and sounds better as it avoids Solder voids which is very concerning for power devices on IMS.  Some says its not worth it and its only hype. instead buy reflow oven with nitrogen (like torch T200N+).

Could you please help me decide which will better suit me ?

[jmelson]

I am doing stuff in this volume range with a modified toaster oven, and a thermocouple temperature controller.  I poke a micro-thermocouple into a plated through hole in the board, and the controller's solid state relay controls the heating elements.  I have done well over 2000 boards with this system so far, and it has worked very well!
The controller I use has the ramp and soak feature, meaning you can program temperature ramps and holds to match the temperature profile.
The big, fancy 3-phase ovens are needed for much higher volume work, like hundreds of boards/day.
Jon

[Rat_Patrol]

I've been using a fleet of Controleo converted toaster ovens for years now, and they work extremely well. So well, every time I look at a conveyor oven, I turn my nose to them. I may be forced to though, as my next project will be 500mm long boards..

Anyway, big endorsement for a Controleo converted toaster oven (either DIY or they have units ready to go for sale).

[Jackster]

I have heard good things about the T961/T960 and was going to pick one up myself for the smaller jobs that come in to my factory.

[Doctorandus_P]

The LCD location on the T961 looks like a really stupid design.

https://duckduckgo.com/?q=T961+smt+oven&iar=images&iax=images&ia=images

Best I know a modified toaster oven does apparently work quite well for a lot of people (Have not build one myself yet). I guess this may be a decent option for you if you do a few PCB's each day. If you run bigger batches (25 boards in a row, every 2 weeks) then the conveyor type does seem more attractive.

[DLE]

50 pcbs a month.  I'd get a small toaster oven.  Smallest volume to fit your PCBs but with the max wattage.  You want fast temperature climb, don't buy a big tall oven to "future proof" yourself.  It won't work as well.

My method used to be turn the oven on max, have a thermocouple on the board, wait till it hit 130C.  turn oven off.  Let temp soak for about 60-90s, just before the temp starts to fall turn the oven back on again.  Let it climb up to 230C.  Turn oven off, open door, set CPU case cooler fan on the oven door to blow air into the oven. 

You can get a controller and whatnot but this method built a few thousand boards without issue. 

[Hanward]

In China there is a very small reflow oven, 2 meters length.But price is a little bite higher,around $3000.

[Electrons]

thank you very much for sharing your experience .

I am surprised that toaster oven is being recommended over puhui benchtop (T937m) oven which is specific for PCBs and both I think work on convection. and the is cost is also higher (380 for Controleo3 kit and 1200$ for ready to run oven) does it really perform better ?

@jmelson : what is the controller that allows you to use external thermocouple on the board directly , you are using is it Controleo3 ?

@Hanward : what is name or specifications about this oven you are talking about ?

anyone tried vapor phase or care to comment if it really makes in difference ?

[Pinkus]

My advise: forget the toaster oven.
The soldering quality of such an toaster oven can be fine. Thus it's OK for single, individual prototypes once a week, but if you do more and if you work in the same room you should know: it will stink up the whole place with its extremely unhealthy exhaust fumes that will appear during the reflow process.
The T937 has two fans on the outside: one for blowing in cold air, one for sucking out the hot air. You should then attach the supplied pipe to the exhaust opening and lead it to the outside: no dangerous fume inside you room.  Thus if you care about your health, get an oven with an exhaust pipe. Though if you are smoking a pack of cigarettes a day, just ignore the above - it does not matter 

[48X24X48X]

I owned both the T937M and also the RF-A250 (or ZB2520HL). The Zhengbang unit built quality is very much better than the Puhui's. The Puhui unit is very flimsy. The infra red tube in the oven has a metal cage around it that reduces the direct heat which is missing on the T937M. So, if you are reflowing plastic parts like JST connectors, they melt like candies in the T937M but will be okay in the ZB2520HL with some tweaks on the profile.
But, what I like more on the T937M is the way they implemented the profile which follows your profile very much closer with the climb rate accordingly.
The ZB2520HL on the other hand, is just a ramp-soak-ramp PID controller, so it stays at a temperature set point for some time before moving on to the next setpoint.
However, both units effective area for lead free is much smaller than the physical size available. So, size up to the next higher power unit if you think you need to reflow larger PCB.
The T937M is very hard to service and if you need to replace the tube, you basically have to tear down the entire unit (unlike the smaller and simpler T962).
But, I still think a hacked toaster oven have a much better solder quality albeit the size can be a limitation. Too big toaster oven just won't work.

[Pinkus]

So, if you are reflowing plastic parts like JST connectors, they melt like candies in the T937M ...

Well, i often use JST connectors and I do have a T937M. I never had a JST connector melting. Sometimes they get a bit discolored, but they never melt. See a recent prototype attached: the upper left JST connectors are a kind of getting dark because of the heat but ... no melting.
I guess it is all about the correct profile which sometimes need to be dialed in - as with every soldering oven. After a while some know what profile would probably be the best one.
Edit: note there is a T937M and a T937 on the market. The latter is smaller. It might make a difference regarding the heat distribution etc.

[Rat_Patrol]

thank you very much for sharing your experience .

I am surprised that toaster oven is being recommended over puhui benchtop (T937m) oven which is specific for PCBs and both I think work on convection. and the is cost is also higher (380 for Controleo3 kit and 1200$ for ready to run oven) does it really perform better ?

The cost difference is just the labor, and probably the "I'd rather not do this" price. They take a bit of work (figure a full working day) to convert a toaster oven to reflow oven.

As for the fumes, I have mine under a fume hood with exhaust fan, so no smell from the reflow process.

[jmelson]

@jmelson : what is the controller that allows you to use external thermocouple on the board directly , you are using is it Controleo3 ?

It is an Omega CN4801-F1-AL2-RAMP, which usually costs about $600, but I got it on eBay for a song.  The model I have has an analog output, which I didn't need, but it works fine with a solid state relay.  I got a roll of type E micro-thermocouple wire, and had to reset the calibration of the controller for that junction type.
Jon

[48X24X48X]

So, if you are reflowing plastic parts like JST connectors, they melt like candies in the T937M ...

Well, i often use JST connectors and I do have a T937M. I never had a JST connector melting. Sometimes they get a bit discolored, but they never melt. See a recent prototype attached: the upper left JST connectors are a kind of getting dark because of the heat but ... no melting.
I guess it is all about the correct profile which sometimes need to be dialed in - as with every soldering oven. After a while some know what profile would probably be the best one.
Edit: note there is a T937M and a T937 on the market. The latter is smaller. It might make a difference regarding the heat distribution etc.

Discolored or melt, for me it's a big no to ship these out to clients. It should look like before it went into the oven.

[Electrons]

So I ordered a RF-A350 Oven . seems that this is the best bang for buck .

but I will try to build a vapor phase relfow machine since it seems like the concept is simple but the machines are overpriced wonder why Chinese companies have not created cheap copies like they made with reflow ovens. There is  Vapor phase One which is opensource so might be helpful and I have a weller WHP1000 that Could use to heat the Galden .

[Mechatrommer]

But price is a little bite higher,around $3000.

huh! i reflow with my $100 kitchen oven. dial a little bit higher than paste's melting temperature for 15 minutes and its done. i know there are oven diy modification to match factory profile but i guess its only for proper vaporize water out of pcb and components and avoid too much thermal stress. so i guess underpowered (small) oven is better at this. ymmv.