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Reflow oven - searching for a compact device for low volume, small PCBs
Posted by cowana on 24 Oct, 2014 09:28 -
Up to now, I have always assembled PCBs using hot air reflow. However this can be a slow process, and often struggles for large components where the entire package must be reflowed at once (for example a 10mm QFP package).
I am looking to switch to a reflow oven for this. My requirements are very modest:
- Most PCBs around 5x5cm, however some up to 10x10cm
- Usually just one board to be reflowed at once
- I'm looking for a compact machine - say within a 40x40x30cm area (this is not a hard constraint though)
I do like the look of the chinese T962 oven - they are very compact at 30x30x20cm, and the working area suits my requirements well. I'm very aware the quoted 180x230mm working area will suffer from uneven heating - however with the forced air circulation modification and small PCBs in the centre, I don't see this as being an issue.
I have no problems with making and fitting a proper PID controller into chinese machine - in fact this sounds like it would be a good project.
The reviews for the T962 seem to either say it is terrible and does not heat evenly at all - or that with modifications and the fan constantly running it is a capable machine that performs well (although I appriciate it costs more than a toaster oven doing the same job).
The alternative to a T962 oven is a modified toaster oven and seperate controller. While these seem widely available in the US, the very popular models (such as the Black and Decker used by many people) are not available in the UK. I would be very hesitant to buy an untested oven with the hope its thermal performance is good enough - with the T962 I know it will be able to carry out my required heating/cooling rates.
If anyone has a link to a compact toaster oven *available in the uk* that can achieve the required rates, I would be very interested to see it.
Currently I'm biased towards picking the T962. From the outside it looks neat, and would require minimum mechanical modifications to work well. I would replace the controller with my own running a PID system and running the fan (slowly) at all times - this should even out the heating and improve the temperature profiles. Raising the PCB above the metal bed and putting a termocouple against the board being soldered should give the controller proper feedback on the board being soldered.
I look forward to hearing any thoughts on the matter, or if there are any other reflow ovens around this size and price.
Andy -
FWIW, I have done a few lead free boards in a cheapo toaster oven I got from Currys (I'm also in the UK). It was literally the cheapest one they had and works fine for me with no modifications at all. I just set the thermostat to full with all elements on and plug it into an external PID controller I botched up out of an old LPCExpresso dev board and a solid state relay.
The model I used doesn't appear on their website any more but you might be able to find one somewhere, its a LOGIK - L18MOV13 Electric Mini Oven.
(Edit: I paid £24.99 for it) -
My requirements are similar to yours (one board at a time, relativley small boards, etc) and I also used to reflow using hot air. 6 monthes ago I got on ebay a T962 (seller is CHAOCHAO WEI) and am very happy with it. You place the board, select the profile you want (I am using the preset leaded reflow, you can also define your own) and 6~7 minutes later this little marvel beeps and your board is ready. I am happy with the reflow quality and never had a problem with some areas not reflowing.
The one I have is with the window in the front. Not terribly useful but nice to have.
It has a problem with the buttons (they are not debounced very well) but I learn how to handle it and it's not a show stopper.
I recommend it. One alternative is using a hot plate instead. Check iantube (Dangerous Prototypes) on youtube, he had a few episode on this topic. -
People complain a lot about poor heat control with the T-962. However, comments seem much more positive about the similar looking Qinsi QS-5100. The guys at Dangerous Prototypes have a video about this model on YouTube.
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I got a £20 900W oven from Robert Dyas. I've done a successful reflow with a meat-based (i.e. me) PID controller and it seemed to work well. It manages about 2C/s heating up. It looks a lot like this one, but mine is black and I don't think it was branded as Salter.
http://www.robertdyas.co.uk/salter-9l-toaster-oven-black
I was in the middle of a reflow controller project but have decided to back the Zallus one on Kickstarter and get on with something else.
https://www.kickstarter.com/projects/1070729460/zallus-oven-controller -
Cheap? Small? Controllable? Low volume?
Consider using a gas hob, a non-contact thermometer, plus a saucepan with a glass lid and optionally with 2mm of sand on the bottom. The sand buffers and spreads the heat, preventing scorching. Temperature profile is easily variable with a little practice: turn the gas up/down! Non-contact thermometer measures the temperature of the board+components, which is what matters. Glass lid allows monitoring of solder paste.
Somewhat surprisingly, it works well when components are only on one side, and could probably be made to work with components on both sides by suspending the PSB in mid air. I've used it with 100-way SMD connectors with a pitch of 0.8mm, 0603 components, small 0.5mm pitch ICs, 800uH SMD inductors.
Typical search terms: skillet solder pcb smd -
You can reflow with virtually any heat source but to make a lasting quality job of it you really need an oven that is able to provide the right temperature curve for your solder paste. I use one of these http://uk.farnell.com/cif/f31114/reflow-oven-190-x-290mm-230v/dp/1120351 but that might be a bit costly for DIY use.
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I have a JEM-310 convection batch oven that is fantastic. 5 digital zones and a graphic LCD. Well thought out configuration with 2 thermocouples and an insulated window on top which is really great for building a profile because you can watch the whole process. I looked at so many options from DIY to the Chinese IR ovens and none of them were something I wanted to put my prized PCB's into. The JEM-310 is very consistent so I can confidently push the start button and walk away. I have built profiles for various size and type of PCB's both leaded and non-leaded.
Mine is in constant use making prototypes and small batch PCB's. I may be able to dig up a photo somewhere.
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Im still using my home-converted $80 oven with the original Spark Fun Controller.. It works a dream.
The chinese machines are pretty good as well. If you can live with the odd thing going wrong every so often, then its just fine. Maybe not so great if you are using expensive BGA's.. -
Just to update the forum on this topic - after your helpful advice I decided to buy one of the T962 ovens.
I was very impressed by the build quality - while it's certainly not a professional bit of kit, the sheet metal is pretty tick, and it certainly feels well made and quite tough. The electronics inside look slightly questionable (and are covered in hot glue) - I'll certainly consider replacing them some time soon.
The mains connections are all pretty good - live fused, earth crimped to the case (although needed the paint scraping off some more), and all the wires were covered in heat resistant sleeving. Not bad.
I decided to plot the temperature of the reflow 'out the box' - I am planning to make a few modifications and possibly replace the controller entirely at some point. My setup was a thermocouple touching the surface of an unpopulated PCB, supported a few mm off the tray of the oven. This temperature was then plotted every second, as the profile 'Wave 2' was run - this says it is for 63/37 solder (which I use).
The recorded profile is attached. I'm really impressed - I was expecting the machine to be unusable in it's current form, but it seems to match standard reflow requirements for leaded solder, with the timings and temperatures being pretty good. The machine was pulsing the elements (and fan) during all of this, so it could certainly heat up and cool down a lot faster if it needed to.
I'm very happy with the oven, and for the small boards I tend to design, it looks really great. The built in controller is much more usable than I was expecting - I think I'll stick with it for a few boards before I consider replacing it with something more customisable.
Andy
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You can reflow with virtually any heat source but to make a lasting quality job of it you really need an oven that is able to provide the right temperature curve for your solder paste. I use one of these http://uk.farnell.com/cif/f31114/reflow-oven-190-x-290mm-230v/dp/1120351 but that might be a bit costly for DIY use.
Have you seen a tread I started last year about fucking awesome quality of this CIF junk? https://www.eevblog.com/forum/reviews/deadly-insane-design-(cif-ft-02-reflow-oven)-teardown-rant-safety-fix/
If you didn't modify it yet, I highly recommend before it killed you or burned your house. As I got it for only 480 pounds delivered to Latvia from UK, I can live with it. But if somebody bought it for 1720 pounds + VAT, it is just ridiculous junk for that money. Temperature uniformity is crap too. I did partially fix it by installing metal screens to cover hottest places and reflect IR to coldest ones. Temperature profiles and the way how temperature is controlled is a total joke too, maybe will make a new controller in the future If I have a time and desire. -
Just to update the forum on this topic - after your helpful advice I decided to buy one of the T962 ovens.
I was very impressed by the build quality - while it's certainly not a professional bit of kit, the sheet metal is pretty tick, and it certainly feels well made and quite tough. The electronics inside look slightly questionable (and are covered in hot glue) - I'll certainly consider replacing them some time soon.
The mains connections are all pretty good - live fused, earth crimped to the case (although needed the paint scraping off some more), and all the wires were covered in heat resistant sleeving. Not bad.
I decided to plot the temperature of the reflow 'out the box' - I am planning to make a few modifications and possibly replace the controller entirely at some point. My setup was a thermocouple touching the surface of an unpopulated PCB, supported a few mm off the tray of the oven. This temperature was then plotted every second, as the profile 'Wave 2' was run - this says it is for 63/37 solder (which I use).
The recorded profile is attached. I'm really impressed - I was expecting the machine to be unusable in it's current form, but it seems to match standard reflow requirements for leaded solder, with the timings and temperatures being pretty good. The machine was pulsing the elements (and fan) during all of this, so it could certainly heat up and cool down a lot faster if it needed to.
I'm very happy with the oven, and for the small boards I tend to design, it looks really great. The built in controller is much more usable than I was expecting - I think I'll stick with it for a few boards before I consider replacing it with something more customisable.
Andy
Instead of shelling out the money to replace the controller all together you might have a look at the following project
https://github.com/UnifiedEngineering/T-962-improvements -
Hi eevblog foruma's,
Sorry to revive this old thread, but I have very similar requirements the OP and don't really want to build my own reflow oven, which is probably the best option. So am looking at all the usual suspects on ebay etc. I like the price of the T-962, but don't like the reviews.People complain a lot about poor heat control with the T-962. However, comments seem much more positive about the similar looking Qinsi QS-5100. The guys at Dangerous Prototypes have a video about this model on YouTube.
I agree that the QS-5100 looks much better, does anyone know anything about the Qinsi QS-5182? As I have found this one that I'm interested in and thinking about buying http://www.ebay.com.au/itm/Qinsi-QS-5182-Soldering-IR-Reflow-Oven-240V-220V-Excellent-Condition-/161819401552?hash=item25ad301d50 -
I bought the biggest and baddest $200.00 convention air toaster oven I could find to make my first oven.
Then for about twice the price, I bought a T962A. A real reflow oven has a drawer that slides (very smoothly) all the way out to load. A toaster oven, you drop the door then slide out a rinky tray that only opens halfway. The T862A is a lot more compact than the toaster oven it replaced, yet it effectively handles deeper panels. Up to about 9" x 9".
I don't assemble boards for a living or anything. But even for fairly light to moderate use, I think it's well worth it over a toaster oven. If for the time involved, you ended up with a better or equivalent product, then it might be worth it to mess with a toaster oven. Everyones' time-cost and abilities are different. But there's no way I could make the break-even point on that.
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I don't assemble boards for a living or anything. But even for fairly light to moderate use, I think it's well worth it over a toaster oven. If for the time involved, you ended up with a better or equivalent product, then it might be worth it to mess with a toaster oven. Everyones' time-cost and abilities are different. But there's no way I could make the break-even point on that.
I totally agree, which is why I'm keen to know if anyone has experience with or opinions on the Qinsi QS-5182 http://www.ebay.com.au/itm/Qinsi-QS-5182-Soldering-IR-Reflow-Oven-240V-220V-Excellent-Condition-/161819401552?hash=item25ad301d50
There is barely anything to be found on the web about this oven, but it's sister the QS-5100 gets some pretty good reviews. -
Just to add an update on this (as the starter of this thread) - as I was feeling, I went with a T962 oven.
Straight off, I wasn't that impressed with the built in controller - the fan doesn't run during reflow (so the air is still and subject to hot/cold spots), the control is very primitive (bang/bang control of the heater leading to a poor ramp rate), and the timer is way off (by 20% or so).
I built up a little controller board with an AVR and a few thermocouple amps - this plugs into the original graphical LCD and buttons. It then gives a much more accurate profile (using proper PID), and runs the fan at a very low rpm during heating, so the air is moved around the oven. For the small number of boards I do (maybe 20 in the past year), it's been excellent - I just paste up the board, put on the components, then stick it in the oven and hit 'go'.
With any of these ovens it's worth putting the board on top of a few spare PCBs to raise it above the large metal shelf (which may act as a slight heatsink) - but other than that, with the exception of the included software, it's an excellent oven.
Andy -
I have to say, the T962A looks sexy. I think a year ago I was looking at buying it's original brother, and read bad reviews about it. Plus, me being new to SMD reflow, I decided to spend a little to get my feet wet before I commit to these chinese units.
For $50, I got this 1500Watt convection toaster oven. Pretty big, deep and wide, with 4 heating elements in it and internal fan to circulate the heat evenly.
The front door with glass opens almost flat, and I can slide out the tray fully. Actually, I'm laying down my PCB on the included pan, and then sliding the pan on top of the rack. The pan makes complete flat contact with the PCB, avoids hot spots/lines as the pan will give a more even heating of the PCB (as oppose to the wire rack frame).
I put my tray on the middle rack, so it's approximately the same distance from the top and bottom heating elements. Plus with the fan continuously running, hot spots aren't an issue for this oven.