SMD reflow ovens - Page 1
Forum section: electronics / general

author: RCMR
author_rank: Frequent Contributor
timestamp: November 06, 2012, 04:01:55 am
content: Has anyone got anything to say about these cheap reflow ovens that proliferate on eBay?http://www.ebay.com/itm/T962A-INFRARED-IC-HEATER-REFLOW-OVEN-300X320MM-BGA-SMD-300-x-320mm-/300793665249?pt=LH_DefaultDomain_0&hash=item4608b316e1To date, all my SMD stuff has been soldered by hand but I think it's time I invested in some gear to do the job properly.Pro's and Con's on the cheap eBay ones or pointers to something else would be welcomed.

author: JuKu
author_rank: Frequent Contributor
timestamp: November 06, 2012, 08:40:52 am
content: My experiences:http://dangerousprototypes.com/forum/viewtopic.php?f=2&t=4471

author: Short Circuit
author_rank: Frequent Contributor
timestamp: November 06, 2012, 12:27:10 pm
content: Quote from: Short Circuit on October 02, 2012, 01:17:02 am

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 06, 2012, 01:54:57 pm
content: Just get a cheap toaster oven with a good window and do it by eye.If you're doing a range of random boards, any automatic control is going to be wrong for some of them.Make sure it has elements top and bottom, and run them just below visible glowing to reduce variation due to different IR absorbtion. Use a triac controller (e.g. stage light dimmer) or variac.And obviously avoid leadfree solder.

author: andyturk
author_rank: Frequent Contributor
timestamp: November 06, 2012, 02:52:41 pm
content: I've had good results using a $3 skillet (and a stove). As long as you can apply sufficient heat to melt the solder and ramp it slowly, you can do SMT very cheaply. The biggest problem in my builds has been over-doing the solder and bridging fine pitch pins. It cleans up easily with solder wick and an iron though.What I'd like to find is an inexpensive pcb board heater (e.g.,this), which would be useful for both assembly and rework.

author: ToBeFrank
author_rank: Regular Contributor
timestamp: November 06, 2012, 04:40:45 pm
content: I use this oven:http://www.overstock.com/Home-Garden/Black-Decker-FC150R-Infrawave-Speed-Oven/4260151/product.htmlAnd one of these:eBay auction: #350384161137I use the pid controller to control the max temp as the oven can get way hotter than needed. I didn't know any better at first and bought lead free solder paste. In 50 or so boards I only had 1 cold joint and the rest turned out great. Now that I have leaded solder paste it's even easier.

author: free_electron
author_rank: Super Contributor
timestamp: November 06, 2012, 05:53:02 pm
content: infrared is crap. a black object collects heat faster than a white object. this leads to temperature difference. you fry the tqfp before the filmcaps melt ...hot air is the way to go. get a convection oven.

author: ToBeFrank
author_rank: Regular Contributor
timestamp: November 06, 2012, 07:07:14 pm
content: Quote from: free_electron on November 06, 2012, 05:53:02 pmAnd yet, it works great on my boards that have both those parts.

author: mazurov
author_rank: Frequent Contributor
timestamp: November 06, 2012, 08:19:02 pm
content: What is wrong with lead-free solder paste? I'm through the second kilo and the only issue is that (made for) US electrical skillets won't melt it without tweaking the bi-metallic temperature control thingie.

author: JuKu
author_rank: Frequent Contributor
timestamp: November 07, 2012, 05:57:27 am
content: Quote from: mazurov on November 06, 2012, 08:19:02 pmIn theory, nothing*. Leaded paste melts easier, so the process is easier to control in a hobby environment and the point where components start to suffer is significantly closer. If your process is good, there is no difference, just different parameters. In theory.*: The difference of theory and practice? In theory, nothing.

author: EEVblog
author_rank: Unknown
timestamp: November 07, 2012, 06:33:26 am
content: There has been discussion of these in another thread I think.General consensus is that they are pretty ordinary and not good value.A fan forced convection oven does a much better job than IR. I think even a manual one would do the job nicely, no need for an automated controller unless you get serious.Dave.

author: JuKu
author_rank: Frequent Contributor
timestamp: November 07, 2012, 07:42:59 am
content: Quote from: EEVblog on November 07, 2012, 06:33:26 amOr your eyesight is poor enough that you don't really see the reflow happening inside the oven...or your attention span is shorter than the oven warmup...or you want the peace of mind from knowing exactly what is going on in the process... Easily worth the 129€ I paid for the controller for me, YMMV.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 07, 2012, 08:46:48 am
content: Quote from: mazurov on November 06, 2012, 08:19:02 pmWith leadfree you have a much smaller margin between "reflow" and "incinerate", and with a cheap oven, you want plenty of margin.Even with professional ovens, they sometimes use a nitrogen atmosphere to reduce oxidisation at lead-free reflow temps.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 07, 2012, 08:51:42 am
content: Quote from: ToBeFrank on November 06, 2012, 07:07:14 pmA convection oven may well be better - I've not tried one, but as long as you keep the elements below glowing temps, the heating is going to be primarily by convection, and it works fine - I've done many hundreds of boards with no problems.I'd certainly agree that using an IR oven with no power control could well cause scorching issues.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: November 07, 2012, 03:09:37 pm
content: As far as leadfree goes , do not forget to mention whiskers -file://localhost/Users/johnfaughn/Downloads/tin%20wiskers%20,%202010-Panashchenko-IPC-Tin-Whisker.pdfAs far as ovens , I do one off repairs , and look to pre-heat not to melting temp , and when all is good , use hotair-gun for finish - for install & removal .I can understand doing all in oven , it seems there are reasons for almost all soldering techniques , each having there place .Have not built yet , but like the idea of the toaster oven with home-brew controller .If I had more money & less time I really like getting the best tool for the job , but it seems that you need production to pay for the good stuff , or do reviews ==== nice gig if you can get it .Thanks Dave

author: nukie
author_rank: Frequent Contributor
timestamp: November 09, 2012, 01:59:05 am
content: Tin whisker was a problem before ROHS come in to play. Though not 100%, it can be prevented by applying very thick conformal coating. However, conformal coating is not suitable for electrical connectors(plugs & sockets) where tin whiskers usually forms.tapatalk

author: reagle
author_rank: Unknown
timestamp: November 09, 2012, 12:36:34 pm
content: Quote from: ToBeFrank on November 06, 2012, 04:40:45 pmSo the controller you use does not do ramp up, just max temp? It's not always clear from seller's description

author: ToBeFrank
author_rank: Regular Contributor
timestamp: November 11, 2012, 03:38:01 pm
content: Quote from: reagle on November 09, 2012, 12:36:34 pmI don't think so. With the above setup, these steps haven't failed me yet: put board in oven and close door, plug in, when the temp hits the max as set in the pid controller, wait for 30-60 seconds (depending on what is on the board). Unplug and open the oven door until it cools down. Note that it takes a couple minutes to hit the max temp so that acts as a ramp up.

author: americanhacker1
author_rank: Newbie
timestamp: March 30, 2013, 05:31:27 am
content: try this

author: c4757p
author_rank: Super Contributor
timestamp: March 30, 2013, 05:51:13 am
content: @americanhacker1, an Arduino with custom software? No thanks. Don't want to waste time with that. For my reflow oven, I took a cheap-ass toaster oven, threw on a cheap-ass PID controller with a (non-cheap-ass) SSR and a thermocouple I had lying around. Didn't have to write a line of code or debug a damn thing.And I really, really disagree with the infrared thing. Somebody mentioned above that differently colored items absorb heat differently with infrared, and I agree, I do not like that. Sure, it might "work" usually, but I don't like the idea of having hot spots when the overall temperature is already so high. I specifically put aluminum foil shields between the heating elements and the reflow plane so the heating would be entirely by convection.

author: Dreso12
author_rank: Contributor
timestamp: May 19, 2013, 02:43:33 pm
content: I have been using a domestic reflow oven for soldering for some time. At the beginning it is quite difficult as the set up is not simple, to get the correct temperature ramps and regulation takes time and many tests. Also dispensing the right quantity of solder paste is the pads with a syringe is not easy but with some practice and a good controller you can get really nice results.Check out the video, this is a similar setup to the one I use and it can be useful to build your own system:

author: neslekkim
author_rank: Super Contributor
timestamp: May 20, 2013, 12:41:00 pm
content: this have been discussed here also:http://dangerousprototypes.com/forum/viewtopic.php?f=68&t=5193and someone made an new controller for it:http://www.estechnical.co.uk/products/reflow-controllers/t962a-reflow-oven-controller-upgradeI thought it should be possible to modify the existing controller but..

author: Selectech
author_rank: Regular Contributor
timestamp: May 20, 2013, 01:29:05 pm
content: I use a modified convection oven + PID controller.A few years ago I got one of these { like this, but not from this source }http://elexp.com/sdr_fbud.htmThe PID controller is what I have but the oven might be slightly different. My "oven" is a modified GE that probably came from Walmart before modification. The PID controller has a thermocouple lead that is place in contact with a PCB surface.I've been pretty satisfied with it after several thousand boards. The internal fan stays on all the time to circulate the air and the extra insulation helps making the effective reflow area larger. The sides and front still run a bit cooler but after a few runs & a bit of profiling with some extra thermocouple sensors I learned what it was good at & where to place items and the thermocouple sensor lead on PCB. Typically takes about 3 minutes to run a cycle. Every once in a while I run a profile to see if it's staying close to the desired profile .Only expected it to last for a couple of years, but it's on it's 7th now. I have to work on the circulating fan a once or twice a year as it gets gummed up from flux off-gassing, but that's just routine maintenance.I mostly use Kester R-276 paste { leaded no-clean } from an CNC dispensing system I made myself but have run some unleaded for a few projects.

author: Corporate666
author_rank: Unknown
timestamp: May 20, 2013, 07:54:37 pm
content: Some years ago I scored a 480 volt 12 zone 1-year old reflow oven from a local company. For free. They were a huge local company and they had another company in Germany making their boards - but they bought a complete copy of the production for their R&D headquarters in the USA to verify processes before outsourcing. When I got it, it had maybe 12 hours of use. I also got the original invoice, for over $400,000USD.I have 3-phase power at work, but not 480 volt, so this super nice reflow oven just sat there unused. In the meantime, I saw something online where a guy tested lots of toaster ovens, and a DeLonghi brand model-whatever had a heating profile that was very close to a reflow oven. I bought a few of them.Well, 8 years later and they work so well that we never even considered "upgrading" to a real reflow oven. Nor do I have any sort of PID control or reflow controller on these ovens. They are non-IR convection ovens. Just set them to bake at max temp, set the timer and that's it.We've reflowed maybe 50,000 boards through these things. The only problem was when one caught fire when someone turned it to "on" instead of timed and went to hang out with her boyfriend and the board caught fire (!!). She's no longer with us (the oven or the employee!) and we've had no more problems reflowing.

author: amiq
author_rank: Regular Contributor
timestamp: May 21, 2013, 02:57:51 am
content: Quote from: Corporate666 on May 20, 2013, 07:54:37 pmCould you provide some more details - model number or pics etc.?

author: Corporate666
author_rank: Unknown
timestamp: May 21, 2013, 03:44:51 am
content: Quote from: amiq on May 21, 2013, 02:57:51 amI checked my records... looks like I bought several of them back in early 2007. DeLonghi Airstream AS690 Convection Toaster Oven.Looks like it's out of production now. I don't remember where I found the review - I just remember it was a website of a guy who had a pretty disheveled workbench that looked to be in his garage. But he had tested lots of different toaster ovens and found this one had the closest heating profile to a "real" profile of a PCB oven.We must have run tens of thousands of boards through this... never a problem.I have tried a few others and my experience was that firstly you don't want IR, and secondly you need a relatively powerful oven. Some of them struggle to get up to a sufficient temperature to melt solder (leaded solder in my case - lead free would be worse). You also very much want a convection oven.

author: amiq
author_rank: Regular Contributor
timestamp: May 21, 2013, 11:08:04 pm
content: Thanks for that. I don't think these Airstream ovens were ever marketed in the UK, which is a shame since they do look as if they are ideal for reflow work. I'll have to have a poke around the white goods retailers to see if there is anything similar on the market at the moment.

author: Corporate666
author_rank: Unknown
timestamp: May 22, 2013, 04:42:20 am
content: Quote from: amiq on May 21, 2013, 11:08:04 pmOver the years, I've tried lots of toaster ovens that I've gotten at various home centers. I've never had a problem with any of them (in terms of board failures). The only traits I have noticed are important are high power (or perhaps good insulation - it needs to be able to get to reflow temperature... some of them I've tried take seemingly forever to reach reflow temp, either due to being underpowered or not being well insulated and the heat escaping before temps rise enough). The other important factor is convection.An internal light is very nice to have, if available.I think if you get any powerful unit with convection, it will work fine. It's really not very critical at all as long as you keep an eye on the solder to catch when it reflows, then maybe 10-20 seconds more, turn off the power and open the door. That's my process - works great.