300°C T-960 or 350°C T-960W reflow oven? - Page 1
Forum section: electronics / general

author: sorteper
author_rank: Newbie
timestamp: November 21, 2019, 10:58:42 pm
content: As a content owner of another Aliexpress-grade piece of manufacturing equipment, namely the Wenzhou Yingxing SMT460 pick and place machine, I'm ready to extend my in house capabilities with one of the T-960 conveyor belt reflow ovens.My question is for those who are experienced with the T-960-type ovens. Is the 300C upper limit of the T-960 enough to do lead-free soldering in your experience? Or would I be much better off with the slightly more expensive 350C version (T-960W) for my boards? I use SAC305-type solder paste btw. (eg. GC-10).My boards are typically 150mm by 150mm and use low mass components, with small to medium sized qfp's and small to medium package size electrolytics being the largest ones. I wouldn't call my boards extremely densely populated either.I make 25-150 boards per week and prefer to do my boards in house, since I have many years of experience on the floor at an EMS company and... because I simply still... erhm... enjoy that part of the process.

author: sorteper
author_rank: Newbie
timestamp: November 21, 2019, 10:59:14 pm
content: PS. Hi Eevblog forum. Thank you for existing!

author: Styno
author_rank: Regular Contributor
timestamp: November 22, 2019, 10:06:13 pm
content: I’m not familiar with these ovens (using a batch vapour phase) but, since you mentioned it, can you tell us a bit about your experiences wit the YX SMT460 please (perhaps in another thread)? I think many here would appreciate it.

author: wraper
author_rank: Unknown
timestamp: November 22, 2019, 10:17:47 pm
content: Temperature must never exceed 260oC for normal components and solder and better be kept below 245oC. It's not a hot air station where you blow hotter air on one side of the board.

author: SMTech
author_rank: Frequent Contributor
timestamp: November 22, 2019, 11:03:53 pm
content: It really depends what the temperature sensors are reading. Most forced air reflow ovens that are sold as Lead-Free compatible are capable of 350C but you wouldn't be likely need to set the heat of the air being blown that high for anything but the most challenging of boards. 350C is after all the temp of the air not the board passing through, a decent oven will have a sufficient thermal output that the peak temps are quite low but you're still likely to see 250C in the reflow zone to get ~235-245C on the PCB.On an IR oven that sensor could be the temp of the IR Lamps or something close to it or it could be a reading from some random point in the chamber. I haven't seen or used the oven in question but I have used a similarly sized UK made oven from Mekko. To achieve something approaching a decent profile (~3.5mins IIRC) with leaded paste did in fact require a peak reflow zone temp over 300C, in that oven the thermocouples are mounted directly on top of the IR heaters. Lead-free required a very similar setup and a slower belt. One problem with this kind of oven is that in reality some of the heat transfer does happen via convection in addition to the radiant heat, this means that the "shadowing" effect they are known for is amplified with two larger components if they are one behind the other as the first one takes all the heat out of the air and there isn't that much air movement to put it back quickly. CaseD8 electrolytics are enough to see this in action, there are numerous other issues with IR, its not a process well suited to modern PCBs. There are table-top forced air reflow ovens from China & elsewhere that would almost certainly do a better job and frankly you seem to have the volume to justify it.

author: sorteper
author_rank: Newbie
timestamp: November 23, 2019, 10:52:21 am
content: Sure, Styno. The short version: I bought the SMT460 this spring from a guy who had imported it from China one year earlier. He had no clue how to operate a pick and place machine, to the point where he had broken a feeder in his ONE failed attempt at mounting a reel into one. So he had more or less given up on it and I got it in virtually unused condition and at a relatively cheap price. Which may have a positive influence on my oppinion of the machine.I had prior sporadic hands on experience with a pair of Assembleon Topaz/Opal machines at the EMS where I was head of testing and occasionally ran the wave soldering and rework machines. So I knew how CL-feeders work, at least.I rented a truck, picked it up in Belgium and drove it back to Denmark, crossing my fingers the entire trip back that the machine wouldn't rattle apart during transportation. Then I had to store it for four months, waiting for renovation of my workshop space.Once I got it set up it took me a couple of days to figure out the calibration and setup of new boards. Neither the software, the manual nor the instructional videos are perfect, but in combination - and with a bit of patience, I managed to calibrate and start placing components. This process was actually more rewarding, than frustrating.The SMT460 has been running smoothly for three months now. Which is arguably not a long time and not empirical evidence for its durability, but the thing seems solidly built for what it is and what it costs.My SMT460 is the version without a conveyor belt, which I regret it doesn't have. But used-market-hagglers can't be choosers.One place where I didn't do my homework is the fact that I didn't realize it needed a compressed air/filtration/dryer system to operate. I'm embarrassed I didn't know this, but I didn't. This system set me back almost €1500, because I need a quiet compressor to keep the noise below "unbearable" in my small space.I'd love to set up an "ask me about my SMT460"-thread at some point. But ask, and I may be able to answer your questions, Styno.

author: sorteper
author_rank: Newbie
timestamp: November 23, 2019, 11:04:50 am
content: wraper, as SMTech wrote. You may be thinking of board temperature, which doesn't necessarily correspond to the rated temperature of this oven. The T-960 ovens are as I understand it combining IR heaters with forced air. The 300C versions may or may not be able to dipserse enough of that heat to properly heat the board, and that's what I'm trying to figure out if they are. I believe the rated temperature of vapour phase ovens should be taken much more litterally. But I have no experience with those.

author: sorteper
author_rank: Newbie
timestamp: November 23, 2019, 11:07:51 am
content: SMTech, thanks for the detailed answer! I believe the T-960 ovens are a combination of IR and forced air. But I may be wrong.

author: SMTech
author_rank: Frequent Contributor
timestamp: November 23, 2019, 01:32:48 pm
content: I must admit I've only glanced at eBay listings for them but looking more closely they are a 3-upper 2 lower zone oven, (so a 3-zone oven really) the top seems to be hot air and the lower it would seem is IR, the mesh runs over the top of a grate that covers the IR emitters, I don't see any pictures that show you where they are but I would have thought hat grate seriously reduced the amount of heat that reaches the underside. However there are a couple of happy users on Youtube & it surely has to be better than the desktop IR T962 type drawer based units, however 3-zones really isn't very many.I don't much like the conveyor speed control - why can't it give you a proper speed setting rather than 1-10? The display also seems pretty lame but adequate I guess.It seems cheap enough to try it and see, I would be very tempted to buy at least one spare fan/heater assembly so you have spares on hand and I would also check over the electricals before wiring it in for compliance and workmanship.One Youtube video has a blog link as wellhttps://granasat.ugr.es/2018/03/new-t960-reflow-oven-smt-assembling-unit/no idea what the W adds, if anything.