What is the standard for reflow soldering in Late 2019 for hobbyists? - Page 1
Forum section: electronics / beginners

author: soFPG
author_rank: Frequent Contributor
timestamp: October 24, 2019, 08:18:16 pm
content: The question is basically in the subject already: What reflow oven is "the standard" for hobbyists on a budget in late 2019?

author: rstofer
author_rank: Super Contributor
timestamp: October 24, 2019, 08:39:46 pm
content: A hot plate works well if it has a solid top. Otherwise something like a saw blade or aluminum plate to spread the hear.A toaster oven like the obsolete Black & Decker InfraWave modified with a control system based on the Arduino. There are several, try Google. Or, maybe something like this:https://www.rocketscream.com/blog/product/tiny-reflow-controller-v2/On my toaster oven, I added thermal insulation between the inner and outer metal walls to keep the heat inside the cabinet. It basically won't work without the insulation.

author: soFPG
author_rank: Frequent Contributor
timestamp: October 24, 2019, 09:11:14 pm
content: Thanks for your answer!Maybe I should have said that I am not that low on a budget to play with the hot plateWhat I don't really like about the toaster oven variant is, that I don't know which oven works beforehand. I don't really want to buy a toaster oven only to find out that I can't use it for reflow work (they say it should be capable of 2°C/s).I am able to spend 200$ on something (whatever it is) - maybe there is something "easier" to assemble than toaster + controller? I also plan to do high pin count BGAs, don't know if that makes any difference.

author: MosherIV
author_rank: Super Contributor
timestamp: October 24, 2019, 10:31:22 pm
content: Most toaster ovens will work so long as the temperature can reach 250°CA must have modification is a slow fan to keep the temperature as even as possible through out the oven.High pin count bga will be very hit or miss for hobbiest.How would you verify good solder joints?I think companies x-ray the boards to verify good bga solder joints.

author: soFPG
author_rank: Frequent Contributor
timestamp: October 25, 2019, 07:31:41 am
content: I mean if the oven reaches the required temperature long enough all solder should mealt creating proper solder joints, shouldn't it?Regarding the fan replacement: How do I know beforehand which fan will work and fit properly?Does heating without convection also work e.g. don't use a fan at all?

author: rstofer
author_rank: Super Contributor
timestamp: October 25, 2019, 04:14:32 pm
content: Quote from: soFPG on October 25, 2019, 07:31:41 amThe real problem with toaster ovens is whether they can follow the chip manufacturer's heating profile. Few can, mine probably can't. It comes close enough for my purposes but I'm not doing BGA.QuoteI think you can buy convection style ovens and, in this case, the fan would be included.QuoteMy Black & Decker doesn't have a fan.Don't laugh at the hot plate. It is my preferred method because I can watch the solder flow and I know exactly when to remove the board from the plate. I buy PCBs from ExpressPCB and they are of a standard size. These fit on the flat portion of my hotplate so I don't need a heat spreader.I simply put the board on the hot plate, turn the dial to max and wait. When the solder has flowed, I use tweezers to take the board off the hot plate and set it anywhere else. Then I can turn off the hot plate. I don't allow the board to ramp down on the plate.The hot plate only works on one side of the board and is incompatible with through-hole devices. Sometimes this limitation drives me toward my toaster oven.The toaster oven basically comes on full and stays that way until the soak temperature, it holds for some time and then cranks on full until it reaches the end of the heating cycle. Then it simply shuts off and the temperature ramps down. It works very well but, as I said above, I have no idea whether it meets the manufacturer's specs for reflow soldering. But it works...Somewhere above the toaster oven is a selection of low end reflow ovens. In my view they are unlikely to be demonstrably better than my toaster oven and are really nothing more than lipstick on a pig. Real reflow ovens are out of my price range so I use what I have.If you decide on a commercial oven, go find some video reviews.

author: Peabody
author_rank: Super Contributor
timestamp: October 25, 2019, 05:25:24 pm
content: Quote from: rstofer on October 25, 2019, 04:14:32 pmIndeed. A slightly more elaborate hotplate setup (but still under US$20) uses a circular saw blade mounted a bit above the hotplate to even out the heat, and to provide a more stable way to remove the board at the end - by removing the blade. And a two step heating algorithm can also approximate the reflow curve without risking any overshoot, but still with no thermocouple or controller. You just need a watch.

author: rstofer
author_rank: Super Contributor
timestamp: October 25, 2019, 06:10:17 pm
content: If the board is small enough to avoid the depressed area at the center of the plate (and mine are), this hotplate will work wellhttps://www.target.com/p/oster-single-burner-hot-plate-ckstsb100/-/A-13773420No sawblade required although it wouldn't hurt anything and it makes the depressed area a little more usable.

author: jmelson
author_rank: Super Contributor
timestamp: October 25, 2019, 06:58:13 pm
content: Quote from: soFPG on October 24, 2019, 08:18:16 pmAbout 12 years ago, I got a P&P machine, and dived into the world of reflow. i got the biggest toaster oven they had at Wal-Mart, it was a GE model.It has 4 "cal rod" elements, basically steel tubes with resistance elements inside, running horizontally, two below the rack, two above, parallel to the frontdoor. I got an Omega ramp and soak thermocouple controller on eBay. These are a bit expensive to buy new. The ramp and soak feature allows youto put in a multi-step temperature profile, with temperature ramps and holds. I added a solid state relay to control the heating elements, and that iscontrolled by the Omega controller unit.The trick was that I had to poke the thermocouple into a plated-through hole in the PCB to pick up the temperature. Sensing the air temperature led tobadly burned boards, as the board absorbs most of the IR from the heaters. It only took one fried board to figure out that trick.I have done over 2000 boards with this setup. It takes about 10 minutes/cycle, and I can load 6 or more individual boards in the oven at one time,depending on size.I did luck into a 1000 foot roll of miniature thermocouple extension wire on eBay for a song, so i have a lifetime supply of thermocouple wire.I've only had to replace the thermocouple a few times when it got too close to the heating elements and the insulation melted.Jon

author: jmelson
author_rank: Super Contributor
timestamp: October 25, 2019, 07:00:50 pm
content: Quote from: soFPG on October 25, 2019, 07:31:41 amMy toaster oven has a small fan off to the side. I have not found it helps at all and rarely use it.There IS a problem with uneven temperatures, but it is not real bad. The part of the board closest tothe heating elements does get hotter, and sometimes the board or the silkscreen darkens a bit.Jon

author: soFPG
author_rank: Frequent Contributor
timestamp: October 25, 2019, 07:06:12 pm
content: Quote from: rstofer on October 25, 2019, 04:14:32 pmWhat would be the cheapest "real" reflow oven? Didn't find a lot of information, mostly about the T962 which probably falls into othe category "low end" reflow oven.QuoteHonestly, that's a major problem for my PCB. I often put decoupling caps at the bottom side of the PCB. Hot plate probably works for some use cases but not for all (as you already pointed out).QuoteIf BGAs come into play I really want to make sure that the required temperature is met (that means that I would want to use a specific controller, such as the "Tiny Reflow Controller v2") so that the solder paste melts.@jmelsonBecause you set up your gear 12 years ago I doubt that the oven is still available but can you give me the rough dimensions (volume) it has and how much power?The maximum I was able to find on amazon was 9L with 1000W and max. 230°C.Quote from: jmelson on October 25, 2019, 07:00:50 pmI don't think that should happen if you are working with a PID?

author: rstofer
author_rank: Super Contributor
timestamp: October 25, 2019, 07:47:47 pm
content: Quote from: soFPG on October 25, 2019, 07:06:12 pmI do the same thing, of course, but I hand solder them. I apply solder paste, place the component, hold it with tweezers and hit the joint with my iron. Works well. Slow, but well.On my toaster oven, the thermocouple hangs loose inside. I stuff the end into a via on the PCB to get a good reading of board temperature, not cavity temperature.

author: tggzzz
author_rank: Super Contributor
timestamp: October 25, 2019, 07:49:18 pm
content: Quote from: Peabody on October 25, 2019, 05:25:24 pmI find a few mm of sand in the bottom of a saucepan works well, provided there are components on only one side.Gas hobs are controllable w.r.t. temperature profiles. If the saucepan has a glass lid, watch the progress through that, optionally removing it when using a non-contact thermometer to keep an eye on the temperature.