Reflow Soldering Toaster Oven - Page 1
Forum section: electronics / projects

author: frank26080115
author_rank: Regular Contributor
timestamp: November 14, 2011, 03:15:11 am
content: As I get more serious into my electronics hobby, I need to work with more SMD components. Some component packages are very difficult or impossible to solder with a traditional soldering iron. To solve this problem, I decided to hack a toaster oven to become a reflow soldering oven.Basically, to perform reflow soldering, solder paste is placed on a printed circuit board, and the components to be soldered is placed on top of the solder paste. When the oven heats the solder paste past the melting temperature, the solder paste melts and solders the component to the circuit board.To control the oven's temperature, I created my own reflow toaster oven controller circuit. This circuit uses an ATmega32U4 microcontroller to monitor the oven's temperature using a thermocouple and AD595AQ, and then control the oven's heating element using a solid state relay. The controller features USB logging/debugging, USB bootloading, a graphic LCD display, and 3 buttons. The firmware features tweaking for all settings, manual temperature control, manual heating element control, and automatic temperature profile control (with a nice temperature history graph display). This circuit will plug into a wall outlet, and the oven will plug into this circuit, while the solid state relay basically acts as a switch between the wall outlet and the oven's heating element. Safety is the main design objective (but some things were limited by cost), and ease of use is the second objective.Video, Pics, and More Instructions at Instructables:http://www.instructables.com/id/Hack-a-Toaster-Oven-for-Reflow-Soldering/

author: ablacon64
author_rank: Frequent Contributor
timestamp: November 14, 2011, 03:42:51 am
content: Very nice job! Congratulations!

author: requim
author_rank: Regular Contributor
timestamp: November 14, 2011, 05:14:12 am
content: That's awesome. Total props. I'll have to take a look at the material you published and consider building one myself.

author: 8086
author_rank: Super Contributor
timestamp: November 14, 2011, 06:03:42 am
content: Very good!I am working on a more mass-produceable product much like this so I will have a read of yours and see if you can teach me anythingHow much did it cost to make in total? Those SSRs aren't cheap!Simon

author: frank26080115
author_rank: Regular Contributor
timestamp: November 14, 2011, 06:25:41 am
content: I lost track of the costs, I estimate about $120 maybe? Set aside about $35 for the PCB, $50 for the SSR, and the rest on components. The aluminium, plastic, and hardware are pretty much free from my school's machine shop if you hunt in the scrap piles.The SSR is about $50 and it's specs are much higher than what is actually required, and in the end it turns out my oven doesn't heat fast enough to get much benefit from the SSR as opposed to a mechanical relay, but it is more durable and efficient. In the end I learned a lot about how SSR and TRIACs work through all this.

author: Flavour Flave
author_rank: Regular Contributor
timestamp: November 14, 2011, 07:05:41 am
content: Where did you get the vibrator taped to the soldering iron trick from?

author: ablacon64
author_rank: Frequent Contributor
timestamp: November 14, 2011, 02:04:52 pm
content: I did not understand the vibrator also. Is it to balance shaking hands?

author: ToBeFrank
author_rank: Regular Contributor
timestamp: November 14, 2011, 04:26:59 pm
content: I've been using the TechFX Reflow that was made by Silicon Horizon (they went out of business). It works, but their software is truly horrendous. I may build yours just so I don't have to use it anymore. How well do you follow the temperature profile?

author: frank26080115
author_rank: Regular Contributor
timestamp: November 14, 2011, 05:22:55 pm
content: The vibrator is so that iron tip generates heat when it contacts the PCB, thus making soldering possible. That's just common sense.No I'm not serious.That soldering video is just a joke, showing that even people with shaky hands can solder 0603.my software isn't that great either, the problem comes from the LCD's slow frame rate, and I didn't really code "only update what changes on the screen".the second problem with temperature control is from the slow heat rate of my oven, it's slow enough to make following a curve irrelevant since you will probably follow the curve even if you just turned it on 100% all the time. If I tried a slower curve (but that makes the entire process too long) then it works OK since it is a PID controller, but the switching frequency is quite slow so it probably doesn't meet the same performance as a commercial unit.The good news is that you can just rip apart my code and tweak the behaviour easily. Or adjust the PID values, but honestly with a kitchen toaster oven, you will probably end up doing what I did, which is to keep the P constant so high that it becomes an "on-if-cold, off-if-high" behaviour.

author: george graves
author_rank: Super Contributor
timestamp: November 14, 2011, 08:07:08 pm
content: I'll have to try and read the instructables article. It's just to hard to follow things on that site. Grrrr.Love the project!

author: IanB
author_rank: Super Contributor
timestamp: November 15, 2011, 04:14:33 am
content: You said you could not obtain a thermocouple connector socket. I'm surprised, since it's a very standard connector. Here's one source, though it may not be the cheapest:http://www.omega.com/toc_asp/subsectionSC.asp?subsection=g&book=Temperature&all=1

author: frank26080115
author_rank: Regular Contributor
timestamp: November 16, 2011, 05:39:56 pm
content: Instructables isn't that bad once you have "view all steps on one page" turned on by default, and also I have a "pro" membership which means I don't see as much advertising. My biggest peeve with Instructables right now is the image compression and how the gallery works in general.Thanks Ian, I didn't find it on Digikey and immediately decided it's not worth the effort to buy the real connector, especially since I've planned on using a screw terminal block since the beginning to facilitate more varied thermocouple replacements. Now that I think about it, I could have used both, but I saved a few bucks this way.

author: Bored@Work
author_rank: Super Contributor
timestamp: November 16, 2011, 06:14:58 pm
content: Quote from: frank26080115 on November 16, 2011, 05:39:56 pmInstructables is a piece of shit. E.g. these days you can only turn on the mentioned "view all steps on one page" if you have that paid "pro" account. You don't get the PDF without the paid "pro" account. Some Instructables are reserved for paid "pro" account holders.That would be OK if Instructables didn't start differently. When they started people were submitting content for free with the understanding that everyone can read the submitted content for free. Then Instructables made that freely submitted content practically unreadable and introduced payment. That is unfair to those who submitted content. It is exploiting them.The good thing about Instructables is that most content they add these days is just pure rubbish. So one doesn't miss anything by avoiding that site.QuoteHey, but one of the privileges of your "pro" account is that you are allowed to "help" Instructables to develop new features. Doesn't look like that is really working.

author: 8086
author_rank: Super Contributor
timestamp: November 17, 2011, 01:36:58 am
content: Quote from: BoredAtWork on November 16, 2011, 06:14:58 pmI don't pay for my account and I am able to view all steps on one page.-Simon

author: frank26080115
author_rank: Regular Contributor
timestamp: November 17, 2011, 08:36:33 pm
content: Quote from: BoredAtWork on November 16, 2011, 06:14:58 pmI was a member since 2007 I think, I get special treatment apparently. I don't pay for my "pro" account since you get them for free if you get featured or win contests.QuoteI only really only read some of what goes on their weekly emails. I think you are right, they might be running low on good content lately and I've seen old, and I mean 2007 old Instructables being re-front-paged to keep things interesting.

author: mobbarley
author_rank: Regular Contributor
timestamp: November 24, 2011, 07:36:24 am
content: Quote from: frank26080115 on November 14, 2011, 05:22:55 pmI hope the huge solder wire with a molten ball on the end is part of the joke too

author: JimmyM
author_rank: Regular Contributor
timestamp: December 07, 2011, 03:17:04 am
content: I too use the TechFX2.0. The software is truly awful. I'm considering making my own. I have a few Nokia 3310s and a color version as well. My toaster oven was a 1500W (1300W actual) convection oven and the slopes weren't great. So I bought a second one and scavenged it for the heating elements. It runs on 230V now at 2600W. The convection fan still runs on 115V. I also insulated the box on 5 of the 6 sides with alumina ceramic refractory insulation. It ramps like crazy now if I let it and temps don't fall as fast when the heaters turn off. However, overshoot is NUTS. I need to actually profile a PCB instead of just the air temp. Maybe the actual board isn't overshooting.I figured a few buttons and a rotary encoder for controls. A Mega168 to control things and drive 1 or 2 LCDs.Reflowed boards are great, especially for QFN packages.

author: george graves
author_rank: Super Contributor
timestamp: December 07, 2011, 04:51:42 am
content: "alumina ceramic refractory insulation" - whats a common use for that?

author: JimmyM
author_rank: Regular Contributor
timestamp: December 07, 2011, 11:38:23 am
content: Furnace/kiln insulation. It's rated to 2300 F. A propane torch directly against it will cause smaller stray fibers to melt/fuse, but the blanket stays in tact. I bought it to insulate inside the heads of high output flashlights. 100+W modified Mag-lights. Zirconia insulation is good to around 3000 F.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2011, 06:19:40 pm
content: Quote from: JimmyM on December 07, 2011, 11:38:23 amAre you the same JimmyM from CPF? And do you ever worry about some of those bulbs melting aluminum reflectors? On some very high power bulbs the quartz envelope glows red hot after the lamp has been running for a while--but maybe typical batteries can't run a miniature sun for that long?(PS: Any more of the JM-PhD-D1 in the pipeline?)

author: JimmyM
author_rank: Regular Contributor
timestamp: December 07, 2011, 06:38:02 pm
content: Yes. One and the same. Big bad bulbs can cause the aluminum coating to come off the machined aluminum substrate, but I've never heard of a reflector actually melting.And yes. I do have plans for another batch of D1s. I just want the dust of holiday shopping to settle before I go to the wife for a big chunk of cash to buy parts.