Iron Becomes SMD Hot Plate

Few things have changed our workshops more than surface mount components. In 1980 it would have been strange to see a hobby bench with a microscope, hot air equipment, tweezers, and all the other accouterments that are a necessity today. [Electronoobs] wanted a reflow hot plate and decided that he could repurpose a consumer laundry iron for the job. You can see the results in the video below.

Opening the iron revealed surprisingly simple circuitry, so the build has some additional parts along with a controller and an LCD, of course. The power requirement for the heating element is significant — 13 amps — so the plate uses a solid state relay to turn things on and off.

The iron has a ceramic bottom which is good for heat flow. There’s also a mystery component inside that [Electronoobs] is hoping someone can identify.

The final build uses a single thermocouple for temperature measurement although there is a provision for more sensors. If you want to see the device in operation first, fast forward to about the 9 minute mark.

The device appears to work with some caveats. The center of the plate seems to be cooler than the edges. We wondered if using an electric skillet might have helped or even replacing the plate with something that made direct contact with the heating element. We also wondered if some thermal compound might have helped transfer heat into the plate better.

Of course, using a skillet wasn’t our original idea. You don’t even necessarily need to modify it much.

20 thoughts on “Iron Becomes SMD Hot Plate

  1. yeah, a clothes iron works pretty well: it easily ramps fast enough. But the work area isn’t so big, and you can’t have anything at all on the bottom side.

    But watch the thermal fuse (on american ones anyway): they pop at 230-240C, and are one-time things. Ramp too fast and you can overshoot and pop them.

  2. Video title is a bit off reality. 3000W iron, really? There is an extra 0 there.
    That SSR isn’t mounted on a heatsink and it would need to dissipate somewhere at least teens of watts to switch that amount of power. Good luck if you are using a knock-off SSR.

    1. good luck ironing your pants with 300W… maye you are a bit off reality? ;-) most irons come between 2400W and 3000W. You need to heat the shoe to 100-200°C within seconds, maintain that temperature while running across room temperature clothing and while doing that provide plenty of steam.

        1. I live in Germany, my induction cooktop is 11kW max. I think the tankless water heater is even higher.
          Normal wall sockets are 3.6kW (230V, 16A).

          A single-familiy detached home is supplied with three phase at 50-70kW.

          So 3000W household stuff is not unusual here. Guess charging your electric car at home isn’t feasble with 1500W :)

          1. It’s depend, in France car charger tops at 10A on domestic plug (10A) unless you use a special plug that allow 16A (just a magnet inside it, and supposedly better contacts).
            There is quite a difference between using an iron that draw 16A with cycling for a dozen minutes and a car that use 16A for hours.

          2. The average German wall socket is 10 A by 230 V continuously and 16 A for maximum of 1 hour. If you need 16 A continuously you have to switch to CEE230.

            Most induction cooktops with multiple areas will limit the total power usage by grouping areas together and limit those.

            Flow-type water heater with 33 kw at max needs three-phase electric power and in most areas you have to have a talk with your grid operator to verify that it does not harm the grid.

            Most installations need to be retrofitted to handle that much power.

        2. Yes in the U.S. you would be right on target at 1800 W, most likely 1500 W. Do the math and figure it out. Most household circuits are fused or breakered at 20 amps @ 120 Volts which comes out to 2400 watts. Obviously you won’t likely find an appliance outside of a large microwave which is usually or should be set to its own individual breaker circuit that will draw above 1870 watts. It is almost impossible to even find a room space heater that is rated over 1500 W. I would go as far as to say that even in other countries that run at 230V, The normal line voltage in most countries which is de rated for amps because of the higher voltage, the current is reduced by about half, so the wattage rating remains the same. Either way, to be working with an Iron consuming a full 1500 Watts, I can’t see that because if so that heating element would be so hot it should set cloth on fire very quickly. The Iron has has to have a thermostat inside to switch it on and off to maintain a fairly constant temperature, it only has to be hot enough to boil water mostly to a dry steam. Not that long ago I was over seas and working at a de construction site, the fuse panel in the building had several circuits fuses at 5 amps ! You won’t be using an iron on that line for sure. Unless it’s rated at less than 1kw. All those fuses were feeding lights and even at that, not very many.

          1. I live in Serbia and the room heaters are at least 2kW (for the small ones with the fan), but bigger ones are usually 2.5kW and 3kW.
            Newer seen 1.5kw heater.
            The power outlets are limited to 16A (continuously) which goes to 3680W, but devices are usually 10A (used for lights)
            2.5mm2 -> 16A (used for sockets)

      1. And pretty much all of my boards fit it nicely. Just depends on your requirements. take a look at Black Mesa Labs. They have done a nice job for boards less than 1 sq in. Oh, and the power requirements are pretty small compared the skillets, irons, flame throwers and such. Just sayin;.

  3. Hm..I am doing this myself for 15Years. I use an old Siemens iron for 1Euro from Ebay that was made in the 70ies. It is probably easy for me to develop my own electronic, but this was not necessary. If I put it to “cotton” its bi-metal thermostat is hot enought. It is also good to harvest parts from single side PCB. I only had to replace the power-cable, because the old one from the 70 falls apart. :-)

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