It is not difficult to heat up your electronic project. Designing the traces to be too small and accidentally shorting the battery inputs together may reverse the voltage of the MCU. Over the years, we have cooked one or two servings. But how to make a PCB that gets hot deliberately? This is exactly what [Carl Bugeja] did in his second version of the PCB hot plate, which is designed to reflow other PCBs.

[Carl's] The first time I tried to make a hot plate, the result was not tepid. The circuit board is a winding trace on the top of the aluminum substrate, and it does heat up as expected. However, the thin substrate causes a large amount of warpage of the heating plate during heating, reducing the contact with the circuit board being soldered. Most importantly, the resistance is much larger than expected, resulting in a much lower heat output.

The new version of the circuit board uses a thicker substrate and thicker traces, reducing the resistance from the previous design of 36 ohms to only 1 ohm. A thicker substrate with a newer design with fewer grooves makes the surface stronger and will not bend when heated.

We especially like [Paul]'s wiring solution for his new hot plate. Soldering to a resistance heater can be a huge annoyance, because the circuit board will act as a heat sink. Although alligator clips are indeed suitable for testing, they are always likely to slide and short-circuit each other. [Paul] decided to make a custom flexible PCB, connect it to the hot plate with nylon screws, and install it directly to the connection point of his power supply.

Unfortunately, this new version of the board also has some problems. The biggest problem is the poor communication with the circuit board manufacturer, and the solder mask used starts to degrade after a few hours at the working temperature. But for light work and intermittent use, it is the perfect tool.

You can read more about [Paul's]'s first PCB thermal plate in our previous report.

I can see that this works well on aluminum substrates with high temperature dielectrics

Or, buy a ceramic electric stove. The ones we use in our work can reach 1000F, and can maintain that temperature all day long without problems. What you use on eBay may be your best choice. It seems that the HP130915 that everyone uses in the industry, including where I work, sells for more than US$400.

I appreciate his efforts for his own production. Although it is not perfect, it must be the final completion of the work. Although I can't see how useful it is, unless you really need to use thin heating elements for certain projects.

Considering the size of the PCB, it seems that it will be cheaper to just buy a reflow oven! /second

Why…? These things are like 5 15 dollars.

But what is the power supply...

However-12V @12A is easy to get from your car battery, so budget backflow may happen in the garage, there are a few jumpers.

12Vac is also very cheap. A transformer.

Seeing that they are purple, I guess they are from OSH Park. Have you seen their prices? I got a quote for a 95mmx75mm board, two at $56.27!

I finally chose Seeed Studio, which I used in the past, and got 10 boards for less than $30 shipping. I can get almost any color I want, not just purple.

Or jlcpcb. Among them are Chinese; cheap but good quality

For small designs, I found OSH park great... I never paid more than $10 for my circuit boards, including shipping to Germany. But the circuit board I designed is very small, most of which are smaller than one square inch, and there are many tiny SMD components on it.

Will do a good preheating (@ ~ 100 degrees Celsius) for hot air rework, hope this temperature will not adversely affect the solder mask of the heater.

I don't know modern electric stoves (stoves), but General Electric Calrod™ heating elements used in cooking pots can be saved; when new, their top surface is flat (ish) to make good contact with the bottom of the pan. Aluminum plates will spread heat.

Almost everyone knows that these may become orange-yellow hot, but this may be when powered by 240 V (in the US).

The problem may be their low resistance, but the high current triac duty cycle control at 120 V (rated 15 A) should be good, guesswork.

Regarding short-circuiting of alligator clips, at least their insulating boots should extend to their tips.

It reminds me that I was on vacation recently and had no tools and had to repair some electrical appliances.

I used a rice cooker ring to melt some solder from the bottom contact of the old filament bulb (it is too old, it is leaded, which helps), and then used the molten solder block to make a bodge-up.

Has been tracking his progress on this project and saw the video on the day he posted it. Can't wait to watch v3, I really think he will succeed.

Carl has eggs on the surface of his project...I think it's cool...uh...hot!

Been there and tried it. AliExpress has ready-made aluminum hot plates for LED bulb repairs. The problem is that fr4 is a very good thermal insulation material, and it is difficult to reach the required temperature at the top by hearing the sound from the bottom. Where there are huge poligons and many vias, there will be high temperatures, but in other places it is too low. In the end I only invested in an oven. A proven reflow method;)

There may be no solder mask at all, and put some kapton tape on the pcb, it can be more durable.

Why not use PID AC power supply? No need for a $1,000 PSU.

For this, I have used an upside-down (old) iron. At least this is designed to reach 200°C. An ordinary stove can also accomplish this job. Of course, except for gas :-)

One trick for gas stoves is to fill the pot with sand. I have seen it once or twice on HaD and it works well, especially when you use a temperature probe or infrared temperature gun.

The temptation is to add a few thermistors to the circuit board and have some temperature feedback or control loops instead of just dialing in the voltage and keeping your fingers crossed. This reminds me of thermal pads used for terrain or anti-fog rearview mirrors. Although I doubt if they are abused enough, they will reach the reflux temperature safely.

[Paul] Who is it? Was this article copied incorrectly? Regex failed? Suddenly you decide that Carl needs to change his name?

Thanks for your feedback, Jack. Paul is Carl's other self :)

Why not build this feature into one layer of the circuit board you are building? Automatically reflow or self-destruct as needed.

Is there a reason to choose to build an electric furnace on a reflow furnace?

When I see people use waffles or irons to do this, I think the advantage lies in the price, maybe they already have it. However, if you have to work hard, wouldn’t the thrift store’s oven + thermocouple, SSR and Arduino’s cloned products of any Chinese store get better results with less effort instead of so much money?

I'm not trying to be mean. I actually hope someone has a good answer from which I can learn.

Electric stoves are only 2D, so they are much more compact than 3D ovens. In a crowded space, the smaller the better. :-)

I only use an electric frying pan.

This is a very *expensive disposable* reflux heater and will not last long.

The heat conduction is not perfect, so there is a delta T. In order to reflow the PCB, the heater must have a considerable reflow temperature. FR4 (usually 120C (normal)-180C (high Tg)) is only suitable for short-term exposure to reflow temperature. When it is higher than the glass point and delamination, discoloration, etc.

The heater uses an aluminum base instead of FR4. The heated FR4 board is only exposed for a short time.

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