When it comes to home-lab reflow work, there are a lot of ways to get the job done. The easiest thing to do perhaps is to slap a PID controller on an old toaster oven and call it a day. But if your bench space is limited, you might want to put this compact reflow hotplate to work for you.
There are a lot of nice features in [Toby Chui]’s build, not least of which is the heating element. Many DIY reflow hotplates use a PCB heater, where long, thin traces in the board are used as resistive heating elements. This seems like a great idea, but as [Toby] explains in the project video below, even high-temperature FR4 substrate isn’t rated for the kinds of temperatures needed for some reflow profiles. His search for alternatives led him to metal ceramic heaters (MCH), which are commonly found in medical and laboratory applications. The MCH he chose was rated for 20 VDC at 50 watts — perfect for powering with USB-PD.
The heater sits above the main PCB on a Kapton-wrapped MDF frame with a thermistor to close the loop. While it’s not the biggest work surface we’ve seen, it’s a good size for small projects. The microcontroller is a CH552, which we’ve talked about before; aside from that and the IP2721 PD trigger chip needed to get the full 60 watts out of the USB-PD supply, there’s not much else on the main board.
This looks like a nice design, and [Toby] has made all the design files available if you’d like to give it a crack. Of course, you might want to freshen up on USB-PD before diving in, in which case we recommend [Arya]’s USB-PD primer.
Very interesting. The software doesn’t use PID, but a rather crude on/off depending on temperature, with hysteresis (called ‘offset’ in code). I’m wondering how close to the reflow curve this hardware+software manage to be.
The schematics source aren’t provided. I like the choice of wch MCU, which is small/cheap and with a free software toolchain.
The choice of the heater seems pretty good, too. It’s indeed complicated, especially for low voltage and dc. But he doesn’t provide any information on how/where to find one ! Or did I miss something ?
Search for ‘Generic PD hotplate’ on ebay or amazon or aliexpress should get you some results.
With “PD hotplate” you find the usual suspect (hp30 and the cheap pcb-based-heating mentionned in the video). I was speaking about the MCH heater. You only find some very small ones (30x30mm, or 80×20, or..), but even that is lost in lot of MCH-based product, not just heaters.
‘Generic PD Hot Plate’ found me plenty of 5.6cmx5.6cm fully built units using an aluminium hotplate that looks like a mini 3d printer heated bed. You didn’t say you were looking for the mch heater, If the original post doesn’t give give part numbers, not much you can do about it except look for other sources of the same type of thing.
Yes, what you call ‘3d printer lookalike’ is what i call ‘pcb-based-heating, this is the one mentionned in the video. MCH is also mentionned in the video, that’s what i was referring to.
It is really a coincidence that I came across a small form-factor industrial machine manufacturer that have the exact specs I need and they only got 50 pcs of left-over from a previous order-to-made production run. Even if I want to get more I can’t. That is why I made the code to be so easily editable to accept other form factors of MCH (or even PCB) heaters.
I found “Ceramic heating plate, high temperature, 30x30x1.3mm3.7-48v22 infrared round electric heater” on Aliexpress pretty quickly after doing a Google search for “ceramic heater plate”. https://ae01.alicdn.com/kf/H133f1e04c84248a88c82c989d516b9d5e/30x30x1-3mm3-7-48v22.jpg_80x80.jpg_.webp
Also a 50mm x 50mm unit at a variety of operating voltages and wattages – One of them looks like a comparative temperature monster (24V 150W 320C). But searching for stuff on AliExpress with their inscutable search algorithm makes finding something from the top a real crap-shoot. I only found this one by going down a series of “related item” links. FWIW: The 50mm unit was found under the Shop2162076 Store. How do you use that info to find the store? I don’t have a clue.
Here’s a short link https://rb.gy/ctxwjo – but as usual, you should go to a short link expand site and check whether it looks ok before following it.
He mentions that it is a JLCPCB part with Minimum Order Quantity (MOQ) of 50. With that and the basic specs (40x40mm, 20V, 50W) from the .io page, you shouldn’t have too much difficulty in finding it.
That said, he is also selling them on Tindie (https://www.tindie.com/products/tobychui/tobys-automatic-mch-pd-reflow-hotplate/), probably to get rid of the 49 excess hot plates he had to buy!
I found similar heater elements on AliExpress when searching for “MCH ceramic heater”, for example a 40*40mm one but 100W. Most are super cheap though, I’m eager to try it. Only issue is that to solder some of the components I’d need … a reflow hotplate !