Reflow Master v2

Firstly a big shout out to Unexpected Maker https://unexpectedmaker.com/ who inspired this project with his Reflow Master. Published here on GitHub and licenced under CERN OHL 1.2. this allowed me to come up with modifications of my own to expand it's functionality.

Unexpected Maker has since updated his design - I recommend ordering his "Reflow Master Pro" product to avoid needing a SAMD51 which this is based on! See https://reflowmasterpro.com/. I've also changed the name of this page to avoid confusion!

Status	Prototype
Platform	ESP32 Custom PCB SAMD
Budget	$100 ea
Date Completed	May 2022

Summary of Operation

Reflow soldering is a process which requires the temperature of the printed circuit board (and the placed surface-mount components) to traverse a bespoke temperature profile that's specific to the solder paste used.

It's an amazing process to watch if you haven't seen it before. The melting solder and resulting surface tension pulls components into their correct orientation.

If you're interested in seeing some videos - search "reflow soldering" on YouTube. There's lots of examples, including this video by Great Scott which demonstrates a few different methods.

Here's a 30 second clip of reflow soldering the ESP-IO board. Notice the melting grey solder paste pulling items into location.

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Here's some photos of the finished prototype - which was designed to be pin/hardware compatible with the Adafruit Metro M4 Express AirLift development board - giving a huge amount of out-of-the-box functionality to speed up code development.

Engineering Detail

So I wanted a few more inputs and outputs than the standard Reflow Master by Unexpected Maker. I wanted the ability to run heater and fan loads directly up to a couple of amps, as well as control external solid-state relays.

Why do I need the extra sensors and outputs? Because when I was making the larger Fuzzy Clocks I needed multiple heating elements and serious grunt to get them up to temperature given they were nearly 350x400mm size.

Here's a summary of the hardware design/comparision to the original Reflow Master by UM.

Function	UM Reflow Master	Reflow Master v2
Status	Production	Prototype only!
Host Platform	SAMD21	SAMD51 + ESP32
Interface	2.4in LCD	2.4in LCD + Touchscreen
File storage	-	SD Card
Supply Voltage	5V USB	5V USB or 7-12VDC
Heating Outputs	1x 500mA	3x 5A
Fan Outputs	1x 500mA	1x 5A
Thermocouple Inputs	1	2
I2C Ports	-	1x Stemma QT/QWIIC
Terminals	Screw	Würth Screwless

All designed in Fusion 360/Eagle with a 3D printed enclosure (for now).

I will post the design on GitHub under CERN OHL 1.2 to honour the effort by Unexpected Maker and pay it forward! Just need to iron out a few bugs (you can see a fix wire on the back of it!)