This is to document a practical and modestly costing DIY Vapor Phase Soldering Project using a Domestic Electric Frying pan. There has been a lengthy discussion (
https://www.eevblog.com/forum/manufacture/practical-diy-or-modest-cost-vapor-phase-does-it-exist-yet/ ).
After quite a lot of experimenting, i've been able to get very good Vapour Phase Re flow using a domestic frying pan. My experiments have used a wide collection of bits and pieces to 'hack it together' but now i want to tidy it all up so its easy to use and replicate ( i now want to make quite a few of these ).
Vapour Phase Reflow works by heating fluid ( Galden HS230 ), to boiling and creating a cloud of 'hot vapour'. The hot vapor condenses on the PCB and parts and causes it to heat up and solder. There are some advantages of using this technique. Its hard to overheat the boards/parts as the maximum temp they reach is 230C, which is the temp of the vapour. Vapour Phase in fact is not a new tech, it was the first reflow tech used when surface mount was invented. However it used some nasty fluids that were very Unfreindly. Now there are some much better fluids, which are much more inert and safe. Commerical VP is an expensive thing to buy. There have been a couple of attempts at low cost VP but the one which i bought was of very poor quality and implementation.
Its not a particulary complex project, you need to control the heating of an element and then control turning on a fan to cool it.
For this project, i've decided not to create an entire microcontroller system, but just enough electronics so you can connect your favourite single board computer, or in fact PC via USB to it. My experiments have been controlled with code written in python.
The parts;
(a) A frying pan - I've settled on using a Breville BEF560BSS. (
https://www.breville.com/nz/en/products/woks-skillets-deep-fryers/bef560.html). Its highly probable that other pans will work, however there was a few things about this one that make it quite attractive. The list price on this pan is $A269, but i got mine for $80, ( dented box ) but i've regulally seen them for around $120
- Its has a nice even power distribution in the pan. Theres not really any signifncant hot spots.
- Its lid is nicely domed, and any vapor that hits it, seems to roll down the lid. The lid has a nice lip on it, as well, that seals it quite well
- Its got plenty of power, 2400W
- Its easy to remove the cover from the bottom, ( more on that later, but it really helps cooling )
(b) a big decent AC Fan. ( GoldAir GCDF140B ). You want something that can really drive a lot of air, getting enough air over the base of the pan when you want to cool it down, is really important. About $40-50
(c) Some Galden HS230 Fluid ( expensive, but you don't need much, and if you are careful, you dont' consume much
(d) A couple of Solid State relays, and heatsinks. I'm using Fotek SSR-25DA-H. You need to be careful to get genuine ones. Fotek is a good brand but there are 100's of fake copies on aliexpress/ebay. These will set you back about $12 for the SSR's and $3 for a power supply.
(e) In my setup, i'm going to wire in a couple of circuit breakers, and an RCD all on a Dinrail just to make it a bit safer as i intend to use this in a commerical setting where I need to have some compliance and OSH.
(f) A controller system, to glue it all together and control it. I've decided that instead of trying to code it into a dedicated microcontroller ( you coudl fesibly do that ), that it will get plugged into 'somethign' that has a usb port. My codes in Python.
I've sketched up the schematic for the controller board, which is attached. A MCP2221A provides an I2C / USB Bridge. There are a really good set of librarys for python to use with this. (
https://pypi.org/project/PyMCP2221A/ ) and it seems to work well with Windows and linux ( so good for a raspberry PI etc ).
MCP9600's are for connecting a K type Thermocouple to. At present i'm only using 1, but i'm provisioning space for up to four, as it might be useful to add extra measuring points later. If we dont' need them, it will just be blank spots on the PCB. I've also put a MCP23017 GPIO expander on it, which will be used to control those SSR's as well as provide some additional ports if you want to hook up extra things.. I'm thnking i'll put a stop/start button and maybe some indicator leds on. Its easy to put in now, and since its programmed in python really easy to add/modify to your hearts content.
Next job is to design a pcb.. I'm going to make it so it so it will have a coupel of DIN rail mounts on it, as i intend to mount all my peices on a Din Rail inside a nice tidy box.
I've reserved the next two posts, so i can add a BOM, and schematic's and stuff.
This project is entirely open. We will see where it goes, at the moment, i'm building it for my own use and if anyone else gets any interest out of it, then awesome..
I remember a time when we thought, meh, you can't use a home toaster oven to solder.. thats insane.
The project has taken some interesting twists and turns, but its now got simple again, I played with water cooling, and different size pans and systems. What i know now is that we can acehive a nice reflow profile, that can be cooled sufficently and that there is not a noticeable galden loss.
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