Once you begin populating boards with component counts in the tens or hundreds, you get really tired of hand soldering.
In light of the tedious hand assembly required for my previous high voltage power supply designs, I decided to act on the advice of a friend and build a reflow oven.
Why build your own?
- It’s educational
- Chinese reflow ovens in the <$1000 range usually use direct IR on the board, which can melt plastic packages before the solder. They typically require some degree of modification to make useful (and safe).
- DIY oven tech has matured greatly with improvements in open source hardware
I wasn’t interested in rolling my own design completely from scratch. In speaking with a friend, he described his success with an early generation of DIY oven based on a controller named “Controleo”. After a brief search, I discovered the site and sure enough, Controleo has gone through several generations (which was encouraging). I decided to buy a kit for the latest version, along with the same style of Black and Decker toaster used in their build guide.
Not wasting a moment, I set out to build the kit soon after receiving it. The whole job took approximately 10 hours, excluding dry times for the high temp silicone.
After running the self test and getting satisfactory feedback from the controller regarding my oven’s performance, I was ready to reflow a board! I loaded up the reflow profile I had written on my computer for the particular eutectic paste I was using (MG Chemicals 4860P). I did not have a stencil for the board I wanted to reflow, so I applied the paste as carefully as I could using a syringe.
The reflowed board lives! Punching out 200 milliamps at 180 volts with 91% efficiency (from 24 volts in) is no mean feat for a a small power supply like this either. More on this design to come.