Home-made reflow oven for SMD

2013-10-07

I wanted to build electronic devices with SMD components. From what I can see, many people shy away from SMD, trying to solder QFN components with a soldering iron and fighting the trend. I have no idea why.

I find SMD components easy to work with, cheap and small. If you restrict yourself to components 0603 or larger (I use mostly 0603 in my designs) and don't try to use BGA components, you'll be fine. Even the dreaded QFN packages aren't a problem at all.

For reflowing boards you can just get solder paste in a syringe, apply it manually, place your components manually, and then reflow the board. For tiny boards even a hot-air soldering station is enough, for larger ones, it turns out you can get decent results from a cheap assembly involving a tiny oven, a thermocouple (to measure the temperature), a thermocouple interface chip (I used the MAX31855), an SSR (solid-state relay) and a TI MSP430 Launchpad to control it all.

See the graph: it's a plot of temperature vs time. Sure, it isn't perfect, but it's good enough for amateur work.