November 2013’s issue of Electronic Products features an article on the cover titled “Introduction to Polymer Capacitors.” The author is, well, me. This article explains the differences between traditional MnO2-Tantalum and Polymer-Tantalum capacitors. Previously I explained these differences in the post on the fire hazard the Arduino GSM shield poses (due to improper derating).
You can find the Electronic Products article wherever magazines are sold or here: Introduction to Polymer Capacitors. Check below for links to high-resolution pictures.
Tantalum is a really misunderstood capacitor. Well, all capacitors are misunderstood, but that’s a subject for another post. I ran across this post on the Arduino forums on the Arduino GSM shield. In the post, ddewaele, reports that the shield blew up, catching fire. At first some might think it was due to abuse by the user. While it is possible that reversing the polarity or applying over-voltage could cause a catastrophic failure, it is also possible that the user doing nothing wrong could result in the same failure mode!
Wait, what? So what gives? Well, there’s two things to understand. First, Tantalum doesn’t explode. It takes almost 2000°C before Tantalum metal will ignite. Okay, so if Tantalum doesn’t explode what is ddawaele seeing? It’s the cathode material, Manganese Dioxide, (MnO2) that is exploding…