What are aluminum polymer capacitors? These are a solid type of capacitor that replaces the liquid electrolyte with a solid polymer material. Sometimes you might hear these capacitors called “organic aluminum.” Technically, they are still “electrolytic” capacitors. However, the colloquial term of “aluminum electrolytic” refers to the traditional wet electrolyte-based capacitors.
In this video, I meet with Amelia Dalton of EE Journal, and we discuss these capacitor types. Mouser and EE Journal developed the video in joint with KEMET. (Previously I talked on Amelia’s Chalk Talk about SSD Capacitors.)
For me, the release of this video is bittersweet. It is one of my last projects before my departure from KEMET. However, I am excited to talk about aluminum polymer capacitors because they represent one of the “newer” technologies when it comes to capacitors.
Difference between Aluminum Polymer Capacitors and Aluminum Electrolytics
As mentioned, the key difference between the capacitor types is the electrolyte. In a traditional aluminum electrolytic, there is an electrolyte that connects the cathode plate of the capacitor to the cathode electrode. In a polymer capacitor, a solid conductive polymer material replaces the wet electrolyte. The most common polymer material is PEDOT. The use of this material provides an exceptionally low ESR which makes the capacitors can handle more ripple current. Also, because there is no electrolyte to “dry up” or “wear out,” the operational lifetime of these capacitors is much longer. Overall, aluminum polymer capacitors are an excellent alternative to traditional electrolytics.Learn about Aluminum Polymer Capacitors
Hi James, I have listened to your interview about electrolytic polymer capacitors twice now (I am a slow learner) and found it informative. But I would like to have information about the thermal resistance of these capacitors. The data sheets do not give thermal resistance. That is the short version of my question.
The long version is that I am working on a SMPS design, which requires an input capacitor with a working voltage of 40V (so I will use a 50V rated capacitor) with at least 200 uF to give an acceptable ripple. The AC current in the capacitor will be 10 Amps, so to keep the power loss low, the temperature rise low and the lifetime long, the ESR and thermal resistance need to be used. For example if I use 3 KEMET type A759MS107M1HAAE031 in parallel (50V, 100uf, 31 milli Ohm ESR) I should have total ESR of 10.3 milli Ohms, and 1 Watt dissipation across 3 capacitors and thus 0.34 watts per capacitor. But what will be the temperature rise?
Thank you for making your expertise available.
If a vendor doesn’t publish the information, then you’ll need to request it from them. Unfortunately, I can’t provide technical support for KEMET through my website. If you visit http://www.kemet.com/contact-us, you can submit your request there.