Noob capacitor question

[clearchris]

What are the black rectangular caps? Are they electrolytics? Ceramics?

I have a cisco 2600 series router that is acting flaky during high temps, so I suspect capacitors. There are 4 electrolytics, and a whole mess of the black type.

[mariushm]

Re: Noob capacitor question

They're either Tantalum or polymer. Most likely with polymer, because plain tantalum are usually those yellow capacitors.
See for example : http://industrial.panasonic.com/ww/p...AAA8000_e.html



"POSCAP" is a solid electrolytic chip capacitor. The Anode is sintered Tantalum and the Cathode is a highly conductive polymer formed on SANYO Original method.
"POSCAP" has a Lowest E.S.R. (Equivalent Series Resistance) level and excellent performance for high frequency though low profile and high capacitance.
In addition, it has high reliability and high heatresistance.
Therefore, "POSCAP" is an ideal chip capacitor especially for digital, high frequency devices.

[clearchris]

Re: Noob capacitor question

Yeah, there are some yellow tantalum caps on the board, so they are likely polymer.

So could there be a design reason why one wouldn't want a polymer cap (there are 4 electrolytic 330uf 16v)? They used plenty elsewhere on the board.