Details on shiny SMD capacitors

[Bancroftjo]

I just got a new multimeter (Hioki DT4282) and took it apart to see the build quality. On the PCB I found some components I would like to know more about. I assume they are capacitors since they are labeled "C". One can be seen in my attachment and is labeled C211 towards the middle of the photo. They are very shiny and look like the mineral tiger eye. Can someone give me some information about these components, or at least enough for me to find them in a web search?

Thank You
Jon

[rs20]

Interesting, I had sort of considered NP0/C0G MLCCs to have rendered film capacitors kind-of obsolete (high voltage stuff aside), without really thinking about it. Comparison: Film capacitors vs NP0 MLCC capacitors

[spudboy488]

They almost look laser trimmed. Possibly active laser tuning the circuit? C66 and C67 also look like they were tuned.

[julianhigginson]

I would select these particular film caps because the stripes look awesome!

As for why the multimeter designers would... depending on what the multimeter circuit is doing there, there's 2 immediate reasons I can come up with where you could go to film caps instead of the usual ceramics:
1) some kinds of film cap are available in very tight value tolerance, much better than your average COG/NPO ceramic and maybe they really want to nail the corner frequency of some filter stages across the whole production? (and maybe they are also laser trimmed in order to do this?)
2) film capacitors generally exhibit better linearity than ceramics. (though I admit I'm not sure what a handheld DMM would do where this matters? I'd expect you could call that out at the end anyway. IME it's only really audio where people care about film caps anymore... so I'm expecting it'll be 1)

[Mattylad]

C66 and C67 look like they are upside down to me.

[dmills]

C211 is an integrator cap (connected in the feedback loop of the AD8539) for which low dielectric absorption is an important figure of merit, my guess is that this is what drove the choice.

One thing to watch if using surface mount film, is that the reflow profile is critical, they really mean that maximum temperature limit....   

Regards, Dan.