Yes Rob, you're right, but as you've told, the cellular phones are not designed to be reliable for a long time. The use of tantal in this case may be interresting for the cost and the small package.
I can only tell that for industrial applications and especially heavy industrial applications, this kind of capacitor is avoided because an industrial application may be reliable for years. You won't see any tantal in a switched variator for motor speed control or automotive electronic control unit for example. This is also the case for military applications.

Thanks Andy to correct my english. I do appreciate this. It's the best way to improve the knowledge of a langage. French people are usually not very familiar with foreign langages. I've been a lucky man and I've worked with an US compagny in the past on a common project with France. It has increased my level of english.... but I'm affraid there is still a lot of work to do...
In this case, I've wished to say the harmonics of the high frequency. That's why I've used the apostroph, but by reading again I see that was not correct.


Regards
Stephane