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My board consists of a microcontroller, some RF modules (i.e. bluetooth, wifi, etc), and a few other gadgets.

It is powered by a 12V barrel adapter. I've read conflicting reports whether it's best to use MLCC or tantalum capacitors to bypass the power supply near the board's power input.

I previously thought MLCC's have come a long way and now have made tantalum's nearly obsolete in this regard.

Is there a reason why one may use tantalum 0.1uF and 10uF caps instead of MLCC? Why?

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  • \$\begingroup\$ Ask yourself what problem are you solving by the placement of the caps (irrespective of style). \$\endgroup\$
    – Andy aka
    Commented May 17, 2016 at 17:28

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For larger values Tantalums can be cheaper and more space-efficient that the same effective capacitance in ceramics. Depending on the dielectric, ceramics can have very poor voltage and temperature coefficients so a 10uF 10V ceramic cap may only have 1-2uF of capacitance with 10V DC on it.

However, Tantalums are prone to failure from high ripple current and overvoltage. Ceramics are much more rugged. If you have a buck converter (DC-DC) be very careful with tantalums. Polymer tantalums are best and be sure to not exceed the ripple current rating or the voltage rating even for a short period.

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