In the case of SMD Capacitors, the basic types of pad finishing use SAC or NiAu.
In the case of Vertical and Embedded Capacitors, the basic ones use Al or TiWAu (top side) and TiNiAu (bottom side).
Related terms : Silicon Capacitor(Si-Cap), Silicon IPD(Si-IPD, Integrated Passive Device), Pad, finishing, plating, electrode, mounting, gold(Au), aluminum(Al), nickel(Ni)