Thanks for the replys. I know nothing of the intricacies of cap. selection. I will go read the link suggested after posting.
I was going to use the AFK108M50P44T whose data sheet is here:
http://www.cde.com/catalogs/AFK.pdf
I intend to use the cap. as part of a the power supply of a GSM module. The GSM module needs the cap. because it draws up to 2 amps instaneously during bursts of data txing. The cap. is to provide a 'reservoir' to ensure there is no voltage drop during these bursts. V drop will lead to malfunction, so says the manufacuters manuals. Said manuals say to use the biggest cap. you can, 1000uf or larger located as close as possible to the module.
I have several protos pcb Ive designed with the module functioning on them. Im now drawing up another smaller board and as Im trying to stuff the whole design into a much smaller package Im looking at smd parts like the cap above.
Is there any advantage to using a higher voltage rate cap. at all. I saw a note in the mouser catalogue that said you can use a higher rated cap in a smaller V circuit.
Would I be better off using a 6.3V/ 6800uf cap? (The GSM module is running on 3.6V's).
Its in the same package as the 50V part.