no it isn't. Cpu's up to this point have use aluminum but are starting to use copper since it is a better conductor. As for it dispersing heat better I don't know if that is for the transfer for heat to the hsf or if it is used just because they can reach higher clocks easier.
It stands to reason that the interconnects of the cpu would help the cooling processs but realistically there would be no cooling advantage. (it would be a negligable advantage .0001C or something)