A solder preform is provided for forming interconnections between multilayer ceramic substrates comprising an upper layer and lower layer of solder separated by an intermediate layer of a material which is wettable by solder and which does not melt at the temperatures used to reflow the solder and form the connections. The solder preform is used to join the substrates and is particularly useful to simultaneously electrically interconnect the substrates and to form a hermetic seal between the substrates being joined.