A self-constrained low-temperature-cofired ceramic system with a multilayer structure of a low-temperature cofirable CaO-B2O3-SiO2 glass (CBSG) tape and a pure alumina tape has been developed. Because the densification temperature range required for the CBSG layer is much lower than that needed for pure alumina, its lateral shrinkage is inhibited by the presence of a nondensified alumina layer during cofiring. Porosity in the alumina layer is later filled by the capillary infiltration of free glass in the densified CBSG. This leads the linear shrinkage of the multilayer CBSG/alumina laminate to take place only in the Z direction with little shrinkage in the X-Y directions, which exhibits unique characteristics of self-constrained densification.