MECHANISM OF PREVENTING CRYSTALLIZATION IN LOW-FIRING GLASS-CERAMIC COMPOSITE SUBSTRATES

The formation of a crystal phase in the glass matrix of low-firing glass/ceramic composite substrates limits the efficiency of the ceramic substrate when it is used in circuit boards,In the present study, adding approximately 30 vol% or more of alumina to a borosilicate-glass/ceramic composite system as a ceramic filler caused the diffusion of aluminum ions from the alumina filler into the glass matrix and prevented the formation of a cristobalite crystal phase. The diffusion distance between the aluminum ions was similar to 30 mu m when the system was fired at 900 degrees C for 10 min. Raman spectroscopic analysis proved that some of the aluminum ions had diffused into the glass matrix during firing, working as a network former in the grass matrix, Raman spectra near 460 and 1100 cm(-1) indicate the change of network structure in the borosilicate glass. These phenomena indicate that crystallization of the borosilicate glass was prevented in the alumina-filled borosilicate system.