(A) study on high dielectric constant and low tolerance embedded capacitor materials and process

Abstract

Embedded capacitor technology is an essential method for miniaturization and high performance of electronic package systems. High dielectric constant epoxy/ceramic composite have been of great interest as embedded capacitor materials for MCM-L applications, because they have good processability and compatibility with printed wiring boards (PWB), in addition to high dielectric constant. In our study, $epoxy/BaTiO_3$ composite embedded capacitor films (ECFs) has been developed for the fabrication of embedded capacitors with high dielectric constant and low capacitance tolerance $(\lt \plusmm 10%)$ in organic substrate and the properties of the capacitors using ECFs, which were dielectric constant, loss tangent, adhesion strength with organic substrate and temperature dependence, were characterized. ECFs should be formed as thin as possible and there were many methods for casting capacitor film. The rheology of ECFs and composition of epoxy were characterized for forming thin film in the point of surface morphologies and film formability. By using gravure and comma roll tape casting method, the ECFs of low capacitance tolerance $(\lt \plusmm 10%)$ and thickness $(\It 10um)$ was successfully demonstrated and 10um ECFs by comma roll was generalized in this study. The failure site of ECFs and organic substrate was the interfaces of epoxy and $BaTiO_3$ powders. So for high dielectric constant and reliability in high $BaTiO_3$ powder loading, the interface characteristics of epoxy and $BaTiO_3$ should be improved. By using coupling agent of titanate system and encapsuling agent of phosphoric acid system, the adhesion strength of ECFs was improved. In further study, the reactivity of $BaTiO_3$ and each agent will be investigated. In the general fabrication process of embedded passives, film types of embedded capacitor occupy large unnecessary area on the surface of interlayer. However for improving space utilization in the interlayer within organic substrate, whic...