3-D interconnected porous AlN composite: a viable substrate for electronic packaging

A simple conventional ceramic processing method was used. To fabricate 3-D interconnected porous aluminum nitride composites. To demonstrate this and show their applicability as substrates in electronic packaging aluminum nitride powders were cold pressed and sintered under controlled conditions of temperature and time to initiate particle necking and coarsening, but with minimum shrinkage. Initial densification studies show the formation of porous ceramics (≃30% porosity) containing contiguous pores. The composite exhibits a maximum, thermal conductivity of 40 W/m-K and a dielectric constant of 4.73. The thermal conductivity of these composites, however, tends to increase drastically with an increase in the sintering temperature and time, while maintaining the volume fraction of aluminum nitride nearly constant. On the other hand the dielectric constant appears to be independent of the sintering temperature and time. Borsphosphosilicate glass was also infiltrated into the porous AlN composite to form a partially glass-infiltrated 3-D interconnected porous AlN composite. These composites were characterized at room temperature for their thermal conductivity and dielectric constant. Results of these studies show the potential of such composites for use as substrata in electronic packaging