Published online by Cambridge University Press: 15 February 2011
This paper reports the use of hollow ceramic microspheres for a controlled porosity composite application and an emulsion/extraction method to make them. Design guidelines for this application are presented in which the physical properties and geometry of the microspheres are correlated to both dielectric constant and mechanical strength of the composites. The analytical modeling indicates that small size, thin walled ceramic microspheres with thermal expansion coefficients greater than that of common ceramic substrate matrices are needed to lower the dielectric constant significantly while retaining good mechanical strength. An emulsion/water extraction method was developed to prepare such hollow ceramic microspheres. This method shows promise for making very small (< 10 μm) hollow microspheres of various ceramic compositions. The capability and limitation of this synthesis route are shown.