LTCC Technology at High Millimetre Wave Frequencies

Low temperature co-fired ceramic technology (LTCC) has become a viable technology for many millimetre wave applications. In this paper, the dielectric properties of a typical LTCC tape are presented, including relative permittivity, dielectric loss factor and loss tangent. LTCC interconnection losses including dielectric loss, conductor loss and surface roughness loss are also discussed in detail. A scanning electron microscope (SEM) was used to examine the surfaces of the thick-film gold conductors and the significance of surface roughness is discussed with respect to skin depth at these high frequencies. The results of a simple, but novel, experiment illustrating the effect of controlling the surface roughness at millimetre wave frequencies are also presented