In-Situ Evaluation of High Frequency and High Temperature Characteristics of Dielectric in High-Density Substrate

To design a high-speed/frequency system, the dielectric material properties, i.e., dielectric constant and loss tangent are key inputs and their frequency and temperature dependency need to be “in situ” comprehended accurately, since important high-speed quantities, such as characteristic impedance, propagation constant and S-parameters, depend upon the physical dimensions and dielectric material properties of transmission line. This paper investigates frequency and temperature dependent properties of dielectric materials used for high performance microelectronic substrate up to 40 GHz under −40 to 200 deg C, with a general-purpose vector network analyzer (VNA) for obtaining S-parameter of “in situ” test coupons fabricated utilizing the actual process technology. Based on this “in situ” measurement, impact of the frequency and temperature dependent dielectric material properties on the high-speed quantities also have been discussed.