ATTENUATION IN SILVER-FILLED CONDUCTIVE EPOXY INTERCONNECTS

The attenuation of microstrip transmission lines fabricated with a new type of multiphase epoxy adhesive, called area bonding conductive (AB C) adhesive, has been measured from 45 MHz to 10 GHz, This ABC adhesiv e consists of a silver flake fill in a polymer matrix, and allows for both thermal and electrical conductivity in addition to increased stre ngth, The board processing details are discussed along with the screen printing procedure. A technique for extracting the attenuation and sh eet resistivity is presented which is based on network analyzer measur ements of the S-21 scattering parameter, The performance for three dif ferent concentrations of silver flake in the conductive epoxy is compa red with copper microstrip. There is a significant decrease in attenua tion and sheet resistance as the concentration of silver increases, bu t in all cases the attenuation is a well-behaved function of frequency , Also, it is shown that microstrip transmission lines fabricated usin g stencil printing perform better at high frequencies than those made from screen printing.