A New Electroless Method for Low-Loss Microwave Integrated Circuits

A new method of depositing copper on alumina substrates is described. This results in less attenuation and better adhesion than that obtained by the prior method. The measured attenuation of microstriplines made by conventional vacuum evaporation of chromegold and by electroless copper deposition methods is compared in the range of 2-10 GHz. It is found that classical chrome-gold metallization gives higher attenuation. The experimental data for this new method are in good agreement with the theoretically predicted values. The superiority of the new method over the prior methods is discussed.