A novel manufacturing technology of buried RuO/sub 2/-based thick film resistors in copper-polyimide substrate

A novel manufacturing technology of buried RuO/sub 2/-based thick-film resistor (TFR) in copper-polyimide system has been studied. Since electrodes of copper thin film are formed on the TFR by using photolithography and a plating method and the resistance of TFR has a widely linear relation, the resistance is determined only by the geometry of the TFR within 10% variation to the designed value. A specially optimized pulse laser irradiates the TFR through the polyimide film in order to accurately adjust the resistance without any degradation of the overcoating polyimide film on the TFR. The surface of the TFR is modified, and the resistance decreases with the shot number of the laser. Analysis by heat conduction theory suggests that the non-degradation of the polyimide film is based on the shortness of the laser pulse duration. Results of reliability tests show the stability of the resistance of laser-modified buried TFR.<
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