PURPOSE: To obtain a printed wiring board of a high accuracy and excellent characteristics by a method wherein a thin film resistor layer is formed on a ceramic substrate, the surface of a resistor obtainable by firing the resistor layer on the substrate is covered with a chemicalresistant protective layer except the terminal parts of the resistor, a conductor pattern is formed by a wet plating method and a heating treatment is performed.

CONSTITUTION: A thin film firing type resistor paste is coated on a ceramic substrate in the form of a pattern by a screen printing method and is fired in the air to form a resistor. A thick film firing type glass paste is coated on this resistor in the form of a pattern by a screen printing method in such a way that the surface of the resistor and a wall surface are covered with the glass paste excepting the terminal parts of the conductor and is fired in the air. Then, the whole surface of the substrate is covered with an electroless copper plating and moreover, an N-type plated resist is formed in the form of a circuit pattern to deposit an electrolytic copper plating. After that, the resist is peeled and a thinly attached electroless plated part is removed with an etching liquid. Lastly, a heating treatment is performed in a nitrogen-containing atmosphere at 400°C for 10 minutes. In such a way, a plated metal is thermodiffused properly on the terminal parts of the resistor and a printed wiring board of a high accuracy and high characteristics is completed.