MANUFACTURE OF CIRCUIT BOARD

PURPOSE:To form a ruthenium oxide thick film resistor on a resin substrate by printing and drying ruthenium oxide thick film resistance paste on the substrate, and then heating and scanning a condensed heat beam. CONSTITUTION:When a condensed heat beam is scanned on a ruthenium oxide thick film paste 3 dried after printed on a resin substrate 1, an organic binder in the paste is momentarily sublimed, glass frit layer is melted, a conduction passage of the ruthenium oxide is formed to become a resistor 4. In this case, when the condensed heat beam and the scanning speed are selected, the upper end of the thick film resistance layer is preferentially baked, and the lower end can be formed in an unbaked state, and no thermal damage is applied to a resin substrate disposed on the lower layer further under the lower end to form a resistor. When a Nd:YAG laser light is, for example, used as the condensed heat beam, the resistor having various resistance value range is obtained by altering the scanning speed of the laser light, the output or the emitting width of the light.