PURPOSE: To provide a ceramic insulating board having excellent insulation and heat emissivity and adapted for reduction in weight and size by seizing thick film paste printed in a pad pattern on the surface of a thin ceramic board manufactured by a sol-gel method.

CONSTITUTION: A pad for connecting a transistor to a heat sink plate is printed with Cu paste containing Cu fine powder, glass powder, organic solvent and organic binder on both front and rear surfaces of an alumina board 5 manufactured by a sol-gel method by a screen printer. Then, after the above printed paste is seized in nitrogen gas containing very small amount of oxygen, Ni- and Au-plating films are sequentially formed on the surface of the formed Cu printed part to manufacture an insulating board 1 having thick films 6, 6, for connecting transistors to heat sink plates on both front and rear surfaces of the board 5.