2 then a side surface of the insulating substrate 2 is ground to that ground surface titanium ti and palladium pd are applied by spattering in such a manner that the thicknesses of the titanium ti spatter and the palladium pd spatter are 2 000 u00e5 and 5 000 u00e5 respectively thereafter photoresist is applied to the entire side surface of the insulating substrate 2 a photomask formed with a wiring pattern is disposed above the photoresist and exposed to light a portion of the photoresist where a wiring pattern is to be formed is removed by developer and gold au plating is applied thereto then the remaining photoresist is removed and an unnecessary part of the titanium ti and palladium pd spatter is removed by etchant for thereby forming the exterior part of the wiring 3 separately a copper sheet of the thickness of about 0 2 mm is formed into a comblike shape to constitute the metal cores 51 for the leads 5 the metal cores 51 are then plated with nickel ni and gold au in sequence for thereby being formed into the leads 5 further a frame made of koval is prepared and similarly plated with nickel ni and gold au in sequence for thereby being formed into the frame like strip 4 of the part of the wiring 3 located on the exterior surface of the insulating.