PURPOSE: To prevent silver form migrating by a method wherein a wiring conductor layer which is built on an insulating board and whose main component is silver and another wiring conductor which is provided onto the insulating board and whose main component is copper are connected together with a palladium conductor or a conductor mainly formed of palladium.
CONSTITUTION: 30% by weight of alumina, 20% by weight of silica, and 50% by weight of alumino-borosilicate lead glass are mixed to prepare slip, and a green sheet is formed. An insulator sheet provided through-holes is formed of the green sheet, and conductor paste of palladium, palladium-silver, or palladium-copper is filled into the through-holes. Furthermore, a wiring pattern is formed making its one end connected to the through-holes concerned by the use of past composed of 85% by weight of silver and 15% by weight of palladium, and the insulator sheets provided with the through-holes are laminated and bonded together by thermocompression, which is burned into an insulating board. A wiring pattern is formed on the insulating board concerned using conductor paste whose main component is copper so as to be connected to the through-holes, which is burned. By this setup, silver is prevented from migrating.
ONIZUKA KATSUHIKO
YASUI MASAKAZU
