THICK FILM MULTILAYER SUBSTRATE

摘要

PURPOSE:To relax the stress between a multilayer insulator and a substrate and at the same time improve the mechanical strength of the substrate by forming a wiring layer with upper and lower layers and providing a separation recessed part for separating a wiring layer only at the upper layer of the wiring layer. CONSTITUTION:A separation recessed part 5 is provided for relaxing the stress on baking due to the difference in the expansion coefficient between a substrate 1 and an insulator 2. In the insulator 2 formed by multilayer printing, the separation recessed part 5 for separating a wiring layer 7 is provided at an upper-layer part A which is located above the second insulation layer no separation recessed part 5 exists at a lower-layer part B which is equal to or less than the second insulation layer and then an internal conductor 3 and the insulator 2 are provided. With the configuration, since the separation recessed part 5 is provided only at the upper-layer part A of the wiring layer 7, the stress due to the difference in the expansion coefficient between the substrate 1 and the insulator 2 can be absorbed by the separation recessed part 5 regardless of the repeated baking, thus preventing the internal conductor 3 and the insulator 2 from being cracked and warped. Also, no separation recessed part 5 exists at the lower-layer part B of the wiring layer 7 and mechanical strength can also be improved.