Patent ID: 9013247
Filing Date: 2015-04-21
Classification: H03H

Abstract:
1. An elastic wave demultiplexer comprising: an elastic wave filter chip including a longitudinally-coupled-resonator-type elastic wave filter unit that includes a piezoelectric substrate and a plurality of IDT electrodes provided on the piezoelectric substrate; and a wiring substrate including a die-attach surface on which the elastic wave filter chip is mounted, a rear surface opposed to the die-attach surface, a land electrode layer including a plurality of land electrodes, a rear-surface terminal layer including a plurality of terminals, a plurality of intermediate electrode layers including a plurality of wiring electrodes, and at least three dielectric layers, the plurality of land electrodes being provided on the die-attach surface and being connected to the elastic wave filter chip, the plurality of terminals being provided on the rear surface, and the plurality of land electrodes being connected to the plurality of terminals via the plurality of wiring electrodes; wherein each of the at least three dielectric layers is arranged between two of the land electrode layer, the plurality of intermediate layers, and the rear-surface terminal layer and the at least three dielectric layers include a plurality of via-hole electrodes connected to any of the plurality of land electrodes, the plurality of wiring electrodes, and the plurality of terminals; the plurality of terminals include a ground terminal that is grounded; the plurality of land electrodes include ground land electrodes connected to the ground terminal; the plurality of wiring electrodes include a plurality of ground wiring electrodes via which the ground terminal is connected to the ground land electrodes; the plurality of via-hole electrodes include first ground via-hole electrodes via which the ground wiring electrodes are connected to each other, second ground via-hole electrodes via which the ground wiring electrodes are connected to the ground land electrodes, and a third ground via-hole electrode via which the ground wiring electrodes are connected to the ground terminal; and a number of the first ground via-hole electrodes is greater than a number of the second ground via-hole electrodes and a number of the third ground via-hole electrodes.