Electrode structure, and an electronic device

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure, and an electronic device such as a piezoelectric vibration chip, which suppresses the warpage of a substrate to a minimum while reducing unwanted capacitance (parasitic capacitance). SOLUTION: In the electronic device, a concave portion 21a and a first insulating layer 22 are formed in one main surface side of the substrate 21. The piezoelectric vibration piece 3 is mounted on mounting terminals 23a, 23b in the first insulating layer 22. In a third insulating layer 26 formed on the lower surface of the substrate 21, the thickness of the region except for a part just under external connection terminals 27a, 27b, is formed relatively thinner than the thickness of the part just under the terminals. The third insulating layer 26 is formed thickly in the part just under the external connection terminals 27a, 27b, so that the unwanted capacitance (parasitic capacitance) formed between the external connection terminals 27a, 27b and other conductive patterns around the same, is decreased. The third insulating layer 26 is relatively formed thinly in other regions, so that the warpage of the substrate 21 caused by the internal stress in the third insulating layer 26, is suppressed to the minimum. COPYRIGHT: (C)2010,JPO&INPIT