Method for manufacturing resonant element
A resonant element is manufactured through a process including a setting step and a forming step. A substrate of the resonant element is made of a dielectric material. A ground electrode is formed on a rear principal surface side of the substrate. Principal-surface electrodes that define resonators together with the ground electrode and the dielectric material are formed on a front principal surface side of the substrate. An electrode protecting layer is formed on substantially entire surfaces on a front principal surface side of the principal-surface electrodes and the substrate. A coupling adjusting electrode with both ends facing a plurality of the principal-surface electrodes is formed on a front principal surface side of the electrode protecting layer. In the setting step, the shape of the coupling adjusting electrode is set in each manufactured lot. In the forming step, the coupling adjusting electrode having the shape set in the setting step in each manufactured lot is formed on the front principal surface side of the substrate and the electrode protecting layer that are sintered in advance, and the coupling adjusting electrode is baked to the electrode protecting layer.
1. A method for manufacturing a resonant element including a substrate made of a dielectric material, a ground electrode formed on a rear principal surface side of the substrate, principal-surface electrodes formed on a front principal surface of the substrate and that define resonators together with the ground electrode and the dielectric material, an electrode protecting layer formed on substantially entire surfaces on a front principal surface side of the substrate and the principal-surface electrodes, and a coupling adjusting electrode that is formed on a front principal surface side of the electrode protecting layer and that has both ends facing the principal-surface electrodes of two of the resonators, the method comprising in order:
a setting step of setting a shape of the coupling adjusting electrode in each manufactured lot; and
a forming step of forming the coupling adjusting electrode having the shape set in the setting step in each manufactured lot on the front principal surface side of the substrate and the electrode protecting layer sintered in advance, and baking the coupling adjusting electrode to the electrode protecting layer.
2. The method for manufacturing the resonant element according to claim 1 , wherein the setting step is a step of measuring a predetermined characteristic of the resonators in each manufactured lot and setting a formation size of the coupling adjusting electrode based on a result of the measuring.
3. The method for manufacturing the resonant element according to claim 2 , wherein the forming step is a step of forming the coupling adjusting electrode using a photolithography process, and the setting step is a step of setting an exposure time or an opening shape of an exposure mask in the photolithography process in each manufactured lot.
4. The method for manufacturing the resonant element according to claim 1 , wherein the electrode protecting layer has a permittivity that is less than a permittivity of the substrate.
5. The method for manufacturing the resonant element according to claim 4 , wherein the electrode protecting layer is a thick glass layer primarily including SiO 2 .