Method for manufacturing a piezoelectric device

A method for manufacturing a piezoelectric device including a piezoelectric substrate provided with driving electrodes on the opposing major surfaces a plurality of outer coating substrates, each of which is laminated on one of the opposing major surfaces of said piezoelectric substrate, adhesive layers arranged to bond the piezoelectric substrate and the outer coating substrates to each other at the opposing major surfaces of the piezoelectric substrate, and a plurality of external electrodes provided in regions of a lateral side surfaces of a layered body including said piezoelectric substrate, said outer coating substrates, and said adhesive layers, wherein each of the adhesive layers includes a first layer of an adhesive having a Shore D harness after curing of not more than approximately 60 which is provided so as not to be exposed in the regions of the lateral side surfaces of the layered body provided with the plurality of external electrodes thereon, a second layer of an adhesive having a Shore D hardness after curing of at least approximately 60, and a third layer of an adhesive having a Shore D hardness after curing of at least approximately 60, and having a viscosity before curing of at least approximately 3.0×105 mPas, the third layer being disposed between portions of the periphery of the first layer and the regions of the lateral side surfaces of the layered body provided with the plurality of external electrodes thereon, and wherein said second layer is laminated on said first layer and said third layer, the method comprising the steps of:

• applying said third layer of each of the adhesive layers on a major surface of each of the plurality of outer coating substrates;
• applying said first layer of each of the adhesive layers to regions of the major surface of each of the plurality of outer coating substrates where said third layer is not applied;
• applying said second layer of each of the adhesive layers;
• and
• bonding said piezoelectric substrate and said plurality of outer coating substrates to each other through said second layer, the outer coating substrates including the third layer and the first layer.