A method for manufacturing a bonded substrate, the method includes: bonding a first mother substrate including a first substrate and a second mother substrate including a second substrate to form a bonded mother substrate; cutting off a part of the first mother substrate along a dividing line of the bonded mother substrate to form a cutoff portion; dividing the bonded mother substrate along the dividing line; separating a bonded substrate from the bonded mother substrate, the bonded substrate including the first substrate and the second substrate bonded to the first substrate; forming a contact terminal on an end portion of the first mother substrate, the contact terminal contactable with an external terminal; forming a communication path between the first mother substrate and the second mother substrate along the dividing line.

Provided are an MEMS device, a head, and a liquid jet device in which substrates are inhibited from warping, so that a primary electrode and a secondary electrode can be reliably connected to each other. Included are a primary substrate 30 provided with a bump 32 including a primary electrode 34, and a secondary substrate 10 provided with a secondary electrode 91 on a bottom surface of a recessed portion 36 formed by an adhesive layer 35. The primary substrate 10 and the secondary substrate 30 are joined together with the adhesive layer 35, the primary electrode 34 is electrically connected to the secondary electrode 91 with the bump 32 inserted into the recessed portion 36, and part of the bump 32 and the adhesive layer 35 forming the recessed portion 36 overlap each other in a direction in which the bump 32 is inserted into the recessed portion 36.

A flow path structure which forms a flow path of liquid, includes: a light absorbing member (first substrate) having absorbing properties with respect to laser light; a light transmitting member (second substrate) which is joined to the light absorbing member and has transmitting properties with respect to the laser light; a first flow path (flow path) which is surrounded by a welding interface between the light absorbing member and the light transmitting member; and a second flow path which is formed in a flow path pipe (flow path pipe) which protrudes from a front surface opposite of the welding interface in the light transmitting member, and communicates with the first flow path, in which the flow path pipe is included in a region of the first flow path in a plan view from a direction orthogonal to the welding interface.

A piezoelectric device includes a diaphragm provided on a side of one surface of a substrate, and a piezoelectric actuator having a first electrode, a piezoelectric body layer, and a second electrode which are stacked in a first direction on a side of a surface opposite to the substrate of the diaphragm, in which when one area far from an end portion of the second electrode is a first area and one area near the end portion of the second electrode is a second area, of two areas of the second electrode in a second direction intersecting the first direction, the second electrode has a stiffness of 17,000 N/m or more in the second area in the first direction, which is higher than a stiffness in the first area in the first direction, and a length in the second area in the first direction is equal to or less than a length of the piezoelectric body layer in the second area in the first direction.

A piezoelectric actuator is disclosed that may include a insulating layer, individual electrodes, a common electrode, and a piezoelectric layer. The common electrode may include divisional electrodes that are connected with one another. The individual electrodes may be disposed between the insulating layer and the piezoelectric layer while the piezoelectric layer may be disposed between the individual electrodes and the common electrode. Further, the divisional electrodes may be configured to face the individual electrodes.

A piezoelectric film includes a plurality of laminated main baking unit PZT layers. A first seed layer is present at a lower surface side of a lowermost main baking unit PZT layer. A second seed layer is interposed between two adjacent main baking unit PZT layers at an intermediate position between the lowermost main baking unit PZT layer and an uppermost main baking unit PZT layer.

An actuator includes a deformable thin-film member having an opening, an electromechanical conversion element disposed at a periphery of the opening of the deformable thin-film member, an insulating film covering the electromechanical conversion element, a protective film over a surface of the insulating film, the protective film covering the surface of the insulating film and a surface of an electrode wiring connected to the electromechanical conversion element, and an adhesion improving film disposed between the electrode wiring and the protective film.

A liquid discharging head includes a stacked body in which plates are adhered to each other by an adhesive. The stacked body is provided with: individual channels including nozzles and pressure chambers, respectively, and aligned in a predetermined aligning direction, the pressure chambers being configured to be pressurized to discharge liquid from the nozzles; a supply manifold being communicated with the individual channels and supplying the liquid to the individual channels; a return manifold being communicating with the individual channels and configured to allow the liquid, which flows in the individual channels and which is not discharged from the nozzles, to flow therethrough; and a dummy channel arranged side by side with the individual channels in the aligning direction. The dummy channel is positioned at outside with respect to an outermost individual channel in the aligning direction.

An inkjet recording head comprising a flow channel member, wherein the flow channel member is formed of a heat-cured product of a molding material comprising a resin composition comprising a thermosetting epoxy resin and a curing agent, and a filler; the filler comprises alumina and silica; and with d50 as a median diameter of the silica and with alumina A as the alumina having a median diameter of d50/4 or less, the content of the alumina A is 11 parts by mass or more relative to 100 parts by mass of the silica.

An electric current based on electric charge produced on the piezoelectric body changes by going through a first path, a second path, a third path, and a fourth path in this order. On the first path, the electric current becomes larger as the voltage becomes higher. On the second path, the electric current becomes smaller as the voltage becomes higher. On the third path, the electric current becomes larger as the voltage becomes higher. On the fourth path, the electric current becomes smaller as the voltage becomes higher.