JP2011218682A - Ink jet head, method of manufacturing ink jet head, and ink jet drawing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head which does not prevent deformation of an actuator, prevents excessive press and contact failure between a wiring substrate and a piezoelectric element, and improves reliability of electrical connection.SOLUTION: The ink jet head 1 includes: a head substrate 10 having a plurality of nozzles 11a, a plurality of pressure chambers 13a, and the actuator 15; and the wiring substrate 20 having wiring. The ink jet head 1 is structured by crimping the wiring substrate 20 on the head substrate 10 through an adhesive resin layer 30 at a predetermined heating temperature to electrically connect an electrode on a surface of the actuator 15 and the wiring, and join the head substrate 10 and the wiring substrate 20. The electrode on the surface of the actuator 15 and the wiring are electrically connected by bonding a first bump having a melting point higher than the heating temperature and a second bump having a melting point equal to or lower than the heating temperature. One of the first bump and the second bump is arranged on the electrode on the surface of the actuator 15, and the other one is arranged on the wiring.

Description

  The present invention relates to an ink jet head, an ink jet head manufacturing method, and an ink jet drawing apparatus. More specifically, the present invention relates to an ink jet head with improved reliability of electrical connection of wiring for supplying power to an actuator, an ink jet head manufacturing method, and an ink jet drawing apparatus. .

  In recent years, inkjet heads that form images on various recording media by ejecting ink from a plurality of fine nozzles have been required to have a higher density of nozzles in order to achieve more accurate and finer image formation. It has been.

  The ink jet head is provided with a common ink flow path for each nozzle row, and also includes a pressure chamber for applying discharge pressure to the ink, and an individual flow path for supplying ink from the common flow path to each pressure chamber. These are provided individually for a plurality of nozzles. Therefore, if these common flow paths, pressure chambers, and individual flow paths are arranged side by side in the nozzle arrangement direction (horizontal direction), it becomes difficult to arrange a plurality of nozzles at high density.

  Therefore, conventionally, the ink jet head body is configured by a laminated body in which a pressure chamber is provided above the nozzle and a common ink chamber replacing the common flow path is provided above the pressure chamber, thereby suppressing the spread in the nozzle arrangement direction. An ink jet head capable of arranging nozzles at a high density has been proposed (see, for example, Patent Document 1). In this ink jet head, the upper wall of the pressure chamber in the laminate is formed into a thin plate to form a diaphragm, and an actuator formed by an electromechanical transducer such as a piezoelectric element is laminated on the upper surface of the diaphragm.

  In such an inkjet head having a laminated body, it is necessary to form each wiring for supplying power to the actuator with high density. However, since the flow path for supplying ink to each pressure chamber is already arranged on the substrate on which the actuator is installed, in addition to the actuator itself, there is not enough room for drawing the wiring. . For this reason, a wiring board (interposer) on which wiring for supplying power to each actuator is formed is separately formed, and this is laminated on the laminated body from above the actuator to be formed on the surface of each actuator. The wiring is densified by electrically connecting the electrode (upper electrode) and each wiring.

  At this time, it is necessary to form a predetermined gap between the wiring board stacked from above the actuator and the actuator so as not to hinder the mechanical displacement of the actuator. In Patent Document 1, a rib partition made of a photosensitive resin is provided between a wiring board and a laminate so as to surround the periphery of the actuator, thereby forming a predetermined space between the wiring board and the actuator. By forming bumps projecting toward the actuator side on the wiring on the wiring board side, electrical connection between the wiring and the electrode on the actuator surface can be achieved at the time of bonding.

JP 2006-264322 A JP 2004-262190 A

  The bumps used for facilitating electrical connection are generally solder bumps that can be easily melted and joined by heating, but the solder is used for the upper electrode of the actuator (generally a gold electrode is used). Therefore, when both are joined, there is a problem that the solder spreads on the surface of the upper electrode and hinders the deformation of the actuator.

  Further, in the conventional method, when the wiring board is joined from above the actuator, a rib partition made of a photosensitive resin that forms a space between the wiring board and the actuator is thermocompression-bonded. However, at this time, the rib partition wall is compressed and deformed by pressure bonding, so that a dimensional change is likely to occur, and it is difficult to strictly maintain the distance between the wiring board and the actuator. As a result of extensive studies by the inventor, it was confirmed that a reduction in size of about 10% occurred. As a result, a portion that is pressed too much between the bump protruding from the wiring and the electrode on the surface of the actuator is generated, which causes a problem of substrate damage.

  If the bump height is set low in consideration of the size reduction in order to prevent the substrate from being damaged, a part that does not partially contact is generated, resulting in a contact failure.

  For this reason, there is a problem that it is difficult to perform highly reliable electrical connection in a state where everything is properly conducted without fear of causing damage to the substrate.

  The problem of poor contact can be solved by forming the bump protrusion height larger than the distance between the wiring and the actuator surface, but increasing the bump protrusion height will cause excessive pressing. This will result in the risk of damage to the substrate.

  Therefore, the present invention does not hinder the deformation of the actuator, and when the wiring board is laminated above the actuator via the resin adhesive layer, excessive pressing or contact failure occurs between the wiring board and the piezoelectric element. It is an object of the present invention to provide an ink jet head with improved electrical connection reliability.

  In addition, the present invention does not hinder the deformation of the actuator, and when the wiring board is laminated above the actuator via the resin adhesive layer, excessive pressing or contact failure occurs between the wiring board and the piezoelectric element. It is an object of the present invention to provide an ink jet head manufacturing method capable of performing highly reliable electrical connection without any problem.

  Furthermore, the present invention does not hinder the deformation of the actuator, and when the wiring board is laminated above the actuator via the resin adhesive layer, excessive pressing or contact failure occurs between the wiring board and the piezoelectric element. It is an object of the present invention to provide an inkjet drawing apparatus including an inkjet head with improved electrical connection reliability.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

According to the first aspect of the present invention, a plurality of nozzles that eject ink, a plurality of pressure chambers that are respectively disposed corresponding to the nozzles, and that store ink to be ejected from the nozzles, and the pressure chambers, respectively A head substrate having a correspondingly arranged actuator for applying a force for ejecting ink in the pressure chamber from the nozzle, and a wiring substrate having a wiring for supplying power to the electrode on the actuator surface. The wiring substrate is pressure-bonded to the head substrate through a bonding resin layer at a predetermined heating temperature, whereby the electrode on the actuator surface and the wiring are electrically connected and the head substrate. And an inkjet head formed by bonding the wiring board,
The electrical connection between the electrode on the actuator surface and the wiring is performed by joining a first bump having a melting point higher than the heating temperature and a second bump having a melting point lower than the heating temperature. In the inkjet head, one of the first bump and the second bump is provided on the electrode on the actuator surface, and the other is provided on the wiring.

  The invention according to claim 2 is the ink jet head according to claim 1, wherein the tip end of the first bump is electrically connected in a state of biting into the inside of the second bump. .

  The invention according to claim 3 is the ink jet head according to claim 1 or 2, wherein the first bump is a stud bump, and the second bump is a solder bump.

  The invention according to claim 4 is characterized in that the stud bump has a shoulder located at the base and a protrusion protruding from the shoulder, and the solder bump has a flat or spherical tip. The inkjet head according to claim 3.

  The invention according to claim 5 is the ink jet head according to claim 3 or 4, wherein the stud bump is a gold stud bump.

According to a sixth aspect of the present invention, a plurality of nozzles that discharge ink, a plurality of pressure chambers that are disposed corresponding to the nozzles, and that store ink for discharging from the nozzles, and the pressure chambers, respectively. A head substrate having a correspondingly arranged actuator for applying a force for ejecting ink in the pressure chamber from the nozzle, and a wiring substrate having a wiring for supplying power to the electrode on the actuator surface. The wiring board is pressure-bonded to the surface of the head substrate via an adhesive resin layer at a predetermined heating temperature, thereby electrically connecting the electrode on the actuator surface and the wiring and the head. A method of manufacturing an inkjet head for bonding a substrate and the wiring substrate,
A first bump having a melting point higher than the heating temperature is provided on one of the electrode and the wiring on the actuator surface, and a second bump having a melting point equal to or lower than the heating temperature is provided on the other.
A method of manufacturing an ink-jet head, wherein the first bump and the second bump are electrically connected to each other by pressing the wiring substrate against the head substrate at the heating temperature.

  The invention according to claim 7 is the method of manufacturing an ink jet head according to claim 6, wherein the first bump is a stud bump and the second bump is a solder bump.

  The invention according to claim 8 is characterized in that the stud bump has a shoulder located at the base and a protrusion protruding from the shoulder, and the solder bump has a flat or spherical tip. The method of manufacturing an ink jet head according to claim 7.

  The invention according to claim 9 is the method of manufacturing an ink jet head according to claim 7 or 8, wherein the stud bump is a gold stud bump.

The invention according to claim 10 is characterized in that the first bump and the second bump before joining the head substrate and the wiring substrate satisfy the following conditions (I) and (II). It is a manufacturing method of the ink-jet head in any one of Claims 6-9.
(I) Total height of the first bump <thickness of the adhesive resin layer−height from the adhesion surface of the adhesive resin layer to the head substrate to the upper surface of the actuator <total height of the first bump + total height of the second bump (II ) Overall height of the second bump <the thickness of the adhesive resin layer-the height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator

The invention according to claim 11 is characterized in that the stud bump and the solder bump before joining the head substrate and the wiring substrate satisfy the following conditions (III) and (IV). The method for producing an ink jet head according to 8 or 9.
(III) Shoulder Height <Adhesive Resin Layer Thickness-Adhesive Resin Layer Adhesive Surface to Head Surface> Actuator Top Height <Stud Bump Total Height + Solder Bump Total Height (IV) Solder Bump Total Height <Thickness of adhesive resin layer-height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator

  A twelfth aspect of the present invention is an ink jet drawing apparatus comprising the ink jet head according to any one of the first to fifth aspects.

  According to the present invention, the deformation of the actuator is not hindered, and when the wiring board is laminated above the actuator via the resin adhesive layer, there is no contact failure or excessive pressing between the wiring board and the piezoelectric element. It is possible to provide an ink jet head that does not occur and has improved electrical connection reliability.

  Further, according to the present invention, the deformation of the actuator is not hindered, and when the wiring board is laminated above the actuator via the resin adhesive layer, the contact failure or the pressing between the wiring board and the piezoelectric element is prevented. Therefore, it is possible to provide a method for manufacturing an ink-jet head capable of performing electrical connection with high reliability.

  Furthermore, according to the present invention, the deformation of the actuator is not hindered, and when the wiring board is laminated above the actuator via the resin adhesive layer, the contact failure or the pressing between the wiring board and the piezoelectric element is prevented. Therefore, an ink jet drawing apparatus including an ink jet head with improved reliability of electrical connection can be provided.

The figure explaining the connection aspect of bumps in this invention Sectional drawing of the inkjet head which concerns on this invention Partial enlarged sectional view of an inkjet head according to the present invention The figure explaining a mode that bump in the present invention connects The figure which shows the other aspect which bumps connect in this invention Schematic perspective view showing an example of an ink jet drawing apparatus according to the present invention

  The ink jet head of the present invention has a laminate structure in which a head substrate and a wiring substrate are joined. The head substrate is disposed corresponding to each of a plurality of nozzles for discharging ink, a plurality of pressure chambers for storing ink for discharging from the nozzles, and a pressure chamber, And an actuator for applying a force for discharging the ink in the pressure chamber from the nozzle.

  The actuator is stacked on the outside of the upper wall of the pressure chamber located on the surface of the head substrate, and a lower electrode provided on the surface in contact with the head substrate with an actuator body made of a piezoelectric element such as PZT interposed therebetween. And an upper electrode provided on the opposite surface. The actuator body is deformed by applying a predetermined drive signal between these electrodes, and the vibration plate formed by the upper wall of the pressure chamber is vibrated, thereby causing the pressure in the pressure chamber to discharge. Is granted.

  The wiring board has wiring for supplying power to the upper electrode exposed on the actuator surface, and this wiring board is attached to the actuator side surface of the head substrate at a predetermined heating temperature via an adhesive resin layer. By pressure bonding, the surface of the head substrate and the surface of the wiring substrate are joined by the adhesive resin layer. Simultaneously with this joining, the upper electrode on the actuator surface and the wiring are electrically connected.

  The adhesive resin layer is provided between the head substrate and the wiring substrate except for the actuator and its periphery, thereby bonding the substrates to each other so as to ensure an accommodation space for the actuator between the two substrates. This adhesive resin layer has a predetermined elastic modulus (0.1 to 2.5 GPa) before bonding, and is cured by being heated to a predetermined curing temperature (for example, 200 ° C.) at the time of bonding. It is a thermosetting adhesive resin layer that exhibits

  A photosensitive adhesive resin sheet can be preferably used for such an adhesive resin layer. In the photosensitive adhesive resin sheet, an unnecessary portion that becomes an accommodation space for the actuator can be easily removed by exposure and development processing, and a layer having a desired pattern can be easily formed. As a specific adhesive resin layer, for example, Toray Co., Ltd. photosensitive polyimide adhesive sheet, DuPont PerMX series (trade name) or the like can be used.

  The electrical connection between the upper electrode on the surface of the actuator and the wiring is made by joining the first bump whose melting point is higher than the heating temperature at the time of bonding and the second bump whose melting point is equal to or lower than the heating temperature at the time of bonding. Is an electrical connection. The first bump and the second bump may be provided on either the upper electrode or the wiring. That is, one of the first bump and the second bump is provided on the upper electrode on the actuator surface, and the other is provided on the wiring.

  According to the present invention, when the head substrate and the wiring substrate are bonded by thermocompression bonding, the second bumps are melted, and the first bumps are bonded to each other while maintaining a predetermined bump shape. Therefore, even if the adhesive resin layer is compressed and deformed at the time of joining, and the distance between the head substrate and the wiring substrate becomes shorter than the total distance of the protruding heights of the first bump and the second bump. Since the first bumps bite into the melted second bumps to absorb the dimensional change of the adhesive resin layer, there is no excessive pressing between the actuator and the wiring, and the reliability of the electrical connection Can be improved.

  In addition, in order to prevent a contact failure and achieve reliable electrical connection, even if the protruding height is formed so that the bumps overlap each other, the first bumps in the melted second bumps as described above. As the bumps bite in, the overlap portion is absorbed, so that excessive pressing does not occur and there is no possibility of causing damage to the substrate.

  As a result, in the ink jet head of the present invention, the actuator on the head substrate side and the wiring on the wiring substrate side are electrically connected in a state where the tip end of the first bump has digged into the second bump, and reliable. Electrical connection is achieved.

In the manufacturing method of the present invention, in order to ensure reliable electrical connection between the bumps, the first bump and the second bump before joining the head substrate and the wiring substrate are as follows: And it is preferable to satisfy (II).
(I) Total height of the first bump <thickness of the adhesive resin layer−height from the adhesion surface of the adhesive resin layer to the head substrate to the upper surface of the actuator <total height of the first bump + total height of the second bump (II ) Overall height of the second bump <the thickness of the adhesive resin layer-the height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator

  When this condition is satisfied, as shown in FIG. 1, the first bump and the second bump are connected so that the tip of the first bump Bu1 slightly bites into the tip of the second bump Bu2. And the tip of the first bump Bu1 is the second until the one or both of the tip of the first bump Bu1 and the tip of the second bump Bu2 are close to the mating surface. Can take any form within the distance L from the state of biting into the bump Bu2 (shown by the alternate long and short dash line), and the bumps always overlap each other and are always connected. The actuator and the wiring are reliably electrically connected. In addition, since reliable electrical connection is possible within the range of the distance L, there is an advantage that the allowable range that can be absorbed with respect to the dimensional change at the time of joining is wide.

  In FIG. 1, both dome-shaped (hemispherical) bumps are illustrated, but the first bump and the second bump may have any bump shape as long as the above-described melting point condition is satisfied. The first bump and the second bump may have different shapes. For example, the first bump may be a stud bump and the second bump may be a solder bump, which is preferable in the present invention.

  Even if solder bumps are used on the wiring side, the solder bumps need only be joined to the stud bumps on the actuator side, so the solder spreads on the surface of the upper electrode of the actuator and inhibits actuator deformation. No problem arises.

  A stud bump forms a metal ball by discharge heating using a fine metal wire (wire), bonds the metal ball to the electrode surface by ultrasonic assistance, and then tears the fine metal wire to form a bump on the electrode surface. Such a stud bump has a plate-like or hump-shaped shoulder portion derived from the metal ball located at the base and a projection that is a part of the metal thin wire protruding from the shoulder portion by the metal wire being torn off from the metal ball. Part. In addition, the solder bump is formed into a flat surface or a spherical surface by joining a ball-shaped solder to the electrode surface.

  The combination of stud bumps and solder bumps is such that when these bumps are joined together, the protrusions at the tips of the stud bumps easily bite into the tip of the solder bump that is in a molten or flat surface. Further certainty can be achieved.

When the stud bump and the solder bump are used, it is also preferable that the stud bump and the solder bump before joining the head substrate and the wiring substrate satisfy the following conditions (III) and (IV).
(III) Shoulder Height <Adhesive Resin Layer Thickness-Adhesive Resin Layer Adhesive Surface to Head Surface> Actuator Top Height <Stud Bump Total Height + Solder Bump Total Height (IV) Solder Bump Total Height <Thickness of adhesive resin layer-height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator

  According to this, since the shoulder part of the stud bump does not hit the wiring, there is no worry of damage to the board due to excessive pressing, and the projection part plastically deforms even if it contacts the wiring, so that the head board and wiring Since the substrate can be brought close to the substrate, it is possible to widen an allowable range in which the bumps can overlap each other (a possible absorption range corresponding to the dimensional change of the adhesive resin layer).

  The stud bump is preferably a gold stud bump. The gold stud bump is easily plastically deformed even if the protruding part at the tip excessively bites into the solder bump and comes into contact with the mating surface. Even if the protruding height of the stud bump is increased, the reliability of electrical connection can be easily achieved without fear of causing damage to the substrate.

  As the solder bump, a low-melting-point solder bump that melts at a temperature lower than the temperature at which the adhesive resin layer is heated and cured is preferable, and in particular, a bump formed of eutectic solder can be preferably used. Examples of the eutectic solder include Sn-52In-based eutectic solder (melting point: 118 ° C.) and Sn-58Bi-based eutectic solder (melting point: 139 ° C.). In addition, a general low melting point solder, for example, Sn-Bi-Ag solder (Ag is 0 to 1%) (melting point 139 ° C. ) Etc. can also be used.

  Hereinafter, specific examples of the present invention will be further described with reference to the drawings.

  FIG. 2 is a cross-sectional view of an ink jet head according to the present invention, FIG. 3 is a partially enlarged cross-sectional view thereof, and FIG.

  In the inkjet head 1, a head substrate 10 and a wiring substrate 20 are laminated and integrated by an adhesive resin layer 30. A box-shaped manifold 40 is provided on the upper surface of the wiring board 20, and a common ink chamber 41 in which ink is stored is formed between the wiring board 20 and the wiring board 20.

The head substrate 10 includes, from the lower side in the figure, a nozzle plate 11 formed of a Si (silicon) substrate, an intermediate plate 12 formed of a glass substrate, a pressure chamber plate 13 formed of a Si (silicon) substrate, and SiO _2. It has a diaphragm 14 formed of a thin film. A nozzle 11 a is opened on the lower surface of the nozzle plate 11.

  The pressure chamber plate 13 is formed with a pressure chamber 13 a that accommodates ink for ejection. The upper wall of the pressure chamber plate 13 is constituted by the vibration plate 14, and the lower wall is constituted by the intermediate plate 12. The intermediate plate 12 is formed with a communication passage 12a through which the inside of the pressure chamber 13a communicates with the nozzle 11a.

  The actuator 15 is formed by sandwiching an actuator body 15a made of a thin film PZT between an upper electrode 15b and a lower electrode 15c. The lower electrode 15c is formed on the surface of the diaphragm 14, and the actuator body 15a and the upper electrode 15b on the upper surface thereof are individually laminated on the lower electrode 15c so as to correspond to the pressure chamber 13a on a one-to-one basis. In addition, a gold stud bump (first bump) 16 (melting point: 1063 ° C.) is formed on the upper electrode 15 b so as to protrude toward the wiring substrate 20.

  As shown in FIG. 4, the gold stud bump 16 includes a shoulder portion (base portion in contact with the upper electrode 15 b) 16 a that is located at the root and is formed so as to rise from the upper electrode 15 b in a plateau shape or a hump shape, and its shoulder portion. And a protrusion 16b protruding upward from the vicinity of the center of the upper surface of 16a.

Wiring board 20, the upper surface of the substrate body 21 made of Si substrate, upper wiring 23 via the wiring protective layer 22 made of SiO ₂ is formed. An FPC (flexible printed circuit board) 28 on which a driving IC 27 is mounted is electrically connected to the upper wiring 23 by an ACF (anisotropic conductive film) at the end of the wiring board 20.

Some of the upper wiring 23, faces the lower surface of the substrate main body 21 by the through hole 21a formed in the substrate main body 21, which is formed through the wiring protective layer 24 made of SiO ₂ on the lower surface of the substrate main body 21 The lower wiring 25 is electrically connected. A part of the lower wiring 25 is exposed on the wiring protection layer 24 facing the actuator 15, and a solder bump (second bump) 26 protrudes toward the head substrate 10 on the exposed lower wiring 25. Has been.

  Here, the solder bumps 26 are bumps formed of Sn—Bi eutectic solder (melting point 139 ° C.) and are hemispherically raised from the surface of the lower wiring 25 toward the actuator 15 as shown in FIG. Accordingly, the front end surface (lower end surface) 26a has a spherical shape.

  After the head substrate 10 and the wiring substrate 20 are separately manufactured, the actuator 15 side surface of the head substrate 10 and the wiring protection layer 24 side surface of the wiring substrate 20 face each other, and the adhesive resin layer 30 is formed. And integrated.

  The adhesive resin layer 30 is a thermosetting photosensitive adhesive resin sheet (here, set to a curing temperature of 200 ° C.), and the gap between the head substrate 10 and the wiring substrate 20 is equal to the thickness of the adhesive resin layer 30. Is provided in advance on the surface (lower surface) of the wiring protective layer 24 of the wiring substrate 20. Then, the wiring substrate 20 with the adhesive resin layer 30 is connected to the lower electrode 15c formed on the surface of the vibration plate 14 of the head substrate 10 with the adhesion surface of the adhesive resin layer 30 facing the head substrate 10 side. After being laminated on the upper surface, the head substrate 10 and the wiring substrate 20 are bonded via the adhesive resin layer 30 by being heated to a predetermined curing temperature and pressure-bonded. In the adhesive resin layer 30, the actuator 15 and the area corresponding to the periphery thereof are removed by exposure and development after being attached to the wiring substrate 20 and before being laminated with the head substrate 10. Thereby, an accommodation space 31 for the actuator 15 (actuator body 15a and upper electrode 15b) is formed between the head substrate 10 and the wiring substrate 20.

  A through-hole 32 penetrating in the vertical direction is formed in the adhesive resin layer 30 in advance by exposure and development, and one end (upper end) thereof communicates with an ink supply path 29 formed in the wiring board 20. The end (lower end) communicates with the inside of the pressure chamber 13 a through an opening 14 a formed in the vibration plate 14 of the head substrate 10. The ink supply path 29 is opened on the upper surface of the wiring board 20, and the ink in the common ink chamber 41 is allowed to flow into the pressure chamber 13a through the opening 29a.

  The ink supplied into the pressure chamber 13 a is deformed by the drive signal given from the drive IC 27 via the lower wiring 25 of the wiring substrate 20, and the vibration plate 14 vibrates, so that the pressure for ejection is increased. Is applied and discharged as fine droplets from the nozzle 11a through the communication passage 12a.

Here, the gold stud bump 16 and the solder bump 26 are in a state before the head substrate 10 and the wiring substrate 20 are bonded and laminated and integrated by the adhesive resin layer 30 (the total height of the gold stud bump 16 (of the actuator 15)). The height from the upper surface of the upper electrode 15b to the tip of the protrusion 16b is A1, the total height of the solder bump 26 (the height from the lower surface of the lower wiring 25 to the spherical tip surface 26a) is B, and the adhesive resin layer 30 When the thickness is C and the height from the adhesion surface of the adhesive resin layer 30 to the head substrate 10 (here, the upper surface of the lower electrode 15c) to the upper surface of the actuator 15 (the upper surface of the upper electrode 15b) is D (FIG. 4 ( a))
A1 <CD <A1 + B and B <CD
It is formed to become.

  For this reason, when the head substrate 10 and the wiring substrate 20 are laminated with the adhesive resin layer 30 interposed therebetween, the tip of the gold stud bump 16 (protrusion 16b) and the tip of the solder bump 26 (tip surface 26a) are separated from each other. Overlap each other. In this state, when heated and pressure-bonded at the curing temperature (200 ° C.) of the adhesive resin layer 30, the gold stud bump 16 having a melting point higher than the heating temperature remains in its shape. The solder bumps 26 having a lower melting point are in a molten state, permitting the protrusions 16b of the gold stud bumps 16 to be intruded (biting in) at the time of bonding, and absorbing each other's overlap.

  In addition, when the adhesive resin layer 30 is compressed during the thermocompression bonding, the adhesive resin layer 30 is slightly pressed and crushed, and the thickness of the adhesive resin layer 30 decreases. By biting into the melted solder bump 26, the thickness dimension change of the adhesive resin layer 30 is also absorbed. As a result, the tips of the gold stud bumps 16 are securely bited into the solder bumps 26 (see FIG. 4B), and reliable electrical connection between the upper electrode 15b of the actuator 16 and the lower wiring 25 is achieved. Guaranteed.

  When the height of the shoulder 16a (the height from the upper surface of the upper electrode 15b of the actuator 15 to the tip of the shoulder 16a) is A2 (see FIG. 4A), only the protrusion 16b of the gold stud bump 16 is provided. It is known that the height (A1-A2) becomes a value smaller than about three times A2 due to the wire tearing at the time of bump formation. Since the protrusion 16b is extremely thin, the inventors have confirmed that even when a load is applied to the protrusion 16b during thermocompression bonding, the protrusion 16b is easily plastically deformed and crushed.

Therefore, when the first bump having a melting point higher than the curing temperature of the adhesive resin layer 30 is a stud bump having a shoulder portion 16a and a protrusion portion 16b as shown in the present embodiment,
A2 <CD <A1 + B and B <CD
Even if it satisfies the above, only the protrusion 16b that can be easily plastically deformed as described above hits the lower wiring 25, and the shoulder portion 16a does not hit the lower wiring 25. Don't worry. In addition, when this condition is satisfied, as shown in FIG. 5, the head substrate 10 and the wiring substrate 20 are brought close to each other until the protruding portion 16b abuts against the mating surface (the lower surface of the lower wiring 25) and plastically deforms. Therefore, the permissible range in which the bumps can overlap each other (the absorbable range corresponding to the dimensional change of the adhesive resin layer 30) is wider than the case where the above-described conditions are satisfied by the height of the protruding portion 16b. It is possible to obtain a more reliable electrical connection.

  In particular, since gold is soft, when the first bump is a gold stud bump 16, the protrusion 16b can be easily plastically deformed with a force of about 1/10 of the load during crimping, and there is a risk of substrate damage. The effect of obtaining a reliable electrical connection can be obtained more stably.

  FIG. 6 is a schematic perspective view showing an example of an ink jet drawing apparatus equipped with such an ink jet head 1.

  An ink jet drawing apparatus 100 rotates on an apparatus base 101 an ink jet head 1 for performing ink jet drawing, a stage 102 for placing and supporting a substrate W on an upper surface, and a stage 102 to rotate in the θ direction. The θ rotation mechanism 103, the stage 102, and the θ rotation mechanism 103 are both linearly moved along the Y direction, and the Y movement mechanism 104, and both the stage 102 and the θ rotation mechanism 103 are linearly moved along the X direction. Each has.

  The X direction and the Y direction are directions orthogonal to each other on the horizontal plane.

  The ink jet head 1 is attached to a gantry 106 laid in parallel along the X direction in the vicinity of the end portion on the apparatus base 101 through a slider 107 and a θ rotation mechanism 108 so that the nozzle surface is a lower surface. It is arranged so as to face the surface of the recording material W on the stage 102 arranged below it in parallel. The inkjet head 1 reciprocates along the X direction as the slider 107 slides along the gantry 106, and is moved in the Z direction, which is a normal direction perpendicular to the X and Y directions, by the θ rotation mechanism 108. The direction of rotation is rotationally moved in the θ direction, and the Z moving mechanism 109 can be moved up and down in the Z direction together with the θ rotating mechanism 108.

  The stage 102 is a surface plate having a rectangular shape in plan view provided on the X moving mechanism 105 extending along the X direction via the θ rotation mechanism 103, and the upper surface thereof is for placing the recording material W thereon. It is set as a horizontal mounting surface, and this mounting surface is arrange | positioned so that it may become a predetermined height position with respect to the nozzle surface of the inkjet head 1. FIG. The stage 102 moves linearly along the X direction by sliding along the X moving mechanism 105 together with the θ rotation mechanism 103, and the X moving mechanism 105 is moved to the Y moving mechanism 104 extending along the Y direction. By moving along the Y direction together with the θ rotation mechanism 103 by sliding along the Y direction, the direction along the Z direction while maintaining parallel to the nozzle surface of the inkjet head 1 by the θ rotation mechanism 103 is further achieved. The axis can be rotated in the θ direction.

  The ink jet drawing apparatus 100 moves the ink jet head 1 and the stage 102 relatively, and controls the ejection of liquid droplets from the ink jet head 1 based on predetermined ejection pattern data according to each position information at that time. The desired drawing is performed by landing on the surface of the recording material W on the stage 102.

1: Inkjet head 10: Head substrate 11: Nozzle plate 11a: Nozzle 12: Intermediate plate 12a: Communication path 13: Pressure chamber plate 13a: Pressure chamber 14: Vibration plate 14a: Opening 15: Actuator 15a: Actuator body 15b: Upper part Electrode 15c: Lower electrode 16: Gold stud bump (first bump)
16a: shoulder 16b: protrusion 20: wiring board 21: board body 21a: through hole 22: wiring protection layer 23: upper wiring 24: wiring protection layer 25: lower wiring 26: solder bump 26a: tip end surface 27: drive IC
28: FPC
DESCRIPTION OF SYMBOLS 29: Ink supply path 29a: Opening part 30: Adhesive resin layer 31: Accommodating space 40: Manifold 41: Common ink chamber 100: Inkjet drawing apparatus 101: Apparatus base 102: Stage 103: θ rotation mechanism 104: Y movement mechanism 105 : X movement mechanism 106: Gantry 107: Slider 108: θ rotation mechanism 109: Z movement mechanism W: Recording material Bu1: First bump Bu2: Second bump

Claims (12)

A plurality of nozzles for ejecting ink, a plurality of pressure chambers disposed corresponding to the nozzles and containing ink for ejecting from the nozzles, respectively, and disposed corresponding to the pressure chambers; A head substrate having an actuator for applying a force for ejecting ink in the chamber from the nozzle, and a wiring substrate having a wiring for supplying power to the electrode on the surface of the actuator, the wiring substrate being the head The electrode on the surface of the actuator and the wiring are electrically connected to each other and the head substrate and the wiring substrate are bonded to each other by being pressure-bonded to the substrate through an adhesive resin layer at a predetermined heating temperature. An inkjet head,
The electrical connection between the electrode on the actuator surface and the wiring is performed by joining a first bump having a melting point higher than the heating temperature and a second bump having a melting point lower than the heating temperature. An inkjet head, wherein one of the first bump and the second bump is provided on the electrode on the actuator surface, and the other is provided on the wiring.   2. The ink jet head according to claim 1, wherein a tip end of the first bump is electrically connected in a state of being bitten into the second bump.   The inkjet head according to claim 1, wherein the first bump is a stud bump, and the second bump is a solder bump.   4. The ink jet head according to claim 3, wherein the stud bump has a shoulder portion located at the base and a protrusion protruding from the shoulder portion, and the solder bump has a flat surface or a spherical tip. .   5. The ink jet head according to claim 3, wherein the stud bump is a gold stud bump. A plurality of nozzles for ejecting ink, a plurality of pressure chambers disposed corresponding to the nozzles and containing ink for ejecting from the nozzles, respectively, and disposed corresponding to the pressure chambers; A head substrate having an actuator for applying a force for ejecting ink in the chamber from the nozzle, and a wiring substrate having a wiring for supplying power to the electrode on the surface of the actuator, the wiring substrate being the head The electrode on the actuator surface and the wiring are electrically connected and bonded to the head substrate and the wiring substrate by being pressed against the surface of the substrate through an adhesive resin layer at a predetermined heating temperature. A method for manufacturing an inkjet head, comprising:
A first bump having a melting point higher than the heating temperature is provided on one of the electrode and the wiring on the actuator surface, and a second bump having a melting point equal to or lower than the heating temperature is provided on the other.
A method of manufacturing an ink-jet head, wherein the first bump and the second bump are electrically connected to each other by pressing the wiring substrate against the head substrate at the heating temperature.   7. The method of manufacturing an inkjet head according to claim 6, wherein the first bump is a stud bump, and the second bump is a solder bump.   8. The ink jet head according to claim 7, wherein the stud bump has a shoulder portion located at the base and a protrusion protruding from the shoulder portion, and the solder bump has a flat surface or a spherical tip. Manufacturing method.   9. The method of manufacturing an ink jet head according to claim 7, wherein the stud bump is a gold stud bump. 10. The first bump and the second bump before joining the head substrate and the wiring substrate satisfy the following conditions (I) and (II): The manufacturing method of the inkjet head in any one.
(I) Total height of the first bump <thickness of the adhesive resin layer−height from the adhesion surface of the adhesive resin layer to the head substrate to the upper surface of the actuator <total height of the first bump + total height of the second bump (II ) Overall height of the second bump <the thickness of the adhesive resin layer-the height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator The ink jet head according to claim 8 or 9, wherein the stud bump and the solder bump before joining the head substrate and the wiring substrate satisfy the following conditions (III) and (IV). Production method.
(III) Shoulder Height <Adhesive Resin Layer Thickness-Adhesive Resin Layer Adhesive Surface to Head Surface> Actuator Top Height <Stud Bump Total Height + Solder Bump Total Height (IV) Solder Bump Total Height <Thickness of adhesive resin layer-height from the adhesive surface of the adhesive resin layer to the head substrate to the upper surface of the actuator An ink jet drawing apparatus comprising the ink jet head according to claim 1.

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