JP4876701B2 - Inkjet head manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an ink jet head, and more particularly, to a method for manufacturing an ink jet head that can be an ink jet head having a common outer dimension and various channel characteristics.

  Conventionally, a channel is ground on a piezoelectric substrate, an electrode is formed on a drive wall that defines the channel, and a voltage is applied to the electrode to cause the drive wall to be shear-deformed to form ink in the channel. 2. Description of the Related Art A shear mode type ink jet head that discharges ink from a nozzle is known. Among them, an actuator for ejecting ink is constituted by a so-called harmonica type head chip in which drive walls made of piezoelectric elements and channels are alternately arranged in parallel and the outlet and the inlet of the channel are opposed to each other. For example, Patent Document 1 discloses an ink jet head that has a large number of wafers taken from a single wafer and has extremely improved productivity.

  By the way, in general, in an ink jet head that applies energy for ejection to ink in a channel by shearing the drive wall into a dogleg shape, the optimum pulse width for driving is determined by the channel characteristics. This channel characteristic is determined by the length of the channel along the ink ejection direction (referred to as drive length or L length, hereinafter referred to as L length in this specification), and the drive frequency is determined accordingly. For example, in the case of an inkjet head that is required to be driven at a high frequency as channel characteristics, the L length is shortened, and an inkjet head having an extremely short head chip with an L length of 1.7 mm has been created.

Patent Document 2 discloses a method of forming grooves on the front and rear surfaces of a head and using them for electrode extraction.
JP 2005-96414 A Japanese Patent Laid-Open No. 8-309977

  In the case of an inkjet head having a harmonica type head chip, the L length is directly the length of the head chip (the length along the ink ejection direction of the channel), and the L length becomes shorter as the drive frequency becomes higher. Not only does it become difficult to assemble, but the strength of the head chip itself is reduced, making it necessary to handle it with great care, and also causing problems when attaching to the exterior. .

  Further, since the inkjet head is attached to the exterior using its nozzle surface as an alignment surface, if the L length is different, the design of the exterior itself needs to be changed accordingly. Therefore, it is necessary to prepare a dedicated exterior for each L length, which raises a problem of increasing costs.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet head manufacturing method that can easily produce head chips having common channel dimensions and various channel characteristics.

  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, driving walls and channels made of piezoelectric elements are alternately arranged side by side, outlets and inlets of the channels are arranged to face each other, and electrodes for applying a voltage to the driving walls are formed. A method of manufacturing an inkjet head, wherein the drive wall is shear-deformed by applying a voltage to the electrode, and ink in the channel is ejected from a nozzle.
The step of creating the head chip includes:
A channel processing step of grooving a large number of channels from the surface of the wafer including at least a piezoelectric element layer on the surface;
Forming an electrode in the channel; and
A cover substrate adhering step of adhering a cover substrate to the surface of the wafer on which the electrode is formed so as to close the upper portion of the channel;
A plurality of counterbores across all of the channels along a direction perpendicular to the channel at a depth from the cover substrate side or the wafer side after the cover substrate is bonded to the bottom or near the bottom of the channel. A counterbored groove processing step in which the groove is processed so that the length between adjacent counterbored grooves is twice as long as the channel characteristics required for the inkjet head;
A laminate bonding step of preparing two sets of wafers processed with the counterbored grooves, and laminating and bonding the side of the counterbored grooves so that the counterbored grooves overlap each other;
The wafer having the counterbored grooves formed on each other and bonded to each other is cut along a cutting line in a direction perpendicular to the channel to cut out a large number of head chips of a predetermined size having two channel rows. Cutting process,
In the cutting step, one of two cutting lines for cutting out one head chip is formed along the counterbored groove from above the counterbored groove, and the other is disposed between the adjacent counterbored grooves. A method of manufacturing an ink jet head, comprising: forming an ink jet head.

According to a second aspect of the invention, in the spot-facing groove machining process, using the processing of the same blade of the counterbore groove claim 1 the outer edge of the wafer, characterized in that parallel to cut and said counterbore groove It is a manufacturing method of the described inkjet head.

Invention of claim 3, wherein in the laminating adhesive process, abuts the cut outer edge of each wafer to the positioning member, the ink-jet head according to claim 2, wherein the positioning the sets of counterbore groove between It is a manufacturing method.

According to a fourth aspect of the present invention, in the method for manufacturing an ink jet head according to the first , second, or third aspect, the counterbored groove is ground by a dicing saw.

  According to the first aspect of the present invention, the length between the adjacent spot grooves is set to twice the channel characteristic required for the ink jet head, and the wafer having the spot grooves formed therein is cut into a predetermined size. Thus, a large number of head chips having a common external dimension and various channel characteristics can be easily produced at a time. The outer dimensions of the obtained head chip remain the same size, so that the strength and handleability of the head chip can be ensured, and a common exterior can be used regardless of the channel characteristics, so the cost can be reduced. It becomes.

Further, it is possible to easily plurality create at once a head chip having a channel two rows. In addition, since a portion unnecessary for driving between each channel row is removed, a capacitance can be lowered, a driving chip can be lowered, and a head chip capable of suppressing heat generation during driving is created. be able to.

According to the second aspect of the present invention, since the outer edge is cut using the same blade as the counterbored groove, the work can be performed in the same workpiece, and the position accuracy from the end is ensured with high accuracy. it can.

According to the third aspect of the present invention, since the position accuracy from the end portion can be ensured with high accuracy, there is no variation in each head chip to be created, and uniform accuracy can be ensured. In the case of a head chip having two channel rows, the positions of the counterbored grooves can be positioned with high accuracy.

According to the invention of claim 4 , further, grinding by mechanically high-precision positioning is possible, and the width and depth at the time of machining the counterbored groove can be set with high precision, so that desired channel characteristics can be obtained. It can be ensured with high accuracy.

  Hereinafter, an ink jet head manufacturing method according to the present invention will be described with reference to the drawings.

(First embodiment)
First, as shown in FIG. 1, two piezoelectric element substrates 12 a and 12 b each subjected to a polarization treatment are bonded to each other using an epoxy adhesive, and a piezoelectric element layer is provided on the surface. Wafer 10 is created. As the piezoelectric material used for each of the piezoelectric element substrates 12a and 12b, a known piezoelectric material that is deformed by applying a voltage can be used, and lead zirconate titanate (PZT) is particularly preferable. The two piezoelectric element substrates 12a and 12b are laminated with their polarization directions (indicated by arrows) opposite to each other, and are bonded to the substrate 11 using an adhesive.

  Next, as shown in FIG. 2, a plurality of parallel channels 13 are ground into a groove shape using a dicing saw over the two piezoelectric element substrates 12a and 12b from the surface of the wafer 10 (channels). Processing step). Thereby, between the adjacent channels 13, drive walls 14 made of piezoelectric elements whose polarization directions are opposite in the height direction are arranged in parallel. 2A is a plan view of the wafer 10, and FIG. 2B is a cross-sectional view taken along line (I)-(I) in FIG.

  Although not shown, the piezoelectric element substrate 12b is thick instead of using the substrate 11, and a plurality of parallel channels 13 extending from the thin piezoelectric element substrate 12a side to the middle of the thick piezoelectric element substrate 12b are ground. By doing so, the portion of the substrate 11 may be formed integrally with the piezoelectric element substrate 12b simultaneously with the formation of the drive wall 14 whose polarization direction is opposite in the height direction.

  Next, the drive electrode 15 is formed on the inner surface of each channel 13 thus formed as shown in FIG. 3 (electrode formation step). The metal that forms the drive electrode 15 includes Ni, Co, Cu, Al, and the like. Al and Cu are preferably used from the viewpoint of electrical resistance, but Ni is preferably used from the viewpoint of corrosion, strength, and cost. Alternatively, a laminated structure in which Au is further laminated on Al may be employed.

  Examples of the formation of the drive electrode 15 include a method of forming a metal film by a method using a vacuum apparatus such as a vapor deposition method, a sputtering method, a plating method, or a CVD (chemical vapor reaction method). It is particularly preferable to form by electroless plating. By electroless plating, a uniform and pinhole-free metal coating can be formed. The thickness of the plating film is preferably in the range of 0.5 to 5 μm.

  Since the drive electrode 15 needs to be independent for each channel 13, a metal film is not formed on the upper end surface of the drive wall 14. For this reason, for example, by attaching a dry film to the upper end surface of each drive wall 14 in advance or forming a resist and forming a metal film, the side walls of each drive wall 14 and each channel 13 are removed. A drive electrode 15 is selectively formed on the bottom surface.

  After the drive electrode 15 is formed, the channel 13 extends along the direction perpendicular to the length direction of the channel 13 at a depth from the surface of the wafer 10 to the bottom or near the bottom of the channel 13 as shown in FIG. A plurality of counterbored grooves 16 are ground in parallel over all of the above (a counterbored groove processing step). 4A is a plan view of the wafer 10, and FIG. 4B is a front view of the wafer 10. FIG.

  The length A between the adjacent spot grooves 16 is twice the channel characteristic (L length) required for the ink jet head, and the spot grooves 16 are equally spaced. Each pitch groove 16 is processed by positioning each pitch P so that the pitch P is twice as long as the length of the head chip to be created (length along the ink ejection direction). These double lengths are the lengths excluding the machining margin at the time of grinding.

  The width of the counterbore groove 16 is appropriately set according to the required L length of the head chip. That is, by appropriately setting the width of the counterbore groove 16, even if the head chips have the same length, head chips having various characteristics with different L lengths can be produced.

  Further, the number of counterbore grooves 16 is appropriately set according to the number of head chips taken from the wafer 10.

  The depth of the counterbore groove 16 may be a depth that reaches the bottom of the channel 13 or near the bottom, but is preferably slightly deeper than the depth of the channel 13. By machining the counterbored groove 16 in this way, the drive electrode 15 at the bottom of the channel 13 located inside the counterbored groove 16 is also scraped off at the same time, so that the capacitance of the obtained head chip can be reduced.

  The machining of the counterbored grooves 16 is not particularly limited as long as the wafer 10 can be grooved. However, it is preferable to use a dicing saw similarly to the groove machining of the channel 13. According to the dicing saw, grinding by mechanically high-precision positioning is possible, and the width, depth, and interval of the counterbored grooves 16 can be set with high accuracy.

  When machining the spot groove 16, it is preferable to cut the outer edge of the wafer 10 in parallel with the spot groove 16 using the same blade. In FIG. 4, reference numeral 17 denotes a margin for cutting the outer shape end, and reference numeral 10 a denotes an end portion of the cut wafer 10. Since the cutting of the outer edge uses the same blade as the counterbored groove 16, it can be performed in the same workpiece as that of the counterbored groove 16, and the positional accuracy from the end must be ensured with high accuracy. Can do.

  After cutting the counterbore groove 16 and the outer edge, the cover substrate 18 is bonded to the surface of the wafer 10 so as to close the upper portion of the channel 13 (cover substrate bonding step). FIG. 5 is a side view of the wafer 10 with the cover substrate 18 bonded to the surface.

  If the same substrate material as the piezoelectric material constituting the drive wall 14 is depolarized and used for the cover substrate 18, the influence of heat generated when the cover substrate 18 is heat-bonded and heat generated when the inkjet head is completed is driven. Therefore, it is possible to reduce variations in speed distribution and driving characteristics due to differences in thermal expansion coefficients.

  Next, two sets of wafers 10 to which the cover substrate 18 is bonded are prepared in the same manner, and the cover substrates 18 are laminated so as to be overlapped with each other and bonded using an epoxy adhesive (stacking bonding step).

  FIG. 6 is a side view showing a state where the cover substrates 18 are bonded together. As shown in the figure, at the time of laminating and bonding, the upper and lower wafers 10 and 10 are overlapped so that the respective channels 13 are in the same direction, and the outer edges are cut in the counterbored groove forming step. The processed surfaces are abutted against a positioning member 100 such as a work table. This cut surface is formed with the position from the counterbored groove 16 positioned with high accuracy by the work in the same workpiece using the same blade when the counterbored groove 16 is processed. The positions of the counterbored grooves 16 and 16 in the vertical direction can be easily and precisely matched.

  After positioning by this abutment, the two wafers 10 and 10 are cut together with the cover substrates 18 and 18 to cut out a large number of head chips 1A (cutting process step).

  Each dashed-dotted line in FIG. 6 has shown the cutting line C at the time of this cutting process. The cutting line C is positioned in parallel along a direction orthogonal to the length direction of the channel 13 and cut along the cutting line C using a dicing saw.

  The interval between the adjacent cutting lines C and C is a length along the ink ejection direction of the head chip 1A to be created. This spacing is optimal for all the cut out head chips 1A, 1A, etc., taking into account the strength of the head chip 1A itself, the assembly workability of the ink jet head, the attachment workability when attaching the ink jet head to the exterior, etc. It is determined to be a long length.

  As shown in FIG. 6, one of the two adjacent cutting lines C, C passes through the center of the counterbored groove 16 along the length direction of the counterbored groove 16 from above the counterbored groove 16. The other is formed between the adjacent counterbored grooves 16 and 16 so as to pass through the center thereof. Accordingly, one head chip 1A is cut out by two adjacent cutting lines C and C.

  FIG. 7 is a side view of one head chip 1A cut out in this way.

  This head chip 1A has two channel rows: a channel row by each channel 13 arranged in parallel on the upper wafer 10 and a channel row by each channel 13 arranged in parallel on the lower wafer 10. ing. An outlet and an inlet of each channel 13 are disposed on the front surface (right side surface in the drawing) and the rear surface side (left side in the drawing) of the head chip 1A, respectively. Each channel 13 is a straight type whose size and shape are not substantially changed in the length direction from the inlet to the outlet.

  Further, on the rear surface side of the head chip 1A, there are two spotted portions 19 and 19 formed by spotted grooves 16 processed in the wafer 10 in a groove shape along each channel row. The L length that determines the channel characteristics of the head chip 1A is formed by the counterbore portions 19 and 19 so as to be a desired length with respect to the length B of the head chip.

  Each of the cut out head chips 1A, 1A,... Has a uniform accuracy with no variation since each counterbored groove 16 and each cutting line C of the wafer 10 are positioned with high accuracy. According to the present invention, a large number of head chips 1A having such a uniform accuracy and a desired L length with respect to the head chip length B can be easily produced at a time. .

  The head chip 1A thus produced has a nozzle plate with nozzles formed on the front surface, an ink manifold attached to the rear surface, and a wiring for applying a voltage to each drive electrode 15. Thus, the ink jet head is completed.

  FIG. 8 is a cross-sectional view showing an example of an inkjet head.

  In the figure, reference numeral 2 denotes a nozzle plate bonded to the front surface of the head chip 1A, and nozzles 21 are formed so as to correspond to the respective channels 13 of the head chip 1A. Reference numeral 3 denotes a wiring board, and 4 denotes an FPC for applying a voltage to each drive electrode 15 from a drive IC (not shown).

  The wiring substrate 3 is formed of a single plate-like substrate made of a ceramic material such as non-polarized PZT, AlN-BN, or AlN. In addition, low thermal expansion plastic or glass can be used. Furthermore, it is also preferable to depolarize and use the same substrate material as that of the piezoelectric element used in the head chip 1A.

  In this structure, the bonding portion between the wiring board 3 and the head chip 1A is separated from the drive wall 14 as the depth of the counterbore 19 increases. When a material having a thermal expansion coefficient different from that of the head chip 1A is used as the wiring substrate 3, a stress due to the difference in thermal expansion coefficient is generated when the temperature returns to room temperature from the time of heat bonding, which may adversely affect driving. In the present invention, since the drive wall 14 can be separated from the bonding portion with the wiring board 3 by the counterbore part 19, this influence can be reduced, and a material having a thermal expansion coefficient different from that of the head chip 1A is used as the wiring board 3. Makes it easy to use.

  The material constituting the wiring substrate 3 is not limited to a single plate, and a plurality of thin plate-like substrate materials may be stacked to form a desired thickness.

  The wiring substrate 3 has the same width as the width direction of the head chip 1A, and extends in a direction that extends perpendicularly to the channel row direction of the head chip 1A (the vertical direction in FIG. 8).

  In the head chip 1A, an extraction electrode 150 extending from the drive electrode 15 in each channel 13 to the rear surface of the head chip 1A through the front surface, the upper surface, and the lower surface of the head chip 1A is formed. The extraction electrode 150 can be formed by a vapor deposition method, a sputtering method, or the like.

  On the bonding surface of the wiring board 3 with the head chip 1A, a wiring 31 connected to the lead electrode 150 of the head chip 1A is formed in a portion that largely protrudes from the head chip 1A. Are respectively positioned with respect to the head chip 1A, and are electrically connected and bonded by an anisotropic conductive film or the like. In addition to this, as an electrical connection method between the lead-out wiring 150 and the wiring 31, at least one of an anisotropic conductive paste containing conductive particles, a pressure contact bonding bonded with a non-conductive adhesive, and the wiring 31 and the lead-out electrode 150 are used. It is also possible to use a method that is used in a normal mounting technique, such as a method of using solder for heating and melting and connecting.

  A wiring 41 of the FPC 4 is electrically connected and bonded to the wiring 31 exposed above and below the head chip 1A of the wiring board 3 by an anisotropic conductive film or the like.

  The adhesion of the wiring board 3 enables voltage application from the drive IC to each drive electrode 15 of the head chip 1A, and each channel 19 and 19 and the recesses 32 and 32 of each head chip 1A have each channel. Ink common chambers 5 and 5 for supplying ink to 13 are formed. Since the ink common chambers 5 and 5 are formed by the concave portion 32 of the wiring substrate 3 and the counterbore portions 19 and 19 of the head chip 1A, a large volume is ensured as compared with that formed by the concave portion 32 alone. Can do.

  In this embodiment, since the two recesses 32 and 32 are formed in the wiring board 3, the two ink common chambers 5 and 5 are isolated by the cover substrates 18 and 18. Therefore, it is possible to supply each channel row with different color inks.

(Second Embodiment)
In the first embodiment, in the lamination bonding step, as shown in FIG. 6, the cover substrates 18 of the two sets of wafers 10 to which the cover substrates 18 are bonded are laminated and bonded, but as shown in FIG. 9. The wafers 10 may be bonded together. Also in this case, similarly to FIG. 6, the cut surface with the outer edge cut is abutted against the positioning member 100, and each pair of counterbores 16, 16 are matched in the vertical direction, and then cut in the same manner. Process it. As shown in FIG. 10, the head chip 1 </ b> B produced in this manner has the reverse aspect of the cover substrate 18 and the wafer 10 of the head chip 1 </ b> A according to the first embodiment.

(Third embodiment)
In the case of producing a head chip having two channel rows, the counterbored grooves 16 can be processed after bonding the cover substrate 18 to the wafer 10 in which the channels 13 are grooved, as shown in FIG. FIG. 11 is a side view showing a state in which the counterbored groove 16 is processed after the cover substrate 18 is bonded to the wafer 10. The same reference numerals as those in FIG. 4B indicate the same configurations.

  In this embodiment, as shown in FIG. 12, the cover substrates 18 and 18 of the two sets of wafers 10 and 10 are overlapped and bonded to each other, and the cut end surface whose outer end is cut is positioned as in FIG. The head chip 1C may be cut out in the same manner after cutting against the member 100 and matching each set of counterbores 16, 16 in the vertical direction. As shown in FIG. 13, the head chip 1 </ b> C cut out in this way has no cover substrates 18, 18 protruding between the upper and lower channel rows as in the head chip 1 </ b> A shown in FIG. 7. One large counterbore portion 190 is formed in which the 16 members are integrated.

  When an ink jet head similar to that shown in FIG. 8 is formed by using the head chip 1C, only one recess 32 needs to be formed on the wiring board 3 so as to correspond to the spotted portion 190, thereby forming one large ink common chamber. Is done.

(Fourth embodiment)
In each of the embodiments described above, the head chips 1A to 1C having two channel rows are created, but the channel row is not limited to two rows, and may be only one row. In this case, the process up to the cover substrate bonding process can be performed in the same process as in the first embodiment.

  Thereafter, the wafer 10 after the cover substrate 18 shown in FIG. 5 is bonded may be cut.

(Fifth embodiment)
The counterbored groove 16 may be processed in a portion that affects channel characteristics, and is not necessarily formed so as to cross from one end to the other end of the wafer 10 as shown in FIG. As shown in FIG. 14, the wafer 10 may be formed only in the region where the channel 13 is formed, and each end portion 10 b of the wafer 10 may be left uncut.

  FIG. 15 is a cross-sectional view of the head chip 1D thus produced. This head chip 1D shows what was produced by the process same as 1st Embodiment except the processing method of the counterbore groove 16. FIG. As shown in the drawing, both ends of the head chip 1D are closed so that ink leakage does not occur at both ends of the counterbore portion 19 because the left ends 10b, 10b of the wafer are not opened. There is no need to take measures such as

  In the present invention, the wiring connection method for applying a voltage to each of the drive electrodes 15 of the head chips 1A to 1D is not limited to the method using the wiring substrate 3, and various methods can be employed.

Side view showing wafer configuration (A) is a plan view of a wafer, (b) is a cross-sectional view taken along line (I)-(I) in (a). Partial enlarged view showing the channel in which the drive electrode is formed (A) is a plan view of a wafer with counterbored grooves, (b) is a front view of the wafer. Side view of wafer with cover substrate bonded to the surface Side view showing a state where cover substrates are bonded together Side view of the head chip according to the first embodiment Sectional view showing an example of an inkjet head The side view which shows the state which bonded the wafers which concern on 2nd Embodiment. Side view of a head chip according to the second embodiment The side view which shows the state which processed the counterboring groove | channel after adhere | attaching a cover board | substrate on the wafer which concerns on 3rd Embodiment. The side view which shows the state which overlap | superposed and bonded the cover substrates of two sets of wafers which concern on 3rd Embodiment Side view of a head chip according to a third embodiment Plan view of wafer processed with counterbored grooves according to fifth embodiment Cross-sectional view of a head chip according to a fifth embodiment

Explanation of symbols

1A to 1D: Head chip 10: Wafer 10a, 10b: End 11: Substrate 12a, 12b: Polarized piezoelectric element substrate 13: Channel 14: Drive wall 15: Drive electrode 150: Lead electrode 16: Counterbored groove 17: Processing margin 18: Cover substrate 19, 190: Counterbore portion 2: Nozzle plate 21: Nozzle 3: Wiring substrate 31: Wiring 32: Recessed portion 4: FPC
41: Wiring 5: Ink common chamber

Claims (4)

A drive chip and a channel made of piezoelectric elements are alternately arranged side by side, and an outlet and an inlet of the channel are arranged to face each other, and an electrode for applying a voltage to the drive wall is formed. A method of manufacturing an ink jet head, wherein a voltage is applied to the electrode to shear the drive wall, and ink in the channel is ejected from a nozzle.
The step of creating the head chip includes:
A channel processing step of grooving a number of channels from the surface of the wafer including at least the surface of the piezoelectric element layer;
Forming an electrode in the channel; and
A cover substrate adhering step of adhering a cover substrate to the surface of the wafer on which the electrode is formed so as to close the upper portion of the channel;
A plurality of counterbores across all of the channels along a direction perpendicular to the channel at a depth from the cover substrate side or the wafer side after the cover substrate is bonded to the bottom or near the bottom of the channel. A counterbored groove processing step in which the groove is processed so that the length between adjacent counterbored grooves is twice as long as the channel characteristics required for the inkjet head;
A laminate bonding step of preparing two sets of wafers processed with the counterbored grooves, and laminating and bonding the side of the counterbored grooves so that the counterbored grooves overlap each other;
The wafer having the counterbored grooves formed on each other and bonded to each other is cut along a cutting line in a direction perpendicular to the channel to cut out a large number of head chips of a predetermined size having two channel rows. Cutting process,
In the cutting step, one of two cutting lines for cutting out one head chip is formed along the counterbored groove from above the counterbored groove, and the other is disposed between the adjacent counterbored grooves. A method of manufacturing an ink jet head, comprising: forming an ink jet head. Wherein the spot-facing groove processing step, said counterbore with processing the same blade grooves, ink jet head manufacturing method according to claim 1, wherein the outer edge of the wafer, characterized in that parallel to cut and said counterbore groove. 3. The method of manufacturing an ink-jet head according to claim 2, wherein, in the laminating and bonding step, the cut outer edge of each wafer is abutted against a positioning member to position each pair of counterbores. 4. The method of manufacturing an ink jet head according to claim 1 , wherein the counterbored groove is ground by a dicing saw.

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