JP2006036865A - Adhesion method of substrate and manufacturing method of inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesion method of a substrate that suppresses the retention of bubbles in an adhesive layer between the substrates and enhances the uniformity of the adhesive layer and that has high productivity and can deal with the enlargement of the substrate, and to provide a manufacturing method of an inkjet head. <P>SOLUTION: The adhesion method of the substrate comprises arranging the adhesive and the bubbles in a pattern-like state between a first substrate and a second substrate by laminating the second substrate on the first substrate through the adhesive after applying the thermo-curing adhesive on the adhered face of the first substrate among the first substrate and the second substrate to be adhered so that the portion in the presence of the adhesive and the portion in the absence of the adhesive are formed into a predetermined pattern, decompressing and dissolving it at the same time as heating at the first heating temperature of less than the curing temperature of the adhesive or after heating, then pressurizing uniformly towards the adhered face direction, followed by heating at the second heating temperature of the curing temperature or more of the adhesive to integrate the first substrate and the second substrate mutually by curing the adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for adhering a base material capable of forming a uniform adhesive layer without bubbles remaining between the base materials, and a method for manufacturing an ink jet head using the adhering method.

  The ink jet head discharges from the nozzle by applying a pressure change to the ink. As a method for applying a pressure change to ink, a method using a piezoelectric element that mechanically deforms when a voltage is applied, or a method using an expansion action of bubbles generated by heating ink using a heater Various methods are known.

  An example of an ink jet head using a piezoelectric element is shown in FIG. This ink-jet head has an actuator substrate 10 in which drive walls 14 and ink channels 13 are alternately arranged in parallel. By forming the drive wall 14 with a piezoelectric element, the drive wall 14 is sheared and deformed. The ink in the channel 13 is ejected from the nozzle 21 provided on the nozzle plate 20. As shown in FIG. 2, the actuator substrate 10 is a thin piezoelectric material substrate 11 having a polarization direction (indicated by an arrow) in the opposite direction, as shown in FIG. Two sheets with a thick piezoelectric material substrate 12 are bonded using a thermosetting adhesive to create a laminate 1, and then using a diamond blade 100, from one end of the laminate 1 to the other, By cutting a large number of parallel grooves at a depth from the thin piezoelectric material substrate 11 to the middle portion of the thick piezoelectric material substrate 12, the piezoelectric material substrates having different polarization directions left between the ink channels 13 A drive wall 14 composed of 11 and 12 is juxtaposed.

  A cover substrate 30 provided with an ink circulation port 31 is joined to the upper surface of the actuator substrate 10, and an ink manifold 40 is joined to the upper surface of the cover substrate 30 so as to cover the ink circulation port 31. The nozzle plate 20 is joined across the front end surfaces of the substrate 10 and the cover substrate 30.

  A drive electrode 15 is provided on the side surface of each drive wall 14, and is drawn out to the upper surface of the rear end of the actuator substrate 10 via a shallow groove portion 13 a at the rear end of each ink channel 13. A signal voltage is applied from a drive circuit (not shown) by joining the FPC and the like not to be connected. Here, for example, as shown in FIG. 3, when a predetermined signal voltage is applied to the drive electrode 15 in one ink channel 13 and the drive electrode 15 of the ink channel on both sides thereof is grounded, the signal voltage is applied. An electric field perpendicular to the polarization direction of the piezoelectric material is generated on both the drive walls 14, 14 provided with the drive electrode 15, and each piezoelectric material is shear-deformed in the opposite direction, thereby expanding the volume in the ink channel 13. . When the application of the signal voltage is stopped, pressure is applied to the ink in the ink channel 13 when the drive walls 14 and 14 are restored, and the ink is ejected from the nozzles 21.

  By the way, it is not limited to the case where the piezoelectric material substrates 11 and 12 are bonded when forming the actuator substrate 10 of such an ink jet head, but in general, an attempt is made to bond flat plate-like base materials having rigidity with an adhesive. When this is done, since the entire adhesive surfaces are made to face each other almost simultaneously, air bubbles are often sandwiched between the adhesive surfaces. When cutting such a thing into a predetermined size, or processing a groove, when cutting the vicinity of the bubble portion sandwiched between the adhesive surfaces, due to the cutting resistance of a cutting tool such as a diamond blade, The substrate may peel from the cut surface.

  In particular, when the actuator substrate 10 of the ink jet head described above is prepared, a ceramic substrate weak in cutting resistance such as PZT (lead zirconate titanate) is generally used for the piezoelectric material substrates 11 and 12, and the ink channel 13 Since it is processed at an extremely fine pitch of only a few tens of μm, if bubbles remain on the bonding surface between the piezoelectric material substrates 11 and 12, the drive wall 14 is destroyed during processing for the reasons described above. There is a fear. Further, even if not destroyed, the bubbles are scattered, so that the uniformity of the adhesiveness between the piezoelectric material substrates 11 and 12 cannot be obtained, which causes a variation in driving characteristics.

  For this purpose, it is possible to increase the adhesive strength by forming the adhesive layer thick, so that even if bubbles are present in the adhesive layer, the drive wall can be prevented from being destroyed during processing. As can be seen from (a) and (b), in the case of an ink jet head, when the adhesive layer is thick, the drive voltage increases and the drive pulse width also increases, making it difficult to drive at high speed with a low voltage. come. This is because, in the case of an ink jet head, the adhesive layer absorbs operating energy during shear deformation of the drive wall. Therefore, in order to drive the inkjet head at a high speed with a low voltage, it is desired to make the adhesive layer thin with a high hardness.

  Further, when bubbles remain between the piezoelectric material substrates 11 and 12 constituting the drive wall 14, the electrode metal enters the bubbles when the drive electrode 15 on the side surface of the drive wall 14 is formed by plating or the like. As a result, the drive electrode 15 in the adjacent ink channel 14 is connected. Even if the electrode metal does not enter, there is a possibility that a short circuit may occur due to the ink entering the bubbles, and in any case, there is a problem that the signal voltage cannot be applied.

  Therefore, conventionally, adhesive that has been preheated to reduce the viscosity is applied to the adhesive surface to reduce the thickness of the adhesive to reduce the remaining bubbles in the adhesive, and pressurize in the joining direction after joining. At the same time, Patent Document 1 describes that the temperature of the adhesive is raised to a temperature at which it becomes the lowest to further reduce the thickness of the adhesive so that no bubbles remain in the adhesive.

In addition, by applying centrifugal defoaming treatment before applying the adhesive to the adhesive surface of the substrate, not only removal of bubbles in the adhesive, but also expansion of fine bubbles contained in the adhesive during heat treatment In addition, the thermosetting adhesive applied to the adhesive surface of the base material is semi-stabilized (B-stage), and then the base materials are overlapped with each other in the direction of the adhesive surface from one end to the other end. By sequentially applying pressure and then curing the adhesive and integrating the base materials with each other, there is no positional displacement between the base materials and no bubbles are included in the adhesive surface. It is described in.
JP-A-9-123466 JP 2000-190511 A

  In the method described in Patent Document 1, when the member to be bonded becomes large, not only air bubbles are likely to remain in the vicinity of the center of the bonding surface but also the viscosity of the adhesive at the time of bonding is lowered, so that the mutual displacement occurs. There is a problem that tends to occur.

  On the other hand, in the method described in Patent Document 2, since the adhesive is joined after being metastabilized, it is considered that the problem of misalignment does not occur. The time and labor required for defoaming treatment and metastabilization after application of the adhesive take into account the improvement of productivity when considering mass production.

  In addition, the adhesive layer is not sufficiently uniform, and each ink is used for bonding where the thickness of the adhesive layer correlates with the performance of the head, particularly when the piezoelectric material substrates are bonded together in the manufacture of an inkjet head. There is a problem that leads to variations in driving performance in the channel. Furthermore, when the substrate is enlarged to increase the mass productivity, it is estimated that the effect becomes remarkable. In addition, if there is a change in the B-stage state due to variations in adhesive physical properties during mass production, defoaming may be insufficient, which may affect the quality.

  In the method described in Patent Document 2, it is considered difficult to control the thickness of the adhesive because of the defoaming principle of the adhesive layer.

  However, in recent years, there has been an increasing demand for line heads from the viewpoint of inkjet throughput and high precision from the viewpoint of high-definition drawing, and the production of long and highly productive inkjet heads by increasing the size of the substrate. However, there is a demand for a manufacturing method that does not vary the drive performance of each ink channel.

  Therefore, the problem of the present invention has been made in view of the above-described conventional circumstances, suppresses the remaining of bubbles in the adhesive layer between the substrates, improves the uniformity of the adhesive layer, and improves the productivity. It is an object of the present invention to provide a method of bonding a substrate that can be applied to an increase in the size of the substrate and a method for manufacturing an ink jet head using the bonding method.

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

  In the first aspect of the present invention, a thermosetting adhesive is present on the adhesive surface of the first base material of the first base material and the second base material to be bonded, and the adhesive is present. After applying so that a site | part and the site | part which does not exist may be formed in a predetermined pattern shape, the said 2nd base material is piled up on the said 1st base material through the said adhesive agent, and said 1st The adhesive and bubbles are arranged in a pattern between the substrate and the second substrate, and the pressure is reduced simultaneously with or after heating at the first heating temperature lower than the curing temperature of the adhesive. After the bubbles are dissolved, pressure is uniformly applied in the direction of the adhesive surface, and then heated at a second heating temperature equal to or higher than the curing temperature of the adhesive to cure the adhesive and the first A base material bonding method, wherein the base material and the second base material are integrated with each other.

  The invention according to claim 2 is characterized in that pressure is applied uniformly toward the bonding surface direction of the first base material and the second base material simultaneously with the heating at the second heating temperature. 1 is a method for bonding a substrate according to 1;

  According to a third aspect of the present invention, there is provided the substrate bonding method according to the first or second aspect, wherein the adhesive is applied to the bonding surface of the first substrate in a pattern by a screen printing method. is there.

  In the invention according to claim 4, after the first base material and the second base material are overlapped, the first base material and the second base material are decompressed by a vacuum laminator device. The method for adhering a base material according to claim 1, 2 or 3.

  Invention of Claim 5 arrange | positions the site | part in which the said adhesive agent exists in the adhesive surface of a said 1st base material in many dot shape, It is described in any one of Claims 1-4 characterized by the above-mentioned. This is a bonding method of a substrate.

  According to a sixth aspect of the present invention, there is provided the substrate bonding method according to the fifth aspect, wherein the portions where the adhesive is present are arranged in a grid pattern vertically and horizontally on the bonding surface of the first substrate. It is.

  A seventh aspect of the present invention is the substrate bonding method according to the fifth aspect, wherein the portions where the adhesive is present are arranged in a staggered manner on the bonding surface of the first substrate.

  The invention according to claim 8 is the method for adhering a base material according to claim 5, 6 or 7, wherein the maximum diameter of the dot-like adhesive shape is 1 mm or less.

  The invention according to claim 9 is characterized in that on the adhesive surface of the first base material, the portions where the adhesive is present are arranged in a stripe shape crossing each other. It is the adhesion method of the base material.

  A tenth aspect of the present invention is the substrate bonding method according to the ninth aspect, wherein the width of the striped adhesive is 1 mm or less.

  In the invention described in claim 11, the adhesive has a viscosity of 1000 cp or more when applied to the adhesive surface of the first substrate, and a viscosity of 100 cp or less when heated at the first heating temperature. It is a bonding | bonding method of the base material in any one of Claims 1-10 characterized by the above-mentioned.

  The invention according to claim 12 has a large number of ink channels in parallel, the drive wall between the ink channels is made of at least two types of materials, and at least one of the at least two types of materials is piezoelectric. A method of manufacturing an ink jet head that ejects ink in each ink channel by deformation of the piezoelectric material, and includes a first base material and a second base material constituting the at least two kinds of materials After applying the thermosetting adhesive to the adhesive surface of the first base material so that the part where the adhesive is present and the part where the adhesive is not present are formed in a predetermined pattern, By overlapping the second base material on the base material via the adhesive, the adhesive and bubbles are arranged in a pattern between the first base material and the second base material. The curing temperature of the adhesive Simultaneously with heating or after heating at the full first heating temperature, the pressure is reduced, the bubbles are dissolved, and pressure is applied uniformly in the direction of the adhesive surface, and then the second temperature equal to or higher than the curing temperature of the adhesive. After heating at a heating temperature and curing the adhesive to integrate the first base material and the second base material, the first base material and the second base material are spread over. A method of manufacturing an ink jet head, wherein the plurality of ink channels are grooved.

  The invention according to claim 13 is characterized in that, simultaneously with heating at the second heating temperature, pressure is applied uniformly toward the bonding surface direction of the first base material and the second base material. 12. A method for producing an inkjet head according to item 12.

  The invention according to claim 14 is the method of manufacturing an ink jet head according to claim 12 or 13, wherein the adhesive is applied to the adhesive surface of the first base material in a pattern by a screen printing method. is there.

  The invention according to claim 15 is to depressurize the first base material and the second base material with a vacuum laminator device after the first base material and the second base material are overlapped. The method of manufacturing an ink jet head according to claim 12, 13 or 14.

  The invention according to claim 16 is characterized in that a portion where the adhesive is present is arranged in a large number of dots on the adhesive surface of the first base material. It is a manufacturing method of an inkjet head.

  According to a seventeenth aspect of the present invention, there is provided an inkjet head manufacturing method according to the sixteenth aspect, characterized in that the portions where the adhesive is present are arranged vertically and horizontally in a grid pattern on the adhesive surface of the first base material. It is.

  The invention according to claim 18 is the method of manufacturing an ink-jet head according to claim 16, wherein the portions where the adhesive is present are arranged in a staggered manner on the adhesive surface of the first substrate.

  The invention according to claim 19 is the method of manufacturing an ink jet head according to claim 16, wherein the maximum diameter of the dot-like adhesive shape is 1 mm or less.

  According to a twentieth aspect of the present invention, in the adhesive surface of the first base material, the portions where the adhesive is present are arranged in a stripe shape crossing each other. This is a method for manufacturing the inkjet head.

  A twenty-first aspect of the invention is the method of manufacturing an ink-jet head according to the twenty-first aspect, wherein the width of the striped adhesive is 1 mm or less.

  According to a twenty-second aspect of the present invention, the adhesive has a viscosity of 1000 cp or more when applied to the adhesive surface of the first substrate, and a viscosity of 100 cp or less when heated at the first heating temperature. It is a manufacturing method of the inkjet head in any one of Claims 12-21 characterized by the above-mentioned.

  23. The invention according to claim 23, wherein the adhesive has a thermosetting property at a second heating temperature lower than a Curie point of the piezoelectric material. It is a manufacturing method of an inkjet head.

  According to the present invention, it is possible to suppress the residual bubbles in the adhesive layer between the substrates, improve the uniformity of the adhesive layer, have high productivity, and can cope with an increase in the size of the substrate. And a method of manufacturing an ink jet head using the bonding method.

  Hereinafter, embodiments of the present invention will be described. Here, the first base material and the second base material to be bonded are the piezoelectric material substrates 11 and 12 in the ink jet head described in FIGS. A case will be described. Detailed description of the same configuration and manufacturing method as those of the above-described inkjet head and the manufacturing method thereof will be omitted.

  First, before the piezoelectric material substrate 11 (first base material) and the piezoelectric material substrate 12 (second base material) constituting the actuator substrate 10 are bonded using an adhesive, the wettability improving process of the adhesive surface is performed. It is preferable to give. The wettability improving process is a general single wafer type precision ultrasonic cleaning in which each piezoelectric material substrate 11 and 12 is set in a holder and an alkali cleaning liquid tank, a first rinsing tank, a second rinsing tank, and a dryer are set. It can be performed by washing and drying with an apparatus. Note that the cleaning method only needs to ensure wettability of the adhesive surface, and a plasma cleaning apparatus that is also one of dry processing methods can be used. As an example of the cleaning liquid, Van Rise D-20 manufactured by Joban Chemical Industry Co., Ltd. is used at a concentration of 2%, and the liquid temperature of each liquid tank is 38 ° C.

  Next, as shown in FIG. 4, a thermosetting adhesive is applied to the adhesive surface 11 a of the piezoelectric material substrate 11 that has been subjected to the wettability improving process and the piezoelectric material substrate 12. In the figure, a hatched area A indicates an adhesive application area. In the present invention, the adhesive application is performed in a predetermined area between the area where the adhesive is present and the area where the adhesive is not present. It is important to apply so as to form a pattern.

  Here, the predetermined pattern means that when the two piezoelectric material substrates 11 and 12 are overlapped with the adhesive interposed therebetween, the applied adhesive is around the portion where the adhesive is not present on the adhesive surface 11a. By surrounding, it is a form that regularly encloses innumerable air (bubbles) between the substrates. In this way, it is possible to apply and form an adhesive with a uniform thickness on the adhesive surface, and thereby the adhesive layer formed can be made thin, and bubbles between the substrates as described later. Can be dissolved and easily disappeared.

  In order to form the adhesive in such a predetermined pattern, by applying the adhesive in dots on the bonding surface, the portions where the dot-like adhesive is present and the portions where there is no dot are patterned. It can be mentioned that it is preferable. For example, as shown in FIG. 5 (a), a dot-shaped adhesive A1 having a diameter of 400 μm is formed on the adhesive surface 11a of the piezoelectric material substrate 11 having a size of 70 mm × 50 mm by being regularly arranged in a grid pattern vertically and horizontally at a pitch of 1 mm. In this case, the site where about 5000 dot-shaped adhesives A1 are present and the site A2 where no adhesives are present can be formed regularly. In this case, when the other piezoelectric material substrate 12 is overlaid on the bonding surface 11a of the piezoelectric material substrate 11 in the subsequent process, the dot-shaped adhesive A1 is slightly crushed as shown in FIGS. Adjacent adhesives A1 are connected to each other, and by surrounding the portion A2 where no adhesive is present, it is possible to wrap countless bubbles A3 in the adhesive surface 11a.

  When applying the dot-shaped adhesive A1 so that the portion where the adhesive A1 is present and the portion A2 where the adhesive A1 is not present are formed in a predetermined pattern, the present invention is not limited to those arranged in a grid pattern vertically and horizontally. It is also preferable to arrange them in a zigzag pattern as shown in FIG.

  Similarly, in order to apply and form a part where the adhesive A1 is present and a part A2 where the adhesive is not present on the adhesive surface 11a of the piezoelectric material substrate 11 in a predetermined pattern, the part where the adhesive A1 is present is formed. They can also be arranged in stripes crossing each other. FIG. 5C shows an example in which a stripe-shaped adhesive A1 is regularly crossed vertically and horizontally to form a lattice shape. In the case of such a lattice shape, it may be an oblique lattice shape. In short, when the two piezoelectric material substrates 11 and 12 are superposed on the adhesive A1 applied to the adhesive surface 11a of the piezoelectric material substrate 11 via the adhesive, an infinite number of bubbles are regularly wrapped between the substrates. What is necessary is just to form the site | part A2 in which adhesive A1 exists, and the site | part A2 which does not exist so that it may become such a form. In the present invention, the adhesive is applied and formed so that innumerable regular bubbles can be formed in the adhesive layer between the substrates formed when the two piezoelectric material substrates 11 and 12 are superposed in this way. It becomes important.

  As shown in FIGS. 5A and 5B, when the adhesive A1 has a dot shape, the maximum diameter of the adhesive shape is preferably 1 mm or less. When the thickness exceeds 1 mm, the thickness of each adhesive A1 tends to increase, and the thickness of the adhesive layer between the substrates formed thereby tends to increase. In addition, the time required for dissolving bubbles, which will be described later, also increases. In particular, in order to dissolve bubbles efficiently, it is preferable that the shape of the adhesive is a small diameter, and therefore a more preferable maximum diameter is 500 μm or less, and more preferably 200 μm or less.

  Further, when the adhesive A1 has a stripe shape that crosses each other as shown in FIG. 5C, the width is preferably 1 mm or less. If the thickness exceeds 1 mm, the thickness of each adhesive A1 increases as described above, and the thickness of the adhesive layer between the substrates formed thereby tends to increase. In addition, the time required for dissolving bubbles, which will be described later, also becomes longer. In particular, in order to dissolve bubbles efficiently, it is preferable to make the width of the stripe small, so that the more preferable width is 500 μm or less, more preferably 200 μm or less.

  The height (thickness) of the adhesive A1 by each dot or each stripe and the interval (pitch) between the adhesives A1 are regularly innumerable between the two piezoelectric material substrates 11 and 12 when they are overlapped. It can be appropriately determined depending on the diameter or width so as to enclose the bubbles.

  In order to suppress the protrusion of the adhesive when the two piezoelectric material substrates 11 and 12 are overlapped, as shown in FIG. 4, the outer peripheral edge of the bonding surface 11a of the piezoelectric material substrate 11 covers a certain width. Thus, it is preferable to form a region B where no adhesive is applied.

  The method of applying the adhesive to the adhesive surface 11a of the piezoelectric material substrate 11 so as to be formed in a predetermined pattern in this way is not particularly limited, and is performed by appropriately adopting a known application device or application means. However, from the viewpoint of workability and ease of pattern formation, it is preferable to apply by screen printing. As the screen printing machine, for example, LS150 manufactured by Neurong Seimitsu Kogyo Co., Ltd. can be used, and EX305TYB manufactured by Mesh Co., Ltd. can be preferably used as the screen plate.

  The thermosetting adhesive used in the present invention can be appropriately selected according to the substrate to be bonded, and is not particularly limited. Those that do not melt or change the quality of the ink are preferable. When screen printing is performed as described above, it is preferable to use one having screen printing suitability in addition to this.

  The thermosetting adhesive preferably has a viscosity of 1000 cp or more when applied to the adhesive surface 11a of the piezoelectric material substrate 11 and a viscosity of 100 cp or less when heated at the first heating temperature described later. . By being 1000 cp or more at the time of application, it is possible to suppress positional deviation at the time of bonding, and the viscosity decreases when heated at the first heating temperature. It can be made easier.

  Examples of the thermosetting adhesive satisfying these various conditions include, for example, EPOTE 353ND manufactured by EPOXY TECHNOLOZY, Epoxy 84-3 manufactured by Nippon Able Stick Co., Ecobond, Technodyne AH-3041 manufactured by Taoka Chemical Industries, etc. Is mentioned. In the present invention, these adhesives do not need to be defoamed before application.

  Next, after the thermosetting adhesive is applied and formed on the adhesive surface 11a of the piezoelectric material substrate 11 in a predetermined pattern as described above, the other piezoelectric material substrate 12 is overlaid on the adhesive surface 11a. Match. However, no pressure is applied to the piezoelectric material substrates 11 and 12 superposed here. At this time, the adhesive A1 applied and formed in a predetermined pattern on the adhesive surface 11a of the piezoelectric material substrate 11 is a case where the dot-like adhesive A1 is arranged in a grid pattern vertically and horizontally as shown in FIG. As an example, depending on the weight of the superimposed piezoelectric material substrate 12, as shown in FIG. 6, it is slightly crushed and spreads around, and the adjacent adhesives A1 are connected to each other. As a result, the portion A2 where no adhesive is present is surrounded by the adhesive A1 and the upper and lower sides thereof are covered with the piezoelectric material substrates 11 and 12. Therefore, as shown in FIG. 7, between the piezoelectric material substrates 11 and 12, the portion A2 where no adhesive is present at the time of application is regularly encapsulated as an infinite number of bubbles A3, and the adhesive A1 And bubbles A3 are arranged in a pattern.

  Next, the stacked laminate 1 of the piezoelectric material substrates 11 and 12 is heated at a first heating temperature lower than the curing temperature of the adhesive. As a result, the viscosity of the adhesive A1 existing between the substrates is lowered, and the temperature of the gas in the bubble A3 is raised to increase the diffusion coefficient of air in the adhesive A1. As the heating condition at the first heating temperature, for example, when the adhesive is EPOTEK353ND, it is preferable to perform heating at about 70 ° C. for about 5 minutes.

  As shown in FIG. 8, the steps after the step of heating at the first heating temperature are preferably performed by putting them in a vacuum pressurizing laminator capable of controlling heating, decompression and pressurization. As such a vacuum pressure laminator, a vacuum laminator MVLP600 manufactured by Meiki Seisakusho Co., Ltd. can be preferably used.

  FIG. 8 is a schematic view of a laminate part 200 of a vacuum pressure laminator. The laminating unit 200 has a chamber 203 formed in an upper mold 201 and a lower mold 202 that can be opened and closed, and an inner heating plate 204 and a lower plate each having a heater built in the inner surfaces of the molds 201 and 202, respectively. A hot platen 205 is provided.

  The lower mold 202 is provided with a diaphragm (rubber film) 206 so as to cover the upper side of the lower heating plate 205. The lower heating plate 205 is sealed between the lower mold 202 and the two molds 201. When the molds 202 are closed, the diaphragm 206 divides the chamber 203 into an upper chamber 203a and a lower chamber 203b.

  The upper mold 201 and the lower mold 202 are connected to appropriate pressurizing means and decompressing means (both not shown) through openings 207 and 208, respectively, and the inside of the upper chamber 203a of the chamber 203 and the lower The inside of the chamber 203b can be individually pressurized or depressurized.

  In the laminate part 200 of such a vacuum pressurizing laminator, the laminate 1 of the piezoelectric material substrates 11 and 12 is placed on the diaphragm 206 in the upper chamber 203a and the mold is closed, and then the upper heating plate 204 and the lower heating plate. The laminate 1 in the upper chamber 203a of the chamber 203 is heated by heating 205 to the first heating temperature. At this time, if the inside of the lower chamber 203b of the chamber 203 is depressurized by evacuating from the opening 208 of the lower mold 202, the diaphragm 206 comes into close contact with the lower heating plate 205 as shown in FIG. The heating at the first heating temperature can be performed in a state in which no pressure is applied to 1.

  Here, when vacuuming is performed from the opening 207 of the upper mold frame 201 simultaneously with or after the heating, the inside of the upper chamber 203a of the chamber 203 is depressurized, whereby the laminate 1 can be brought into a depressurized state. . In the present invention, the bubbles between the substrates are dissolved in the adhesive A1 by the heating at the first heating temperature and the reduced pressure state, and disappear.

The theory of the dissolution and disappearance of the bubbles will be described. As shown in FIG. 11, regarding the speed at which the bubble 500 existing at the center of the solvent resin 400 between two PZT substrates 300 having a size of 48 mm × 68 mm diffuses to the end, the bubble is formed at the center of a 42 mmR cylinder. assuming that 500 is present, the diffusion rate _{N a} that bubbles 500 in vacuum 3Torr diffuses in the solvent resin 400 is given by the following equation.

N _A = A _1m D _AB ΔC / (r2-r1)
here,
D _AB : Diffusion coefficient ... calculated by Wilke-Chang's estimation formula
^{_{D AB = 7.4 * 10 -8 *}} (φM B) 0.5 * T / η B * V A 0.6 (cm 2 / s)
M _B : Molecular weight of solvent B 340 (epoxy resin / room temperature liquid)
T: Absolute temperature 20 ° C
η _B : viscosity of solvent B 10 cp
V _A : Molecular volume of solute A at the normal boiling point 29.9 (cm ³ / gmol)
φ: degree of association of solvent B 1
ΔC: Desaturation: Substituting the degree of air unsaturation (normal temperature / 757 Torr) with respect to water A _1m : Logarithmic average area
N _A = 0.28 (cm ² ) * 6.1 * 10 ⁻⁶ (cm ² /s)*0.76*10 ⁻³ (mol / cm ³ ) /4.17 (cm) = 0.31 * 10 ⁻⁹ (mol / s) = 6.9 * 10 ⁻⁶ (cc / s)
It becomes.

Here, if the air quantity V = 1.2 ^{* 10} -5 of the bubble 500 (cc), the diffusion time of the bubble 500 is found to be short and _{V / N A ≒ 1.6 (s} ). Therefore, it can be seen that the bubbles 500 are dissolved in the solvent resin 400 and disappear in a short time by being brought to a predetermined temperature and reduced pressure.

  Since the laminate 1 in the present invention is heated at the first heating temperature as described above, the viscosity of the adhesive A1 existing between the substrates decreases, and the temperature of the gas in the bubbles A3 increases, whereby the adhesive A1. Since the diffusion coefficient of the air inside is increased, the infinite number of bubbles A3, which are regularly arranged by being wrapped by the adhesive A1 between the substrates, are formed in the adhesive A1 by being decompressed in a predetermined time. Dissolves and disappears after being diffused. The term “after heating” means that the viscosity of the adhesive A1 is lowered and the temperature of the gas in the bubble A3 is still raised.

  The conditions for making the laminate 1 in such a reduced pressure state are generally a vacuum degree of 2 Torr to 30 Torr and a reduced pressure time of 10 to 60 seconds. However, the laminate 1 is applied and formed in a pattern on the adhesive surface 11a of the piezoelectric material substrate 11. It can be appropriately adjusted according to various conditions such as the size, pitch and viscosity of each adhesive A1, the amount of bubbles A3 encapsulated between the substrates, and the size of the substrate. For example, when the pitch of the adhesive A1 is large, the adhesive layer becomes thin, and the bubbles A3 are difficult to dissolve in the adhesive A1, so that the decompression time may be set longer.

  As described above, the laminate 1 is brought into a reduced pressure state to dissolve and disappear the bubbles A3, and then evacuation from the openings 207 and 208 of both molds 201 and 202 is stopped. Then, as shown in FIG. When compressed air is supplied from the opening 208 of the lower mold 202 into the lower chamber 203 b of the chamber 203, the diaphragm 206 expands and presses the laminate 1 against the upper heating plate 204 of the upper mold 201. Thereby, a pressure can be uniformly applied with respect to the laminated body 1 toward the bonding surface direction.

  According to the present invention, the bubbles A3 between the substrates are dissolved and disappeared by putting the laminate 1 in a reduced pressure state for a predetermined time as described above. Therefore, the operation step of uniformly applying pressure to the laminate 1 is not intended to dissolve and disappear the bubbles A3, and by applying the pressure to the laminate 1 uniformly, It aims at adjusting the film thickness of an adhesive bond layer to desired thickness by equalizing a film thickness and adjusting a pressurizing condition suitably.

  The applied pressure at this time can generally be 0.5 MPa to 1.5 MPa, but the size, pitch, viscosity, and substrate of each adhesive A1 applied and formed in a pattern on the adhesive surface 11a of the piezoelectric material substrate 11 It can be appropriately adjusted according to various conditions such as the amount of bubbles A3 encapsulated between them, the size of the substrate, and the thickness of the intended adhesive layer. The average thickness of the adhesive layer is preferably 0.5 μm to 3.0 μm from the viewpoint of performing high-speed driving at a low voltage in the case of between the piezoelectric material substrates 11 and 12 constituting the inkjet head. The average thickness means an average value in consideration of the unevenness of the piezoelectric material substrates 11 and 12.

  Thereafter, by raising the temperature of the upper heating plate 204 and the lower heating plate 205, the laminate 1 is heated at a second heating temperature equal to or higher than the curing temperature of the adhesive to cure the adhesive A1 and 12 are integrated with each other. The heating condition at the second heating temperature needs to be lower than the Curie point of the piezoelectric material in order to avoid the disappearance of polarization when the piezoelectric material substrates 11 and 12 constituting the ink jet head are joined. Therefore, it is preferable to use an adhesive that has thermosetting properties at a temperature lower than the Curie point of the piezoelectric material. For example, when the adhesive A1 is EPOTEK353ND, it has thermosetting property by heating at about 100 ° C. for about 20 minutes. Therefore, it can be preferably used when the piezoelectric material substrates 11 and 12 are PZT.

  When heating at the second heating temperature, it is preferable to apply pressure uniformly to the laminate 1 toward the bonding surface simultaneously with the heating. This can be done by continuing the pressurizing step as it is. Even when the laminate 1 is heated at the second heating temperature, it is possible to suppress re-mixing of bubbles during curing of the adhesive and to make the thickness of the adhesive layer more uniform by applying a uniform pressure. it can.

  Thereafter, as shown in FIG. 2, a large number of ink channels 13 parallel to each other are cut by the diamond blade 100 on the laminate 1 of the piezoelectric material substrates 11 and 12 having the adhesive thus cured. . At this time, the adhesive layer of the laminate 1 does not contain bubbles, and is an extremely thin adhesive layer, but is bonded with sufficient strength. Each drive wall 14 made of two types of upper and lower piezoelectric materials having different polarization directions from each ink channel 13 can be easily formed without the substrates 11 and 12 being peeled off or the drive wall 14 left uncut. Can do. In addition, since the adhesive layer can be made thin, the adhesive layer does not absorb the operating energy at the time of shear deformation of the drive wall 14, and ink can be discharged efficiently.

  In addition, since no bubbles remain in the adhesive layer, there is no problem that adjacent electrode metals are formed through the bubbles when the drive electrode 15 is formed, and a highly reliable inkjet head is manufactured. Can do.

  The substrate bonding method according to the present invention is not limited to the method applied to the manufacture of the inkjet head described above, and it is possible to prevent bubbles from remaining between the substrates bonded via the adhesive layer. The present invention can be widely applied to a method for bonding a substrate that is particularly preferable in terms of product performance. Examples of applications other than the manufacture of such an inkjet head include bonding of optical elements and manufacture of a liquid crystal panel.

(Example 1)
A piezoelectric material substrate made of PZT having a size of 70 mm × 50 mm and a thickness of 0.7 mm is prepared, and a screen printing machine “LS150” manufactured by Neurong Seimitsu Kogyo Co., Ltd. is used on one surface (adhesion surface) thereof. By applying a dot-shaped adhesive (EPOXY TECHNOLOZY: EPOTEK353ND) in a grid pattern, a portion where the adhesive is present and a portion where the adhesive is not present are formed in a pattern. Table 1 shows the dot diameter, dot pitch, and dot height of each adhesive.

  A transparent glass substrate having a size of 70 mm × 50 mm and a thickness of 0.155 mm is superimposed on the bonding surface of the piezoelectric material substrate, and a first heating temperature of 70 is used by using a vacuum laminator “MVLP600” manufactured by Meiki Seisakusho Co., Ltd. After heating at 5 ° C. for 5 minutes, the pressure was reduced and the pressure was uniformly applied in the direction of the bonding surface. At the same time, heating was performed at a second heating temperature of 100 ° C. for 20 minutes to cure the adhesive layer.

  In addition, when bonding the glass substrate, each dot-shaped adhesive is slightly crushed and spreads around, so that each adhesive is connected to the adjacent adhesive, and a state in which air bubbles are encased between them is over the entire adhesive surface. It was confirmed.

  Table 1 shows the degree of vacuum, the vacuum processing time, and the applied pressure of each substrate.

(Example 2)
Example 1 was the same as Example 1 except that the vacuum processing time was changed as shown in Table 1.

(Example 3)
The adhesive application pattern was staggered and the same as Example 1 except that the vacuum processing time was changed as shown in Table 1.

(Example 4)
Example 1 was the same as Example 1 except that the vacuum processing time and the applied pressure were changed as shown in Table 1.

(Example 5)
Example 1 was the same as Example 1 except that the dot diameter, dot pitch, and applied pressure of the adhesive were changed as shown in Table 1.

(Example 6)
Example 1 was the same as Example 1 except that the dot diameter, dot pitch, pressure, and vacuum treatment time of the adhesive were changed as shown in Table 1.

(Example 7)
Example 1 was the same as Example 1 except that the dot pitch, dot height, and vacuum treatment time of the adhesive were changed as shown in Table 1.

(Comparative Example 1)
After joining the piezoelectric material substrate and the glass substrate, the pressure was not changed (atmospheric pressure: 760 Torr).

(Comparative Example 2)
Example 3 was the same as Example 3 except that no pressure was applied after bonding the piezoelectric material substrate and the glass substrate.

(Comparative Example 3)
Example 2 was the same as Example 2 except that the piezoelectric material substrate and the glass substrate were not heated at the first heating temperature after bonding.

(Comparative Example 4)
Example 2 was the same as Example 2 except that the dot diameter, dot pitch, and dot height of the adhesive were changed as shown in Table 1. Here, even after the adhesive is applied, even if the piezoelectric material substrate and the glass substrate are joined and the adhesive is slightly crushed, the adjacent adhesives are not connected to each other, and the bubbles are wrapped by the adhesive. It was not in a state.

<Evaluation>
Items evaluated in each of the examples and comparative examples evaluated the residual amount of bubbles, the uniformity of the adhesive layer, and the adhesive thickness.

  The residual amount of bubbles was observed with a microscope from the glass substrate surface, and the presence or absence of bubbles was evaluated. The evaluation criteria are as follows.

○: No bubbles are present.
(Triangle | delta): The bubble remains in a part of bubble position at the time of board | substrate joining.
X: All the bubbles remain at the positions of the bubbles at the time of substrate bonding.

  The uniformity of the adhesive layer was measured by dividing the substrate after curing the adhesive vertically and horizontally into two, and measuring the thickness of the adhesive layer on the cut surface with a microscope at 10 points. A piezoelectric material substrate having a surface roughness (Rz) of 2 μm was used, and the thickness of the adhesive layer was an average thickness considering the unevenness. The evaluation criteria are as follows.

(Circle): The difference of MAX and MIN of adhesive layer thickness is 0.5 micrometer or less.
(Triangle | delta): The difference of MAX and MIN of adhesive layer thickness exceeds 0.5 micrometer, and is less than 2 micrometers.
X: The difference between the adhesive layer thickness MAX and MIN is 2 μm or more.

  For the adhesive layer thickness, an average thickness in the evaluation of the uniformity of the adhesive layer was calculated. The results are shown in Table 1.

  As can be seen from Table 1, in Examples 1 to 7, when the glass substrate was joined after application of the dot-shaped adhesive, each dot-shaped adhesive was slightly crushed by the weight of the glass substrate and adjacent to each other. Dot-shaped adhesives are connected to each other, so that innumerable bubbles are encapsulated between the substrates. By heating this at the first heating temperature and reducing the pressure, the bubbles in the adhesive layer Was dissolved and disappeared, so that it was partially observed in the adhesive layer (Example 1) or not at all (Examples 2 to 7).

  After that, by applying pressure uniformly toward the bonding surface direction and heating and curing at the second heating temperature, a substantially uniform adhesive layer could be formed.

  However, in Comparative Example 1, since the reduced pressure state was not passed after the substrates were superposed, the bubbles could not be dissolved and disappeared, and bubbles remained and the adhesive layer was not uniform.

  Moreover, in Comparative Example 2, since the pressure was not applied when the adhesive was cured after the reduced pressure state, the adhesive layer showed nonuniformity. If the adhesive layer becomes non-uniform, it will lead to the occurrence of variations in driving of the ink-jet head, which is unsuitable for use as an actuator substrate for the ink-jet head.

  Furthermore, in Comparative Example 3, since the heating at the first heating temperature was not performed after the substrates were overlaid, the diffusion coefficient of air in the adhesive did not increase, and even when the pressure was reduced, bubbles between the substrates were put into the adhesive. It was insufficient to diffuse and dissolve, air bubbles remained, and the adhesive layer was not uniform.

  Further, in Comparative Example 4, even when the substrates were overlapped after applying the adhesive, the adjacent adhesives were not connected to each other, and the bubbles were not enveloped by the adhesive. However, it was insufficient to diffuse and dissolve the bubbles between the substrates in the adhesive, the bubbles remained, and the adhesive layer was not uniform.

An exploded perspective view showing a cross section of the inkjet head Explanatory drawing showing how ink channels are processed Explanatory drawing showing drive of inkjet head Plan view showing the bonding surface of the piezoelectric material substrate coated with adhesive (A) is a pattern in which dot-like adhesives are regularly arranged horizontally and vertically, (b) is a pattern in which dot-like adhesives are arranged in a staggered pattern, and (c) is a stripe-like adhesive vertically and horizontally. A plan view showing patterns crossed and positioned in a grid pattern The top view which shows the state where the adjacent dot-like adhesives when the board | substrates were piled up were connected Sectional drawing which shows the state in which the adjacent dot-like adhesives when the board | substrates were piled up were connected Explanatory drawing which shows the state which mounted and laminated | stacked the laminated body in the laminate part Explanatory drawing which shows the state which mounted and put the laminated body in the laminate part (A) is a graph showing the relationship between the driving voltage, the thickness of the adhesive layer and the adhesive hardness, and (b) is a graph showing the relationship between the driving pulse width, the thickness of the adhesive layer and the adhesive hardness. Diagram explaining the theory of disappearance of bubbles

Explanation of symbols

1: Laminate 10: Actuator substrate 11, 12: Piezoelectric material substrate 11a: Adhesive surface 13: Ink channel 14: Drive wall 15: Drive electrode 20: Nozzle plate 21: Nozzle 30: Cover substrate 31: Ink distribution port 40: Ink Manifold 100: Diamond blade 200: Laminate part A: Adhesive application area A1: Adhesive A2: Site where no adhesive exists A3: Bubble B: Area where no adhesive is applied

Claims (23)

  A thermosetting adhesive is provided on a bonding surface of the first substrate of the first substrate and the second substrate to be bonded, and a portion where the adhesive is present and a portion where the adhesive is not present are predetermined. Then, the first base material and the second base material are overlaid on the first base material via the adhesive. The adhesive and bubbles are arranged in a pattern between the substrate, and at the same time as or after heating at a first heating temperature lower than the curing temperature of the adhesive, after being heated to a reduced pressure state, the bubbles are dissolved, Pressure is applied uniformly in the direction of the adhesive surface, and then heated at a second heating temperature equal to or higher than the curing temperature of the adhesive to cure the adhesive and the first substrate and the second substrate. A method for adhering a base material, wherein the materials are integrated with each other.   The method for bonding a substrate according to claim 1, wherein pressure is applied uniformly toward the bonding surface direction of the first substrate and the second substrate simultaneously with the heating at the second heating temperature. .   3. The substrate bonding method according to claim 1, wherein the adhesive is applied in a pattern to the bonding surface of the first substrate by a screen printing method.   The first base material and the second base material are depressurized with a vacuum laminator device after the first base material and the second base material are overlapped with each other. Or 3. The method for adhering a substrate according to 3.   The method for adhering a base material according to any one of claims 1 to 4, wherein a portion where the adhesive is present is arranged in a number of dots on the adhesive surface of the first base material.   The method for adhering a base material according to claim 5, wherein a portion where the adhesive is present is arranged in a grid pattern in the vertical and horizontal directions on the adhesive surface of the first base material.   6. The method for bonding substrates according to claim 5, wherein the portions where the adhesive is present are arranged in a staggered manner on the bonding surface of the first substrate.   The method for adhering a base material according to claim 5, 6 or 7, wherein the maximum diameter of the dot-like adhesive shape is 1 mm or less.   The method for adhering a base material according to any one of claims 1 to 4, characterized in that on the adhesive surface of the first base material, the portions where the adhesive is present are arranged in a stripe shape crossing each other.   The substrate bonding method according to claim 9, wherein a width of the striped adhesive is 1 mm or less.   The viscosity of the adhesive when applied to the adhesive surface of the first substrate is 1000 cp or more, and the viscosity when heated at the first heating temperature is 100 cp or less. The adhesion | attachment method of the base material in any one of 1-10. A plurality of ink channels are provided in parallel, and a drive wall between the ink channels is formed of at least two types of materials, and at least one of the at least two types of materials is a piezoelectric material. A method for manufacturing an inkjet head that ejects ink in each ink channel by deformation, comprising:
The thermosetting adhesive is present on the adhesive surface of the first base material of the first base material and the second base material constituting the at least two types of materials, and the portion where the adhesive is present. The first base material is applied by superimposing the second base material on the first base material with the adhesive after being applied so that the portion not to be formed is formed in a predetermined pattern. The adhesive and bubbles are arranged in a pattern between the first substrate and the second base material, and the bubbles are reduced in pressure simultaneously with or after heating at a first heating temperature lower than the curing temperature of the adhesive. Then, pressure is applied uniformly in the direction of the adhesive surface, and then heated at a second heating temperature equal to or higher than the curing temperature of the adhesive to cure the adhesive and the first substrate and After the second base material is integrated with each other, the first base material and the second base material are A method of manufacturing an ink jet head, characterized by grooving the plurality of ink channels I.   13. The method of manufacturing an ink jet head according to claim 12, wherein pressure is applied uniformly toward the bonding surface direction of the first base material and the second base material simultaneously with the heating at the second heating temperature. .   The method of manufacturing an ink jet head according to claim 12 or 13, wherein the adhesive is applied to the adhesive surface of the first base material in a pattern by a screen printing method.   The first base material and the second base material are superposed on each other, and then the first base material and the second base material are decompressed by a vacuum laminator device. Or the manufacturing method of the inkjet head of 14.   The method for manufacturing an ink jet head according to claim 12, wherein a portion where the adhesive is present is arranged in a large number of dots on the adhesive surface of the first base material.   17. The method of manufacturing an ink jet head according to claim 16, wherein the portions where the adhesive is present are arranged in a grid pattern vertically and horizontally on the bonding surface of the first base material.   The method of manufacturing an ink jet head according to claim 16, wherein the portions where the adhesive is present are arranged in a staggered manner on the adhesive surface of the first base material.   19. The method of manufacturing an ink jet head according to claim 16, wherein the maximum diameter of the dot-like adhesive shape is 1 mm or less.   The method of manufacturing an ink jet head according to claim 12, wherein a portion where the adhesive is present is arranged in a stripe shape crossing each other on an adhesive surface of the first base material.   21. The method of manufacturing an ink jet head according to claim 20, wherein a width of the striped adhesive is 1 mm or less.   The viscosity of the adhesive when applied to the adhesive surface of the first substrate is 1000 cp or more, and the viscosity when heated at the first heating temperature is 100 cp or less. The manufacturing method of the inkjet head in any one of 12-21.   The method of manufacturing an ink jet head according to any one of claims 12 to 22, wherein the adhesive has a thermosetting property at a second heating temperature lower than a Curie point of the piezoelectric material.

Images