JP3109154B2 - Method of manufacturing ink jet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ink jet recording head for performing recording by discharging ink, and more particularly to a method of manufacturing an ink jet recording head formed by bonding substrates.

[0002]

2. Description of the Related Art A general method of manufacturing an ink jet recording head used in an ink jet recording method is to form a multi-nozzle by bonding a substrate having a plurality of grooves on at least one side.

[0003] As a method for bonding the substrate, as disclosed in Japanese Patent Application Laid-Open No. 63-34152, a thin adhesive layer is formed on a flexible substrate, and the thin adhesive layer is formed on the bonding surface. A transfer method of transferring and bonding by applying an adhesive, and as disclosed in JP-A 1-255552,
There is known a permeation method in which a liquid adhesive is permeated into a superposed surface of substrates to be bonded by capillary action to perform bonding.

Meanwhile, a thermal ink jet head has been receiving attention as an ink jet recording head.
A thermal ink jet head ejects ink droplets by the pressure of bubbles generated by a heating element. Japanese Patent Application Laid-Open No. 62-33648 defines a growth area of bubbles generated by a heating element. A head structure for stabilizing ink ejection is described.
Specifically, a resin layer having a thickness of several tens of μm is formed on a heater substrate, and concave portions called pits are formed by photolithography. The heating element is located at the bottom of the pit. Also,
Japanese Patent Application Laid-Open No. 60-206663 discloses a head in which a drive circuit and a logic circuit for controlling on / off of a heating element are mounted on a heater substrate. Further, Japanese Patent Application Laid-Open No. Sho 61-230954 generally describes a method of manufacturing a head, such as a method of manufacturing a channel, a bonding method, and a cutting method.

In the process of manufacturing a conventional thermal ink jet head having such pits, generally, first, two substrates are manufactured. That is, after a heating element, a drive circuit, a logic circuit, a protective layer, and the like are formed on a silicon substrate, a thick resin layer is laminated, and pits are patterned to form a heater substrate and ink such as a channel and an ink reservoir. The channel substrate is a channel substrate formed by forming a channel on a silicon substrate by anisotropic etching. For example, as disclosed in JP-A-63-34152, an adhesive is applied to the channel substrate by a selective adhesive application method, and the heater substrate and the channel substrate are aligned and bonded. After that, the wire bonding pad is exposed, and cut and separated into individual chips by a dicer to form a nozzle surface. In a head adopting such a manufacturing process, an adhesive state,
Nozzle chipping during dicing has a significant effect on stabilization during ejection and high print quality.

The state of adhesion will be described. A state in which a heater substrate is bonded to a channel substrate having a groove, for example, using a transfer method will be described. FIG. 4 illustrates a part of the cross section of the channel substrate to which the adhesive has been transferred. In the figure, 11 is a channel substrate, 12 is a groove, 14
a and 14b are adhesives. When the adhesive is transferred to the channel substrate 11 using a flexible substrate to which the adhesive is attached, a sufficient adhesive force can be obtained between the grooves by the swelling of the adhesive 14a. On the other hand, in a relatively wide bonded portion having no groove or the like, the adhesive 14b spreads, and a surface may have irregularities, which may cause poor bonding.

The bonding state described with reference to FIG. 4 causes a problem even when the bonding surface is flat. However, when the bonding surface is not flat, it further causes poor bonding. When a thick resin layer such as that used for forming the above-mentioned pits is formed on a substrate, flatness of the adhesive surface of the resin layer surface becomes a problem.

FIG. 8 is an explanatory view of a bonded state of a substrate having a thick resin layer according to a conventional method. This figure shows a cross section in a plane parallel to the channel axis near the dicing surface in a state where two substrates are bonded. In the figure, 3
1 is a channel substrate, 32 is a heater substrate, 33 is a thick resin layer, 34 is a laminate, 35 is an adhesive, 36 is a channel groove, 37 is a pit, 38 is a nozzle surface position, and 39 is a recess. Since the cross section between the channel grooves is not visible, the cross sections of the channel grooves 36 and the pits 37 are not visible, and are shown by dotted lines. The laminated body 34 includes a driving circuit, a logic circuit, a heating element, an electrode, a protective film, and the like formed on the silicon wafer. The cross section of the electrodes and the like is not visible.
Both substrates are cut by the dicing blade at the position indicated by the one-dot chain line after the bonding is completed, so that the cut surface becomes the nozzle surface. The illustrated laminate has a thickness of about 4 to 5 μm at the maximum, so that the unevenness on the heater substrate surface before the thick resin layer 33 is laminated is about 4 to 5 μm. On this surface, for example, when spin-coated with a photosensitive polyimide resin, it is leveled to some extent and becomes flat,
It is not perfect and a dent 39 occurs. As described in page 225 of “Latest heat-resistant polymer” (published by Sogo Gijutsu Center), the leveling level is usually 50%.
It is about. Actually, when spin coating is performed so as to stack several tens of μm thick resin layers, a maximum of 1-2 μm
It is inevitable that unevenness before and after remains. Furthermore, when the thick resin layer is patterned and then cured, a phenomenon in which the edges of the pattern swell is added, so that irregularities of up to about 4 μm may occur. In order to obtain good printing quality, the thickness of the adhesive layer between the heater substrate and the channel substrate is desirably 1 μm or less. In order to prevent the adhesive from protruding into the channel, the amount of the adhesive applied is
An average of about 1 μm is desirable. As a countermeasure against the swelling of the edge of the pattern of the thick resin layer, Japanese Patent Application No. 2-285204 proposes forming an escape groove in the channel wafer, which can be solved to some extent. The depression 39 due to the influence of the laminated body 34 causes poor adhesion between the two substrates. Insufficient adhesion of the substrate causes problems such as instability of ink ejection, ink leakage and insufficient bonding strength, and inducing chipping of the nozzle surface during dicing.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method of manufacturing an ink jet recording head which does not cause defective bonding.

[0010]

According to a first aspect of the present invention, there is provided a method for manufacturing an ink jet recording head, comprising: bonding at least two substrates to form an ink flow path and a nozzle for discharging ink. A plurality of grooves whose tip positions are sequentially shifted in the length direction are formed outside the ink flow path, and the grooves are used as confirmation marks for cutting positions.

By forming the groove outside the ink flow path such that the leading end position is sequentially shifted in the length direction, the groove can also be used as a position confirmation mark when dicing is performed.

According to the second aspect of the invention, there is provided a method for manufacturing an ink jet recording head in which a laminate is formed on one substrate, a resin layer is formed on the laminate, and the other substrate is adhered on the resin layer. In the method, the correction layer serving as an underlayer of the resin layer, which is not overlapped with the laminate, and which has the same height as the laminate, is formed first. After correcting the level difference of the base of the layer,
The method is characterized in that the resin layer is formed, and then the other substrate is bonded on the resin layer.

The correction layer can be formed by a layer formed when a logic circuit, a high-voltage drive circuit, a heating element, a protective layer, an electrode, and the like of the ink jet recording head are formed. Further, the correction layer may be made of a thick resin layer.

[0014]

According to the first aspect of the present invention, by forming the grooves as described above, the joining portion having a relatively large area where the adhesive is not preferably applied is divided by the grooves.
A substantially narrow set of joints can be formed, and sufficient adhesive strength can be obtained.

By forming a plurality of grooves whose tip positions are sequentially shifted in the length direction outside the ink flow path, the grooves can be used as position confirmation marks during dicing.

Further, according to the second aspect of the present invention, the step of the underlayer is leveled by the correction layer, and the thick resin layer which is the substrate bonding surface becomes flat, and the adhesion becomes good.

[0017]

FIG. 1 is an explanatory view of a channel substrate for explaining a first embodiment of the present invention. (A) Figure is a plan view,
(B) is a sectional view taken along line BB of (A). In the figure, 11
Is a channel substrate, 12 and 13 are grooves, and 14a and 14b are adhesives. The channel substrate 11 is provided with a groove 12 for forming an ink flow path and a nozzle.
Although the bonding surface between the grooves 12 is narrow, the area on the right side in the figure is a wide bonding surface. In this embodiment, the groove 13 is formed in the area of the wide bonding surface in parallel with the groove 12. The adhesive is applied by a method in which a thin adhesive layer is formed on a flexible substrate and transferred to the adhesive surface side of the channel substrate. The adhesive 14a between the transferred grooves 12 can obtain a sufficient adhesive force by appropriately swelling as in the related art. In the region where the groove 13 is formed, a sufficient adhesive force can be obtained because the adhesive 13 b is appropriately raised due to the groove 13. As described above, the grooves 13 for improving the adhesive strength are formed in an appropriate pattern at appropriate intervals.

FIG. 2 is an explanatory view of a channel substrate for explaining a second embodiment of the present invention. (A) is a plan view schematically showing the entire channel substrate, (B) is a plan view in which an end portion is enlarged, and (C) is a cross-sectional view taken along the line CC of FIG. In the figure, 11 is a channel substrate, 12 and 13 are grooves,
Reference numeral 15 denotes an ink chamber. The groove 12 is a groove for forming an ink flow path and a nozzle, and the groove 13 is a groove according to the present invention provided for improving the adhesive force. In this embodiment, the groove 13 is formed so as to be slightly shifted in the length direction.

A plurality of the channel substrates 11 are formed on a silicon wafer. These grooves are formed by anisotropic etching with an aqueous solution of potassium hydroxide. Separately, a heater substrate corresponding to the channel substrate 11 is prepared. The heater substrate has a structure in which a heating resistor, an electrode, a transistor, and the like are formed on the surface thereof, and the surface thereof is covered with polyimide. ing.

In order to bond the two silicon wafers described above, an adhesive is transferred to the channel substrate 11 using a flexible substrate having a thin adhesive layer applied thereto. By providing the groove 13 for improving the adhesive strength in a portion having a relatively large area, the applied adhesive does not spread, and a sufficient adhesive strength can be obtained.

Next, two silicon wafers are bonded to each other, and dicing is performed to cut off each individual head. At this time, the groove 13 for strengthening the adhesive force is
(B) As shown in the figure, since it is formed so as to be shifted in position, it becomes a position confirmation mark at the time of dicing. That is, if four grooves 13 for strengthening the adhesion are formed so that the vertical deviation d of the grooves is 8 μm, the desired dicing position is set to the position of the line BB, and −
Assuming that dicing is performed at the position of the line C, the shape of the cut surface is such that the cross section of the third groove from the right, which is the cut position limit, does not become a perfect triangle, as shown in FIG. At this time, the dicing error can be said to be within ± 4 μm.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention. (A) is a plan view in which an end portion of the heater substrate is enlarged, and (B) is a cross-section taken along a line corresponding to line BB in (A) in a state where a top plate is attached to the heater substrate. FIG. In the figure, 21 is a heater substrate, 22 is a photosensitive resin layer, 23 is a top plate, 24 is an adhesive, and 25 and 26 are grooves. The groove 25 is a groove for forming an ink flow path and a nozzle, and the groove 26 is a groove according to the present invention provided for improving the adhesive force. In this embodiment, a substrate having a groove for forming an ink flow path and a nozzle on the surface is provided.
This is an example in the case of forming using a photosensitive resin.

A pressure generating unit for discharging ink, for example,
On a heater substrate 21 having a heater, a photosensitive resin composition, for example, a photosensitive polyimide is laminated using a method such as spin coating, and then the grooves 25 and 26 are formed using a photolithography technique, an etching technique, or the like. To form A plurality of heater substrates are formed on the same large substrate. The difference from the second embodiment using a silicon wafer is that the groove 25 for forming the ink flow path and the nozzle and the groove 26 for improving the adhesive strength have a pressure generating portion for discharging the ink. Although they are formed on a substrate, there is no problem even if they are formed on separate substrates.

Next, the adhesive is transferred from a flexible substrate on which a thin adhesive layer is applied, or the substrate is provided with a groove for improving the adhesive strength by another method. Is applied and joined. Thereafter, dicing is performed to separate the heads individually. The grooves for strengthening the adhesive strength can be used as position confirmation marks for dicing, as in the second embodiment.

The substrate having these grooves for improving the adhesive strength is not limited to the above-described embodiment, but may be a silicon substrate processed by etching, a resin processed by molding, a photosensitive resin, or a photosensitive resin. Glass, etc.
The present invention can be applied to all substrates made of a material to which an adhesive can be applied by transfer.

FIG. 5 is an explanatory view of a fourth embodiment of the present invention, and shows a cross section in a plane parallel to a channel axis near a dicing plane in a state where two substrates are bonded. . In the figure, the same parts as those in FIG. Reference numeral 40 denotes a correction layer. Also in FIG. 5, as in FIG. 8, since the cross section is between the channel grooves, the cross sections of the channel grooves 36 and the pits 37 are not visible, so they are shown by dotted lines. The laminated body 34 includes a driving circuit, a logic circuit, a heating element, an electrode, a protective film, and the like formed on the silicon wafer. The cross section of the electrodes and the like is not visible. Both substrates are cut by the dicing blade at the position indicated by the one-dot chain line after the bonding is completed, so that the cut surface becomes the nozzle surface. In this embodiment, a convex layer that fills the steps and depressions of the base of the thick resin layer 33 is formed as the correction layer 40, so that the depression of the thick resin layer 33 is corrected. The dent of the thick resin layer 33 becomes negligible,
Adhesion failure can be prevented.

The correction layer 40 is patterned in a region that is not laminated in a normal manufacturing process. The correction layer 40 can be manufactured by adding a new process. However, from the viewpoint of manufacturing cost, the correction layer 40 is simultaneously formed by a process of forming a logic circuit, a high-voltage drive circuit, a heating element, a protective layer, an electrode, and the like of the head. Is good. In this case, the correction layer 40 may be formed of only one of the layers of the laminate 34, or may be formed of a plurality of layers.

A part of the layered body 34 is replaced with a correction layer 40.
In the case of utilizing the glass layer, it is preferable to use the same glass layer having a relatively large thickness. Thermal oxide film,
Reflow glass, PSG (Phospho-Silic)
ate-Glass). A convex portion having a thickness of 3 μm can be obtained only by laminating the glass layers, and can be used as the correction layer 40. Further, in order to reduce the occurrence of chipping at the time of dicing, a layer of a relatively thick and soft material can be selected as the correction layer 40. For example, it is an aluminum or polysilicon film. Tantalum films that are rigid but not brittle may be used.

The thickness of the correction layer 40 thus formed is desirably the same as the thickness of the adjacent laminate 34. From this point of view, it is also a good method to have a layer configuration equivalent to that of the adjacent stacked body 40.

The distance D between the laminate 34 and the correction layer 40 is 0
About 50 μm is desirable. In the case where the neighboring laminate 34 and the correction layer 40 are formed of different layers, if both patterns overlap each other, they become local abnormal protrusions, which is not preferable. On the other hand, if the two patterns are too far apart from each other, the portion of the thick film resin layer 33 at the interval D is dented, which is not good.

FIG. 6 is a diagram for explaining leveling when a thick resin layer is formed by spin coating. Like the thermal ink jet head, the thickness of the underlying pattern 41 formed on the heater substrate 32 is 4 to 5 at the maximum.
In the case where the thickness of the thick resin layer 33 is several tens of μm, as shown in FIG. It is about ± 50 μm. Here, as shown in FIG. 6B, when the underlayer patterns 43 and 44 having substantially the same thickness are formed and the interval D is set to about 50 μm, the surface of the thick film resin layer 33 has less dents. It will be. Therefore, the interval D between the base patterns 43 and 44 is 50 μm
It is desirable that:

FIG. 7 is an explanatory view of a fifth embodiment of the present invention. Similar to FIG. 6, a cross section taken along a plane parallel to the channel axis near the dicing plane when two substrates are bonded together. Is illustrated. In the figure, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the correction layer 4
No. 0 was formed by using the same material as the thick film resin layer 33 and patterning it to the same thickness as the underlying pattern. After formation, the layer structure is the same as that of the conventional example, so it is difficult to distinguish them. However, since there is no dent of the thick resin layer 33 due to the step of the base, the bonding surface becomes flat, and a good bonding structure can be realized.

In the fourth and fifth embodiments, the material used for fabricating the head is used as the material for the correction layer. However, it is natural that the process for fabricating the correction layer and the material are separately prepared. It is possible.

In the above embodiment, the structure near the nozzle surface has been described. However, it is obvious that the method of the present invention can be applied to other regions. In addition, the method of the present invention can be widely applied to bonding of microdevices, where the bonding layer is thin or the bonding surface is not flat.

[0035]

As is apparent from the above description, according to the present invention, it is possible to perform more reliable bonding of an ink jet recording head formed by a plurality of substrates, and to improve the yield. This has the effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a bonding state of a conventional inkjet recording head.

FIG. 5 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 6 is an explanatory view of a formation state of a thick resin layer.

FIG. 7 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a thermal inkjet head according to a conventional method.

[Explanation of symbols]

11 channel substrate, 12, 13 groove, 14a, 14
b adhesive, 21 heater substrate, 22 photosensitive resin layer, 24 adhesive, 25, 26 groove, 31 channel substrate, 32 heater substrate, 33 thick resin layer, 34
Laminate, 35 adhesives, 40 correction layers.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-206657 (JP, A) JP-A-61-249765 (JP, A) JP-A-58-220755 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41J 2/16

Claims (2)

(57) [Claims] 1. A method of manufacturing an ink jet recording head in which at least two substrates are bonded to form an ink flow path and a nozzle for discharging ink, a tip position is sequentially shifted in a length direction outside the ink flow path. Wherein a plurality of grooves are formed and the grooves are used as confirmation marks for cutting positions. 2. A method for manufacturing an ink jet recording head in which a laminate is formed on one substrate, a resin layer is formed on the laminate, and the other substrate is bonded thereon.
The correction layer serving as a base of the resin layer is formed at an interval so as not to overlap with the laminate, and the correction layer having substantially the same height as the laminate is formed first to form a base for the resin layer. Forming the resin layer after correcting the step, and then bonding the other substrate on the resin layer.