JP2843176B2 - Inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet head, and more particularly to an ink-jet head formed by anodically bonding a substrate and a diaphragm constituting the head.

[0002]

2. Description of the Related Art FIG. 3 is a structural sectional view of an example of an already proposed on-demand type head. As shown in the drawing, a groove corresponding to the nozzle 11, the pressure chamber 4, the ink supply path 7, and the ink reservoir 6 is formed on the substrate 1, and the diaphragm 2
Are bonded to the substrate 1 to form flow paths having respective functions. An electromechanical transducer 3 is joined to a portion of the diaphragm 2 corresponding to the pressure chamber 4. The ink reservoir 6 is communicated with an external ink supply system (not shown). Next, the operation principle of the ink jet head using the on-demand type head will be briefly described. When a drive signal is applied to the electromechanical transducer 3, the electromechanical transducer 3 tends to deform in the lateral direction, but is restrained by the diaphragm 2. Therefore, a pressure is generated in the pressure chamber 4. This pressure causes the ink to be pushed out of the nozzle 11 and fly as an ink droplet 8. When the energization of the drive signal ends, the electromechanical transducer 3 returns to the original state, the pressure chamber 4 temporarily becomes a negative pressure, and the ink is transferred from the ink reservoir 6 to the pressure chamber 4 via the ink supply path 7. It flows in and returns to the initial state. By performing this series of operations as appropriate, the ink droplets 8 fly and are transferred to paper to perform printing.

In such an ink jet head, since it is necessary to fly very small ink droplets having a diameter of 50 μm to 100 μm, the nozzle 11 has a width of 50 μm.
It is necessary to form a fine groove having a diameter of about 100 μm and a depth of 50 μm, and precise processing of the pressure chamber 4, the ink supply path 7, and the ink reservoir 6 communicating with the nozzle 11 is also required. Normally, the substrate 1 is made of glass or silicon, and since the fine channels are formed by photoetching, an adhesive or the like that may protrude cannot be used, and direct bonding such as diffusion bonding or anodic bonding is used. Is used. Here, these flow path forming methods will be described in detail. FIG. 4 shows a series of steps of a conventional method for forming the flow path 5 in the substrate 1. As shown in FIG. 4A, a corrosion-resistant coating 9 is applied to the substrate 1 on which the flow channel is formed. As a material of the substrate 1, borosilicate glass is generally used. Generally, polycrystalline silicon or amorphous silicon is used as the corrosion-resistant coating 9, and the former is applied using low-pressure CVD, and the latter is applied using plasma CVD. In addition, the thickness of the corrosion-resistant coating 9 is generally 0.3 μm to 1 μm.

A portion of the corrosion-resistant coating 9 other than the portion corresponding to the flow path 5 is masked with a photoresist using a photoresist method, and the corrosion-resistant coating 9 in the portion corresponding to the flow path 10 is removed by plasma etching. Next, as shown in FIG. 4C, the substrate 1 is etched to form the flow channel 5a. Since the material of the substrate 1 is borosilicate glass, hydrofluoric acid is suitable as an etching solution. Since hydrofluoric acid alone hardly attacks polycrystalline silicon or amorphous silicon, only the flow path equivalent portion 10 that is not covered with the corrosion resistant coating 9 is etched to form the flow channel 5a. Finally, FIG.
As shown in (d), the borosilicate glass vibration plate 2 is overlaid on the substrate 1 with the corrosion-resistant coating 9 adhered thereon, and heated to 450 ° C., and the substrate 1 is used as an anode, and the vibration plate 2 is used as a cathode.
When a DC voltage of 0 V is applied, the anodic bonding is completed in a few minutes.
When the process is completed up to this point, all the flow paths 5 of the ink jet head are formed. In this state, electrodes are formed in a portion corresponding to the pressure chambers 4 on the vibration plate 2, and the electric conversion element 3 is bonded thereon. The ink jet head is completed.

[0005]

The object of the invention is to, however Inkuji
Most suitable for anodic bonding of glass substrate suitable for jet head
Materials such as polycrystalline silicon and amorphous silicon
In general, the shape of isotropic etching tends to vary due to lack of adhesion to a glass substrate, and it has been difficult to form a flow channel having a constant shape.

[0006]

In order to solve the above problems, an ink jet head according to the present invention has a flow channel.
A glass substrate, and the flow channel groove over the substrate and a nozzle
A glass diaphragm formed in the ink supply path and the pressure chamber;
A thin film member for anodically bonding the substrate and the diaphragm
Wherein the thin film portion
A flow channel is formed in the substrate at the lowermost layer where the material is in contact with the substrate.
As an etching mask for
Multilayer with the uppermost layer in contact with the anode bonding film suitable for anodic bonding
It is characterized by comprising a structure .

[0007]

[Action] For ink on the substrate of the ink jet head
When a glass substrate with good wettability is used,
The channel formed in the substrate also has good wettability.
Also, a depth of several tens of microns for forming a flow path in a glass substrate
If you try to etch up to
Since the disk cannot withstand the etching solution, the glass substrate
A layer of a material suitable as an etching mask for a glass substrate
Suitable for bonding to the diaphragm and anodic bonding with the diaphragm
The thin film member has a multilayer structure so that the material layer contacts the diaphragm.
This makes it possible to join with the diaphragm,
Adhesion to the glass substrate is improved and a flow channel with a stable shape is formed.
can get.

[0008]

FIG. 1 shows an embodiment of an ink jet head according to the present invention, and FIG. 2 is an explanatory view of a manufacturing process thereof. In these figures, the same components as those of the conventional example shown in FIG. 3 are denoted by the same reference numerals. First, the manufacturing method will be described with reference to FIG. 2. As shown in FIG. 2A, a material having good wettability with ink, for example, on a substrate 1 made of borosilicate glass, Silicon nitride film 9a and silicon carbide 9b
Then, a corrosion-resistant coating 9 having a three-layer structure of amorphous silicon 9c is applied using plasma CVD. The corrosion-resistant coating 9 has a thickness necessary to function as an etching mask. However, if the thickness of the coating becomes too large, the coating may be cracked or peeled off by heating when the diaphragm is joined later due to a difference in thermal expansion. Can not be thicker than necessary. Therefore, the thickness of the corrosion-resistant coating 9 is 0.5 μm for the silicon nitride film 9a,
It is appropriate that the silicon carbide 9b is 0.3 μm to 3 μm, and the amorphous silicon 9c is 0.1 μm to 1 μm. Next, as shown in FIG. 2B, the corrosion-resistant coating 9 is masked with a photoresist, and the corrosion-resistant coating 9 of the flow path equivalent part 10 is removed by plasma etching. Next, as shown in FIG. 2C, the substrate 1 is etched to form the flow path 5. Since the material of the substrate 1 is borosilicate glass, hydrofluoric acid is suitable as an etching solution. Hydrofluoric acid alone does not substantially attack amorphous silicon or silicon carbide, so the flow path equivalent portion 10 not covered with the corrosion-resistant coating 9
Only the channel is etched to form the flow channel 5a. Thereafter, as shown in FIG. 2D, the diaphragm 2 made of borosilicate glass is placed on the
When the substrate 1 is heated to 0 ° C. to 450 ° C. and a DC voltage of 600 V to 1000 V is applied using the substrate 1 as an anode and the diaphragm 2 as a cathode, anodic bonding is completed in a few minutes. When this is completed, all the flow paths 5 of the ink jet head have been formed. Therefore, as shown in FIG. 2D, an electrode is formed in a portion corresponding to the pressure chamber 4 on the diaphragm 2 and an electric machine is formed thereon. Conversion element 3
The ink jet head is completed by bonding. In the ink jet head manufactured by such a method, since the inner surfaces of the flow path grooves 5a of the substrate 1 are all made of a hydrophilic glass surface, the ink has good fluidity, and air bubbles can be entrapped in the flow path. Since the accuracy of the flow path 5 is kept very low, good injection characteristics can be obtained.

In this embodiment, borosilicate glass is used for the substrate 1, and the corrosion-resistant coating 9 has a three-layer structure of a silicon nitride film 9a, silicon carbide 9b and amorphous silicon 9c. It may be a multilayer structure such as a structure. There are various materials that can be used in the present invention. As the material of the substrate 1 and the vibration plate 2, sodium glass or the like can be used by matching the thermal expansion with the corrosion-resistant coating 9 in consideration of the thermal expansion due to heating during bonding. is there. The lower layer of the corrosion-resistant coating 9 can be used as long as it is an anodic bonding member that is not affected by the etchant and has higher adhesion to the substrate 1 than the upper layer of the corrosion-resistant coating 9. For example, tantalum pentoxide, sialon, or the like is used. be able to. The upper layer is chrome,
Germanium or the like can be used.

[0010]

As described above, according to the present invention, a thin film member which can be used as an etching mask for forming a flow channel on a substrate and which can be anodic-bonded to a vibration plate is used to reduce the adhesive force between the substrate and the diaphragm. A multi-layered structure with a corrosion-resistant coating on the bottom layer is attached to the substrate, and the diaphragm is anodically bonded to this thin film member.This simplifies the groove processing and bonding process of the substrate, which is a part of the inkjet head manufacturing process. However, it is possible to provide a highly reliable head by configuring a precise and fine flow path and realizing a head structure that does not hinder the flow of ink.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a flow path manufacturing process of the inkjet head of the present invention.

FIG. 3 is a configuration sectional view schematically showing an on-demand type inkjet head.

FIG. 4 is a cross-sectional view showing a flow path manufacturing process of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Vibration plate 3 Electromechanical conversion element 4 Pressure chamber 5 Flow path 5a Flow path groove 6 Ink pool 7 Ink supply path 8 Ink droplet 9 Corrosion-resistant coating 9a Silicon nitride film 9b Silicon carbide 9c Amorphous silicon 10 Flow path equivalent part 11 nozzle

Claims (1)

(57) [Claims] A glass substrate having a 1. A flow channel, a diaphragm of glass that forms the flow passage overlaying the substrate to the nozzle and the ink supply path and the pressure chamber, and the substrate and the diaphragm
And a thin film member for anodically bonding the substrate to the substrate.
An etching mask for forming a path groove; and
The uppermost layer in contact with the diaphragm is an anodic bonding film suitable for anodic bonding
An ink jet head characterized by having a multilayer structure .