JPH0280252A - Ink jet head - Google Patents

Abstract

PURPOSE:To provide a precise ink jet head having good characteristics to ink by using a material having good ink wettability as a substrate and forming a mask used for applying etching processing to the groove corresponding to a flow passage to the substrate or a vibration plate from a material anodically bondable to the vibration plate or the substrate. CONSTITUTION:A corrosion-resistant film 10b is applied to a base 1b having a flow passage groove formed thereto. As the material of a base 1, borosilicate glass is used and, as the corrosion-resistant film, polycrystalline silicon or amorphous silicon is proper. A photoresist method is adapted to said corrosion-resistant film 10b to mask the part other than the part corresponding to a flow passage by a photoresist and the corrosion-resistant film 10B of the flow passage corresponding part 11b is removed by plasma etching. The etching of the substrate 1 is performed in order to form a flow passage 5b and only the flow passage corresponding part 11b not covered with the corrosion-resistant film is etched to form the flow passage 5b. At last, a borosilicate glass vibration plate 2 is superposed on the base 1b having the corrosion- resistant film 10b applied thereto to be heated to 450 deg.C and, when DC voltage is applied by using the base as an anode and the vibration plate 2 as a cathode, anodic bonding of several min is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet head, and particularly to an inkjet head formed by positively bonding a substrate and a diaphragm constituting the head.

1. Prior Art] FIG. 2 shows a structural sectional view of an example of an on-demand head that has already been proposed.

As shown in the figure, grooves corresponding to the nozzle 5, pressure chamber 4, ink supply path 7, and ink reservoir 6 are formed in the substrate 1. This results in a flow path with

Further, an electric mechanical transducer 3 is connected 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 by U).

To briefly explain the operating principle of such an inkjet head, when a drive signal is applied to the electromechanical transducer 3, the electromechanical transducer 3 tries to deform in the lateral direction, but (because it is restrained by the radial plate) It deforms toward the pressure chamber 4 and generates pressure in the pressure chamber 4.

This pressure forces the ink out of the nozzle 5 and causes it to fly as ink droplets 8. At this time, the driving signal of the electromechanical transducer 3 is cut off, and the original state is restored, and the pressure chamber 4 temporarily becomes a negative pressure, and ink flows from the ink reservoir 6 through the ink supply path 7 into the pressure chamber. 4 and return to the initial state.

By appropriately performing this series of operations, ink droplets are ejected and transferred to paper, thereby performing printing.

In such an inkjet head, the diameter is 50 mm.
Since it is necessary to eject very small ink droplets of 100 μm from um, the nozzle 5 has a width of 50 μm to 100 μm.
In addition, the pressure chamber 4 communicating with the nozzle 5, the ink supply path 7, and the ink reservoir 6 also require precise processing. Usually, the substrate 1 is made of glass or silicon, and the flow path is precisely formed by etching 741. Also, when bonding the diaphragm 2 to the substrate 1, adhesives that may ooze out cannot be used to form the microchannels, and direct bonding such as diffusion bonding or anodic bonding cannot be used. A bonding method is used.

Here, a series of these flow path forming methods will be explained in detail using figures.

FIG. 2 shows a series of steps for forming a flow path on a substrate. First, as shown in FIG. 3(a), a silicon nitride film 10a serving as an etching mask is deposited on a silicon substrate 1a by thermal nitridation or CVD. Next, Figure 3 (b
11a is formed by removing the silicon nitride film in the portion that is to become a flow path by photo-etching as shown in FIG. Next, as shown in FIG. 3(C), using the silicon nitride film 10a left in the step of FIG. 3(b) as a mask, the silicon substrate 1a is
is etched to form a flow path 5a.

Next, as shown in FIG. 3(d), in the channel 5a formed as described above, since the silicon is exposed, it may be corroded by the alkaline ink, or the silicon itself may be corroded by the alkaline ink.
Since it is water-repellent, the flow of the ink may be impaired and bubbles may form easily, so it is necessary to attach a protective film to the surface.When the substrate 1a is thermally oxidized, silicon oxidation occurs only on the exposed silicon channel surface. A film 11a is formed and serves as the above-mentioned protective film.

In the process shown in FIG. 3(e), when the glass diaphragm 2 is finally anodically bonded, the silicon nitride film 10a which becomes an obstacle is removed.
is removed using heat. This old silicon oxide film 11a
cannot be removed with hot phosphoric acid, so it remains on the inner wall of the channel 5a. Finally, as shown in FIG. 3(f), the silicon substrate 1a and the diaphragm 28 are bonded and integrated by anodic bonding. *The specific method for bonding is to heat the substrate 1a and diaphragm 2 to 450°C in a stacked state, and then use the silicon substrate 1a as an anode and the diaphragm 2 as a negative (~
When a voltage of 600V is applied, bonding is completed within a few minutes. This method is extremely effective for products such as inkjet heads that have precise and minute grooves because the bonding surface is strong, no adhesive is used, and precise bonding can be easily achieved. There are several combinations of materials that can be used: - The inside of the shell is made of an inorganic insulator, while the other part is made of a metal or semiconductor.

Problem 15 Teimei is trying to solve 1 However, even if silicon, which is easy to process, was used as the substrate, the silicon nitride film used as the mask material had to be removed, making the process complicated. . If silicon is exposed in the flow path, it will be corroded by alkaline ink, and silicon is water-repellent, which will hinder the flow of the ink. It was necessary to add a step to attach an oxide film, etc. later, which made the process quite complicated.As a way to avoid this inconvenience, there is a method that uses glass on the substrate side and silicon on the diaphragm side. A similar oxide film treatment was required for the portion corresponding to the flow path on the diaphragm side, and the process was similarly complicated.

An object of the present invention is to solve the above-mentioned problems and to provide an inkjet head that is precise and has good characteristics with respect to ink, by effectively using anodic bonding, which is a simple process but is effective when used as a bonding method. It is in.

[Means for solving the problems] The present invention has been made to achieve the above-mentioned objects.
The substrate is made of a material with good ink wettability, and the mask used when etching grooves corresponding to the flow channels on the substrate or diaphragm is made of a material that can be positively (water-bonded) with the diaphragm or substrate. It is characterized by this.

[Operation] The above-mentioned means operate as follows. When a material with good wettability for ink, such as glass, is used for the substrate, the wettability remains good even if a flow path is formed in the substrate. In addition, such highly wettable materials are generally non-porous insulators, but in order to etch such materials to a depth of several tens of microns to form flow channels, organic resist masks are required. Since the etching solution cannot withstand the etching solution, a corrosion-resistant film that can withstand the etching solution is applied to the substrate, and the film corresponding to the flow path is etched away and a mask is formed before etching the substrate. good.

At this time, if the corrosion-resistant coating that will serve as the mask is made of a material that can be bonded to the diaphragm material O'1 and positive, etching will be possible.
The mask used in step 4 now acts as the m'IfA bonding material, making it possible to easily bond it to the diaphragm.

[Example] An example will be shown using FIG. In FIG. 1 (a), a corrosion-resistant coating 10b is applied to a substrate 1b on which a channel groove is formed.Borosilicate glass is used as the material for the substrate 1.As the corrosion-resistant coating, polycrystalline silicon or a[
Schiff 1 series silicon is suitable, and the latter can be deposited using low-pressure CVD, and the latter can be deposited using plasma CVD.

The thickness of the corrosion-resistant coating is approximately 0.3 μm to 1 μm.

This corrosion-resistant leather 11Sl! 10b using the photo resist method, masking the parts other than the part corresponding to the flow path with resist 741, and plasma etching the part corresponding to the flow path 11.
The corrosion-resistant coating 10b of b is removed. Next, as shown in FIG. 1(C), the substrate 1b is etched to form a flow path 5b. Since the material of the substrate is borosilicate glass, fluorinated hydric acid is suitable as the etching solution. Since hydrofluoric acid alone hardly soaks polycrystalline silicon or amorphous silicon, only the channel-corresponding portion 11b that is not covered with the corrosion-resistant film is etched to form the channel 5b. Finally, as shown in FIG. 4, a borosilicate glass (transistor 2) is placed on top of the substrate 1b on which the corrosion-resistant coating 10b is still attached, heated to 450'C, and the substrate 1 is used as an anode, and the diaphragm 2 is heated to 450'C. When a DC voltage of 600V to 1000V is applied to the cathode, anodic bonding is completed in a few minutes.

By completing this step, all the channels of the inkjet head have been formed, so in this state, electrodes are formed on the part of the diaphragm that corresponds to the pressure chambers, and an electromechanical transducer is glued on top of the electrodes to form the inkjet head. The head is completed.

Inkjet heads created using this method have good fluidity of the ink because the inner surface of the flow path is entirely made of hydrophilic glass, and there are fewer air bubbles trapped in the flow path, which improves the precision of the flow path. Since C is maintained extremely well, excellent injection characteristics can be obtained.

In this example, boronic acid lath was used for the diaphragm and substrate, and polycrystalline silicon or amorphous silicon was used for the corrosion-resistant coating, but there are various combinations of materials that can be used in the present invention. It goes without saying that the invention is not limited to this embodiment, as long as it is a substrate, a hydrophilic material, a corrosion-resistant coating during etching of the substrate, or a material that can be anodically bonded to the diaphragm material.

[Effect of the invention 1] As explained above, the present invention simplifies part of the manufacturing process of an inkjet head, such as the groove processing of the substrate and the bonding process, while also making it possible to form precise and fine flow channels. This has the effect of realizing a structure that does not impede the flow of ink and providing a highly reliable head.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the flow path manufacturing process of the inkjet head of the present invention, Fig. 2 is a structural cross-sectional view showing the strategy of an on-demand type inkjet head, and Fig. 3 is a flow path N)b of a conventional inkjet head. It is a sectional view showing a process. 1. la, Ib... Substrate 2... Vibration plates 5a, 5b... Channels 10a, 10b...・Corrosion-resistant coating

Claims (2)

[Claims] (1) In an inkjet head comprising a substrate having a channel groove, and a diaphragm that covers the substrate and forms the channel groove into a nozzle, an ink supply channel, and a pressure chamber, the substrate has the channel groove. What is claimed is: 1. An inkjet head comprising: an etching mask for forming an inkjet head; and a thin film member that can be anodically bonded to the diaphragm. (2) In an inkjet head that includes a substrate on which a flow channel groove is formed, and a diaphragm that covers this substrate and forms the flow channel groove into a nozzle, an ink supply path, and a pressure chamber, the flow is An inkjet head, characterized in that it is an etching mask for forming grooves and is coated with a thin film member that can be anodically bonded to the substrate.