JP3253598B2 - Method of manufacturing 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 a method for manufacturing an ink-jet head for performing recording by discharging ink droplets.

[0002] The ink jet recording system has features such as a simple structure, easy colorization, and no noise, and is expected as a mainstream of the recording system in the future.

[0003]

2. Description of the Related Art In order to discharge ink droplets from an ink jet head, a vibration plate provided facing a pressure chamber is vibrated to apply a discharge pressure to ink in the pressure chamber.

Generally, a piezoelectric element vibrates the vibration plate, and is provided in close contact with the surface of the vibration plate corresponding to the position of the pressure chamber. Conventionally, such a piezoelectric element is formed independently of the diaphragm in a size corresponding to the size of the pressure chamber and then adhered to the surface of the diaphragm one by one.

[0005]

However, since it is necessary to mount the same number of piezoelectric elements as the number of ink ejection nozzles on the ink jet head, it takes a lot of time to adhere the piezoelectric elements to the diaphragm one by one. This increases the manufacturing cost of the head.

Further, in order to reduce the size of the head, the pressure chambers must be arranged at a high density. Therefore, the piezoelectric element must be formed small accordingly, and the thickness must be reduced accordingly. .

However, if the piezoelectric element is formed too small and thin (for example, 1 × 1 mm or less in size and 0.1 mm or less in thickness), it becomes difficult to handle at the time of assembly or the like. It could not be made too small, which was the bottleneck for miniaturizing the head.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing an ink jet head which can greatly reduce the manufacturing cost and can be reduced in size with high accuracy.

[0009]

In order to achieve the above object, a method of manufacturing an ink jet head according to the present invention comprises a pressure chamber for applying a discharge pressure to ink on a silicon single crystal wafer and an ink flow path connected thereto. And printing a piezoelectric paste containing a piezoelectric material on the back side of the wall surface facing the pressure chamber, followed by heating and baking to form a piezoelectric layer.

The pressure chamber and the ink flow path are
The silicon single crystal wafer may be formed by etching. Further, a plurality of the pressure chambers are provided in one silicon single crystal wafer, and a plurality of the piezoelectric layers are printed and baked correspondingly, and then the silicon single crystal wafer is divided into one inkjet head unit. Is also good.

[0011]

Embodiments of the present invention will be described with reference to the drawings. 1 to 11 show a first embodiment of the present invention. First, as shown in FIG. 2, a silicon single crystal wafer 1 having a thickness of, for example, 0.5 mm is formed with a pressure chamber 2 by etching. Each of the ink flow paths 3 is formed at a predetermined depth.

FIG. 2 shows one pressure chamber 2, but as shown in FIG. 3, one silicon single crystal wafer 1 is large enough to collectively form a number of ink jet heads 4. As shown in FIG. 4 showing a part A of one of the ink jet heads 4, a large number (for example, 64) of pressure chambers 2 are provided in each ink jet head 4.
Are arranged.

Next, as shown in FIG. 5, the silicon single crystal wafer 1 is ground to a thickness of, for example, 0.1 mm from the surface opposite to the side on which the pressure chamber 2 is formed. Thereby, the portion on the back side of the pressure chamber 2 has a predetermined thickness (for example, 0.
02 to 0.025 mm).

Next, as shown in FIG. 6, a nozzle plate 7 made of a silicon single crystal wafer having a nozzle hole 6 formed by etching is attached to the silicon single crystal wafer 1 so as to cover the surface of the pressure chamber 2. Join.

This bonding can be performed by so-called direct bonding in which the bonding surfaces are completely adhered to each other and heated in vacuum at, for example, 1100 ° C. for 30 minutes to integrate the bonding surfaces.

The positional relationship between the nozzle hole 6 and the pressure chamber 2 is as shown in FIG. 7, and the silicon single crystal wafer 1 and the nozzle plate 7 are positioned so that the nozzle hole 6 is located near the end of each pressure chamber 2. Are combined.

Next, as shown in FIG. 8, the surface of the silicon single crystal wafer 1 on the side opposite to the pressure chamber 2, that is, the diaphragm 5
A conductive paste whose viscosity is adjusted to, for example, 2,000 cP by mixing, for example, silver and palladium powders, a binder for binding them, and an organic solvent, is printed to a thickness of 5 μm by, for example, a screen printing method, After drying, the lower electrode layer 8 is fired by heating in an electric furnace at a high temperature of, for example, 1000 ° C. for 2 hours.

Since the silicon single crystal wafer 1 is not melted up to a high temperature of about 1200 ° C. and does not generate distortion, it can sufficiently withstand the above-described heat treatment during firing.

Next, the surface of the lower electrode layer 8 is mixed with a piezoelectric fine powder (PZT) composed of, for example, lead oxide, zirconium oxide and titanium oxide, a binder for binding the powders, and an organic solvent. 3000 cP viscosity
Is adjusted to a thickness of 30 μm by screen printing.

When the piezoelectric layer 9 is formed by screen printing, its thickness is suitably in the range of 5 to 100 μm, and the electrode layers 8 and 10 may be formed in a thickness of 1 to 10 μm. it can. The temperature at which the electrode layers 8, 10 and the piezoelectric layer 9 are fired varies depending on the material used.
A range of １1500 ° C. is used.

As the material of the piezoelectric paste, a material such as barium titanate ceramic, PMN-PT or PNN-PTPZ to which a compound having a perovskite structure is added can be used.

In the screen printing, as schematically shown in FIG. 9, a screen 21 on which a printing pattern is formed is arranged on the surface of the silicon single crystal wafer 1, and a conductive paste or a piezoelectric paste 22 is applied thereon. This is performed by moving the squeegee 23 while pressing it.

At this time, the printing of the piezoelectric paste 22 is performed as follows.
The pressure chamber 2 is adjusted in position and size. When the printed piezoelectric paste 22 is dried, the piezoelectric paste 22 is heated at a high temperature of, for example, 1000 ° C. for 2 hours in an electric furnace to evaporate an organic solvent or the like from the piezoelectric paste 22.

As a result, as shown in FIGS. 10 and 11, the piezoelectric layer 9 is fired on the surface of the vibration plate 5 so as to match the position and size of each pressure chamber 2. When the piezoelectric layer 9 is fired in this manner, finally, as shown in FIG.
Print and bake at μm. The material and firing conditions of the upper electrode layer 10 may be the same as those of the lower electrode layer 8.

As described above, in the present invention, the diaphragm 5
Since the electrode layer 8 and the piezoelectric layer 9 are formed on the surface of the substrate by direct printing, it is excellent in manufacturability, and a desired thickness, size, and shape can be formed with high reliability.

When the piezoelectric layer 9 and the upper and lower electrode layers 8 and 10 are formed on the surface of the vibration plate 5 in this manner, the whole is shown in FIG.
Is cut into individual inkjet heads 4 as shown in FIG.

In the ink-jet head thus formed, ink is supplied from the ink flow path 3 to the pressure chamber 2.
By applying a voltage between the upper and lower electrodes 8 and 10, the piezoelectric layer 9 is deformed, whereby the vibration plate 5 vibrates, and the ejection pressure is applied to the ink in the pressure chamber 2.
The ink in the pressure chamber 2 is ejected as ink droplets from the nozzle holes 6 to perform recording.

In the present invention, by controlling the thickness of the printing plate, the thickness of the piezoelectric layer 9 can be freely formed in the range of 2 to 200 μm. Therefore, by setting the thickness of the piezoelectric layer 9 to the most preferable thickness with respect to the thickness of the vibration plate 5, the particles can be ejected from the nozzle at a high particleization efficiency and a low driving voltage.

Further, since the diaphragm 5 and the electrode layer 8, and the electrode layer 8 and the piezoelectric layer 9 are directly joined by printing and baking, there is no adhesive layer as in the prior art, and the efficiency of particle formation is further improved. Can be.

FIGS. 12 and 13 show a second embodiment of the present invention, in which photosensitive glass is used as the nozzle plate 7 and the lower electrode layer 8 is formed by depositing platinum by sputtering. Things.

In this case, since the photosensitive glass cannot withstand the sintering temperature of the piezoelectric layer 9, as shown in FIG. 9 and the upper electrode layer 10 are printed and fired, and thereafter, as shown in FIG.
Is bonded to the silicon single crystal wafer 1.

The present invention is not limited to the above-described embodiments. For example, a printing method other than screen printing, such as letterpress or intaglio, may be used.

[0033]

According to the present invention, since the piezoelectric layer is formed on the surface of the diaphragm by printing and firing, the number of assembly steps is reduced, and a significant cost reduction is achieved. Moreover, since the piezoelectric layer can be formed as thin as possible and at a high density to the limit of the printing technology, the size of the ink jet head can be remarkably reduced.

Further, in the present invention, since a single crystal silicon wafer is used as a material for printing and firing the ink jet head, the coefficient of thermal expansion is small. The silicon single crystal wafer is hardly generated, and a single-crystal silicon wafer is handled up to a large size (for example, a diameter of 300 mm), so that one to many ink jet heads can be manufactured, and high dimensional accuracy is obtained with little unevenness on a plane. be able to.

In addition, a silicon single crystal wafer can be formed into a thin film as a diaphragm uniformly by using anisotropic etching, grinding, or the like. An ink jet head with high accuracy can be manufactured even from the characteristics that it hardly occurs.

[Brief description of the drawings]

FIG. 1 is a front partial sectional view showing a manufacturing process of a first embodiment.

FIG. 2 is a partial front sectional view showing a manufacturing process of the first embodiment.

FIG. 3 is an overall plan view showing a manufacturing process of the first embodiment.

FIG. 4 is a plan sectional view showing the manufacturing process of the first embodiment.

FIG. 5 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 6 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 7 is a plan view showing the manufacturing process of the first embodiment.

FIG. 8 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 9 is a schematic side view showing the manufacturing process of the first embodiment.

FIG. 10 is a plan view showing the manufacturing process of the first embodiment.

FIG. 11 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 12 is a partial front sectional view showing a manufacturing process of the second embodiment.

FIG. 13 is a partial front sectional view showing a manufacturing process of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon single crystal wafer 2 Pressure chamber 3 Ink channel 5 Vibration plate 9 Piezoelectric layer

────────────────────────────────────────────────── ─── Continuing on the front page (72) Minoru Tsukada 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Katsuharu Hida 4-chome, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Fujitsu Limited (56) References JP-A-4-229279 (JP, A) International Publication 92/9111 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/16 B41J 2/045

Claims (2)

(57) [Claims] A pressure chamber for applying ejection pressure to ink and an ink flow path connected thereto are provided on a silicon single crystal wafer.
A method for manufacturing an ink jet head, comprising: forming a film by etching; and printing a piezoelectric paste containing a piezoelectric material on the back side of the wall surface facing the pressure chamber, and then heating and firing to form a piezoelectric layer. . 2. A plurality of pressure chambers are provided in one silicon single crystal wafer, and a plurality of piezoelectric layers are printed and fired in correspondence with the plurality of pressure chambers. The method for manufacturing an inkjet head according to claim 1, wherein the inkjet head is divided.