JP2716418B2 - Manufacturing method of thermal ink jet print head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head and a method of manufacturing the same, and more particularly, to a print head capable of self-aligning nozzles and a method of manufacturing the same. 2. Description of the Related Art A conventional thermal ink jet print head 2 is shown in FIG. As a problem to be solved technically in thermal ink jet, there is a problem of assembly, that is, a problem of detachment of the nozzle plate 1. Conventionally, each nozzle plate 1 is individually mounted on the resistance structure 3 by epoxy as shown in FIG. 3A. This is a very costly process and has the potential to cause various problems. For example, in this operation, the alignment of the nozzle plate 1 often does not go well. 3A briefly showing the prior art
In the figure, detailed parts are omitted. Since the various components of the thermal inkjet printhead 2 have different coefficients of thermal expansion, the nozzle plate tends to detach when the adhesive cures. Due to such a problem of adhesion, the conventional thermal inkjet printhead has a disadvantage that the number of nozzles is limited. Conventional thermal ink jet print head 2
Then, the ink replenishment speed also becomes a problem. The print speed is limited by the replenishment speed. In the conventional thermal ink jet printhead 2 shown in FIG. 3B, the ink reaches the nozzle 6 through a high friction groove 7 which restricts the ink flow. The invention described in US Pat. No. 4,438,191 (Japanese Patent Application Laid-Open No. 59-95156, filed by the applicant of the present application) entitled "Monolithic Inkjet Printhead" cited as a conventional example, A “monolithic inkjet printhead” that can partially solve the above-mentioned problems has been proposed. However, the production of the print head has the following new problems. That is, the formation of the ink hole, the heating chamber (firing chambe
r) removal of dry film residues from other places,
Accurate nozzle alignment and various other manufacturing issues. Also, the nozzles of conventional monolithic printheads have not been able to diverge. [0005] Also, conventional ink jet printheads are impacted by the collapse of bubbles and the replenishment ink. There is a drawback that the resistance is destroyed by repeatedly applying the force of the cavitation (pitting). A monolithic thermal ink jet print head in which a nozzle and an ink well are integrally formed and a method of manufacturing the same according to the present invention are described above. It is to solve the problems of nozzle installation and ink flow in the head. Another object of the present invention is to reduce the manufacturing cost and increase the reliability. Part of the reduction in manufacturing costs is achieved by automation of the manufacturing process, which eliminates all difficulties in aligning the heating means with the nozzles. Part of the reliability improvement is that the life of the resistor has been extended,
This is achieved by the smooth flow of ink in the print head. The present invention makes it possible for the first time to construct a pagewidth printhead array in a thermal ink jet printhead. As a feature of the present invention, as shown in FIG. 1, a nozzle 19 for automatically performing alignment is provided. In the conventional method, the nozzle plate 1 shown in FIG. 2 may be shifted from the center (misalignment). Misalignment causes dots to spread and prints to be skewed. These disadvantages are eliminated by the present invention. The monolithic print head 2 of the present invention
0 reduces resistance failure. In the conventional thermal inkjet printhead shown in FIG. 2, the resistance is impacted due to the collapse of bubbles and the replenishment of ink. Monolithic thermal inkjet printhead 2 shown in FIG.
At 0, the collapsed bubbles will collide with the refilled ink. Therefore, the ink absorbs almost the cavitation force. The remaining cavitation force is determined by the cantilever beam (cantilever beam) on which heating means such as resistance are placed.
ever beam. Hereinafter, it is also referred to as an overhang portion). The cantilever beam made of ductile nickel is formed so as to float in the ink holding portion. The mechanical force on the resistance is buffered by the flexibility of the cantilever beam, as is the ink itself. According to the present invention, the printing speed is not limited by the ink replenishment speed. As shown in FIG. 1, the ink holding unit 11 is directly connected to the heating element 15. This direct connection reduces the resistance to ink flow. Therefore, the printing speed is not limited by the ink replenishment speed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 shows a monolithic heat having an integrated nozzle and an ink well (hereinafter referred to as an ink supply or an ink holding part) according to an embodiment manufactured by the method of the present invention. 1 shows a cross-sectional view of an ink jet print head. FIG. 4 shows a plan view of the monolithic print head 20.
The ink holding unit is located in the substrate 10 and holds and supplies ink. The resistance layer 15, which is a heating means (heating element), evaporates the ink. The gaseous ink (water vapor, glycol and ink pigment particles) moves to the nozzle unit 17. Compound bore (for example, a hole having a common center and a continuous curved surface having different inner diameters) nozzle 1
Numeral 9 guides the gaseous ink so that the ink is released from the nozzles by the accumulated pressure of the gaseous ink. The heat barrier, that is, the heat insulating layer 21 prevents heat from flowing to the nickel cantilever beam (overhang portion) 12 and the nickel substrate 40. With such a combination, the heat from the resistive layer 15 heats the ink and does not waste in the print head 20. The conductor layer 23 formed in the (predetermined) pattern short-circuits the resistance layer 15 except on the cantilever beam 12. Protective layer 25
Functions to prevent a short circuit due to the conductor 23 during the nickel plating process for forming the nozzle 19. Protective layer 25
Also protects each layer from chemical and mechanical damage. The conductor layer 27 is applied during the manufacturing process to form a surface on which the nozzle 19 is formed. That is, the nozzle 19 is formed on that surface. The process of manufacturing a monolithic thermal ink jet printhead 20 comprises several steps. On the glass or silicon substrate 10 shown in FIG. 5A, a conductor layer 30 of about 1000 Å (about 0.1 μm) is deposited using a sputtering technique. By applying a current to the conductor layer 30, a process is performed to make the surface of the conductor layer 30 a surface on which nickel plating can be applied. Next, the fifth
As shown in FIG. B, a dry film mask 32 is put on the conductor layer 30. The mask 32 has a diameter of 2 to 3 mils (about 50 μm to 75 μm) and positions the cantilever beam 12 of FIG. 1 and 13 of FIG. FIG. 5C shows various alternative embodiments that the mask 32 can take. Mask 3
Reference numeral 8 corresponds to the print head 20 shown in FIG. The mask 34 corresponds to the print head 60 shown in FIG. Next, the exposed substrate 1 is formed by electroplating.
At 0, a nickel layer 40 of 1 to 1.5 mils (about 25 μm to 38 μm) is formed. The cantilever beam 12 is formed in this way. After plating, the dry film mask 38 is removed to expose the cantilever beam 12 shown in FIG. 6B. The holding unit 11 is also formed by a multi-step process. First, the protective metal layer 42 is deposited by sputtering. This layer is made of gold and has a thickness of 100
0 Å (0.1 μm). Next, the position of the holding unit is determined by the mask 44. Then, the holding portion 11 is formed by a chemical wet etching process such as KOH for silicon and HF for glass. When the holding section 42 and the mask layer 44 are removed, a structure as shown in FIG. 6C is obtained. Next, LPCVD (low pressure CVD: low pres
A heat insulating layer 21 made of SiO2 or other dielectric material is applied by sure chemical vapor deposition.
As shown in FIGS. 1 and 7, this is applied to the inside of the holding portion 11, on the nickel plating layer 40, around the cantilever beam 12, with a thickness of 1.5 μm. Heat insulation layer 21
Helps the resistance layer 21 work efficiently. Heat insulation layer 21
On top of this, a resistive layer 15 made of a material such as tantalum aluminum is deposited to a thickness of 1000 angstroms (0.1 μm) to 3000 angstroms (0.3 μm) as shown in FIG. 7A of FIG. . Next, the thickness 50
A conductive layer 23 of 00 Å (0.5 μm) of gold or aluminum is selectively patterned on the resistive layer 15 to short-circuit a portion of the resistive layer 15. The conductor layer 23 is not provided on the cantilever beam, so that the resistance layer 15 can work on the cantilever beam. On the conductor layer 23, silicon carbide (SiC) or Si3
A protective layer of N4 or other dielectric material is deposited using LPCVD. This layer protects the printhead from chemical and mechanical damage. The conductor layer 27 has a thickness of 1000 to 5000 angstroms (0.1 to 0.5 μm) and a thickness of the protective layer 2.
5 is attached. It is formed by sputtering. The conductor layer 27 has a surface on which the nozzle 19 is formed by electroplating. Next, as shown in FIG. 7B, a predetermined portion of the conductor layer 27 is etched in a wet etching process,
Only the remaining conductor layer 27 is located at the base of the nozzle to be formed. Next, a donut-shaped dry film block 52 is laminated on the conductor layer 27. These blocks 52 form a frame for forming the nozzles 19. In this embodiment, the nozzle 19 is constituted by a two-stage plating process. When the first step is completed, it is as shown in FIG. 8A. When the base of the nozzle 19 is:
The conductive layer 27 is electroplated to a thickness of 5 to 2.0 mils (about 38 to 51 μm), which is equal to the height of the (final) nozzle 19. Next, a glass plate or other plate-like dielectric material 56 is applied to the 8B
It is pressed against the nozzle 19 as shown in the figure. This plate 56
Is the nozzle 1 in the second stage of the nickel plating process.
Acts as a template for Nin. Further, the electroplating process is continued, and a nozzle 19 is formed as shown in FIG. 8C. After the nozzle 19 is completed, the plate 56 is removed. As a result,
A print head 20 as shown in FIG. 1 is configured. The nozzle 19 may be formed by using another method. For example, the nozzle 19 can be formed by a single-stage plating process without using the plate 56. FIG. 9 shows another embodiment of the print head 20. This type of nozzle 19 can also be referred to as a compound bore. This regulates the ink flow emitted from the nozzle 19. The ink stream emitted from the compound bore nozzle has a small diameter and a very small spread. The cantilever beam (projection portion) 13 protrudes toward the center, and the heating element 15 is placed on the projection portion 13. This embodiment of the printhead is formed in the same manner as the printhead 20 shown in FIG. The main difference in the process is the type of mask used when plating layer 40 on substrate 10. Instead of the mask 38 for the cantilever beam 12, a mask 34 or 3
A mask such as 6 is used. In the embodiment of the present invention described above, the print head ejects ink, and this ink is described as containing water, glycol, and pigment particles, but ejects other substances. Needless to say, it can also be used for As described above, in the print head according to the present invention, the nozzle portion and the ink holding portion are integrally formed, and the heating element is mounted on the overhang portion located therebetween. As a result, the cavitation force due to the collapse of the bubbles is buffered by the supplementary ink, so that the damage to the heating element is extremely small, and the life is greatly extended. As a result, an effect that a highly reliable print head can be provided is obtained. Further, since the nozzle portion and the ink holding portion are directly connected, the effect is obtained that the ink replenishment speed is increased and the printing speed itself can be increased. In the method of manufacturing a print head according to the present invention, the positions of the heating elements and the nozzles are not separately determined. In the manufacturing process, the positions of the heating elements and the nozzles naturally coincide with each other. It is unlikely to occur, so that the spread and inclination of the dots due to misalignment are prevented, and since there is no need for a meticulous alignment work as in the related art, the effect that the manufacturing cost can be reduced can be obtained. Further, there is an effect that a print head having a large number of nozzles over a wide range can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a thermal inkjet print head according to an embodiment of the present invention. FIG. 2 is a perspective view of a thermal ink jet print head according to a conventional example. FIG. 3A is a cross-sectional view of a thermal inkjet print head according to a conventional example. FIG. 3B is a partial cross-sectional view of the print head shown in FIG. 3A. FIG. 4 is a plan view showing the print head according to the embodiment of the present invention, from which nozzles are removed. FIG. 5A is a sectional view showing a substrate in a manufacturing step according to the embodiment of the present invention. FIG. 5B is a cross-sectional view showing a state where a mask is placed on the substrate shown in FIG. 5A. FIG. 5C is a plan view showing the shape of the mask according to the embodiment of the present invention. FIG. 6A is a cross-sectional view showing a step of forming a cantilever beam (extending portion) and a holding portion. FIG. 6B is a sectional view showing a step of forming a cantilever beam (extending portion) and a holding portion. FIG. 6C is a sectional view showing a step of forming a cantilever beam (extending portion) and a holding portion. FIG. 7A is a sectional view showing formation of a resistance layer and a protective layer. FIG. 7B is a sectional view showing a conductor layer for forming a nozzle and a donut-shaped frame. FIG. 8A is a sectional view showing a step of forming a nozzle. FIG. 8B is a sectional view showing a step of forming a nozzle. FIG. 8C is a sectional view showing the step of forming the nozzle. FIG. 9 is a sectional view of a thermal inkjet print head according to another embodiment. FIG. 10 is a plan view of the print head shown in FIG. 9; [Description of Signs] 10: substrate 11: ink holding unit 15: resistance heating element 17: nozzle unit

Claims (1)

(57) [the claims] 1. Message provided with a transducer element on a base plate
A first step of forming an opening through which liquid, before Symbol transducer elements and set <br/> only a frame surrounding the opening on the substrate, position for plating the support plate (56) above the frame
A second step of forming a nozzle portion by plating and growing a metal layer inside the frame from the frame while leaving a nozzle opening, and a third step of removing the support plate for plating.
And a method of manufacturing an ink jet print head. 2. The second step includes the step of forming the frame (52) on the substrate.
After the layer forming the nozzle is partially grown by plating on a portion other than the inside of the plate, the plating support plate (56) is removed.
Position and grow a metal layer on the inside of the frame by plating
The claims, characterized in that one which 1
Item 14. The method for producing an ink jet print head according to item 8.