JPH08230192A - Production of thermal ink jet print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the exact and easy alignment between a heat generating resistor for evaporating ink and a nozzle and, in addition, reduce cavitation damage and heighten ink feeding speed. SOLUTION: By providing an annular frame so as to position in the fashion for surrounding a heat generating resistor 15 and forming a nozzle part 17 inside the annular frame by growing metal layer by plating, the automatical alignment between the heat generating resistor and the nozzle is realized. Thus, the manufacturing of a large-scaled print head becomes also possible. in order to make plating possible, an ink holding part 11 and the nozzle part 17 are directly connected with each other. On a beam locating between the ink holding part 11 and the nozzle part 17, the heat generating resistor 15 is provided. Thus, the effect such that the cavitating force due to the collapse of bubble is absorbed by the ink to be supplied and feeding of ink is also quick is realized.

Description

Detailed Description of the Invention

[0001]

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 with nozzle self-alignment and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional thermal ink jet print head 2 is shown in FIG. As a technical problem to be solved in the 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 attached to the resistance structure 3 by epoxy, as shown in FIG. 3A. This is a very expensive process and can cause various problems. For example, this operation often results in poor alignment of the nozzle plate 1. 3A showing the prior art briefly
Detailed parts are omitted in the figure. Since the various components of the thermal inkjet printhead 2 have different coefficients of thermal expansion, when the adhesive cures, the nozzle plate tends to detach. Due to such a problem of adhesion, the conventional thermal inkjet printhead has a drawback that the number of nozzles is limited.

Conventional thermal inkjet printhead 2
Then, the ink replenishment speed also becomes a problem. The replenishment speed limits the print speed. In the conventional thermal inkjet printhead 2 shown in FIG. 3B, ink reaches the nozzle 6 through a high friction groove 7 that limits ink flow.

According to 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), which is referred to as a conventional example and is referred to as "monolithic ink jet print head", A "monolithic inkjet printhead" that can partially solve the above-mentioned problems has been proposed. However, the manufacturing of this print head has the following new problems. That is, the formation of ink holes and the heating chamber (firing chamber)
r) removal of dry film residue from other locations,
Accurate nozzle alignment and various other manufacturing issues. Also, the nozzles of conventional monolithic printheads have not been able to diverge.

Also, conventional ink jet printheads are subject to resistance impact due to bubble collapse and also because of the refill ink. There is a drawback in that the resistance is destroyed by the repeated application of the force of this cavitation (pitting).

[0006]

SUMMARY OF THE INVENTION A monolithic thermal ink jet print head having a nozzle and an ink well integrally formed according to the present invention and a method for manufacturing the same are provided in the conventional print head. It is a solution to the problem of mounting and ink flow.

The present invention also seeks to achieve the objectives of reducing manufacturing costs and increasing reliability. Part of the reduction in manufacturing cost is achieved by automating the manufacturing process, which eliminates all the difficulty of aligning the heating means and the nozzle. Part of the improvement in reliability is that the life of the resistor is extended,
This is achieved by the smooth flow of ink in the printhead. For the first time, the invention enables the construction of pagewidth printhead arrays in thermal ink jet printheads.

[0008]

As a feature of the present invention, as shown in FIG. 1, there is provided a nozzle 19 which is automatically aligned. In the conventional method, the nozzle plate 1 shown in FIG. 2 may be displaced from the center (misalignment). Due to misalignment, the dots may spread and the print may be slanted. These drawbacks are eliminated by the present invention.

The monolithic print head 2 of the present invention
0 reduces resistance failures. In the conventional thermal inkjet printhead shown in FIG. 2, the resistance is impacted due to bubble collapse and ink replenishment. The monolithic thermal inkjet printhead 2 shown in FIG.
Bubbles that collapse at 0 collide with the ink that is being replenished. Therefore, the ink almost absorbs the cavitation force. The remaining cavitation force is the cantilever beam (cantilever beam) on which the heat generating means such as resistance is 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 dampened by the flexibility of the cantilever beam as well as the ink itself.

Further, according to the present invention, the print speed is not limited by the ink replenishment speed. As shown in FIG. 1, the ink holding portion 11 is directly connected to the heating element 15. This direct connection reduces resistance to ink flow. Therefore, the print speed is not limited by the ink replenishment speed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the 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 unit or an ink holding unit) according to an embodiment manufactured by the method of the present invention. FIG. 3 shows a cross-sectional view of an inkjet printhead. FIG. 4 shows a plan view of the monolithic print head 20.
The ink holding unit is inside the substrate 10 and holds and supplies ink. The resistance layer 15 which is a heat generating means (heating element) evaporates the ink. The gaseous ink (water vapor, glycol, and ink pigment particles) moves to the nozzle portion 17. Compound bore (for example, a hole having a common center and a continuous curved surface with different inner diameters) Nozzle 1
Reference numeral 9 guides the gaseous ink so that the accumulated gaseous pressure causes the ink to be ejected from the nozzle.

The heat barrier, that is, the heat insulating layer 21, prevents heat from flowing to the cantilever beam (overhanging portion) 12 of nickel and the nickel substrate 40. With such a combination, the heat from the resistance layer 15 heats the ink and is not wasted 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
Serves 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 for constituting the nozzle 19. That is, the nozzle 19 is formed on that surface.

The process of manufacturing the monolithic thermal inkjet printhead 20 consists of several steps. A conductor layer 30 of about 1000 angstroms (about 0.1 μm) is deposited on the glass or silicon substrate 10 shown in FIG. 5A using a sputtering technique. By energizing the conductor layer 30, the surface of the conductor layer 30 is treated so that it can be nickel-plated. Next, the fifth
As shown in FIG. B, the dry film mask 32 is covered 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 of the mask 32. 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 substrate 1 exposed 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 the plating is completed, the dry film mask 38 is removed to expose the cantilever beam 12 shown in FIG. 6B. The holding portion 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
It is 0 angstrom (0.1 μm). Next, the position of the holding portion 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 portion 42 and the mask layer 44 are removed, the structure shown in FIG. 6C is obtained.

Next, LPCVD (low pressure CVD method: low pres
A heat insulating layer 21 made of SiO2 or other dielectric material is deposited by sure chemical vapor deposition).
As shown in FIGS. 1 and 7, this is deposited to a thickness of 1.5 μm on the inside of the holding portion 11, on the nickel plating layer 40, and around the cantilever beam 12. Heat insulation layer 21
Helps the resistive layer 21 to work efficiently. Heat insulation layer 21
As shown in FIG. 7A of FIG. 1, a resistance layer 15 made of a material such as tantalum aluminum is deposited to a thickness of 1000 angstrom (0.1 .mu.m) to 3000 angstrom (0.3 .mu.m). . Next, thickness 50
A conductor layer 23 of 00 Angstroms (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 present in the cantilever beam, and thus the resistance layer 15 can work in the cantilever beam. Silicon carbide (SiC) or Si3 is formed on the conductor layer 23.
A protective layer of N4 or other dielectric material is deposited using the LPCVD method. This layer protects the printhead from chemical mechanical damage.

The conductor layer 27 has a thickness of 1000 to 5000 angstroms (0.1 to 0.5 μm), and the protective layer 2 is formed.
5 is attached. It is formed by sputtering. The conductor layer 27 forms 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 step,
Only the remaining conductor layer 27 should be located at the base of the nozzle to be formed.

Next, the doughnut-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 composed of a two-step plating process. When the first step is completed, it is as shown in FIG. 8A. The base of the nozzle 19 is 1.
It is formed by electroplating on conductor layer 27 with a thickness of 5 to 2.0 mils (about 38 to 51 μm), which is equal to the (final) nozzle 19 height. Next, a glass plate or other flat plate-shaped dielectric material 56 is applied to the 8B
It is pressed against the nozzle 19 as shown. This board 56
Is the nozzle 1 in the second stage of the nickel plating process.
9 acts as a template. Further, the electroplating process is continued to form the nozzle 19 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 constructed.

The nozzle 19 may be formed by using another method. For example, the nozzle 19 may be configured by a one-step plating process without using the plate 56.

FIG. 9 shows another embodiment of the print head 20. This type of nozzle 19 should also be called a compound bore. This regulates the ink flow emitted from the nozzle 19. The ink flow emitted from the compound bore nozzle has a small diameter and a very small spread. The cantilever beam (overhang portion) 13 projects toward the center, and the heating element 15 is placed on the overhang portion 13. This printhead embodiment is formed in the same manner as 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, the mask 34 or 3
Use a mask like 6.

In the above-described embodiments of the present invention, the print head was described as ejecting ink, and the ink was described as containing water, glycol, and pigment particles, but other substances are ejected. It goes without saying that it can also be used for

[0021]

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 placed on the overhang portion located therebetween. The effect that the cavitation force due to the collapse of bubbles is buffered by the replenishing ink, the damage to the heating element is extremely small, and the life is dramatically extended. This has the effect of providing a highly reliable printhead. Further, since the nozzle portion and the ink holding portion are directly connected, the ink replenishment speed is increased, and the printing speed itself can be increased. Further, in the method of manufacturing the print head according to the present invention, the positioning of the heating element and the nozzle is not performed separately, but in the manufacturing process, the positions of both are naturally matched, so that there is a theoretical misalignment. It is less likely to occur, the spread and inclination of dots due to misalignment are prevented, and the detailed alignment work unlike the related art is not required, so that the manufacturing cost can be reduced. In addition, it is possible to manufacture a print head having a large number of nozzles over a wide range.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thermal inkjet printhead according to an embodiment of the present invention.

FIG. 2 is a perspective view of a thermal inkjet printhead according to a conventional example.

FIG. 3A is a cross-sectional view of a thermal inkjet printhead according to a conventional example.

3B is a partial cross-sectional view of the printhead shown in FIG. 3A.

FIG. 4 is a plan view showing a state in which nozzles of a print head according to an exemplary embodiment of the present invention are removed.

5A is a sectional view showing a substrate in a manufacturing process according to an embodiment of the present invention. FIG.

5B is a cross-sectional view showing a state in which the substrate shown in FIG. 5A is covered with a mask.

FIG. 5C is a plan view showing the shape of a mask according to an embodiment of the present invention.

FIG. 6A is a cross-sectional view showing a process of forming a cantilever beam (overhanging portion) and a holding portion.

FIG. 6B is a cross-sectional view showing a process of forming a cantilever beam (overhanging portion) and a holding portion.

FIG. 6C is a sectional view showing a process of forming a cantilever beam (overhanging 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 cross-sectional view showing a conductor layer for forming a nozzle and a donut-shaped frame.

FIG. 8A is a cross-sectional view showing a step of forming a nozzle.

FIG. 8B is a cross-sectional view showing a step of forming a nozzle.

FIG. 8C is a sectional view showing a step of forming a nozzle.

FIG. 9 is a cross-sectional view of a thermal inkjet printhead according to another embodiment.

FIG. 10 is a plan view of the print head shown in FIG.

[Explanation of symbols]

 10: Substrate 11: Ink holding part 15: Resistance heating element 17: Nozzle part

[Procedure amendment]

[Submission date] March 29, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

7. The step of forming the nozzle is performed with the seed layer.
From which the layer forming the nozzle from the middle is plated and grown halfway
Process, and further cover the frame from that layer
So that the plating grows and the tip goes from the back to the inside of the frame
Nozzle shaped so that its diameter gradually narrows toward
And a second step of forming the opening.
Inkjet pre according to claim 6
Method of manufacturing a front head.

Claims (1)

[Claims] 1. A resistance heating element is provided in a substrate so as to be connected to an ink holding portion, an annular frame is provided on the substrate so as to surround the resistance heating element, and a metal layer is provided inward from the annular frame. A method for manufacturing a thermal ink jet print head, which comprises a step of forming a nozzle portion by performing plating growth while leaving an orifice opening.