JPH1128821A - Method of manufacturing inkjet print head - Google Patents

Abstract

(57) [Summary] The present invention relates to an ink jet print head, and its object is to provide a bonding method which has a low temperature and high reliability while simplifying a manufacturing process. SOLUTION: An Ag thin plate having an ink flow path formed by plating, press punching or electric discharge machining is manufactured, and the Ag thin plate itself is used as a bonding layer, and bonding is performed by heating and pressing with the bonding surfaces facing each other.

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 print head.

[0002]

2. Description of the Related Art Conventionally, an ink jet print head comprising a joining member having a thickness of 7 μm to 5 mm made of an iron-based, Ni-based, or copper-based material has been joined using an organic adhesive, solder, or brazing material. Have been.

[0003]

SUMMARY OF THE INVENTION For water-soluble inks,
Ink jet printers using hot melt inks are solid at room temperature, so they do not stain during handling, and solidify immediately after jetting without bleeding.
There is an advantage that various types of paper, such as Japanese paper, drawing paper, and postcards, can be used without any preprocessing. However, in many cases, the head used is always heated and held at the ink melting temperature even in a non-printing state due to its characteristics. Therefore, compared with an ink jet print head using a water-soluble ink, it is required to greatly improve durability at a high temperature. Therefore, there is a problem that the organic adhesive is deteriorated by thermal cycling together with corrosion by ink.

A method of joining with a low melting point metal, that is, a low melting point solder is disclosed in Japanese Patent Application Laid-Open No. 62-70051. Furthermore, the method of joining with an Au-Ni row is disclosed in
No. 07450 discloses this. However, low-melting-point solder, like the organic adhesive, has problems of corrosion by ink and deterioration by thermal cycling. Although the brazing material is resistant to ink corrosion resistance and thermal cycling, it is bonded at a high temperature of 450 ° C. or higher, so that there are limitations on the bonding members that can be used.

On the other hand, ink jet print heads
In order to form a fine three-dimensional ink flow path, it is necessary to laminate and join thin plates on which a fine two-dimensional pattern is formed by using a technique such as etching or electroforming. It is important to reduce the thickness of the material and reduce the amount of protrusion from the ink flow path.

[0006] In this case, the application of the adhesive to the joint is sprayed, and the method of supplying the solder and the solder is plating on the joint member.
Alternatively, a method of vapor deposition / sputtering is used.
In this case, although it depends on the shape, the thickness of the adhesive is 30 μm.
m or less, and the thickness of the joining solder and the brazing material is 10 μm or less. However, among these, the allowable range of the film thickness that does not cause protrusion or leak that affects the printing characteristics is, for example, 3 ± 0.3.
It is limited to a narrow range of μm. However, in any case, it is difficult to completely control the behavior of the adhesive, solder, or brazing material having high fluidity at the time of joining, so that the ink tends to protrude into the ink flow path, which causes a variation in printing characteristics. In some cases, clogging occurs and ink is not ejected. Diffusion bonding using Ni-P has been studied as a method of completely preventing the protrusion, but the bonding temperature is as high as 700 ° C. or more, so there are limitations on the parts that can be used. In any case, in addition to the production of thin plates,
A high-precision adhesive spraying technique or a vapor deposition / sputtering technique for solder and solder is required.

When a hot melt type ink is used, the temperature of the ink jet print head rises to 100 to 150 ° C. during use of the printer, so that the adhesive is easily deteriorated by heat. In the solder, the compound easily grows between Sn and the base plating.

In the case of joining with a solder or a brazing material, plating is often required on an underlayer in order to make the solder or the brazing material adhere to the base material thin plate. Do not melt at the specified joining temperature because the solder material and the base material react to form brittle intermetallic compounds, or the solder or the solder material composition changes due to the reaction with the base material before the joint reaches the melting point. Also, there are problems such as deterioration of mechanical properties and corrosion resistance of the solder or the brazing material.

Further, when a bond is formed by plating, gas is occluded in the film, so that when the solder or the brazing material is melted and solidified at the time of bonding, voids are likely to be formed at the bonded portion, resulting in reduced bonding strength or leakage. Easy to cause.

As a method for solving these problems, Ag, Au, Pt,
There is a method in which one of the bonding layers of Pd is formed by a plating method, and the bonding is performed by applying heat and pressure below the melting point of the bonding layer. In addition to the corrosion resistance and heat resistance of the ink, the problem of protrusion into the ink flow path or the reaction between the solder and the base plating can be solved.

The remaining problem with this method is that two steps of manufacturing a thin plate and a bonding layer are required, which increases the cost.
The bonding layer is formed by plating, vapor deposition, or sputtering, and high-precision uniformity of the film thickness is required. However, plating is difficult for plates that form complex ink channels.
Due to the concentration of current density at the time of plating, the edge portion becomes thicker and the film thickness distribution is poor. Vapor deposition and sputtering require vacuum equipment and the efficiency of film formation is about 20%
In the case of a relatively expensive bonding layer as described above, there is a problem that the cost is further increased.

SUMMARY OF THE INVENTION An object of the present invention is to make a thin plate itself also serve as a bonding layer without separately forming a bonding layer. An object of the present invention is to provide a bonding method that can easily control the protrusion and that has excellent ink corrosion resistance and heat resistance.

[0013]

According to the present invention, in order to achieve the above object, a thin plate constituting an ink flow path is made of Ag or A
u, Pt, or Pd, and the thin plate itself as the bonding layer,
The joining is performed by heating and pressing at a temperature lower than the melting point of the thin plate, desirably below the heat resistant temperature of the constituent materials of the ink jet print head.

In the production of the thin plate, an ink flow path forming pattern is previously formed on a substrate which is easy to peel off, and then Ag, Au, Pt, or Pd is formed thereon by plating and peeled off from the substrate. A method of forming an ink flow path and a method of forming an ink flow path forming pattern by stamping any one of Ag, Au, Pt, and Pd rolled to a predetermined thickness in advance. Electric discharge machining may be used instead of press punching.

As an example of the use of the above-mentioned thin plate manufacturing method, as an example, a method of peeling from a substrate by plating is a method of manufacturing a thin plate having a thickness of about 20 μm or less serving as a diaphragm and a thin plate having a hole of about 30 μm or less as a filter hole. Suitable for you. This method is also easily used for a thin plate having an orifice serving as an ink ejection hole, since a smooth hole shape can be obtained.

The material of the thin plate is preferably Ag or Au, Pt, or Pd, which is soft and has a Vickers hardness (hereinafter referred to as Hv) of 130 or less and has excellent ink corrosion resistance. However, at Hv 20 or less, even in the case of solid-phase bonding, protrusion to the ink flow path occurs.

The thickness of the thin plate is not particularly limited as long as it can be formed.

The thin plate may be a single layer or two or more layers. When two or more layers are used, a metal that easily diffuses at a low temperature on the outermost surface is selected, and a metal having a large deformability is selected as the second layer, so that a stronger and more reliable bonding can be performed. Similarly, it is also possible to select a metal having the highest ink corrosion resistance on the outermost surface.

When the above-mentioned thin plate is heat-treated at 200 ° C. or higher before joining, the Vickers hardness is reduced, so that the deformability is increased and the joining property is improved. At the same time, one of the features of the present invention, which is different from simple thermocompression bonding of the prior art, has the effect of removing C or S in the bonding layer, lowering the hardness, and cleaning the surface.

In some cases, a piezoelectric driving element or the like for ejecting ink is attached to the ink jet print head in advance, and depending on the heat resistance of the joining member,
In some cases, the heat treatment at 200 ° C. or higher cannot be performed. In this case, as a method of cleaning the surface, a method of removing carbon or sulfur and harmful substances with ions or neutral atoms may be used.

The method of joining the ink jet print heads will be described with reference to FIG. 9. After adjusting the relative positions of the joining members, the members are pressed and brought into close contact with each other and heated to plastically deform and diffuse the thin plates, thereby joining them. I do.

The joining temperature is 70 ° C. or more at which the hardness of the thin plate is reduced to Hv 60 or less. The higher the bonding temperature, the higher the deformability of the thin plate and the easier the diffusion proceeds, so the higher the bonding strength. However, as described above, heating cannot be performed at a temperature higher than the heat resistance temperature of the bonding member, and since the bonding is solid phase in order to prevent the bonding layer from protruding into the ink flow path, the melting point of the thin plate must not be exceeded. When using the above thin plate,
Even when joining at a temperature of 200 ° C. or lower, a higher joining strength can be obtained than soldering at an equivalent joining temperature.

The pressing force at the time of joining is not less than the proof stress of the thin plate for plastically deforming the joining. Partial joining is possible even with the strength of the thin plate or less, but it is necessary to join the entire surface of the ink jet print head to prevent leakage.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

[Embodiment 1] In this embodiment, an orifice plate 1 (A
g, thickness 50 μm), restrictor plate 2 (Ag, thickness 50 μm), diaphragm plate 3 (Ag, thickness 20 μm)
μm) and the filter plate 4 (Ag, thickness 30 μm) were joined.

FIG. 1 shows the shape of the plate, and FIG. FIG. 2 (a) shows a cross-sectional configuration of the main joint, and FIG. 2 (b) shows, for comparison, a material obtained by plating a base material of Ni7 and Cu8 on a material of an etched product 6 of stainless steel according to a conventional method and sputtering Ag. Indicated.

In this embodiment, the orifice plate and the restrictor plate are manufactured by forming a pattern for forming an ink flow path by press punching an Ag5 plate previously rolled to a predetermined thickness of each plate. In addition, the diaphragm plate and the filter plate were formed in advance by forming an ink flow path forming pattern on an easily peelable substrate, forming Ag thereon by a plating method, peeling off the substrate, and forming an ink flow path forming plate. .

These plates are kept at 200 ° C.
Heat treatment was performed for 15 minutes to soften the hardness of the Ag thin plate to Hv67, and to remove carbon and sulfur from the joint surface.

Next, the above-mentioned components are positioned by aligning the joining surfaces 9, and temporarily fixed by spot welding in the order of the orifice plate 1, restrictor plate 2, diaphragm plate 3, and filter plate 4. These are set in a furnace (not shown), heated in the atmosphere to 200 ° C. with upper and lower heating and pressing jigs, and a pressure of 6 kgf / mm ² is applied. Hold for 15 minutes after the object reaches 200 ° C,
Turn off the heater power and cool as it is.

The composition of the hot melt ink used is, for example, 55% by weight of polyester and 43% of fatty acid by weight%.
% And 2% dye for each of the colors magenta, cyan, yellow and black, and the melting point is 80 ° C.

A printing test was actually performed for one year using each color of the hot-melt ink, and a disassembly test was conducted. As a result, a uniform joint without leakage or protrusion was obtained, and voids observed in solder joining and brazing were found. It was found that an ink jet print head without any problem and no corrosion problem due to ink could be manufactured.

Ag has better heat resistance and bonding strength than organic adhesives and solders. Further, the corrosion resistance of the ink is equivalent to that of the Au—Sn solder having the highest corrosion resistance among the solders. And the joining temperature is usually 7 compared to brazing material and Au-based solder.
Since the bonding can be performed at a low temperature of 0 ° C. or more, the thermal damage to the workpiece is small. In this embodiment, the bonding layer is made of Ag, but Au, Pt, and Pd can be similarly bonded.

Table 1 shows a piezoelectric drive element (PZ), which is one of the parts having low corrosion resistance to the above inks of various thin plates and low heat resistance attached to the ink jet print head.
The bonding temperature for 250 ° C., which is the heat resistant temperature of T), is evaluated and shown.

[0034]

[Table 1]

The evaluation criteria were as follows. In terms of the corrosion resistance of the ink, Δ was 1 when the corrosion rate was less than 1 μm / year, and X was 1 μm / year or more.
The bonding temperature is less than 250 ° C.
A sample having a temperature of not less than ° C was evaluated as x. As a result, Ag,
It was found that Au, Pt, and Pd can satisfy both the corrosion resistance and the bonding temperature.

In this embodiment, the restrictor plate was manufactured by press punching, but the same result was obtained when the restrictor plate was manufactured by electric discharge machining.

Embodiment 2 FIG. 3 shows the configuration of this embodiment.

As in the first embodiment, the orifice plate 1 constituting the ink jet print head shown in FIG.
(Thickness: 50 μm), restrictor plate 2 (thickness: 50 μm)
μm), the diaphragm plate 3 (thickness 20 μm), and the filter plate 4 (thickness 25 μm) were joined. The orifice plate and the filter plate were configured so that Ag5 was clad on the surface of the Pt plate 10 to a thickness of 5 μm on one side. Ag was clad on the bonding surface, that is, the orifice plate was only the surface facing the restrictor plate, and the filter plate was only the surface facing the diaphragm plate.
On the other hand, each of the restrictor plate and the diaphragm plate was clad with 5 μm of Ag on both surfaces of the Pt plate. Further, an ink flow path forming pattern was formed on each thin plate by press punching.

Since Pt has a low proof stress of about 45% with respect to Ag, it has the effect of plastically deforming even at a low pressing force and bringing the bonding surfaces into close contact. Note that Ag is easier to diffuse at low temperature than Pt, and thus, when Ag is arranged on the bonding surface, the strength when bonding at low temperature is higher.

Next, the above components were positioned in the same manner as in the first embodiment, and the orifice plate 1, restrictor plate 2,
The diaphragm plate 3 and the filter plate 4 are temporarily fixed by spot welding in this order. These are set in a furnace (not shown), heated to 200 ° C. in the atmosphere with upper and lower heating and pressing jigs, and a pressing force of 3% of 3 kgf / mm ² of Example 1 is applied. 15 after the workpiece reaches 200 ° C
Hold for one minute, turn off the heater power and cool as it is.

A printing test was actually performed for one year using the same hot-melt ink as in Example 1, and a disassembly investigation was performed. As a result, a uniform joint without leakage or protrusion was obtained as in Example 1. It was found that an ink jet print head having no voids observed in solder joining or brazing and having no problem of corrosion by ink could be manufactured.

Example 3 A peel strength test was performed using a test piece in order to compare the bonding strength in the case of solid phase bonding with Ag and the bonding strength in the case of bonding with an organic adhesive and Au-Sn solder.

Here, the life of the ink jet print head is required to be at least three years or more. When using a hot-melt ink having a melting point of 70 ° C. or more, it is necessary to perform a thermal expansion, a heat shrinkage, and a drive of a piezoelectric element for ejecting the ink for three years or more, based on the result of an epoxy-based adhesive that has been generally used. To withstand, the target peel strength is 200gf
/ Cm or more.

In the peel test, the Ag test piece has a thickness of 50%.
μm, width 10 mm, length 50 mm and thickness 10 μm, width 10 mm, length 50 mm Ag thin plate, 50 μm thickness, width 10 m for Au-Sn solder and epoxy adhesive
m, a length of 50 mm, a thickness of 10 μm, a width of 10 mm, and a length of 50 mm.

The test piece for Ag bonding was set in a furnace (not shown) in the same manner as in Example 1, and heated to 200 ° C. in the air with upper and lower heating and pressing jigs while applying a pressure of 10 kgf / mm ^2. Load. 15 after the workpiece reaches 200 ° C
The heating was performed for 5 minutes, the heater power was turned off, and the device was cooled as it was.

Since it is difficult to apply Au or Sn plating directly to stainless steel, first, Ni plating is applied as a base plating at 1 μm, and then Au plating is applied at 2.7 μm.
m. Then, 2.3 μm of Sn plating was applied on the Au plating. By setting the thickness of each of Au and Sn to the above-mentioned thickness, Au and Sn alone become Au-25 wt% Sn, but actually Ni and Sn of the base react during bonding heating to form a Ni-Sn compound. Therefore, the solder composition after bonding is about Au-20wt
% Sn.

The joint was set in a vacuum furnace (not shown), heated to 320 ° C. with upper and lower heating and pressing jigs at a degree of vacuum of the order of 10 −2 Torr, and 0.1 kgf / m 2.
A pressure of m ² is applied. After the object reaches 320 ° C., the temperature is maintained for 3 minutes, the heater power is turned off, and the object is cooled as it is.

As a test piece of the organic adhesive, an epoxy-based adhesive was directly applied to stainless steel to a thickness of 20 μm by spraying.

The joint is set in a furnace (not shown), heated to 150 ° C. in the atmosphere by means of a heating and pressing jig at the top and bottom, and a pressure of 0.05 kgf / mm ² is applied. After the object reaches 150 ° C., the temperature is maintained for 8 hours, the heater power is turned off, and the object is cooled as it is.

As is clear from FIG. 4, the result of the peel test is that the peel strength of the Ag test piece using the main joint is 400.
While it can clear the target value of ~ 450 gf / cm, A
The u-Sn solder product is 100 to 150 gf / cm, and the organic adhesive product is 50 to 75 gf / cm, which is lower than the target values.

Example 4 In order to investigate the effect of the hardness of the thin plates to be joined, the relationship between the hardness of Ag and the joint area ratio / ink channel opening ratio and the relationship between the heat treatment temperature and the hardness were determined. 5 is shown. The joining conditions and test pieces are the same as in Example 3.

As shown in FIG. 5, the pressing force is 10 kgf /
In the case of mm ² , the bonding area ratio is 100% when Hv is 130 or less.
Becomes On the other hand, when the pressing force is 6 kgf / mm ² , Hv7
Below 0, the bonding area ratio is 100%. When the pressure is 6
Even in the case of kgf / mm ² , if it falls below Hv15, the ink flow path opening ratio falls below a predetermined 80%. Therefore, a suitable hardness range is Hv 15 to 130.

Here, in order to increase the bonding area ratio, the lower the hardness, the better. Therefore, the heat treatment temperature for lowering the hardness before bonding was examined using Ag having a hardness of Hv130.

As shown in FIG. 6, as the processing temperature increases, the hardness after returning to room temperature decreases, and after heating at 200.degree. Below 200 ° C., the rate of decrease in hardness decreases. Therefore, before joining, above 200 ° C, but below the melting point of the joining Ag and joining members,
Good heat treatment.

Example 5 In order to remove harmful substances on the surface of a thin plate, heat treatment in the air and irradiation of Ar neutral atoms were performed. FIG. 7 shows the relationship between the results of Auger analysis of the carbon concentration on the Ag surface and the bonding strength after heat treatment for 15 minutes in air. The joining conditions and test pieces are the same as in Example 3.

As a result, at a heat treatment temperature of 200 ° C. or more, the C concentration on the surface is greatly reduced, and is reduced from 93 at% before treatment to 35 at%.
at% or less. Along with that, the joining strength also increases,
The same target value as in Example 3 of 200 gf / cm or more can be satisfied. Therefore, it was found that the heat treatment temperature is preferably 200 ° C. or more. However, the upper limit is equal to or lower than the melting point of the bonding layer and the bonding member. This heat treatment condition is the same as the heat treatment for reducing the hardness of the plating film shown in Example 4.

As a method of removing harmful substances on the surface at a low temperature, irradiation with neutral atoms or ions may be used.

In this embodiment, as an example, Ag neutral atom
The results of Auger analysis of the C concentration on the surface when the plating film surface is cleaned are shown. Utilizing the sputtering phenomenon by Ar neutral atom, acceleration voltage 1KV for 3 minutes,
The surface was cleaned. FIG. 8 shows the result. As in the heat treatment, the C concentration on the surface is 93 at% to 20 at%.
Could be lowered to

[Embodiment 6] The concept and the joining conditions of the solid-state joining using Ag or Au, Pt, and Pd thin plates will be described. FIG. 9 shows the basic concept.

The first step (a) is a state in which the bonding member is positioned, the second step (b) is a state in which the bonding layer is brought into full contact by plastic deformation by heating and pressing, and the third step (c). As a result, the bonding line disappears due to the diffusion caused by heating and holding, and the bonding is completed.
The result of finding the proper range of the joining temperature and the joining pressure, which are the joining conditions at this time, will be described below. The test piece was Example 3
Is the same as

FIG. 10 shows the relationship between the bonding temperature of Ag and the bonding area ratio, and FIG. 11 shows the relationship between the heating temperature of Ag and the hardness. The pressure was 10 kgf / mm ² , and heating was performed in the atmosphere. As a result, the bonding area ratio becomes 100% at a bonding temperature of 70 ° C. or higher. Further, it can be seen that the hardness is rapidly reduced at 70 ° C. or higher. Therefore, it is appropriate that the bonding temperature is 70 ° C. or higher and the melting point of the bonding layer and the bonding member is lower than the melting point.

FIG. 12 shows the result of obtaining the relationship between the pressing force and the bonding area ratio. The joining temperature is 70 ° C. As a result, 6
The bonding area ratio becomes 100% at kgf / mm ² . This causes plastic deformation beyond the proof stress of Ag at 6 kgf / mm ² ,
This is because the bonding interface adheres. Therefore, the appropriate pressing force is not less than the proof stress of the thin plate to be joined and not more than the proof stress of the joining member.

[0063]

According to the present invention, the thin plate itself can also serve as the bonding layer without separately forming the bonding layer, so that the simple bonding in one step can be performed in comparison with the conventional two steps of manufacturing the thin plate and the bonding layer. A method is obtained. In addition, since the bonding can be performed at a lower temperature as compared with the solder bonding or the brazing, the range of selection of the material of the bonding member is increased.

In addition, this bonding is a solid-phase bonding. The melting point of the bonding portion is the melting point of the bonding layer and is higher than the melting points of the organic adhesive and the solder. Can be raised. Since the bonding layer does not melt during bonding, it is easy to control the protrusion of the bonding layer into the ink flow path.

These Ag, Au, Pt, and Pd are also excellent in ink corrosion resistance.

Conventionally, since the solder plating film used for the main bonding contains a gas at the time of plating, voids are liable to be generated at the time of soldering or brazing at the time of melting and solidification at the time of bonding, so that the bonding strength is reduced or the leakage is reduced. Easy to cause. However, this bonding method does not cause voids because it is not melted by solid phase bonding.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a shape of a thin plate constituting an ink jet print head to which the present invention is applied.

FIG. 2 is a cross-sectional view illustrating an example of a thin plate configuration of an ink jet print head to which the present invention is applied.

FIG. 3 is a cross-sectional view of a thin plate constituting an ink jet print head to which the present invention is applied and having a two-layer structure.

FIG. 4 is a graph showing the relationship between the joint strength of a test piece and the joint strength of a solder and an organic adhesive.

FIG. 5 is a graph showing the relationship between the hardness of an Ag thin plate, the bonding area ratio, and the ink channel opening ratio.

FIG. 6 is a graph showing a relationship between a heat treatment temperature and a hardness before joining of an Ag thin plate.

FIG. 7 is a graph showing the relationship between the heat treatment temperature of an Ag thin plate, the carbon concentration on the surface, and the bonding strength.

FIG. 8 is a graph comparing the carbon concentration on the surface of an Ag thin plate before and after irradiation with Ar neutral atoms.

FIG. 9 is a basic conceptual diagram of a bonding interface in the present bonding method.

FIG. 10 is a graph showing a relationship between a bonding temperature and a bonding area ratio.

FIG. 11 is a graph showing the relationship between the heating temperature of an Ag thin plate and the hardness at that temperature.

FIG. 12 is a graph showing a relationship between a bonding temperature and a bonding area ratio.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Orifice plate, 2 ... Restrictor plate, 3 ... Diaphragm plate, 4 ... Filter plate, 5 ... Pt, 6 ... Ag

Claims (13)

[Claims] 1. An ink jet printer having a thin plate laminated print head, wherein Ag or Au, Pt, or Pd is used alone or in two or more layers by using the thin plate itself constituting an ink flow path as a bonding layer. A method for manufacturing an ink jet print head, comprising forming and joining. 2. A method of manufacturing an ink jet print head according to claim 1, wherein an ink flow path forming pattern is formed on a substrate which is easy to peel in advance, and Ag or one of Au, Pt and Pd is plated thereon. An ink-jet printhead formed by forming a plurality of plates of various shapes by laminating the plates, peeling them off from a substrate to form an ink flow path forming plate, laminating these plates, and applying heat and pressure. Method of manufacturing. 3. A method for manufacturing an ink jet print head according to claim 1, wherein one of Ag, Au, Pt, and Pd, which has been rolled in advance to a predetermined thickness, is press-punched to form an ink flow path forming pattern. A method of manufacturing an ink-jet printhead, comprising: preparing a plurality of plates of various shapes; laminating them; 4. A method for manufacturing an ink-jet printhead according to claim 1, wherein an ink flow path forming pattern is formed by subjecting any one of Ag, Au, Pt, and Pd, which has been rolled to a predetermined thickness, to electrical discharge machining. A method of manufacturing an ink-jet printhead, comprising: preparing a plurality of plates of various shapes; laminating them; 5. The method for manufacturing an ink jet print head according to claim 1, wherein said thin plate has a Vickers hardness of 20 to 130. 6. A method for manufacturing an ink jet print head according to claim 5, wherein said thin plate is subjected to a heat treatment before its joining to have a Vickers hardness of 15 to 70. Production method. 7. The method for manufacturing an ink jet print head according to claim 1, wherein the thin plate is subjected to heat treatment in an atmosphere containing oxygen to remove carbon or sulfur existing on the surface before joining. Of producing an inkjet print head. 8. The method of manufacturing an ink jet print head according to claim 7, wherein the heat treatment temperature is 200 ° C. or higher and lower than the melting point of the thin plate. 9. The method according to claim 1, wherein the thin plate removes carbon, sulfur and other harmful substances existing on the surface with ions or neutral atoms before joining. Method for producing an ink jet print head. 10. The method of manufacturing an ink jet print head according to claim 1, wherein the bonding method of the thin plates is such that after adjusting the relative position of the thin plates, the thin plates are brought into close contact with each other and heated, so that the thin plates are joined to each other. A method for producing an ink-jet printhead, wherein surfaces are plastically deformed and diffused and joined. 11. A method for manufacturing an ink jet print head according to claim 10, wherein said bonding temperature is 70 ° C. or higher and lower than the melting points of said thin plate and said bonding member. Method. 12. The method of manufacturing an ink jet print head according to claim 1, wherein the pressing force at the time of joining the thin plates is equal to or higher than the proof stress of the thin plates. 13. The method for manufacturing an ink jet print head according to claim 1, wherein the ink used for the ink jet print head is a hot melt type having a melting point of 70 ° C. or more and a melting point of the thin plate or less. Of producing an inkjet print head.