DE68925843T2 - Ink jet recording arrangement - Google Patents

Description

Background of the invention Field of the invention

This invention relates to a recording element assembly, a recording element driving unit, an ink jet unit, an ink jet driving unit, and an ink jet apparatus using the same.

Relevant state of the art

A recording element unit to be used for an ink jet recording apparatus, etc., for example, a recording element unit shown in Fig. 19(a) has been known as a prior art. A section taken along the line A-A' in Fig. 19(a) is shown in Fig. 19(b).

In Fig. 19(a) and Fig. 19(b), 1501 is a support member, 1502 is a HfB2 layer as the heat generating resistance layer, 1503 is the common electrode made of Al, 1504 is individual electrodes made of Al, 1505a and 1505b are conductor patterns made of Al, 1506 is a SiO2 layer as the oxidation resistant and the insulating layer, 1507 is a photosensitive polyimide layer as the ink resistant and the insulating layer, and 1508 is a Ta layer as the cavitation resistant layer.

The recording element assembly shown in Fig. 19(a) and Fig. 19(b) supplies current to the HfB2 layer 1502 as the heat generating resistance layer, thereby generating heat energy from this HfB2 layer. Specifically, by allowing the drive current to flow into the HfB2 layer from the outside through the individual electrodes 1504 and the conductor patterns 1505a and further allowing the current to flow outward through the conductor patterns 1505b and the common electrode 1503, heat energy can be generated at the HfB2 layer.

In the inkjet recording device, recording is accomplished by ejecting liquid using heat energy.

Usually, this combination of the HfB2 layer 1502, the individual electrodes 1504, the conductor patterns 1505a and 1505b (hereinafter referred to as a heat generating element) is formed in a larger number in the recording unit as shown in Fig. 19(a). Thus, by providing a plurality of heat generating elements to the recording element assembly, an ink jet recording apparatus capable of simultaneously performing recording of a plurality of dots is obtained, thereby making it possible to achieve a higher recording speed. In particular, at present, since the requirements for higher density and higher speed recording are high, simultaneous recording of a single main scanning line has been generalized, and therefore recording element assemblies having a large number of high density heat generating elements are coming to the public.

In the case of performing simultaneous recording of a plurality of dots by arranging a plurality of heat generating elements on a single recording element assembly, on-off control must be performed individually for the respective heat generating elements. The means for performing this control (hereinafter referred to as a driving element) may also be formed within the recording element assembly, but is generally formed on an independent substrate (hereinafter referred to as the driving element substrate) connected to the recording element unit, because if the recording element and the driving element are formed integrally, there is a problem that if a failure occurs in a part of either the recording element or the driving element, the whole fails to operate.

In the prior art, the following methods have been known as the prior art as the process technology for electrically connecting the recording element substrate and the driving element substrate.

(1) Wire bonding method:

The wire bonding method is a method shown in Fig. 20, in which the electrode 1614, 1615 of the recording element substrate 1604 is electrically connected to a desired electrode of the driving element substrate 1605 using an extremely fine metal wire 1616, e.g., made of gold, etc.

(2) The method using an electrical connector body:

This is a method in which the electrode part of the recording element substrate is connected to the electrode part of the drive element substrate using the electrical connection body as described in JP Patent Application No. 63-133395.

Figs. 21(a) to 21(c) are schematic diagrams for explaining this method. In the figures, 1704 is a recording element substrate, 1705 is a driving element substrate, 1714 and 1715 are electrode parts, and 1719 and 1720 are insulating films. 1703 is an electrical connection body, 1717 is an electrically conductive member, and 1718 is a holding member for holding the electrically conductive member 1717. The pitch of the electrically conductive member 1717 is determined to be narrower than the pitch of the electrodes 1714 and 1715.

The recording element substrate 1704, the driving element substrate 1705 and the electrical connection body 1703 are first arranged as shown in Fig. 21(a), and they are then brought into pressure contact with each other as shown in Fig. 21(b). Fig. 21(c) shows the overall view after the pressure contact.

The prior art electrical connection methods described above had the following objectives.

(1) Wire bonding method:

(a) In the wire bonding method, however, in order to avoid mutual contact between the adjacent very fine metal wires, the pitch of the connecting part on the recording element substrate or the driving element substrate (distance between the centers of the connecting parts adjacent to each other) must have a certain interval. Accordingly, once the sizes of the recording element substrate and the driving element substrate are determined, the maximum number of the connecting parts is necessarily determined. However, since according to the wire bonding method, the pitch is generally as large as about 0.2 mm, the number of the connecting parts cannot be few.

Conversely, this means that if the number of the connecting parts of the recording element substrate or the driving element substrate is fixed, the sizes of the recording element substrate and the driving element substrate must be made extremely long.

(b) The height h of the very fine metal wire measured from the connecting part to the driving element is generally 0.2 to 0.4 mm; however, since it is difficult to make the thickness less than 0.2 mm, no reduction can be effected.

(c) Wire bonding processing takes a long time. In particular, as the number of connection points is increased, the bonding time becomes longer, thus deteriorating the production efficiency.

(d) If the range of transfer forming conditions is exceeded by some influencing factors, the very fine metal wire may be deformed or, in the worst case, even severed.

Also, Al corrosion is prone to occur at the connecting part on the driver element because Al, which does not form an alloy with the very fine metal wire, is exposed, thereby reducing reliability.

(e) If the driver element becomes defective, it is difficult to replace only the driver element.

(2) The method using an electrical connector body:

This method has the advantages that the unit can be miniaturized, high-precision adjustment is not required, and the cost can be reduced, etc., but further miniaturization and cost reduction are required.

Reference is made to JP-A-59111338 which discloses a circuit board with a glass paste film, through openings of which extend projections which are connected to circuit board electrodes and bonded to electrodes of the semiconductor device.

According to the invention there is provided a recording head assembly comprising at least two modules, namely a first module containing at least one heat-generating resistor and a second module containing at least one driver circuit, characterized in that said first module includes a substrate, a heat-generating resistor layer, a wiring layer for supplying electrical signals to said resistor layer and electrodes carried by said substrate and electrically connected to said wiring layer, said electrodes being raised from their respective surrounding surfaces so as to protrude from said wiring layer, said second module comprising a driver element substrate with a driver circuit and a wiring layer connected to said driver circuit, wherein said projecting electrodes of the first module provide an electrical connection to the wiring layer of said second module, and said modules are easily detachable from one another, whereby one or the other module is interchangeable.

An ink jet recording apparatus may be provided having a member adapted to support said head assembly.

The attached drawings show:

Fig. 1 is a schematic sectional view showing a state in which the recording element substrate is bonded to the driving element substrate;

2A(a) to 2F(c) are schematic diagrams for explaining the manufacturing steps of the recording element assembly according to a first example of this invention, in which (a) is a plan view and (b) and (c) are sectional views, respectively;

Fig. 3 is a schematic sectional view showing the connecting part of the recording element assembly according to the first example of this invention;

Fig. 4 is a schematic sectional view showing an example of the ink jet unit and the ink jet driving unit according to this invention;

Fig. 5 is a perspective view showing an example of the main part of the serial scanning type ink jet recording apparatus according to this invention;

Fig. 6 is a perspective view showing an example of the main part of the planar scanning type ink jet recording apparatus according to this invention;

Fig. 7 is a schematic sectional view showing the recording element assembly according to a third example of this invention;

8A(a) to 8G(c) are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to the third example of this invention, wherein (a) is a plan view and (b) and (c) are sectional views, respectively;

9A and 9B are schematic sectional views showing the recording element assembly according to a fourth example of this invention, wherein Fig. 9A is a diagram showing the recording element assembly without a common electrode and Fig. 9B is a diagram showing the recording element assembly with a common electrode;

10A(a) to 10F(c) are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to the fourth example of this invention, in which (a) is a plan view and (b) and (c) are sectional views, respectively;

Fig. 11 is a schematic sectional view showing the recording element assembly according to a fifth example of this invention;

12A(a) to 12G(c) are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to the fifth example of this invention, in which (a) is a plan view and (b) and (c) are sectional views, respectively;

Fig. 13 is a schematic sectional view showing the recording element assembly according to a sixth example of this invention;

14A(a) to 14G(c) are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to the sixth example of this invention, in which (a) is a plan view and (b) and (c) are sectional views, respectively;

15A(a) to 15F(c) are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to another example of this invention, in which (a) is a plan view and (b) and (c) are sectional views, respectively;

Fig. 16 is a schematic sectional view showing the connecting part of the recording element assembly according to the above further example of this invention;

Fig. 17 is a schematic perspective view showing an example of the head assembly of the ink jet unit and the ink jet driving unit of this invention;

Fig. 18 is a schematic perspective view showing an example of the external appearance of the ink jet apparatus according to this invention;

Fig. 19(a) and Fig. 19(b) are schematic diagrams showing the prior art recording element assembly, Fig. 19(a) being a plan view and Fig. 19(b) being a sectional view;

Figs. 20(a) and 20(b) are schematic diagrams for explaining the connection process by the wire bonding method in the recording element assembly according to the prior art;

Fig. 21(a) to 21(c) are schematic diagrams for explaining the connection method using an electrical connection body in the recording element driving unit according to the prior art.

Detailed description of the invention

The present invention will be described in detail below as to its nature.

(Recording element, driver element)

As the recording element in this invention, for example, a heat energy generating electrically heated transducer (heat generating element) and other recording elements such as a piezoelectric element can be used.

(conductor structure and protruding electrode)

The conductor structure of the recording element substrate (recording element assembly) and the driving element substrate are formed on the surface of the support member. When a protective film is formed on the surface of the support member to protect and insulate the conductor pattern, a conductor pattern having a sufficient area to form a protruding electrode can also be exposed.

The conductor structure can be formed, for example, from an electrically conductive material such as Al, etc.

For the conductor pattern of the recording element substrate (the recording element assembly), a connecting part including a protruding electrode is formed.

The protruding electrode may be formed only alone or in a plurality per a single connection part. On the other hand, it is not necessary that a protruding electrode be formed on the conductor structure of the driver element substrate. The connection part comprising a protruding electrode is intended to establish an electrical connection to another circuit board (e.g. the driver element substrate), i.e., an electrical coupling is effected by directly connecting to the connection part of another circuit substrate.

The protruding electrode may be made of the same material as the conductor pattern or a different material therefrom. As the material for forming the protruding electrode, for example, metals such as Cu, Ni, Au, Cr, Rh, etc., or alloys comprising combinations of these may be available. Also, the protruding electrode and the conductor pattern may be formed as a unit from the beginning, or alternatively, the conductor pattern may be formed first and then the protruding electrode may be formed thereon. When the protruding electrode is formed after forming the conductor pattern, it is desirably formed by the electroplating method with the conductor pattern as the electrode for the reason described below. In this case, the conductor structure should desirably be made of Cu.

In the present invention, for the reason described below, the conductor pattern that becomes the common electrode may also be provided on the driving element substrate rather than on the recording element substrate.

In the recording element substrate (in the recording element assembly) in the present invention, it is desirable to provide recording elements and the conductor patterns corresponding to the recording elements in numbers one or more than the necessary number. By doing so, the connection between the connection part of the recording element substrate and the conductor pattern of the driving element substrate can be effected without the need for strict precise adjustment. Also, for the same reason, it is desirable to provide driving elements and conductor patterns of the driving element substrate in numbers one or more than the necessary number.

(protective layer)

In the recording element substrate (the recording element assembly) of this invention, a protective layer should desirably be formed on the surface of the wire member for protecting and insulating the conductor pattern. This protective layer may include, for example, an oxidation-resistant protective layer formed of SiO2, a protective layer resistant to cavitation formed of Ta, an ink-resistant protective layer formed of a photosensitive polyimide, etc. The protective layer may be a single one, or two or more layers may also be present depending on the purpose.

(Insulating layer and insulating film)

In the recording element substrate (recording element assembly) of this invention, it is desirable to further provide an insulating layer on the protective layer for the reason explained below. As the material for forming the insulating layer, phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, vinyl chloride resin, styrene resin, acrylic resin, polyimide resin, polycarbonate resin, polypropylene, urea resin, etc. are used. Since this invention is intended to eliminate the influence of warpage or unevenness of the surface of the assembly by providing the insulating layer as described later, the thickness of the layer should preferably be as thick as possible.

Instead of forming an insulating layer, an insulating film can also be provided on the protective layer.

As the material for forming the insulating film of this invention, similarly to the case of the insulating layer, phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, vinyl chloride resin, styrene resin, acrylic resin, polyimide resin, polycarbonate resin, polypropylene resin, urea resin, etc. can be used.

The insulating film has a through hole, and the protruding electrode is exposed from the surface therethrough. The position, size and number of the through holes are not particularly limited. For example, they are not required to be positioned only at the electrode forming part, they may be present at other parts without exerting any influence. Also, a single through hole may be formed in correspondence with a single protruding electrode, or a large number of through holes may also be formed around the connecting part, as shown in Figs. 14F and 14G described below. When a large number of through holes are formed around the connecting part is advantageous in that no strict precision in the regular interval in the formation of the insulating film or no strict precision in the exact adjustment during an application of the insulating film is required (or no exact adjustment may be required).

Since this invention is intended to eliminate the influence of curvature or unevenness of the surface of the assembly by providing the insulating film as described later, it is preferable that the thickness of the film be as thick as possible.

(Connection)

The connection is realized as shown in Fig. 1. In this figure, 104 is a recording element substrate, 105 is a driving element substrate, 106 is a driving element, and 107 is a base plate. The surface of the driving element substrate on which the driving element is provided and the surface having the connection part are not required to be the same, but may be the opposite surfaces.

(Connection method)

The present invention is particularly effective when the connecting part of the recording element substrate (the recording element assembly) and the connecting part of the driving element substrate are connected according to the pressure bonding method. Also, connecting by means of metallization and/or alloying or methods other than metallization and/or alloying are possible, and these methods can also be used in conjunction with the pressure bonding method.

In the following, joining by means of metallization and/or alloying and joining by methods other than metallization and/or alloying are described.

(1) Joining by metallization and/or alloying:

When the protruding electrode of the recording element substrate and the conductor pattern of the driving element substrate (of the conductor pattern, the part to be connected to the protruding electrode of the recording element substrate is hereinafter referred to only as the connecting part) to be connected to each other comprise the same kind of pure metal, the layer to be formed by metallization develops to acquire the same kind of crystalline structure of the protruding electrode of the recording element substrate or the conductor pattern of the driving element substrate. As the method of metallization, for example, after the bump-like electrode of the recording element substrate is brought into contact with the connecting part of the driving element substrate corresponding to the above-mentioned protruding electrode, the contacting parts may be heated to an appropriate temperature. In this case, diffusion of atoms, etc. occurs in the vicinity of the contacting parts by heating, and the diffusion parts are metallized to form a metal layer.

When the projecting electrode of the recording element substrate and the connecting part of the driving element substrate to be connected to each other comprise different kinds of pure metals, the connecting layer to be formed becomes an alloy of the two metals. As the method of alloy formation, similarly to that described above, for example, after the projecting electrode of the recording element substrate is brought into contact with the connecting part of the driving element substrate corresponding to the above-mentioned projecting electrode, the contacted parts are heated to an appropriate temperature. In this case, diffusion of atoms, etc. occurs in the vicinity of the contacted parts by heating, whereby an alloy layer comprising a solid solution or an intermetallic phase is formed in the vicinity of the contacted parts.

The heating temperature may preferably be set at 200-350°C when, for example, the connecting part (the protruding electrode) of the recording element substrate is formed of Au and the connecting part of the driving element substrate is formed of Al.

If one of the projecting electrode of the recording element substrate and the connecting part of the driving element substrate to be connected to each other comprises a pure metal and the other comprises an alloy, or if both comprise the same kind of alloy or different kinds of alloys, the connecting interface contains an aluminum alloy.

Regarding mutually projecting electrodes of the recording element substrate, the case where the respective projecting electrodes comprise the same kind of metal or alloy, the case where the respective electrodes comprise different kinds of metals or alloys, and other cases may be included, but in any case, the above metallization or alloying described above is effected. On the other hand, the same is the case with the connecting part of the driving element substrate.

The protruding electrode of the recording element substrate or the connecting part of the driving element substrate may be a metal or an alloy at the contacted parts of the both, and they may also be in the state of, for example, a metal formed with an inorganic material such as glass or a metal formed with an organic material such as resin, etc.

A galvanized layer comprising a metal that is easily formed into an alloy or an alloy may also be provided on the surface to be joined.

As the heating method, in addition to the method of, for example, pressure adhesion under heat, etc., the internal heating methods such as the sonic heating method, the RF induction heating method, the RF dielectric heating method, the microwave heating method, etc. or other external heating methods may be used, and the above heating methods may also be used in combination. In each of the heating methods, the bonding parts of the driving element substrates are directly or indirectly heated to effect bonding.

(2) Joining by methods other than metallization and/or alloying:

To effect bonding by methods other than the above metallization or alloying, for example, bonding can be effected by pressing the bonding part of the driving element substrate against the protruding electrode of the recording element substrate by means of an appropriate means.

As other bonding methods, the bonding methods using an adhesive, etc. may be included, that is, the methods are available wherein bonding is effected by adhering the driving element substrate to the protruding electrode of the recording element substrate at least at a part excluding the driving element substrate.

Regarding the bonding between the recording element and the driving element substrate, the bonding should preferably be effected freely detachably.

(Respective units)

The recording element driving unit in the present invention is a unit that drives the recording elements formed in the recording element assembly in response to the image signals input from the outside. The recording element driving unit comprises the above-mentioned driving element substrate and the above recording element substrate (the recording element assembly).

The ink jet unit has a liquid passage provided with a discharge port for discharging ink developed on the recording element substrate (recording element assembly) that performs ink discharge by allowing the energy of the recording element to act on ink. The shape, dimensions, etc. of the liquid passage may be any as desired.

The ink jet driving unit is a unit for discharging ink through the ejection port in accordance with the image signals input from the outside, and includes an ink jet unit and a driving element substrate.

(Inkjet recording device)

The ink jet recording apparatus in this invention is an apparatus which performs recording by discharging ink through a discharging port in response to image signals input from the outside and causing the ink to adhere to a recording paper. This ink jet recording apparatus has at least the above ink jet driving unit and means for supporting the ink jet driving unit. As the typical member of the ink jet recording apparatus, there are the so-called serial scanning type (printing is effected while the print head moves in a reciprocating manner in the transverse direction with respect to the paper) and the full line type (recording of a single main scanning line is effected simultaneously using a print head having a main scanning line width). Figs. 5 and 6 show an example of the main components of the ink jet recording apparatus of this invention, with Fig. 5 illustrating the serial scanning type and Fig. 6 illustrating the full-line type. In Fig. 5, 512 denotes the ink jet driving unit.

The present invention exhibits its effect particularly in a very long ink jet driving unit, and therefore it is preferable to adopt the full line type.

(Operating mode)

(1) In this invention, since a protruding electrode is provided at the connecting part of the recording element substrate (the recording element assembly), electrical coupling of high reliability can be effected by directly connecting the above-mentioned recording element substrate and driving element substrate.

As a result, it has become possible to allow the connecting portions of the recording element and the driving element substrate to be present at a high density, thereby enabling higher density.

In addition, miniaturization is possible even in a very long unit.

Because no part is required for electrical connection at all, it also becomes possible to reduce the thickness of the unit and its cost.

Furthermore, since the amount of metal elements used for the protruding electrode of the recording element substrate is small, even if an expensive metal part may be used, it becomes possible to reduce the cost.

Furthermore, by arranging the recording elements and the conductor patterns corresponding to the recording elements in a number one or more than the necessary number, or further by providing the driving elements or the conductor patterns of the driving element substrate in a number one or more than the necessary number, it becomes possible to achieve connection between the recording element substrate and the driver element substrate without performing precise adjustment or without performing adjustment with high precision, if at all.

Particularly, when the bubble ink jet system is used as the ink jet recording system, accurate adjustment can be made with difficulty because higher density wiring is required. However, according to the present invention, such accurate adjustment can be carried out with utmost ease even in the case of such high density wiring.

Furthermore, in this invention, since the recording element substrate and the driving element substrate can be freely detachably bonded to each other, the driving element substrate can be easily separated and thus also replaced without difficulty.

(2) In the present invention, without forming a common electrode on the recording element unit, respective individual conductor patterns are formed, connecting parts are also formed on these conductor patterns, and further, a conductor pattern which becomes the common electrode on the side of the driving element substrate is formed with a higher degree of freedom in design, and the connecting part of the conductor pattern on the side of the recording element assembly is connected to the common electrode. With such a configuration, further miniaturization of the recording element assembly or the recording element driving unit can be achieved.

Since large currents flow through the common electrode, a dimension to a certain extent (thickness and width) is to be kept small to suppress resistance, and because the dimension of the common electrode also becomes larger when the number of recording elements increases, the Dimension of the common electrode in the recording element assembly with a very long and high-density wiring is not negligible. However, by making a design to form a common electrode on the driving element substrate side with higher design freedom and by making the connection part of the common electrode connected to the connection part on the recording element assembly side, it becomes possible to greatly miniaturize the recording element assembly as well as the recording element driving unit, the ink jet unit, the ink jet driving unit and the ink jet apparatus by using them.

In particular, such a configuration is very effective when the ink jet is a bubble ink jet because higher density wiring is required.

When the prior art connection method such as wire bonding is used, it has been substantially impossible to form a conductor pattern which becomes the common electrode on the side of the driving element substrate and to electrically connect the individual conductor patterns formed on the recording element substrate to the conductor pattern of the common electrode. Because the reliability of the connection part is inferior to that in the case of this invention, if the number of connection parts is excessively increased, there is a problem that the reliability of the unit as a whole is lowered, or there is a problem that the recording element driving unit, etc. are disadvantageously increased if the number of connection parts is more. In contrast, in the present invention, since a connection part having a protrudingly formed electrode is provided, even in the case where a conductor pattern which becomes the common electrode is provided on the side of the driving element substrate, no problems such that the reliability of connection between the above individual conductor patterns and the conductor pattern of the common electrode as a whole, or that the recording element driving unit, etc. are increased in size.

(3) In the present invention, when the protruding electrode of the connecting part of the recording element assembly is formed using conductor patterns of the recording element assembly, in the steps of manufacturing the above protruding electrode, it is not necessary to form the intermediate conductive layer to be the electrode, which is generally used in the electroplating method. Therefore, the manufacturing steps can be simplified, and the material for forming the electroplated intermediate conductive layer becomes unnecessary, whereby the material cost can be reduced. In particular, in the prior art method, for a very long recording element substrate (a very long recording element assembly), a large amount of materials for forming the electroplated intermediate conductive layer is necessary, and therefore the present invention is very effective.

Also, when electroplating is carried out using the conductor structure as the electrode, a protruding electrode of a convex cross-sectional shape can be formed at its free end, and therefore the contact resistance during pressure contact can be made lower. When an electroplated interconductive layer is used as the electrode, the cross-sectional shape of the free end of the protruding electrode becomes concave. Even though the cross-sectional shape of the free end of the protruding electrode may be concave, the contact resistance during pressure contact is practically within a sufficiently allowable range. However, according to the study of the inventors of this invention, the contact resistance can be made further smaller if the shape is convex rather than concave.

In other words, electroplating using the conductor pattern as the electrode is highly desirable because a recording element substrate (a recording element assembly) capable of ensuring electrical connection with a smaller contact resistance than in the case of forming an electrode by forming an electroplated interconductive layer can be obtained at a lower cost than in the case of forming an electrode by forming an electroplated interconductive layer.

(4) In the present invention, by providing an insulating layer or an insulating film newly on the protective layer of the prior art recording element substrate, a protruding electrode having a long root length can be configured as the protruding electrode forming the connecting part of the recording element substrate, whereby a deviation in the position of the free end of the above protruding electrode caused by a warpage or unevenness of the surface of said recording element substrate during the press-contact of the connecting part of said recording element substrate with the connecting part of the drive element substrate can be absorbed to further increase the reliability of the electrical connection between the recording element substrate and the drive element substrate.

The reason for this is described in detail below.

The recording element and driving element substrates should most desirably be a completely flat plate without any warpage or unevenness, because then bonding can be easily effected and therefore reliability in electrical connection can be obtained without difficulty.

However, electric circuit boards are generally not flat boards, but warp or unevenness is more or less present. Also, warp may sometimes be caused by heat generation during operation. If a substrate having large warp or unevenness is used, there is a fear that faulty connection may occur at the electrical connection between the recording element substrate and the driving element substrate. In order to prevent faulty connection, it is necessary to make the connection stable or to use a substrate without warp or unevenness (or which is difficult to be curved), but such a method involves the problem of challenging increased costs.

The present invention improves the reliability in electrical connection to a greater extent than the prior art, and the influence from warpage and unevenness is much smaller as compared with the prior art. Accordingly, no such problem generally arises. However, although the influence from warpage becomes larger as the recording element assembly is longer in the longitudinal direction, the recording element assembly of this invention can exhibit its advantage as the length in the longitudinal direction is longer, and therefore, in view of the possibility of a demand for enlargement of the recording paper size in the future, it may be considered necessary to have the technology to eliminate the influence from warpage of the substrate, etc.

The inventors have intensively studied to solve this problem and consequently got the idea that the above problem can be solved by forming a protruding electrode through a layer having a large film thickness to absorb the warpage and unevenness of the substrate.

For this purpose, the inventors first tried to improve defective connection by making the thickness of the protective layer such as an oxidation-resistant layer, an ink-resistant layer, etc. provided in the prior art recording element substrate larger. However, a sufficient effect could not be obtained according to this technique. Accordingly, the inventors made investigations into this reason and consequently obtained the following findings.

(1) According to the inventors' investigation, a warp or unevenness of the recording element substrate is generally about several tens of microns to several hundred microns. Also, according to the inventors' investigation, in order to sufficiently accommodate such a warp or unevenness, a layer having at least a film thickness comparable to that warp or unevenness is required. However, it is inherently impossible to form a protective layer such as an oxidation-resistant layer to a film thickness of several hundred microns. For example, since the oxidation-resistant layer is a protective film of a heat-generating element, if the film thickness is made larger, the heat transfer performance is lowered, and therefore it is necessary to make the applied voltage larger; however, since the resistance performance of the heat-generating resistance material is limited, it is difficult to make the thickness a certain level or higher.

(2) Also, the inventors have found that it is not preferable to accommodate a warpage or unevenness by making the thickness of the protective layer such as the oxidation-resistant layer or the ink-resistant layer, etc., larger, because the layer for accommodating the warpage or unevenness is also different in the characteristic required from the oxidation-resistant layer or the back-resistant layer. An oxidation-resistant layer is required to have an oxygen barrier layer, thermal conductivity, heat resistance and no defect, etc., and for this purpose, it may preferably be formed of an inorganic material. On the other hand, an ink-resistant layer is required to have no defect, ink resistance (excellent adhesiveness to ink or difficult deterioration in ink), heat resistance, etc. In contrast, as a result of the inventors' investigations, the warpage or unevenness absorbing layer is required to have excellent insulating characteristics, flexibility, plating resistance, adhesiveness, etc., as well as a small thermal expansion coefficient and the ability to form a thicker film. According to the inventors' investigations, it is extremely difficult to form a layer having both the characteristics required for the warpage or unevenness absorbing layer and the characteristics required for an oxidation-resistant or ink-resistant layer.

For the above reasons, the inventors thought that the protective layer of the prior art and the layer for absorbing a warp or unevenness should be formed separately, and they came to know that it is preferable to provide a new insulating layer for absorbing a warp or unevenness.

Also, the inventors made further investigations and obtained the idea that the influence from warpage or unevenness of the substrate can be avoided by forming a new film by applying an insulating film on the protective film and forming a protruding electrode with a long foot length using it. Furthermore, the inventors made investigations on the method of performing the step of applying an insulating film at a low cost and, as a result, found that no precise adjustment of an insulating film is substantially required when a large number of through holes are formed at and around the connecting part.

example 1

As an example of this invention, the recording element assembly having substantially the same configuration as in Figs. 19(a) and 19(b) and having a protruding electrode for the individual electrodes 1504 will be described.

The manufacturing steps of the recording element assembly according to this example are explained below.

Figs. 2A-2F are schematic diagrams for explaining an example of the manufacturing steps of the recording element assembly according to the present invention.

(1) First, a HfB₂ layer 202 of 350 x 10⁻¹⁰ m (350 Å), a Ti layer (which is omitted in Fig. 2A) of 50 x 10⁻¹⁰ m (50 Å), and an Al layer 203 of 6000 x 10⁻¹⁰ m (6000 Å) are formed on the entire substrate surface 201 by the sputtering technique (Fig. 2A).

(2) To form the wiring pattern, a topcoat is applied on the film formed in (1), then patterned by exposure and development using the photolithography technique, and further, the Al/Ti/HfB2 is etched to form a wiring. The topcoat is peeled off after etching.

(3) On the Al/Ti/HfB2 circuit electrode substrate formed in the above (2), a resist is patterned using the same photolithography technique as in (2), and further, Al is partially removed by etching to form a heater part. The resist is peeled off after etching (Fig. 2B).

(4) A SiO₂ layer 204 of 9000 × 10⁻¹⁰ m (9000 Å) as the heat and oxidation resistant and intermediate insulating layer, a Ta₂O₅ layer (omitted in Fig. 2C A SiO2-Ta adhesion layer 205 of 500 x 10⁻¹⁰ m (500 Å) and a Ta layer 205 of 5000 x 10⁻¹⁰ m (5000 Å) as the cavitation resistant layer are formed on the entire substrate surface by continuous sputtering.

(5) According to the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to form a Ta pattern. The top resist is peeled off after etching (Fig. 2C).

(6) Following the same method as in (2) above, a topcoat was patterned and SiO2 patterning was achieved by partially removing SiO2 by etching. The topcoat was stripped after etching (Fig. 2D).

(7) An organic insulating film 206 of 2.5 µm as the ink-resistant layer and the intermediate insulating layer is coated, and a pattern is formed by the same method as in (2), or a pattern is formed by coating a photosensitive organic insulating film of 2.5 µm, followed by exposure and development (Fig. 2E).

(8) As the electroplated intermediate conductive layer (omitted in Fig. 2F), a Gu layer of 3000 x 10⁻¹⁰ m (3000 Å) and a Ti layer of 500 x 10⁻¹⁰ m (500 Å) were formed on the entire substrate surface.

(9) A top coat to form a plating structure is applied, exposed and developed.

(10) According to the electroplating, a conductive raised part 207a, 207b is formed with, for example, Cu, Ni, Au, Cr, Rh, etc. The film thickness is made to be several microns to several tens of microns. Finally, the top coat is peeled off (Fig. 2F).

A typical case of the manufacturing steps of this example has been described above.

In this example, the raised part 207a prepared in (10) becomes the prepared connection part. Fig. 3 shows an enlarged view of this part. By connecting this part to the connection part of another substrate as shown in Fig. 1, electrical coupling with another conductor substrate (e.g., a driving element substrate) can be established.

Thus, according to this example, only by connecting to another circuit substrate, e.g., a drive element substrate, etc., electrical coupling of the substrates can be effected with high reliability.

Example 2

In the above Example 1, the recording element assembly according to a typical case of this invention was described. Examples of the recording element driving unit, the ink jet unit, the ink jet driving unit and the ink jet apparatus according to this invention are described here, respectively.

The recording element driving unit according to this example is formed by bonding a driving element substrate to the recording element assembly manufactured as described in Example 1 above, and takes a configuration as shown in Fig. 1. In this figure, 104 is a recording element substrate (i.e., the recording element assembly according to Example 1), 105 is a driving element substrate, and 106 is a driving element.

The ink jet unit and the ink jet driving unit according to this example are described below. The ink jet unit according to this example has a liquid channel, which communicates with an ejection port formed on the recording element assembly manufactured in the above example, and the ink jet driving unit has a driving element substrate connected to the ink jet unit. Fig. 4 shows the typical case of the ink jet unit and the ink jet driving unit according to this example. In Fig. 4, 408 is the ink jet unit according to this invention, 405 is a driving element substrate, and 406 is a driving element.

Finally, the ink jet recording apparatus according to this example will be described. Fig. 5 is a schematic diagram showing a typical case of the ink jet recording apparatus according to this invention. In Fig. 5, a recording sheet 503 is fed by a paper feed roller (not shown) to sheet feed rollers 501 and 502 which are arranged at a predetermined vertical distance from each other, and the sheet is discharged in the direction of an arrow A.

Also, a carriage 510 is provided which moves in front of the above-mentioned recording sheet 503 along the guide rod 513. As mentioned, the ink jet driving unit 512 is mounted on the carriage 510.

The aforementioned carriage 510 is driven in a reciprocating manner by the belt drive mechanism 501 by means of a carriage drive motor (not shown).

During recording synchronized with the operation of the carriage 510 in the width direction of the recording sheet 503, recording is effected while ink is ejected as droplets from the ejection port of the above-mentioned ink jet driving unit toward the recording sheet 503. In the ink jet driving unit, an ejection port directed toward the side of the recording sheet 503 is formed, and ink droplets fly in accordance with the signals from the driver element out of the ejection opening.

Fig. 6 shows another example of the ink jet recording apparatus of this invention. The difference between this example and the above ink jet recording apparatus is that the ink jet driving unit 512 of this example has recording elements corresponding to the recording width of the recording paper. Accordingly, reciprocating operation of the carriage is not necessary, and therefore the mechanism can be simple, as well as high-speed recording is possible. Since a very long unit is used in this example, the effect of putting this invention into practice is enormous.

Example 3

As a third example of this invention, the case will be described where no common electrode is provided on the recording element assembly.

Fig. 7 is a schematic sectional view showing the recording element assembly according to this example. In Fig. 7, 701 is a support member, 702 is an HfB₂ layer as the heat-generating resistance layer, 703 and 704 are single electrodes made of Al, 705a and 705b are conductor patterns made of Al, 706 is an SiO₂ layer as the oxidation-resistant and insulating layer, 707 is a photosensitive polyimide layer as the ink-resistant and insulating layer, and 708 is a Ta layer as the cavitation-resistant layer.

A typical case of the manufacturing steps of the recording element assembly according to this example will be described below with reference to Figs. 8A-8G.

(1) First, the HfB₂ layer 702 (thickness 350 × 10⁻¹⁰ in (350 Å)), the Ti layer (omitted in Fig. 8A) (thickness 50 · 10⁻¹⁰ m (50 Å)) and the Al layer 705 (thickness 6000 · 10⁻¹⁰ m (6000 Å)) were formed on the entire substrate surface by the sputtering technique (Fig. 8A).

(2) To form the conductor pattern, a topcoat is applied to the film formed in (1), then the film is patterned by exposure and development using the photolithography technique, and further the Al/Ti/HfB2 layers are etched to form conductors. The topcoat is removed after etching.

(3) On the Al/Ti/HfB2 circuit electrode substrate formed in (2), a resist is patterned using the same photolithography technique as in (2), and further, Al is partially removed by etching to form a heater part. After etching, the resist is peeled off (Fig. 8B).

(4) The SiO2 layer 706 (thickness 9000 x 10-10 m (9000 Å)) as the heat and oxidation resistant resistive layer and the intermediate insulating layer, the Ta2O5 layer (thickness 500 x 10-10 m (500 Å)) (omitted in Fig. 8C) as the SiO2-Ta adhesion layer and the Ta layer 708 (thickness 5000 x 10-10 m (5000 Å)) as the cavitation resistant layer are formed on the entire substrate surface by continuous sputtering.

(5) Following the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to form a Ta pattern. The top resist is removed after etching (Fig. 8C).

(6) A topcoat was patterned by the same method as in (2) above, and a SiO2 structure is prepared by partially removing SiO2 by etching. The topcoat is removed after etching (Fig. 8D).

(7) An organic insulating film (film thickness 2.5 µm) as the ink-resistant and intermediate insulating layers is coated, and a pattern is formed according to the same method as in (2), or a pattern is formed by coating a photosensitive organic insulating film 707 (film thickness 2.5 µm), followed by exposure and development (Fig. 8E).

(8) As the electroplated interconductive layer 709, a Cu layer (thickness 3000 × 10⁻¹⁰ m (3000 Å)) and a Ti layer (thickness 500 × 10⁻¹⁰ m (500 Å)) were formed on the entire substrate surface.

(9) A topcoat to form a plating pattern was applied, exposed and developed.

(10) According to the electroplating, a conductive protruding electrode 710 is formed with, for example, Cu, Ni, Au, Cr, Rh, etc., or a combination of these, and the resist is removed.

(11) Finally, the electroplated interconductive layer is removed by etching (Fig. 8G). In this example, first, Cu was removed by immersion in 1 g/cm3 of ammonium persulfate for about 60 sec, and then Ti was removed by immersion in a 2% aqueous hydrofluoric acid solution for about 10 sec.

A description has been given above regarding a typical case of the manufacturing steps of the recording element assembly of this example.

By bonding a driving element substrate to such a recording element assembly in a similar manner as described in Example 2, the recording element driving unit could be miniaturized.

Also, by forming a liquid passage on the recording element assembly of this example, which communicates with an ejection port for ejecting inks, the ink jet unit could be miniaturized.

By electrically connecting a driving element unit to the ink jet unit, an ink jet driving unit could be miniaturized. Furthermore, by manufacturing an ink jet recording apparatus using the ink jet driving unit, the ink jet recording apparatus could be miniaturized. Moreover, when a recording test was conducted for the ink jet recording apparatus, stable recording could be accomplished.

Example 4

Next, as a fourth typical case of this invention, that of forming a protruding electrode according to the electroplating method using the conductor pattern as the electrode will be described.

9A and 9B are schematic sectional views showing the recording element assembly according to this example, in which Fig. 9A shows the recording element assembly without a common electrode and Fig. 9B shows the recording element assembly with a common electrode. In Figs. 9A and 9B, 901 is a support member, 902 is an HfB2 layer as the heat-generating resistance layer, 903 is a common electrode made of Cu, 904 is a single electrode made of Cu, 905a and 905b are conductor patterns made of Cu, 906 is an SiO2 layer as the oxidation-resistant and the insulating layer, 907 is a photosensitive polyimide layer as the ink-resistant and the insulating layer, and 908 is a Ta layer as the cavitation-resistant layer.

As shown in Figs. 9A and 9B, in this example, the cross-sectional shape of the free end of the protruding electrode is convex.

Next, a typical case of the manufacturing steps of the recording element assembly according to this example will be described with reference to Fig. 10, considering the case of a common electrode.

(1) First, an HfB2 layer 902 (thickness 350 x 10-10 m (350 Å)), a Ti layer (thickness 50 x 10-10 m (50 Å)) (omitted in Fig. 10), and a Cu layer (thickness 6000 x 10-10 m (6000 Å)) are formed on the entire substrate surface 901 according to the sputtering technique (Fig. 10A).

(2) Using the photolithography technique, a topcoat is applied to the film formed in (1), the film is subjected to patterning by exposure and development, and further, the Cu/Ti/HfB₂ layers are each etched to form a conductor pattern. After etching, the topcoat is removed.

(3) On the circuit electrode substrate made of the Cu/Ti/HfB2 layer formed in (2), a resist is patterned using the same photolithography technique as in (2), and further Cu is partially removed by etching to form a heater part. After etching, the resist is peeled off (Fig. 10B).

(4) A SiO2 layer 906 (thickness 9000 x 10-10 m (9000 Å)) as the heat and oxidation resistant layer and the intermediate insulating layer, a Ta2O5 layer (thickness 500 x 10-10 m (500 Å)) (omitted in Fig. 10C) as the SiO2-Ta adhesion layer and a Ta layer (thickness 5000 x 10-10 m (5000 Å)) as the cavitation resistant layer are formed on the entire substrate surface by continuous sputtering.

(5) Following the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to produce a Ta pattern. The top resist is removed after etching (Fig. 10C).

(6) Following the same method as in (2) above, a topcoat was patterned and a SiO2 pattern was prepared by partially removing SiO2 by etching. The topcoat is peeled off after etching (Fig. 10D).

(7) An organic insulating film (film thickness 2.5 µm) as the ink-resistant and intermediate insulating layers is coated, and a pattern is formed according to the same method as in (2), or a pattern is formed by coating a photosensitive organic insulating film 907 (film thickness 2.5 µm), followed by exposure and development (Fig. 10E).

(8) Finally, according to the electroplating method, for example, a conductive protruding electrode 904 is formed with, for example, Cu, Ni, Au, Cr, Rh, etc. or a combination of these.

Here, if the recording element assembly has a common electrode, the common electrode 903 can also be formed simultaneously with the projecting electrode 904. In this case, a plating coating is initially developed per individual section on the common electrode part, but the plating must be continued until the plating between the adjacent sections is sufficiently bonded. On the other hand, the individual electrodes must be manufactured so that no contact can occur between the adjacent sections (Fig. 10F).

A typical case of the manufacturing steps of the recording element of this example has been described above.

Thus, the recording element assembly of this example does not require any of the steps of forming an electroplated interconductive layer on the entire substrate surface, patterning by applying a resist, and removing the resist by etching, etc., which are required in the prior art. technology was required in its production and therefore it could be manufactured at very low cost.

Since a protruding electrode with a convex cross-sectional shape could be formed at the free end, it also became possible to further lower the contact resistance at the connecting part.

By bonding a driving element substrate to such a recording element assembly as shown in Fig. 1, a recording element driving unit having a low contact resistance at the bonding portion could be manufactured at a low cost.

By forming a liquid passage communicating with an ejection port in the recording element assembly of this example to eject ink, an ink jet unit could also be manufactured at a low cost.

By electrically connecting a driving element unit to the inkjet unit, an inkjet driving unit with low contact resistance at the connecting part could be manufactured at a low cost.

Furthermore, when an ink jet recording apparatus was manufactured at a low cost with low contact resistance at the connecting part by using the ink jet driving unit and a recording test for the ink jet recording apparatus was conducted, stable recording could be accomplished.

Example 5

In the following, as a fifth example of the present invention, the case with a protruding electrode of a single electrode formed long in the substrate thickness direction, by newly providing an insulating layer on the surface of the recording element assembly.

Fig. 11 is a schematic sectional view showing the recording element assembly according to this example. In Fig. 11, 1101 is a support member, 1102 is an HfB₂ layer as the heat generating resistance layer, 1103 is a common electrode made of Al, 1104 is a single electrode made of Al, 1105 is a conductor pattern made of Al, 1106 is an SiO₂ layer as the oxidation resistant and the insulating layer, 1107 is a photosensitive polyimide layer as the ink resistant and the insulating layer, 1108 is a Ta layer as the cavitation resistant layer, and 1109 is an insulating layer for forming the protruding electrode of a single electrode long in the substrate thickness direction.

Since the protruding electrode of the single electrode is made long in the substrate thickness direction by thus providing a new insulating layer in this invention, the influence from warpage of the substrate can be eliminated.

A typical case of the manufacturing steps of the recording element assembly according to this example will be described below with reference to Figs. 12A-12G.

(1) First, an HfB2 layer 1102 (thickness 350 x 10-10 m (350 Å)), a Ti layer (thickness 50 x 10-10 m (50 Å)) (omitted in Fig. 12A), and an Al layer (thickness 6000 x 10-10 m (6000 Å)) are formed on the entire substrate surface by the sputtering technique (Fig. 12A).

(2) To form the conductor structure, a topcoat is applied to the film formed in (1) using the photolithography technique, which is then subjected to structuring by exposure and development, and further the Al layer/Ti layer/HfB₂ layer is etched to form a wiring. The top coat is removed after etching.

(3) On the Al/Ti/HfB2 circuit electrode substrate formed after the above step (2), a resist is patterned using the same photolithography technique as in (2), and further Al is partially removed by etching to form a heater part. After etching, the resist is peeled off (Fig. 12B).

(4) A SiO2 layer 1106 (thickness 9000 x 10-10 m (9000 Å)) as the heat and oxidation resistant layer and the intermediate insulating layer, a Ta2O5 layer (thickness 500 x 10-10 m (500 Å)) (omitted in Fig. 12C) as the SiO2-Ta adhesion layer, and a Ta layer 1108 (thickness 5000 x 10-10 m (5000 Å)) as the cavitation resistant layer are formed by continuous sputtering on the entire substrate surface.

(5) Following the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to produce a Ta pattern. The top resist is removed after etching (Fig. 12C).

(6) Following the same method as in (2) above, a top resist is patterned and a SiO2 pattern is prepared by partially removing SiO2 by etching. The top resist is removed after etching (Fig. 12D).

(7) An organic insulating film 1107 (film thickness 2.5 µm) as the ink-resistant and intermediate insulating layer is coated, and a pattern is formed by the same method as in (2), or a pattern is formed by coating a photosensitive organic insulating film (film thickness 2.5 µm), followed by exposure and development (Fig. 12E).

(8) An insulating layer 1109 is formed by deposition to form a pattern (several to several hundred µm). The layer thickness may be as thick as possible within the range capable of forming a pattern. Since this layer is unnecessary for the heater part, it is removed after the layer formation.

(9) A Cu layer (thickness 3000 x 10⁻¹⁰ m (3000 Å)) and a Ti layer (thickness 500 x 10⁻¹⁰ m (500 Å)) as the electroplated interconductive layer (omitted in Fig. 12F) are formed on the entire surface of the substrate.

(10) A topcoat to form a plating structure is applied, exposed and developed.

(11) Finally, after the electroplating process, a conductive protruding electrode 1104 is formed with, for example, Cu, Ni, Au, Cr, Rh, etc. or a combination of these, and the topcoat is peeled off (Fig. 12G).

A typical case of the manufacturing steps of the recording element of this example has been described above.

By bonding a driving element substrate to such a recording element substrate as shown in Example 2, a recording element driving unit having excellent electrical connection reliability at low cost could be manufactured.

By forming a liquid passage connected to an ejection port for ejecting ink in the recording element assembly of this example, an ink jet unit could also be manufactured.

An inkjet driving unit was manufactured by electrically connecting a driving element unit to the inkjet unit.

Furthermore, when an inkjet recording apparatus was manufactured using the inkjet driving unit and a recording test was conducted for the inkjet recording apparatus, stable recording could be achieved.

Example 6

Next, as a sixth example of the present invention, the case of a projecting electrode of a single electrode formed long in the substrate thickness direction by newly providing an insulating film on the surface of the recording element assembly will be described.

Fig. 13 is a schematic sectional view showing a recording element assembly according to this example. In Fig. 13, 1301 is a support member, 1302 is an HfB₂ layer as the heat generating resistance layer, 1303 is a common electrode made of Al, 1304 is a single electrode made of Al, 1305 is a conductor pattern made of Al, 1306 is an SiO₂ layer as the oxidation resistant and the insulating layer, 1307 is a photosensitive polyimide layer as the ink resistant and the insulating layer, 1308 is a Ta layer as the cavitation resistant layer, and 1309 is an insulating film for forming the protruding electrode of a single electrode long in the substrate thickness direction.

Since the protruding electrode of the single electrode is formed long in the substrate thickness direction by thus providing a new insulating layer in this invention, the influence from warpage of the substrate can be eliminated.

A typical case of the manufacturing steps of the recording element assembly according to this example will be described below with reference to Figs. 14A-14G.

(1) First, an HfB₂ layer 1302 (thickness 350 x 10⁻¹⁰ m (350 Å)), a Ti layer (thickness 50 x 10⁻¹⁰ m (50 Å)) (omitted in Fig. 14A), and an Al layer 1305 (thickness 6000 x 10⁻¹⁰ m (6000 Å)) are formed on the entire substrate surface 1301 by the sputtering method (Fig. 14A).

(2) To form the wiring pattern, a topcoat is applied to the film formed in (1) using the photolithography technique, the film is then subjected to patterning by exposure and development, and an Al layer/Ti layer/HfB2 layer is etched to form a wiring. The topcoat is removed after etching.

(3) On the Al/Ti/HfB2 circuit electrode substrate formed in the above step (2), a resist is patterned using the same photolithography technique as in (2), and further Al is partially removed by etching to form a heater part. The resist is peeled off after etching (Fig. 14B).

(4) A SiO2 layer 1306 (thickness 9000 x 10-10 m (9000 Å)) as the oxidation-resistant layer and the intermediate insulating layer, a Ta2O5 layer (thickness 500 x 10-10 m (500 Å)) as the SiO2-Ta adhesion layer, and a Ta layer 1308 (thickness 5000 x 10-10 m (5000 Å)) as the cavitation-resistant layer are formed by continuous sputtering on the entire substrate surface.

(5) Following the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to form a Ta pattern. The top resist is peeled off after etching (Fig. 14C).

(6) A topcoat was patterned by the same method as in (2) above, and SiO2 patterning is achieved by partially removing SiO2 by etching. The topcoat is removed after etching (Fig. 14D).

(7) An organic insulating film (film thickness 2.5 µm) as the ink-resistant layer and the intermediate insulating layer is applied, and a pattern is formed by the same method as in (2), or a pattern is formed by applying a photosensitive organic insulating film 1307 (film thickness 2.5 µm), followed by exposure and development (Fig. 14E).

(8) On the surface of the organic insulating film formed in the above step (2), an insulating film 1309 having through holes is deposited.

(9) On the entire surface of the substrate, a Cu layer (thickness 3000 × 10⁻¹⁰ m (3000 Å)) and a Ti layer (thickness 500 × 10⁻¹⁰ m (500 Å)) are formed as the electroplated intermediate conductive layer.

(10) A top coat to form a plating structure is applied, exposed and developed.

(11) Finally, an electrode 1304 (a protruding electrode) is formed with, for example, Cu, Ni, Au, Cr, Rh, etc. or a combination of these by the electroplating method, and the topcoat is peeled off (Fig. 14G).

A typical case of the manufacturing steps of the recording element of this example has been described above.

By connecting a driving element substrate to such a recording element assembly as shown in Fig. 2, a recording element driving unit having excellent reliability of electrical connection at the connecting part could be manufactured at a low cost.

Also, by forming a liquid passage connected to a discharge port for discharging ink on the recording element assembly of this example, an ink-jet assembly was manufactured.

By electrically connecting a drive element unit to an inkjet unit, an inkjet drive unit with excellent reliability in electrical connection was produced.

When an inkjet recording apparatus was manufactured using the inkjet driving unit and a recording test was conducted for the inkjet recording apparatus, stable recording could be achieved.

Example 7

As an example of this invention, the recording element assembly having substantially the same structure as shown in Figs. 19(a) and 19(b) which has a protruding electrode, that is, an electrically conductive protruding member as the single electrode 1504 will be described.

First, a typical case of the manufacturing steps of the recording element assembly according to this invention will be explained below.

Figs. 15A-15F are schematic diagrams for explaining the manufacturing steps of the recording element assembly according to this invention.

(1) First, a HfB2 layer 1402 of 350 x 10-10 m (350 Å)), a Ti layer 1402 of 50 x 10-10 m (50 Å) (omitted in Fig. 15A), and an Al layer 1405 of 6000 x 10-10 m (6000 Å) are formed on the entire substrate surface 1401 by the sputtering method (Fig. 15A).

(2) To form the conductor structure, a topcoat is applied to the film formed in (1) using the photolithography technique, which is then subjected to patterning by exposure and development, and furthermore, the Al/Ti/HfB2 layers are etched to form a wiring. The topcoat is removed after etching.

(3) On the Al/Ti/HfB2 circuit electrode substrate formed in (2) above, a resist is patterned using the same photolithography technique as in (2), and further Al is partially removed by etching to form a heater part. After etching, the resist is peeled off (Fig. 15B).

(4) A 9000 × 10-10 m (9000 Å) SiO2 layer 1406 as the heat and oxidation resistant resistive layer and the intermediate insulating layer, a 500 × 10-10 m (500 Å) Ta2O5 layer (omitted in Fig. 15C) as the SiO2-Ta adhesion layer, and a 5000 × 10-10 m (5000 Å) Ta layer 1408 as the cavitation resistant layer are formed by continuous sputtering on the entire substrate surface.

(5) Following the same method as in (2) above, a top resist is patterned and Ta is partially removed by etching to form a Ta pattern. The top resist is peeled off after etching (Fig. 15C).

(6) According to the same method as in (2) above, a top resist is patterned and SiO2 patterning is accomplished by partially removing SiO2 by etching. The top resist is removed after etching (Fig. 15D).

(7) An organic insulating film of 2.5 µm as the ink-resistant layer and the intermediate insulating layer is deposited, and a pattern is formed by the same method as in (2), or a pattern is formed by depositing a photosensitive organic insulating film 1407 of 2.5 µm, followed by exposure and development (Fig. 15E).

(8) As the electroplated intermediate conductive layer (omitted in Fig. 15E), a Cu layer with 3000 · 10⁻¹⁰ m (3000 Å) and a Ti layer of 500 x 10⁻¹⁰ m (500 Å) were formed on the entire substrate surface.

(9) A top coat to form a plating structure is applied, exposed and developed.

(10) After the electroplating process, an electrically conductive raised part 1404 is formed with, for example, Cu, Ni, Au, Cr, Rh, etc. The film thickness is made to be several microns to several tens of microns. Finally, the topcoat is peeled off (Fig. 15F).

A typical case of the manufacturing steps of this example has been described.

In this example, the part that becomes the connecting part is the protruding part 1404. An enlarged view of this part is shown in Fig. 16. By connecting this part to the connecting part of another substrate, as shown in Fig. 1, an electrical connection is effected between the panels of the substrates.

Thus, according to the present invention, an electrical connection of high reliability can be made only by connecting two sheets of substrates.

Fig. 17 is a schematic perspective view showing an example of the head part of the ink jet unit and the ink jet driving unit according to this invention.

In Fig. 17, 61 is an ejection opening, 62 is an ink channel communicating with the ejection opening 61, and 63 is an ink chamber communicating with the ink channel 62. The liquid path in this example has the ink channel 62 and the ink chamber 63. In this example, the ink channel 62 and the ink chamber 63 are formed by bonding the recording element substrate 184 (for better understanding of the description, the length is drawn shorter), the wall-forming member 64 and the cover member 65 are bonded to each other. Furthermore, in this example, a heat generating part 67 is provided as the recording element associated with each ink channel 62 and electrodes (not shown in Fig. 17) are arranged on these heat generating parts 67. In Fig. 17, 66 designates an ink supply opening to the ink chamber 63.

Fig. 18 is a schematic external perspective view showing an example of the ink jet recording apparatus according to this invention. In Fig. 18, 1000 denotes the main body of the apparatus, 1100 the power source switch, and 1200 the operation panel.

The present invention brings about excellent effects particularly in the recording head and the recording apparatus of the bubble jet system among the ink jet recording systems.

As for their typical construction, those using the principle disclosed in U.S. Patent Nos. 4,723,129 and 4,740,796 are preferred, for example. Although this system is applicable to both the signal-dependent type and the continuous type, it is particularly effective in the case of the signal-dependent type because by applying at least one drive signal which causes a rapid temperature rise above a nucleation boiling point to the electrically heated transducer corresponding to the layer or liquid channel where liquid (ink) is retained, heat is generated to cause film evaporation at the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) which correspond one by one to each of the drive signals. By ejecting the liquid (ink) through the orifice by means of growth and shrinking of the bubble, at least one droplet is generated. When the driving signal is made pulse-shaped, adequate growth and shrinking of the bubble can be more preferably effected to realize ejection of the liquid (ink) which is particularly excellent in response characteristics. As the driving signal in the form of a pulse, those described in U.S. Patent No. 4,463,359 and No. 4,345,262 are suitable. By applying the conditions disclosed in U.S. Patent No. 4,313,124 regarding the temperature rise rate of the above heat acting area, further excellent recording can be performed.

Regarding the design of the writing head, in addition to the combination of the ejection opening, the liquid channel and the electrically heated transducer (linear liquid channel or rectangular liquid channel)

the configuration using U.S. Patent No. 4,558,333 or No. 4,459,600 which disclose a configuration having a heating part in a bent portion is also included in this invention. Moreover, the present invention is also effective for such a configuration based on JP Unexamined Patent Publication No. 59-123670 which describes the configuration comprising a common slot as the ejection part of an electrically heated transducer for a plurality of electrically heated transducers, or JP Unexamined Patent Publication No. 59-138461 which discloses the configuration having an opening which absorbs a pressure wave of the heat energy corresponding to the ejection part.

Further, as the full-line type recording head having a length corresponding to the width of the maximum recording medium on which recording can be made by the recording apparatus, either a configuration satisfying this length or a configuration as an integrally formed according to a combination of a plurality of recording heads formed single recording head as disclosed in the above-mentioned documents can be used, and the present invention can exhibit the above-described effects more effectively.

Moreover, the present invention is also effective in the case of using a freely replaceable chip type recording head which enables electrical connection with the main body or supply of ink from the main body by mounting it in the main body, or in the case of using a cartridge type recording head which is provided integrally with the recording head itself.

Also, for further stabilizing the effects of the present invention, it is preferable to add a recovery means, a preliminary auxiliary means, etc. to the recording head provided for the embodiment of the recording apparatus of this invention. These may include, in particular, capping means, cleaning means, pressure or absorption means, preliminary heating means using electrically heated transducers, heating means separate from these, or the combination of these, and performing a preliminary ejection operation separately from recording is also effective for stable recording.

Furthermore, as the recording mode of the recording apparatus, not only the recording mode with only one main color such as black, etc., but a configuration that forms the recording head integrally or a plurality of colors can be adopted, and for an apparatus having at least one of complex colors, different colors, or a full color by color mixing, the present invention is extremely effective.

(1) As described above, according to the present invention, since electrical connection of the substrates can be effected only by connecting the recording element substrate to the driving element substrate, it becomes possible to allow the connecting parts of the recording element and the driving element substrate to be present at a high density, thereby offering the possibility of increasing the number of connecting parts of the driving element substrates and effecting higher densification. This also leads to miniaturization of even a very long unit.

Because no part is required for electrical connection, the unit can also be made thinner and at a lower cost.

Furthermore, since the amount of metal parts used for the raised part of the recording element is small, even if an expensive metal such as gold, etc., may be used, cost reduction is possible.

Also, because at least one extra element more than is necessary for the recording elements and the conductor patterns corresponding to the recording elements can be provided, and further because at least one extra element more than is necessary for the driver elements or the conductor patterns of the drive element substrate can be provided, connection without performing a precise adjustment or without requiring a high-precision adjustment, if at all, becomes possible.

Particularly, in the case where the ink jet is a bubble ink jet, accurate alignment can be performed with difficulty because higher density wiring is required, but according to this invention, accurate alignment can be performed with extreme ease even in the case of such high density wiring.

Furthermore, in this invention, the recording element substrate and the driving element substrate can be freely detachably connected, and the driving element substrate can be separated without difficulty and thus also easily replaced.

(2) According to the present invention, by providing a common electrode on the driving element substrate, further miniaturization of the recording element assembly as well as the recording element driving unit, the ink jet unit, the ink jet driving unit and the ink jet recording apparatus is enabled by using them.

Particularly, when the bubble ink jet system is applied as the ink jet recording system, very high density wiring is required, and the present invention can achieve a particularly large effect in the case of this high density wiring.

(3) According to this invention, by forming protruding electrodes using the electroplating method on conductor patterns as electrodes, the recording element assembly as well as the recording element driving unit, the ink jet unit, the ink jet driving unit and the ink jet recording apparatus can be provided at low cost. Furthermore, a recording element driving unit, an ink jet driving unit and an ink jet recording apparatus having a low contact resistance at the connecting part of the recording element substrate and the driving element substrate can be provided.

(4) According to the present invention, since the influence of warp or unevenness of the substrate can be eliminated, electrical connection of high reliability can be effected even in a long unit easily and at low cost.

In particular, when the recording element unit or the ink jet unit is very long, a great effect can be obtained.

Claims (5)

1. A recording head assembly comprising at least two modules, namely a first module (104) containing at least one heat-generating resistor (202) and a second module (105) containing at least one driver circuit (106), characterized in that said first module (104) includes a substrate (201), a heat-generating resistor layer (202), a wiring layer (203) for supplying electrical signals to said resistor layer, and electrodes carried by said substrate and electrically connected to said wiring layer (203), said electrodes being raised from their respective surrounding surfaces so as to protrude from said wiring layer (203), said second module includes a driver element substrate with a driver circuit (106) and a driver circuit connected to said driver circuit Wiring layer, wherein said projecting electrodes of the first module (104) establish an electrical connection to the wiring layer of said second module (105), and that said modules are easily detachable from each other, whereby one or the other module is interchangeable. 2. An assembly according to claim 1, characterized in that said first module (104) includes a fluid passage communicating with an ejection opening for ejecting ink in response to energy generated by said recording element. 3. An ink jet recording apparatus comprising an assembly according to claim 1 or 2, characterized by a carriage member (510) capable of detachably supporting said assembly. 4. A method of manufacturing a recording head assembly according to claim 1 or 2, said method comprising the steps of: - forming a heat-generating resistance layer (202) and a wiring layer (203) on a substrate (201); and - forming electrodes (207a, 207b) on the wiring layer (203) by electroplating such that the electrodes are supported by the substrate, electrically connected to the wiring layer (203) and raised from their respective surrounding surface so as to protrude from the wiring layer (203). 5. A method according to claim 4, further comprising the step of forming an interconductive layer to create the electrodes prior to the step of forming the electrodes.