JP2831793B2 - Method of manufacturing ink jet recording head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ink jet recording head using a heating element for discharging ink.

2. Description of the Related Art In a recording head of this type, a large number of heating elements are formed on a semiconductor substrate of the head to achieve high-density recording, and a drive for driving the heating element as an electrothermal transducer. In many cases, a recording head is miniaturized in the form of an integrated circuit in which circuits are integrated on a semiconductor substrate of a head.

On the other hand, in a head having a configuration in which a large number of heating elements such as 128 to 1720 are formed, a driving circuit (hereinafter referred to as a driving IC)
May be required in addition to one.

On the head substrate, signal wiring for connecting the heating element and the driving IC or connecting between the driving ICs is formed corresponding to one or more driving ICs to be mounted. In the manufacturing process after mounting the drive IC, the connection pads on the drive IC and the connection pads on the signal line
For example, the connection is made by a flip chip method.

[Problem to be Solved by the Invention] Here, when manufacturing the head substrate, there is a case where a step of inspecting an electrical open / short of a heating element and a wiring to the heating element is sometimes included.

The present inventor has performed such an inspection process, for example, before completing the connection pad, that is,
This is performed at the stage when a pad base made of a wiring material such as that described above is obtained. After the inspection, the pad base was covered with metal plating or the like to form a final connection pad.

However, when the inspection method is repeated many times, the inspection method is often performed by bringing a probe pin into contact with a pad base such as Al. The challenge turned out to be inherent.

(1) FIG. 9 (a) is for describing the technical problem of FIG. 1 first, 9 is a substrate, 8 is a protective film, 7 is a pad base, and 5 is a connection pad. As shown in FIG. 9 (a), if the pad base 8 formed on the substrate 9 is raised by the probe pins, the pad portion 5 formed by metal plating or the like in a later process will not be flat. Sometimes. If connection is attempted to the pad in such a state by the flip-chip method, a connection failure is likely to occur.

(2) As shown in FIG. 9 (b), the pad base 7
May not be completely covered with metal plating. If the process proceeds to the subsequent process in such a state, the exposed pad base 7 is corroded depending on the process, causing a change in wiring resistance or disconnection.

The present invention, when employing the above-described inspection method for a recording head for an inkjet recording apparatus, the ejection characteristics change if there is a slight change in the wiring resistance due to the above-described cause,
This has been made in view of the finding that the obtained recorded image is greatly disturbed.

An object of the present invention is to solve these technical problems and to improve the yield and reliability of a recording head by preventing disconnection or the like due to corrosion in a manufacturing process.

[Means for Solving the Problems] For this purpose, the present invention generates a discharge port for discharging ink, a liquid path communicating with the discharge port, and heat energy for discharging ink from the discharge port. A heating element,
A wiring electrically connected to the heating element, a test pad provided on the wiring for testing the heating element, and a connection pad for connecting to a drive circuit for driving the heating element In the method for manufacturing an ink jet recording head having, a step of preparing a substrate, a step of forming a wiring having the inspection pad portion and the connection pad portion on the substrate, and a step of forming the heating element, Inspecting the heating element by contacting a probe pin with the inspection pad portion; coating the wiring with a material having high corrosion resistance after the inspection; and forming a liquid path on the substrate after the coating process. And forming the inspection pad portion so as to extend beyond the connection pad portion, or the inspection pad portion is provided to be branched from the connection pad portion. The features.

Here, the coating made of a material having high corrosion resistance on the inspection pad portion may be gold plating.

In addition, the liquid channel forming step is performed by providing a dissolvable solid layer at a liquid channel forming portion on the substrate, coating the fixed layer with a photosensitive resin, and then dissolving the solid layer. May be.

[Operation] According to the present invention, after the step of inspecting the heating element using the inspection pad, the wiring having the inspection pad portion and the like is coated with a material having high corrosion resistance, and after this coating step, the wiring is formed on the substrate. By forming the liquid path, the coating can prevent the arrangement from being corroded by a liquid such as a solvent or ink used in forming the liquid path. In addition, even if the inspection pad portion, which is difficult to cover properly, starts to corrode, the inspection pad portion is provided extending beyond the connection pad portion, or is branched from the connection pad portion. Because of this, the corrosion of the inspection pad does not affect the wiring between the drive circuit and the heating element. Therefore, it is possible to avoid changes in wiring resistance and disconnection due to corrosion and maintain high print quality. And the yield during the manufacture of the inkjet recording head can be improved.

Examples Hereinafter, the present invention will be described in detail with reference to the drawings.

In a preferred embodiment of the present invention, a wiring portion for electrically connecting an electrothermal converter and a drive circuit for driving the electrothermal converter includes a pad portion wider than the connection wiring portion. Is to provide a pad portion wider than another wiring portion.
The pad portion is a portion of the wiring that is further extended beyond the connection pad portion, or a portion of the wiring that branches off from the connection pad portion. If this portion is a portion that does not affect the drive current to the electrothermal transducer even if deformation, alteration, etc. occur in itself, the position and the shape of the pad are described in each embodiment specifically described below. It is not limited.

First Embodiment FIG. 1 shows, as an example of a recording head to which the present invention can be applied, an ink jet recording head that forms a recording image by using thermal energy to form ink droplets. This figure shows a so-called full-multi type in which hundreds to thousands of orifices are aligned over a range corresponding to the entire width of the medium.

Here, reference numeral 4 denotes a heating resistor as a heating element for generating ink by causing a state change due to a film boiling phenomenon in the ink to generate a bubble and causing ink to be ejected. 1 is formed through the same manufacturing process as the thin film resistor forming process in the semiconductor integrated circuit technology. Reference numeral 2A denotes a liquid path forming member for defining the discharge port 2 and the liquid path 3 communicating with the discharge port 2 corresponding to the heating element 4, a top plate 6, an adhesive layer 6A, and a wall member 6B. Further, the substrate 1 has a heat storage layer 1A and a protective layer 1B thereon. Reference numeral 15 denotes a liquid chamber commonly kneaded with each of the liquid passages 3 and stores ink supplied from an ink supply source (not shown).

FIG. 2 schematically shows wiring on a substrate 1 made of a semiconductor or an insulator in FIG.

Here, V _H is a common electrode for applying a voltage at the time of recording as a supply of a plurality of heating resistors 4 (R ₁ ~R _m) to the recording signal. Those indicated by S _{1 to} S ₅ and S ₁ ′ to S ₅ ′ are signal sequence wirings. These are provided with input / output terminals at the ends on the head substrate 1 and are juxtaposed on the head recording surface side of a plurality of driving ICs (IC _{1 to} IC _n ). With these signal lines, storage data (DATA), signal transmission clock (SCLK), latch signal (LAT), and strobe signal (STR)
B) Various signals such as a transfer clock (ECLK) of the IC division drive signal are transmitted. _GH is a semiconductor to which the ground potential of the recording current applied to both sides of each driving IC is applied,
The terminal to which the voltage V _DD for driving IC1 to ICn is applied is arranged between the _GH terminals.

FIG. 3 is an enlarged view of a portion where the driving ICs (IC1 to ICn) in FIG. 2 are mounted. Here, a dotted line indicated by reference numeral 10 indicates a space for mounting a driving IC (IC1 to ICn) having elements functioning as a shift register, a latch circuit, a driver, and the like. Wirings connected to the plurality of heating resistors indicated by reference numeral 20 are arranged. Also, a plurality of ground terminal wires of the driving IC are denoted by reference numeral 30.
As shown by, they are arranged to share the ground terminals on both sides of the adjacent driving IC, and occupy a large area. One of a pair of wires connected to the heating resistor is connected to a ground terminal wire according to an image signal by a switch element inside the driving IC to be at a ground potential, and at this time, a common bias is applied to a positive potential. A current flows from the electrode _VH to the heating resistor 1, the wiring 20, and the ground terminal wiring 30. In this way, the heating resistor 1 generates heat by energization, and ink is ejected.

Incidentally, 40 is a signal sequence lines S ₁ to S ₅ of FIG. 2, S ₁ '~S _5'
This is the wiring corresponding to. 45 connects (joins) the driving IC to the substrate 1 by, for example, a flip chip bonding method.
Connection pad. Reference numeral 46 denotes an inspection pad for inspecting an open / short circuit wiring, which is provided corresponding to a wiring (heating element wiring) 20 for connecting the heating resistor 4 and the driving IC. Similarly, in this example,
Since a plurality of ICs are provided and are connected by the signal series wiring 40, they are also provided for the signal system arrangement lines 40, respectively. And
These test pads 46 are provided at portions further extended by the connection pad forming portions of the respective wirings, that is, in the middle of the connection path between the heating resistor 4 and the drive IC on the electric circuit, and between the drive ICs. It is provided in a portion that does not affect the flowing drive current or the like.

As described above, since the inspection pad 46 is specially provided, the contact of the probe pin to the connection pad 45 is not performed, so that the connection failure as described with reference to FIG. Disturbance of the recorded image due to the occurrence of problems such as a change in wiring resistance and disconnection can be avoided. That is, even if a state as shown in FIG. 9A or 9B occurs with respect to the inspection pad 46, such a defect does not occur in the connection pad 45, and the inspection pad 46 is connected to the driving IC. This is because the connection or signal transmission at the time of mounting is not directly involved. Here, the inspection process may be performed on the pad base such as Al of the inspection pad 46 before the pad is completed, or may be performed after the pad base is covered with metal plating or the like. In any case, since the connection pad 45 does not need to be brought into contact with the probe pin for inspection, there is no problem such as damage to that portion. Further, the inspection pad 46 may not necessarily be covered with metal plating as long as it is used only for inspection before pad completion.

FIG. 4 shows an example of the configuration of a control system for the recording head according to the above configuration. Here, reference numeral 202 denotes a recording head.

As described above, the head driving ICs (IC ₁ ,..., IC _n ) provided for each predetermined number (for each block) of the heating elements 4 (R _{1 to} R _m ) transmit the data signal DATA of one line to each heating element. A shift register for aligning one bit corresponding to the element 4; a latch circuit for latching bit data according to a latch signal LAT; and on / off of energization of the heating element 4 based on bit data according to a strobe signal STRB. And a switch for performing the above. Reference numeral 50 denotes an image memory for storing image data IDATA supplied directly from the host device H as an image data supply source or via the main controller 60 of the storage device. Reference numeral 70 denotes a recording signal generating unit which reads out image data developed in the image memory 50 in accordance with a drive timing signal T from the main control unit 60 and generates a data signal DATA, clock signals SCLK, ECLK, and a latch signal LAT. In addition, a strobe signal STRB or the like for dividing and driving the head driving ICs ₁ to IC _n is generated.
80 is a head driving power supply device for applying a predetermined voltage to the common electrode V _H during recording.

Using the recording head and its control system as described above,
For example, a full line printer capable of full color printing as shown in FIG. 5 can be constructed.

In FIG. 5, 201A and 201B are rollers as conveying means provided to carry with clamping the recording medium R in a sub-scanning direction V _S. 202BK, 202Y, 202M and 202C are
Each of these is a full multi-type recording head having four nozzles arranged over the entire width of the recording medium R to perform black, yellow, magenta, and cyan recording. As shown in FIG. 5, the heads are arranged in the order of black, yellow, magenta, and cyan from the upstream side in the recording medium conveyance direction to form a head assembly as recording means. Reference numeral 200 denotes an ejection recovery unit, which is configured to oppose the recording heads 202BK to 202C in place of the recording medium R in the ejection recovery processing, and includes a cap, an ink absorber, a wiping blade, and the like.

(Second and Third Embodiments) The locations of the test pads are not limited to those shown in FIG. 3, and a substantial current path relating to the recording signal is not formed in accordance with the design of the head wiring. It can be provided at the site. That is, for example, the wiring is branched as follows.

Specifically, as shown in FIG. 6, the test pads 45 related to the signal series wirings 40 may be provided at positions deviated from the center of each wiring.

In addition, as shown in FIG. 7, the test pad 45 for the wiring 20 connecting the driving IC and the heating resistor may be provided at a position deviated from the center of each wiring.

In particular, if the inspection pads are alternately arranged in a staggered manner, or the inspection pads and connection pads are alternately arranged in a staggered manner, not only can errors due to erroneous operations during the inspection be reduced, but also the recording head can be reduced. Sufficient reliability can be obtained even when the density of the wiring portion is increased.

(Other Embodiments) FIGS. 8A to 8E are schematic plan views for explaining another embodiment according to the present invention, wherein one set of a connection pad 45 and an inspection pad 46 is provided. Is shown.

FIGS. 8 (a), (b) and (d) show examples in which the inspection pad 46 is on the extension of the connection pad 45, and the shape of each pad is different.

FIGS. 8 (c) and 8 (e) show examples in which the inspection pad 46 and the connection pad are branched, and the shape of the pad and the shape of the branch portion are different from each other.

Although not shown, the wiring shape, pad shape, size, material, and the like described in detail above can be arbitrarily combined as appropriate.

(Description of Manufacturing Method) First, a substrate made of single crystal silicon was prepared. Alternatively, a glass substrate may be used. The surface of the substrate was thermally oxidized to form SiO ₂ as a heat storage layer. An HfB ₂ layer as a heating resistance layer was formed thereon by a sputtering method, and an Al layer as a conductive layer for an electrode was formed thereon by a sputtering method. These layers were patterned into a thin-film resistor to form a heating element array including 4700 heating elements. At this time, an inspection pad base and a connection pad base were also formed so as to have the above-mentioned shape at the same time. Thereafter, an inspection mask was formed using a positive resist. Then, a probe pin of a measuring instrument for inspecting the electrical connection state of the wiring, that is, the open / short state, was applied to the inspection pad portion, and the open / short state of the circuit was inspected. Here, when there was a short, the short was separated by laser processing. This is performed to increase the substrate yield. Al exposed in the through hole part
Inspection pads and connection pads were formed by applying gold plating to the surface of the layer. Thereafter, the open / short state was inspected again, and only non-defective products were sent to the subsequent process.

Next, using a positive resist, a solid layer capable of being dissolved and removed was formed on a portion of the substrate on which a plurality of liquid paths were to be formed and a portion on which a common liquid chamber communicating with the plurality of liquid paths was to be formed. Although a positive resist is used here, a positive dry film resist can also be used as the solid layer.

Thereafter, a photosensitive resin was coated on the substrate on which the solid layer was formed, and a glass top plate was placed thereon and joined.
Unnecessary portions and the solid layer of the photosensitive resin were removed to form the ink discharge ports, ink liquid paths, and common liquid chambers of the photosensitive resin.

At this time, triethane was used as the current liquid for removing the photosensitive resin. For removing the solid layer, an aqueous NaOH solution was used as an alkaline liquid. In addition, an organic solvent can be used for removing the solid layer. In particular, when an alkaline NaOH aqueous solution is used, corrosion of aluminum as an electrode or wiring material is likely to occur, so that the state shown in FIG. 9 should be minimized at the connection pad. I have to. Therefore, the test pad of the present invention is extremely effective. The driving IC was placed at a predetermined position, and the connection pad portion and the pin of the driving IC were connected and fixed by a flip-chip method, that is, solder. The recording heads manufactured as described above were combined into four heads for black, yellow, Ian, and magenta to form a head assembly, which was mounted on an apparatus body to form an ink jet recording apparatus. The method of manufacturing a head described above, particularly the use of a solid layer and a photosensitive resin, is disclosed in JP-A-62-2534.
The detailed description is omitted here since it is described in detail in Japanese Patent Publication No. 57-57. In addition, the configuration of the head is not limited to the above-described embodiment because there are many modifications so that, for example, the top plate can be replaced with metal, ceramic, plastic or the like other than glass.

(Others) The present invention can be widely applied not only to the ink jet recording method but also to a thermal recording method or the like as long as it has a plurality of heating resistors. This provides excellent effects in a recording head and a recording apparatus of a system. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to any of the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). Applying at least one drive signal corresponding to recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate heat energy, and This is effective because it causes film boiling on the hand-free action surface, and as a result, bubbles in the liquid (ink) corresponding one-to-one to this drive signal can be formed. A liquid (ink) is ejected through an ejection opening by the growth and shrinkage of the bubble to form at least one droplet. When this drive signal is formed into a pulse shape,
Since the growth and shrinkage of the bubbles are performed immediately and appropriately, the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. U.S. Pat. No. 44
Those described in JP-A-63359 and JP-A-4345262 are suitable. Further, when the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to a combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned specifications, A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed irrespective of the form of the recording head.

Further, the present invention can be effectively applied to a device driven under severe conditions such as a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording device can record, in which a large current flows. Such a recording head may have a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head integrally formed.

In addition, even with a serial type, a recording head fixed to the apparatus main body, or an exchangeable print head that can be electrically connected to the apparatus main body or supplied with ink from the apparatus main body when attached to the apparatus main body. The present invention is also effective when a chip type recording head or a cartridge type recording head in which an ink tank is provided integrally with the recording head itself is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different print colors and densities. May be used. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at or below room temperature and softens or liquefies at room temperature, or the ink itself in an inkjet method. In general, the temperature is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. I just need. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. The ink in such a case is disclosed in
No. -56847 or JP-A-60-71260, while being held as a liquid or solid substance in a porous sheet recess or through hole, facing the electrothermal converter. It is good also as a form. In the present invention,
The most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention may be used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, or a facsimile apparatus having a transmission / reception function. Or the like.

[Effects of the Invention] As described above, according to the present invention, after the step of inspecting the heating element using the inspection pad portion, the wiring having the inspection pad portion and the like is covered with a material having high corrosion resistance. By forming a liquid path on the substrate after this coating step, the coating can prevent corrosion of the wiring due to a liquid such as a solvent or ink used in forming the liquid path. In addition, even if the inspection pad portion, which is difficult to cover properly, starts to corrode, the inspection pad portion is provided extending beyond the connection pad portion, or is branched from the connection pad portion. Because of this, the corrosion of the inspection pad does not affect the wiring between the drive circuit and the heating element. Therefore, it is possible to avoid changes in wiring resistance and disconnection due to corrosion and maintain high print quality. And the yield during the manufacture of the inkjet recording head can be improved.

[Brief description of the drawings]

FIG. 1 shows an example of a recording head to which the present invention can be applied.
FIGS. 2 and 3 are a schematic plan view showing an example of wiring on a print head substrate shown in FIG. 1 and an enlarged main part thereof, respectively. FIG. 4, FIG. 4 and FIG. 5 are a block diagram showing a control system of an ink jet printing apparatus constituted by using the print head according to the present embodiment, and a schematic perspective view showing main mechanical structures, respectively. FIG. 7 and FIG. 7 are enlarged views of a main part of a head substrate according to second and third embodiments of the present invention, respectively. FIGS. 8 (a) to (e) show other embodiments of the present invention. FIGS. 9 (a) and 9 (b) are cross-sectional views for explaining a problem that has occurred in a conventional head substrate. 1,9 ... substrate, 4, R _{1 to} R _m ... heating resistor, 7 ... pad base, 20 ... heating element wiring, 45 ... connection pad, 46 ... inspection pad, IC ₁ to IC _n … driving IC, V _H … common electrode for applying recording voltage, 40, S _{1 to} S ₅ , S ₁ ′ to S ₅ ′… signal line wiring, G _H … recording current grounding conductor, V _DD …… IC drive voltage.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/05 B41J 2/16 B41J 2/335

Claims (3)

(57) [Claims] A discharge port for discharging ink, a liquid path communicating with the discharge port, a heating element for generating thermal energy for discharging ink from the discharge port, and an electrical connection to the heating element. Ink-jet recording, comprising: a wiring connected to a heating element; an inspection pad provided on the wiring for testing the heating element; and a connection pad connected to a drive circuit for driving the heating element. In the method for manufacturing a head, a step of preparing a substrate; a step of forming a wiring having the inspection pad portion and the connection pad portion on the substrate; and a step of forming the heating element; Inspecting the heating element by contacting a probe pin; coating the wiring with a highly corrosion-resistant material after the inspection; and forming a liquid path on the substrate after the coating step And the inspection pad portion is provided so as to extend beyond the connection pad portion, or is provided so as to be branched from the connection pad portion. Head manufacturing method. 2. The method according to claim 1, wherein the coating made of a material having high corrosion resistance on the inspection pad is gold-plated. 3. The step of forming a liquid path includes providing a dissolvable solid layer at a liquid path forming portion on the substrate, coating the fixed layer with a photosensitive resin, and then dissolving the solid layer. 2. The method for manufacturing an ink jet recording head according to claim 1, wherein the method is performed.