JP2002172781A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head having a heat dissipation layer which can be formed at a high rate and having no possibility of short-circuiting to an electrode, or the like. SOLUTION: A long ink jet head for line printer comprises a plurality of stripe heat sinks 31 provided at the upper part of an insulating substrate 30 of glass or the like, an insulation layer 32 provided on the upper layer of the heat sinks 31, heaters 33 provided on the upper layer of the insulation layer 32, and electrodes 34 (discrete wiring electrodes 34-1, common electrode 34-2) provided on the upper layer of the heaters 33. Ink channels are formed thereon by barrier walls and an orifice plate is placed thereon, and then a large number of ejection nozzles corresponding to the widthwise direction of the sheet are formed at positions corresponding to the heaters 33 on the orifice plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head having a structure excellent in heat dissipation and insulation.

[0002]

2. Description of the Related Art Conventionally, there is a printer which performs printing by discharging ink from an ink jet head onto a paper surface. In a printing method using this printer, ink droplets (print dots) are ejected from fine holes (ejection nozzles) arranged in large numbers on the ink ejection surface of an ink jet head, and the ink droplets (print dots) are printed on a print medium such as paper or cloth. Let it land and absorb it,
Thus, printing of characters, images, and the like is performed, the generation of noise is small, no special fixing process is required, and full-color recording is a relatively easy recording method.

As a method of discharging ink droplets, a heating element is arranged in a fine ink pressurizing chamber, and an electric pulse is applied to the heating element to generate heat, thereby generating film bubbles at an interface between the ink and the heating element at high speed. There is a thermal ink jet head that discharges ink droplets from discharge nozzles by using the instantaneous expansion force of the film bubbles.

[0004] The above-mentioned thermal type ink jet head has two configurations depending on the direction of ink droplet ejection. One is a configuration in which ink droplets are ejected in a direction parallel to the surface of the heating element. The other is configured to discharge ink droplets in a direction perpendicular to the surface of the heating element. Above all, those that eject ink droplets in the direction perpendicular to the surface of the heating element are called roof shooter type or top shooter type inkjet heads, and eject ink droplets in a direction parallel to the surface of the heating element. Compared to the configuration,
It is known that power consumption is extremely small.

[0005] As a method of manufacturing this roof shooter type ink jet head, for example, a large number of pieces of about 10 mm x 15 mm divided into, for example, 90 pieces or more on one silicon wafer having a diameter of 6 x 25.4 mm or more. A large number of heating elements, a driving circuit for individually driving these elements, an ink flow path for supplying ink thereto, and ejection of ink droplets on the chip substrate by utilizing LSI forming technology and thin film forming technology. And the discharge nozzles to be formed are collectively formed monolithically.

As described above, an ink jet head individually formed on a chip substrate having a size of about 10 mm × 15 mm is mainly an ink jet head for a serial printer which performs printing by moving the ink jet head in the width direction of paper. Although used as a head, in recent years, a large and long inkjet head for a line printer, which has a discharge nozzle array that is full width of the paper and is fixed to the printer main body, and only the paper moves to perform printing, is created. A method using a glass substrate instead of a silicon wafer having a limited size has also been proposed.

FIGS. 3 (a), 3 (b) and 3 (c) are views showing a basic manufacturing method of such a conventional ink jet head in the order of steps. c) The upper part is a schematic plan view of the state formed on the substrate in a series of steps, the middle part is an AA 'sectional view of the upper part, and the lower part is an BB' sectional arrow of the upper part. FIG.

In FIGS. 1 (a), 1 (b) and 1 (c), for convenience of illustration, 64 pieces are originally used for a serial printer.
A large number of ejection nozzles, such as 128 or 256, or thousands for a line printer, are represented by five ejection nozzles. In these figures, for convenience of description, a monochrome inkjet head having only one row of ejection nozzles is shown. First, a small-sized inkjet head formed on a silicon wafer will be described.

In this method of manufacturing a print head, first, as a step 1, a drive circuit and its terminals are formed by LSI forming processing on a plurality of subdivided chip substrate sections on a silicon substrate of 4 × 25.4 mm or more. At the same time, an oxide film (SiO ₂ ) having a thickness of 1 to 2 μm is formed as an insulating layer, and then, in step 2, using a thin film forming technique, tantalum (Ta) -silicon (Si) -oxygen (O 2) ) Or Ta
A heat-generating resistor film made of -Si-ON (nitrogen);
An electrode film made of Au or the like is sequentially laminated with an adhesive layer such as -W interposed therebetween. Then, the electrode film and the heating resistor film are each patterned by photolithography technology to expose a region of the heating resistor film in the form of a stripe, which serves as a heating element, and a wiring electrode is superimposed on the heating resistor films on both sides thereof. Then, a heating element including a heating element and wiring electrodes on both sides is formed. In this step, the position of the heating element is determined.

FIG. 3A shows a state immediately after the steps 1 and 2 have been completed. That is, the driving circuit 2 is formed along the vicinity of one end (right side in the drawing) of the chip substrate 1 in the width direction. Although not shown, a drive circuit terminal for connecting to an external power supply terminal is formed at an end of the chip substrate 1 in a vertical direction (or in a horizontal direction). An insulating layer 3 is formed on the entire surface of the chip substrate 1 from above, and a heating element 4 is formed on the insulating layer 3. A common electrode 5 is connected to one end of the heating element 4, and an individual wiring electrode 6 is connected between the other end and the drive circuit 2.

Subsequently, in step 3, an ink pressurizing chamber corresponding to each heating element 4 and an ink flow path for supplying ink to these ink pressurizing chambers are formed of an organic material such as photosensitive polyimide. A partition member is formed to a height of about 20 μm by coating, and after patterning this by photolithography, heat of 300 ° C. to 400 ° C. is applied for 30 minutes.
Then, curing (dry curing, baking) is performed for about 60 minutes, and a partition made of the photosensitive polyimide having a height of about 10 μm is formed and fixed on the chip substrate. Further, as step 4,
An elongated ink supply groove is formed on the surface of the chip substrate by wet etching or sand blasting, and an ink supply hole communicating with the ink supply groove and opening on the lower surface of the substrate is formed.

In step 4, since the shape of the ink supply groove on the front side where the heating elements, wiring electrodes, partition walls, etc. are formed and the shape of the ink supply hole on the back side are different, processing is performed separately from the front and back. . For example, an ink supply groove is formed on the front side to about half the thickness of the chip substrate, and an ink supply hole is formed from the back side to penetrate the front and back.

FIG. 3B shows a state immediately after Steps 3 and 4 are completed. That is, an elongated ink supply groove 7 and a round or square ink supply hole 8 are formed, and a portion where the common electrode 5 located on the left side of the ink supply groove 7 and a right individual wiring electrode 6 are disposed. , And a partition 9 (seal partition 9-)
1, 9-2 and a partition wall 9-3) are formed.

Each of the heat generating elements 4 and the heat generating elements 4 can be formed by forming the above-mentioned partition wall 9 by using a sealing wall 9-2 on the individual wiring electrode 6 as a comb body.
The partition wall 9-3 extending between them has a shape corresponding to the teeth of a comb. As a result, the fine partition sections in which the heating elements 4 are located at the roots between the teeth are formed by the number of the heating elements 4 with the comb-shaped partition walls 9-3 of the comb as partition walls. .

Thereafter, in step 5, an orifice plate of a film made of polyimide having a thickness of 10 to 30 μm was used, and thermoplastic polyimide as an adhesive was coated on both sides or one side of the orifice to an extremely thin thickness of, for example, 2 to 5 μm. In the state, placed on the uppermost layer of the laminated structure, that is, the partition,
While heating at 200 to 50 ° C. in a vacuum, 9.8 × 10
^-4 Pa at a pressure several times as high as this, and this is continued for several tens of minutes.
The orifice plate is fixed. Subsequently, the thickness of Ti, Ni, Cu or Al is reduced to 0.
A metal film of about 5 to 1 μm is deposited on the surface of the orifice plate.

In step 6, the metal film on the surface of the orifice plate is patterned to form a mask for selectively etching polyimide, and then, for example, dry etching using a helicon wave is performed in accordance with the metal film mask. A large number of holes of 20 μmφ to 40 μmφ are formed in the orifice plate as discharge nozzles.

FIG. 3C shows a state immediately after the steps 5 and 6 have been completed. That is, the orifice plate 11 covers the entire area, and the partition formed by the seal partition 9-2 and the partition 9-3 is also covered on the top, and the height of the partition 9 corresponds to a thickness of 10 μm. The ink pressurizing chamber 12 is formed, and its opening is directed toward the ink supply groove 7. In addition, an ink flow path 13 having a height of 10 μm is formed to connect the opening of the ink pressurizing chamber 12 and the ink supply groove 7.

A discharge nozzle 14 is formed in the orifice plate 11 at a position facing the heating element 4 of the ink pressurizing chamber 12 by dry etching. Thus, a mono-color inkjet head 15 having 64, 128, 256, etc. ejection nozzles 14 in one row.
Are completed on a silicon wafer.

The processing up to this point is performed in the state of a silicon wafer. Finally, in step 7, the silicon wafer is cut along a scribe line using a dicing saw or the like, divided into individual chip substrate units, die-bonded to a mounting substrate, and connected to terminals to form a practical unit. Is completed.

As described above, the ink-jet head 15 having one row of discharge nozzles 14 is a monochrome ink-jet head. However, in full-color printing, the three primary colors of subtractive color mixing are yellow (Y) and magenta (M). ), Cyan (C) and black (Bk) dedicated to the black part of characters and images, and a total of four colors of ink are required. Therefore, at least four nozzle rows are required. According to the above-described manufacturing method, it is possible to monolithically configure the monochromatic inkjet head 15 to have a four-row configuration, and the positional relationship between the four-row nozzle rows is also determined by today's semiconductor manufacturing technology. Can be arranged more accurately.

As described above, there is a method in which a glass substrate is used to produce a large and long ink jet head for a line printer. FIG. 4A is a plan view schematically showing the appearance of a large and long inkjet head formed using such a glass substrate.
FIG. 1B is a plan view showing a plurality of inkjet heads completed on a glass substrate, FIG. 1C is a cross-sectional view taken along the line CC ′, and FIG. ′ FIG.

This ink jet head 16 is
As shown in (a), (b), (c) and (d), the large glass substrate 17
The drive circuit, heating element,
Internal structure 21 composed of wiring electrodes, partition walls, etc. ((c), (d)
Orifice plates 18 are laminated on top of each other through an adhesive 22, and the orifice plates 18 are provided with four ejection nozzle rows 19 for each ink jet head 16.
After the formation of the scribe line 2 (see FIG.
3 (see FIGS. (B) and (c) in the same figure).
Each 7 'is cut out as shown in FIG.

The above-described drive circuit, heating element, wiring electrode,
The method for forming the partition walls, the method for laminating the orifice plates, the method for perforating the discharge nozzles, and the like are slightly different from the methods described with reference to FIG. 3, but are the same as the methods described with reference to FIG. The difference is generally the same, so the description is omitted here.

In the case of the small ink jet head 15 shown in FIG. 3, the substrate is a silicon wafer, and the silicon wafer has a high thermal conductivity. Can be dissipated to the outside. However, in the ink-jet head 16 shown in FIG. 4, the heat generation amount when the ink-jet head 16 is actually driven to generate heat is large, and the heat conductivity of the base glass substrate is small. As in the case of the head 15, natural heat radiation cannot be left. Therefore, in the ink jet head 16 shown in FIG.
A heat radiation layer is required under the lowermost layer, that is, below the insulating layer.

FIG. 5A shows the ink jet head 1 described above.
6 is an enlarged plan view of a portion around the heating element of the internal structure 21 of FIG. 6, and FIG. 6B is a cross-sectional view taken along the line EE ′ of FIG. As shown in FIGS. 7A and 7B, a radiator plate 24 is provided on the entire surface of the glass substrate 17. An insulating layer 25 is provided on the radiator plate 24. A heating resistor film forming the heating element 26 is patterned and attached on the upper layer 25. Except for the portion where the heating element 26 is formed on the heating resistor film, the heating resistor film is formed. The individual wiring electrodes 27 and the common electrodes 28 are connected to both ends of the body 26.
Is covered. Excess heat after the heating element 26 generates heat
The heat is transmitted to the heat radiating portion of the printer main body on which the ink jet head 16 is mounted via the heat radiating plate 24 to radiate heat and cool the ink jet head 16.

As a method of forming the heat radiating plate 24, a method of forming a film of amorphous silicon or polycrystalline silicon to a thickness of about 20 μm has been proposed.
As these film forming methods, a CVD method, a microwave plasma CVD method, an electron beam evaporation method, a sputtering method and the like are known.

[0027]

Incidentally, the above-mentioned heat-dissipating plate material such as amorphous silicon or polycrystalline silicon is certainly a material having high thermal conductivity but having conductivity. Therefore, the insulating layer formed on the heat sink composed of the above is provided with a highly reliable insulating material without pinholes to prevent short circuits with the individual wiring electrodes, common electrodes, heating elements, and the like. Must be a membrane. If Pinho
If a short circuit occurs between the upper wiring portion and the lower heat radiating plate due to the presence of a heat sink or the like, the heat generating function of the heating element 26 is impaired, and the entire inkjet head 16 becomes defective.

However, it is extremely difficult to form the insulating layer at a high speed as a high quality film without pinholes by any film forming method. In order to form an insulating layer as a high-quality film without pinholes, it is necessary to form a dense film with a low film formation rate, which results in a film formation process with low productivity. Since a film forming process with low productivity must be performed using an expensive film forming apparatus, there is a problem that not only the manufacturing cost of the inkjet head increases but also the yield decreases.

The object of the present invention is to solve the above-mentioned conventional situation,
It is an object of the present invention to provide an ink jet head having a heat radiating plate capable of forming a film at a high speed and not causing a short circuit with an electrode or the like.

[0030]

According to the ink jet head of the present invention, a film bubble is generated in the ink on the surface of the heating element which generates heat by energization, and the ink on the heating element is discharged by instantaneous expansion of the film bubble. An ink jet head for performing printing on a print medium by discharging ink droplets from nozzles, comprising a plurality of striped radiators provided on an insulating substrate, and an insulating layer provided on an upper layer of the radiator. And a heating element provided on the insulating layer, and an electrode provided on the heating element.

The heat radiator is provided in a groove formed on the insulating substrate, for example. Further, the radiator may be mounted on a surface of the insulating substrate, for example. In this case, it is preferable that an insulator is provided between the heat radiators, for example.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is an enlarged plan view of a portion around an exothermic body of an internal configuration of an ink jet head according to an embodiment, and FIG. 1B is a sectional view taken along the line FF 'of FIG. In the internal configuration shown in FIGS. 3A and 3B, the configuration of the partition walls and the ink grooves are not shown, and the orifice plate and the orifice plate that should be the uppermost layer as a completed drawing are not shown. The illustration of the formed discharge nozzle is also omitted.

As shown in FIGS. 3A and 3B, this ink jet head has, as its internal configuration, a plurality of striped radiators 31 provided on an insulating substrate 30 made of glass or the like. An insulating layer 32 provided on the heat radiator 31 and a heating element 33 provided on the insulating layer 32;
And an electrode 34 (individual wiring electrode 34-1 and common electrode 34-2) provided in an upper layer of the heating element 33.

As shown in FIGS. 3A and 3B, the radiator 31
Has a height of 10 to 30 μm, a width of 30 to 40 μm, and an adjacent interval of 5 to 15 μm. In addition, the length is parallel to the individual wiring electrode 34-1 and up to the end of the ink jet head, and is exposed to be communicable with an external radiator.

As described above, when the heat radiator 31 is formed in a stripe shape without forming a layer on the entire surface of the substrate, the heat radiator 31 becomes smaller in plan area than when formed on the entire surface of the substrate. If the heat radiator 31 is formed under the design conditions of ４０40 μm, the plane area of the heat radiator 31 can occupy more than half of the substrate area.

In addition, a height of 1 to 30 to 40 μm and a height of 1
If the heat radiator 31 is formed under the design conditions of 0 to 30 μm, the cross-sectional area for conducting heat in the lateral direction has a heat radiating plate 24 having a thickness of 10 to 20 μm formed on the entire surface of the conventional substrate shown in FIG. There is no inferiority in the cross-sectional area and the size, and sufficient thermal conductivity can be obtained.

As for the plane area, a simulation was carried out. As a result, a glass substrate was coated with aluminum (Al) having a thickness of 10 to 20 μm over the entire surface as a heat dissipation layer. It turns out that there is almost the same heat radiation effect. Therefore, depending on the occupied area of the radiator, a metal having a higher thermal conductivity other than Al, for example, copper (C
By forming a metal material such as u or copper having a thermal conductivity of about 1.6 times that of Al to a thickness of about 10 to 30 μm, it can be used as an excellent radiator having a stripe shape.

By disposing the radiator 31 in a stripe shape in parallel with the heating element 33 and the individual wiring electrode 34-1 as described above, even if the insulating layer 32 has a defect such as a pinhole, the individual wiring electrode is formed. Since a short circuit cannot occur between the heating elements 34-1 and 34-1, it is possible to reduce the problem of the ejection failure of the heating element 33, thereby contributing to an improvement in the processing yield.

The individual wiring electrode 34-1 and the common electrode 3
Since a heating resistor layer continuous with the heating element 33 is laid on the entire surface below 4-2, the heating resistor layer and the insulating layer 32 are provided.
Is very large, but the contact area between the electrode and the insulating layer 32 is extremely small. That is, the bottom area of the individual wiring electrode side surface portion 34-1-1 surrounding the periphery of the striped heating resistor layer extending from the heating element 33 to the individual wiring electrode side is extremely small. It can be said that the probability of pinhole formation is extremely small. However, in order to eliminate the short circuit between this portion and the common electrode, it is preferable to reduce the width of the heat radiator 31 so that it is formed within the same width as the heat generator 33. In this case, only the common electrode that is originally common to the heat generation resistance layer having low conductivity is short-circuited through the generated pinhole.
Problems due to short circuits are greatly reduced.

FIGS. 2A and 2B are diagrams showing two examples of a method of forming the heat radiator 31. FIG. First, in the method of forming the radiator 31 shown in FIG. 3A, the groove 35 is formed on the insulating substrate 30 by wet etching or dry etching in the same manner as the formation of the ink supply groove. The heat dissipating body 31 is provided in the groove 35 formed in the above. Then, the insulating layer 32 is deposited on the entire surface of the resultant structure. The components such as the heating element 33, the individual wiring electrode 34-1 and the common electrode 34-2 shown in FIGS. 1 (a) and 1 (b) which are formed thereon are not shown.

Next, in the method of forming the heat radiator 31 shown in FIG. 4B, the heat radiator 31 is attached in a stripe shape by the same thin film forming technique as when the wiring electrodes are formed on the surface of the insulating substrate 30. An insulator 36 made of a suitable insulating material, for example, polyimide or the like is provided between the formed heat radiators 31. Even in this case, the same structure as that shown in FIG. 1A can be obtained by applying the insulating layer 32 over the entire surface.

[0042]

As described above in detail, according to the present invention, the radiator is made of a metal having a good thermal conductivity according to its occupied area, and its shape is parallel to the heat generator and the individual wiring electrodes. Since it is provided in the form of a stripe, even if there is a defect such as a pinhole in the insulating layer, occurrence of a short circuit between the individual wiring electrodes is eliminated, thereby reducing the problem of ejection failure of the heating element of the inkjet head. An inkjet head with improved processing yield can be provided.

[Brief description of the drawings]

FIG. 1A is an enlarged plan view of a portion centering on a heating element of an internal configuration of an inkjet head according to an embodiment, and FIG. 1B is a cross-sectional view taken along the line EE ′ of FIG.

FIGS. 2A and 2B are diagrams illustrating two examples of a method of forming a heat radiator according to an embodiment.

3 (a), (b), and (c) are views showing a conventional method of manufacturing an ink jet head in the order of steps, and the upper part is a schematic plan view showing a state of being formed on a chip substrate in a series of steps. In the figure, the middle part is an AA 'cross-sectional view of the upper part, and the lower part is a BB' cross-sectional view of the upper part.

FIG. 4A is a plan view schematically showing the appearance of a large and long inkjet head formed using a glass substrate, and FIG. 4B is a plan view showing a plurality of inkjet heads completed on a glass substrate. FIG. 3 (c) is a sectional view taken along the line CC ′, and FIG. 3 (d) is a sectional view taken along the line DD ′.

FIG. 5A is an enlarged plan view of a portion centering on a heating element of an internal configuration of a conventional inkjet head formed on a glass substrate, and FIG. 5B is a cross-sectional view taken along the line EE 'of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chip board 2 Drive circuit 3 Insulating layer 4 Heating element 5 Common electrode 6 Individual wiring electrode 7 Ink supply groove 8 Ink supply hole 9 Partition 9-1, 9-2 Seal partition 9-3 Partition partition 11 Orifice plate 12 Ink application Pressure chamber 13 Ink flow path 14 Discharge nozzle 15, 16 Ink jet head 17 Glass substrate 18 Orifice plate 19 Discharge nozzle row 21 Internal structure 22 Adhesive 23 Scribe line 24 Heat sink 25 Insulating layer 26 Heating element 27 Individual wiring electrode 28 Common electrode 30 Insulating substrate 31 Heat radiator 32 Insulating layer 33 Heating element 34 Electrode 34-1 Individual wiring electrode 34-1-1 Individual wiring electrode side surface 34-2 Common electrode 35 Groove 36 Insulator

Claims (4)

[Claims] 1. A printing medium, wherein a film bubble is generated in ink on a surface of a heating element which generates heat by energization, and ink on the heating element is ejected from an ejection nozzle as an ink droplet by instantaneous expansion of the film bubble. An inkjet head for performing printing on the insulating substrate, comprising: a plurality of striped radiators provided on an insulating substrate; an insulating layer provided on the radiator; and an upper layer provided on the insulating layer. An ink-jet head comprising: a heating element; and an electrode provided on an upper layer of the heating element. 2. The ink jet head according to claim 1, wherein the heat radiator is provided in a groove formed on the insulating substrate. 3. The ink jet head according to claim 1, wherein the heat radiator is attached to a surface of the insulating substrate. 4. The ink jet head according to claim 3, wherein an insulator is provided between each of said heat radiators.