JPS62202742A - Preparation of liquid jet recording head - Google Patents

Abstract

PURPOSE:To make the saving of electric power, high durability, and high response velocity possible and at the same time, to improve the quality of printing, by a method wherein the thermal energy generation means by which discharged energy is supplied to recording liquid is provided and a protection layer is formed by reflowing of the upper layer laminated on the thermal energy generation means. CONSTITUTION:After forming the thermal energy generation means consisting of a couple of electrodes 3, 4 electrically connected to a thermal resistance layer 2 on the substrate 1 consisting of required materials such as, for instance, glass, ceramics, or plastics, etc. and an upper layer on this means, the protection layer 5 obtained by reflowing of this upper layer is provided. Therefore, lamination faults such as the nonhomogeneity of film quality or the like causing the occurrence of pinholes and cracks can be eliminated. Further, because the lamination and reflowing of the upper layer are repeatedly carried out as required, the thickness of the protection layer can be optionally set and the points on issue following the thickening of the protection layer 5 for the purpose of elimination of lamination faults and improvement of step coverage can be removed. Then, the liquid jet recording head saving electric power and excellent in durability and thermal response can be furnished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a liquid jet recording head, and particularly to a method of manufacturing a liquid jet recording head having thermal energy generating means.

[Conventional technology]

Among the various recording methods currently known, this is a non-impact recording method that generates almost no noise during recording, is capable of high-speed recording, and can record on plain paper without the need for special fixing treatment. The so-called liquid jet recording method (inkjet recording method) is an extremely useful recording method. Regarding this liquid jet recording method, a variety of methods have been proposed, some of which have been improved and commercialized, while others are still being worked on to put them into practical use.

The liquid jet recording method uses recording liquid e4 (called ink).
drop let,) is made to fly using various principles of operation,
Recording is performed by attaching it to a recording material such as paper.

The applicant has already proposed a new method related to such liquid jet recording method. This new method has been proposed in Japanese Patent Application Laid-Open No. 52-118798, and its basic principle is as outlined below. In other words, in this liquid jet recording method, a thermal pulse is applied as an information signal to the recording liquid introduced into an action chamber that can contain the recording liquid, whereby the recording liquid generates vapor bubbles and self-contracts. In this method, recording liquid is ejected in ml from a liquid ejection port communicating with the action chamber according to the acting force generated in the process, flying as small droplets, and making the droplets adhere to a recording material to perform recording.

By the way, this method is easy to adapt to high-speed recording and color recording by forming a high-density multi-array configuration, and the configuration of the implementation device is simpler than the conventional Sowa, so the overall recording head can be made more compact. To be suitable for mass production,
By making full use of the advantages of IC technology and micro-processing technology, which have seen remarkable technological progress and improved reliability in the semiconductor field, it has the advantage of being easy to lengthen, and is a method with a wide range of applications. be.

A characteristic recording head of a liquid jet recording apparatus used in the liquid jet recording method is provided with thermal energy generating means for ejecting recording liquid from a liquid ejection port to form flying droplets.

The thermal energy generating means is configured to efficiently apply the generated thermal energy to the recording liquid, and to eliminate the thermal effect on the recording liquid.
In order to increase the N-OFF response speed, etc., it is considered desirable to provide it in direct contact with the recording liquid.

However, since the heat energy generating means described above basically consists of a heat generating resistor layer that generates heat when energized and a pair of electrodes for supplying current to the heat generating resistor layer, the heat generating resistor layer is If it is in direct contact with the recording liquid, depending on the electrical resistance of the recording liquid, electricity may flow through the liquid, the recording liquid itself may be electrolyzed by the flow of electricity through the recording liquid, or the heating resistance layer may When the heating resistor layer is energized, the recording liquid reacts with the heating resistor layer, resulting in a change in resistance value due to corrosion of the heating resistor layer, or damage or destruction of the heating resistor layer.

Therefore, in the past, alloys such as NiCr and 7r
The heating resistor layer is made of an inorganic material that has relatively excellent properties as a heating resistor material, such as metal boride such as B2.1lfB2, and 5i is formed on the heating resistor layer made of the material.
By providing a protective layer made of a material with excellent oxidation resistance such as 02, it prevents the heating resistance layer from coming into direct contact with the recording liquid, solving various navigation problems and improving reliability and repeated use. It has been proposed to try to improve durability.

By the way, when forming the thermal energy generating means of such a liquid jet recording head, it is common to form the heat generating resistive layer on a desired substrate, and then sequentially stack electrodes and protective layers. The protective layer of such a thermal energy generating means includes these heat generating resistive layers in order to partially fulfill various functions as a protective layer such as preventing damage to the heat generating resistive layer and preventing short circuit between electrodes as described in F. It is required to uniformly cover the required portions of the electrodes and electrodes without layer defects such as pinholes.

In addition, in such a liquid jet recording head, as mentioned above, the electrodes are generally formed on the heat generating resistor layer.
A step occurs between the electrode and the heat-generating resistor layer, but unevenness in layer thickness is likely to occur at such a step, so the step must be sufficiently covered to avoid any exposed parts. (step coverage) layer formation must be carried out. In other words, if step coverage is insufficient, the exposed portion of the heat generating resistor layer may come into direct contact with the recording liquid and the recording liquid may be electrolyzed, or the recording liquid and the heat generating resistor layer may react and the heat generating resistor layer may be damaged. Sometimes it was destroyed. In addition, uneven film quality and
Such non-uniformity in film quality causes local concentration of thermal stress generated in the protective layer due to repeated heat generation, and causes cracks in the protective layer. In some cases, the heat-generating resistor layer may be destroyed as described above. Furthermore, the heating resistor layer may be destroyed due to the recording liquid entering through the pinhole.

Conventionally, in order to solve such problems, the general practice has been to increase the thickness of the protective layer to improve step coverage and reduce pinholes. However, although increasing the thickness of the protective layer contributes to reducing step coverage and pinholes, increasing the thickness of the protective layer obstructs the heat supply to the recording liquid, causing new problems such as the following. became.

In other words, the heat generated in the heat generating resistor layer is transferred to the recording liquid through the protective layer, but the thermal 9'J resistance between the surface of the protective layer, which is the surface on which this heat acts, and the heat generating resistor layer is Increasing the thickness of the protective layer increases the size, which makes it necessary to apply more power load than necessary to the heat-generating resistor layer. ■ It is disadvantageous to save power. ■ More heat than necessary accumulates in the base, causing heat This results in problems such as poor responsiveness, and (2) poor durability of the heating resistor layer due to more power than necessary.

Is it possible to overcome such problems by making the protective layer thinner? Conventional liquid jet recording head fabrication methods that use film forming methods such as sputtering or vapor deposition to form the protective layer suffer from poor step coverage and other problems. For,
It has the disadvantages in terms of durability as mentioned above, and it has been difficult to make the protective layer thinner.

It is also known that during recording with the liquid jet recording head as described above, the foaming stability of the recording liquid generally improves as the recording liquid is heated more rapidly. In other words, the shorter the pulse width of the electric signal applied to the thermal energy generating means, which is generally a rectangular electric pulse, the better the bubbling stability of the recording liquid will be, which will improve the ejection stability of flying droplets. This improves recording quality. However, in conventional liquid jet recording heads, the thickness of the protective layer must be increased as described above, which increases the thermal resistance of the protective layer and causes the thermal energy generating means to generate more heat than necessary. As a result, durability deteriorates and thermal responsiveness decreases, and it is therefore difficult to shorten the pulse width, and there is a natural limit to the improvement of recording quality.

(Problems to be Solved by the Invention) The present invention has been made in view of the problems of the prior art described above, and achieves power saving, high durability, and high-speed response, and also improves recording quality. The main purpose of this invention is to provide a method for creating a new liquid jet recording head that can be measured.

[Means for solving problems]

The present invention that achieves the above object includes a liquid ejection port for ejecting a recording liquid, a thermal energy generation means for supplying ejection energy to the recording liquid, and a protective layer for the means on the means. In the method for producing a liquid jet recording head in which the thermal energy generating means includes a heat-generating resistive layer and at least a pair of electrodes electrically connected to the heat-generating resistive layer, forming the protective layer serves as the protective layer. This method of manufacturing a liquid jet recording head is characterized in that the upper layer is laminated on the thermal energy generating means and then the upper layer is remelted.

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

1 and 2 are diagrams illustrating an example of a liquid jet recording head obtained by applying the method of the present invention, and FIG. 1 is a partial plan view of the vicinity of the thermal energy generating means of the head. However, FIG. 2 also shows an X-Y sectional view of FIG. 1.

As illustrated in FIGS. 1 and 2, a liquid jet recording head to which the present invention is applied has a substrate (generally a substrate 1 of various shapes) made of a desired material such as glass, ceramics, or plastic. h) a heating resistance layer 2 and at least one pair of electrodes 3 electrically connected to the layer 2;
After forming at least one set of thermal energy generating means consisting of 4 and an upper layer serving as a protective layer 5 on the means,
It has a protective layer 5 obtained by remelting (reflowing) the upper layer. 6 is a heat-acting surface that supplies power to the heat generating portion 6a of the heat generating resistor layer 2 formed between the TL electrode and transmits the generated heat to the recording liquid, and 7 is a heat acting surface that transfers the generated heat to the recording liquid. This is the step that occurs between 3.4 and 3.4.

FIG. 10 is a schematic cross-sectional view in a completed state of an example of a liquid jet recording head obtained by applying the method of the present invention, a part of which is shown in FIGS.
is a liquid ejection port for ejecting recording liquid.

In this liquid jet recording head, after forming thermal energy generating means including the above-mentioned protective layer 5 on a substrate l, working chambers corresponding to each of the thermal energy generating means and liquid ejection ports communicating with the working chambers are formed. This is obtained by bonding a top plate 16 as illustrated in FIG. 9, which has grooves formed to provide grooves 21, to a substrate l. In addition, in Fig. 9, I
7 is a groove for forming a liquid flow path which is an action chamber, and 19 is a groove serving as a common liquid chamber for supplying recording liquid to the liquid flow path 17. A liquid supply pipe 20 as illustrated in FIG. 10, for example, is connected to the common liquid chamber 19 as necessary, and recording liquid is introduced from outside the head through the liquid supply pipe 20. Further, when joining the top plate 16, it is desirable that sufficient positioning be performed so that each of the thermal energy generating means corresponds to each side of the liquid flow path 17.

When creating such a liquid jet recording head, the third
In the conventional liquid jet recording head as illustrated in the figure, layer defects such as pinholes are likely to occur in the protective layer 5 as described above.
Particularly in step 7, the thickness of the protective layer is made thicker than necessary (usually at least twice the electrode thickness) because exposed parts are likely to occur.
I had to do it. However, in the present invention,
After forming the upper layer that will become the protective layer 5, the upper layer is remelted, and if necessary, the L layer is repeatedly laminated and remelted, so that no pinholes or cracks are generated. It is possible to eliminate layer defects such as non-uniformity in film quality, which are the cause of the occurrence.

In addition, since the lamination and remelting of the upper layer are repeated as necessary, the thickness of the protective layer can be set arbitrarily, and the protective layer can be used to eliminate layer defects as described above and improve step coverage. The problems associated with the thickening of the layer 5 are solved, and it is possible to provide a liquid jet recording head that not only saves power but also has high durability and high-speed thermal response. Incidentally, in the present invention, it is sufficient that the thickness of the protective layer is 1.5 times or less the thickness of the electrode.

In the present invention, the heat generating resistive layer and the electrodes are formed using well-known raw materials, for example, by a sputtering method such as radio frequency (RF) sputtering, or by chemical vapor deposition MI (CVD).
The film may be formed using a well-known film forming method such as a vacuum evaporation method or a vacuum evaporation method without particular limitation. The upper layer can also be formed using well-known raw materials and the same film forming method as above, but in consideration of remelting, it is necessary to use low melting point glass, specifically PbO-5i02 glass, etc. Those that melt relatively easily by heating and have excellent flowability are preferred. More specifically, it is preferable that the reflow temperature is about 500°C to 800°C.
In addition to bO-5i02 glass, Ge02S 102 &
Glass or the like is preferably used.

The remelting of the upper layer in the present invention is carried out using any well-known heating means, such as a heating furnace or laser light, without any particular limitation. When using a device that can selectively heat, such as a laser beam, the layer may be remelted by heating only the upper layer, or when using a device that cannot perform selective heating, such as a heating furnace. The heating may be performed by heating the entire substrate including the upper layer. Such remelting of the upper layer is
This can be done under desired conditions depending on the material of the upper layer, etc., but when using a material with a high reflow temperature, 1.
It is also preferable to use electrodes and the like other than those in the seventh layer described above that have good heat resistance.

Hereinafter, an example of a method for manufacturing a liquid jet recording head of the present invention will be explained based on FIGS. 4(a) to 4(c).

First, as shown in FIG. 4(a), a heat generating resistor layer 2 is formed on a desired substrate l using, for example, vacuum evaporation or sputtering. Although not particularly shown in this example to simplify the explanation, a functional layer such as a heat storage layer 9 as illustrated in FIGS. 5 and 6, which will be described later, may be provided on the substrate l. be.

Next, in order to form an electrode 3.4 on this heating resistance layer 2,
An electrode layer is uniformly formed on the resistance layer 2 to a desired thickness by vacuum evaporation or sputtering. Thereafter, the electrode layer and the heating resistor layer 2 are patterned using a well-known photolithography technique,
A thermal energy generating means consisting of a heat generating resistive layer 2 and electrodes 3.4 formed in a desired pattern on a substrate 1 is obtained.

Next, as shown in FIG. 4(b), in order to form a protective layer on the thermal energy generating means, an upper layer 5a made of, for example, the above-mentioned low melting point glass is formed by vacuum evaporation, sputtering or CVD method similar to that described above. Electrode 3.4 using etc.
The thickness should be approximately twice that of the previous one.

Thereafter, in order to remelt the upper layer 5a, the layer 5a is heated to a temperature higher than one reflow temperature (for example, about 400°C or higher in the case of the above-mentioned PbO-5i02 glass), and as shown in FIG. A thick protective layer 5 is obtained.

Although not specifically explained above, when forming the protective layer 5, convex portions 7a and concave portions 7 as shown in FIG. 4(b) are formed.
b. This tends to occur in step 7. Such irregularities not only cause layer defects but also obstruct heat supply to the recording liquid, so it is desirable to remove them. However, in conventional methods, such irregularities such as the convex portions 7a and concave portions 7b are removed. Effective removal could not be performed.

However, in the present invention, since the upper layer 5a is remelted after being laminated, not only the convex portions 7a are melted and removed, but also the concave portions 7b are filled by the melting, as shown in FIG. 4(C), for example. As shown, it is possible to form a uniform and high quality protective layer 5 without any unevenness as described above on the step portion without increasing the layer thickness.

Although it is sufficient to form and remelt the upper layer 5a once, the formation and remelting of the layer 5a may be performed as necessary to improve the functionality of the protective layer 5. There is absolutely no problem in forming the protective layer 5 by repeating the steps. Of course, when such repetition is performed, it is not necessary to remelt all of the repeatedly formed upper layer 5a, and it is sufficient to remelt at least the lowermost upper layer 5a. In addition, the protective layer 5
It is not necessary to use a single material. It may also have a multi-layer structure made of more than one type of material.

After sufficient positioning, a top plate 16 as illustrated in FIG. 9 having grooves as described above is bonded to the substrate 1 having the thermal energy generating means on which the protective layer 5 is formed as described above. A liquid supply pipe 20 for introducing recording liquid supplied from a liquid supply system (not shown) into the head is connected to this to complete a liquid jet recording head as illustrated in FIG. 1O.

Although not specifically explained above, the formation of liquid discharge ports, liquid flow paths, etc. does not necessarily require the use of a grooved plate as illustrated in FIG. It may be formed by Further, the present invention is not limited to a multi-array type liquid jet recording head having a plurality of liquid ejection ports as described above, but a single array type liquid jet recording head in which liquid ejection [I is one]. Of course, it can also be applied.

[Effect]

In this way, in the present invention, the protective layer is formed by repeatedly forming and remelting the upper layer as necessary, so even if the layer thickness is thin, there are no layer defects such as pinholes, and It is possible to obtain a liquid jet recording head that has a protective layer with good step coverage, and it not only saves power but also
It is possible to provide a liquid jet recording head that achieves high durability and high-speed thermal response, and also has excellent recording quality.

〔Example〕

Examples of the present invention are shown below.

EXAMPLE The liquid jet recording head illustrated in FIG. 1θ was prepared as follows.

First, a substrate 1 was prepared in which a thermally oxidized heat storage layer 9 made of 5I02 having a thickness of 5IIJI was formed on a Si plate 8 as shown in FIGS. 5 and 6. On this substrate 1, a heating resistor layer 10 made of HfB2 is formed with a thickness of 1300 nm by sputtering.
Formed to the thickness of a person.

Next, a Mo layer having good heat resistance and serving as electrodes 11 and 12 was formed on the heat generating resistor layer IO to a thickness of about 500 OA by vacuum evaporation. Thereafter, the Mo layer and the heat generating resistance layer 10 are patterned by a photolithography process, and the heat generating portion I
The size of 3 is width 30- x length 150μ, and the working electrode I+,
A thermal energy generating means having a circuit pattern having a resistance value of 100Ω including +2 was formed on the substrate. In this example, the input side electrode I2 is an individual electrode so that each of the thermal energy generating means can be selectively heated.
The electrode 11 on the return path is a common electrode to simplify the electrode configuration.

Next, as shown in FIGS. 7 to 8, 5i02:B2O3:PbO:ZnO was placed on the thermal energy generating means.
The upper layer 14 is made of low melting point glass (reflow temperature: about 600°C) having a composition ratio of 5:15:64:16.
(It was formed to a thickness of approximately 5,000 mm using an F sputtering device.The forming conditions were: RF power, 1 kW, pressure;
The test was carried out at ×lO°3 Torr.

Thereafter, the -L section layer 14 was remelted in a vacuum heating furnace maintained at a pressure of 1X10°' Torr at about 800°C for 1 hour to form a first layer made of the above-mentioned low melting point glass with a layer thickness of about 5000. A protective layer 14 was formed. In this example, the heating temperature was set to the above value so as not to cause rapid flow of the upper layer and to allow the time required for the unevenness of the step portion to be smoothed out.

Thereafter, in order to improve the cavitation resistance of the first protective layer 14, a second protective layer 15 made of Ta is formed on the layer 14 to a thickness of approximately 5000 mm using the same RF sputtering apparatus as described above. A substrate was obtained in which the first and second protective layers had a total thickness of about 10,000. The protective layer thus obtained was of good quality with good step coverage and no layer defects such as pinholes.

After sufficient alignment, the top plate 16 (material: glass) having grooves as shown in FIG. 20 were connected to complete a liquid jet recording head as shown in FIG.

In addition, in Fig. 9, the liquid flow path! 7 (width 40μ, height 40
μ) and the grooves that will become the common liquid chamber 19 were formed by cutting the top plate 16 using a micro cutter. Further, in FIG. 1θ, a lead board (not shown) having an electrode lead for applying a desired pulse signal from outside the head is attached to the individual electrode 12 and the common electrode 11, and recording is performed based on the signal. It will be done.

The liquid jet recording head created in this way has the following advantages over conventional ones: (1) approximately 50% reduction in power consumption, (2) approximately 40% improvement in thermal response, and (3) approximately 40% improvement in thermal response. Improved performance, such as better durability, was observed when driving with a shorter pulse width. Furthermore, based on the foaming stability achieved by short-width pulse driving, the ejection stability of the recording liquid was improved, and recording quality was improved.

〔Effect of the invention〕

As explained above, the present invention not only reduces the power consumption of the liquid jet recording head, but also enables faster thermal response, improved durability, improved ejection stability, and improved recording quality. It is.

[Brief explanation of drawings]

FIG. 1 is a partial plan view of an example of a liquid jet recording head obtained by applying the method of the present invention, and FIG.
10 is a schematic perspective view of the liquid jet recording head shown in FIGS. 1 and 2 in a completed state, FIG. 3 is an example of a conventional liquid jet recording head, and FIG. a
) to (C) are diagrams for explaining an example of the method of the present invention, and FIGS. The figure shows the structure of the substrate before the formation of the protective layer, and FIGS. 7 to 8 show the structure of the substrate after the formation of the protective layer.
This is an example of a top plate used in the liquid jet recording head shown in the figure. 1: Substrate 2, lO: Heat generating resistance layer 3.4,
II, 12: Electrode

Claims (2)

[Claims] (1) A liquid discharge port for discharging a recording liquid, a thermal energy generation means for supplying discharge energy to the recording liquid, and a protective layer for the means on the means, and the thermal energy generation In the method for producing a liquid jet recording head, the means includes a heat generating resistive layer and at least a pair of electrodes electrically connected to the heat generating resistive layer, in which forming the protective layer comprises:
A method for producing a liquid jet recording head, characterized in that the upper layer serving as the protective layer is laminated on the thermal energy generating means and then the upper layer is remelted. (2) The method for manufacturing a liquid jet recording head according to claim 1, wherein the upper layer is made of low melting point glass.