JPS60137663A - Liquid jet recording head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording head that performs recording by jetting liquid and forming flying droplets.

The inkjet recording method (liquid jet recording method) is capable of high-speed recording in that the noise generated during recording is so small that it can be ignored, but it does not require special processing for fixing on so-called plain paper. Recently, there has been a lot of interest in the ability to record data without having to use it.

Among them, for example, it is described in Japanese Patent Application Laid-Open No. 54-51837: German Opening Publication (DOLS) No. 2843064.

The liquid jet recording method described above has a different feature from other liquid jet recording methods in that thermal energy is applied to the liquid to obtain the motive force for ejecting droplets.

That is, in the recording method disclosed in the above-mentioned publication, the liquid subjected to the action of thermal energy undergoes a state change accompanied by a sharp increase in volume, and based on this state change, the acting force causes the recording head portion to Liquid is ejected from the orifice at the tip to form flying droplets, which adhere to the recording member to perform recording.

In particular, the liquid jet recording method disclosed in DOLS No. 2843064 is a so-called drop-on deman
Not only can it be effectively applied to the d recording method, but it can also easily realize a recording head with a full 1ine type recording head and high-density multi-orifice, allowing high-resolution, high-quality images to be produced at high speed. It has the characteristic that it can be obtained from

The recording head section of the apparatus applied to the above recording method is a part that communicates with an orifice provided for ejecting liquid and where thermal energy acts on the liquid in order to eject droplets. The apparatus includes a liquid discharge part having a liquid flow path in which a heat acting part is a part of the structure, and an electrothermal converter as a means for generating thermal energy.

This electrothermal converter includes a pair of electrodes, and a heat generating resistance layer connected to these electrodes and having a heat generating region (heat generating portion) between these electrodes.

Typical examples showing the structure of such a liquid jet recording head are shown in FIG. 1(al), FIG. 1(b), FIG. 1(c), and FIG. 1(dl). aL is a front partial view of the liquid jet recording head seen from the orifice side;
Figures (bl, c), and (d) are partial views taken along the line indicated by the dashed line XY in Fig. 1(a).

The recording head 100 includes a grooved plate 103 in which a predetermined number of grooves of a predetermined width and depth are provided at a predetermined linear density on the surface of a substrate 102 on which an electrothermal transducer 101 is provided.
By joining so as to cover the orifice 104
It has a structure in which a liquid discharge part 105 is formed. In the case of the recording head shown in the figure (2) is shown as having a plurality of orifices 104, the present invention is of course not limited to such a recording head, and a recording head with a single orifice can also be used. It falls within the scope of invention.

The liquid discharge part 105 has an orifice 104 at its terminal end for discharging the liquid, and thermal energy generated by the electrothermal converter 101 acts on the liquid to generate bubbles, causing rapid expansion and contraction of the volume. It has a heat acting part 106 which is a part that causes a state change.

The heat acting part 106 is the heat generating part 10 of the electrothermal converter 101.
The bottom surface thereof is a heat acting surface 108 which is located at the upper part of the heat generating section 7 and comes into contact with the liquid of the heat generating section 107.

The heat generating section 107 is a lower layer 1 provided on the substrate 102.
09. Heat generating resistance layer 110 provided on the lower layer 109
, a first protective layer 11 provided on the heating resistance layer 110
1. The heating resistance layer 110 includes electrodes 113, 1 for supplying electricity to the layer 110 to generate heat.
14 is provided on its surface. The electrode 113 is a common electrode for the heat generating part of each liquid discharge part, and the electrode 114 is
This is a selection electrode for selectively generating heat in the heat generating section of each liquid discharge section, and is provided along the liquid flow path of the liquid discharge section.

In the heat generating section 101, the first protective layer 111 protects the heat generating resistor layer 110 from the liquid to be used, chemically and physically. The heating resistor layer 110 has a protective function of isolating the filling liquid and preventing a short circuit between the electrodes 113 and 114 through the liquid. The first protective layer 111 also has the role of preventing electrical leakage between adjacent electrodes. In particular, it is necessary to prevent electrical leakage between each selected electrode, or to prevent electrical leakage of the electrodes caused by contact between the electrode and the liquid under each liquid flow path for some reason and applying current to the electrode. Preventing erosion is important,
For this purpose, the first protective layer 111 having the function of a protective layer is provided at least on the electrode located below the liquid flow path.

The upper layers including the first protective layer have different characteristics depending on where they are provided.

That is, for example, in the heat generating part 107, (1) heat resistance, (2)
Liquid resistance, ■Liquid penetration prevention, ■Thermal conductivity, ■Antioxidation,
■It is required to have excellent insulation properties and ■tear resistance.
Areas other than the heat generating portion 107 are relieved by thermal conditions, but are required to have sufficiently excellent liquid penetration prevention properties, liquid resistance, and tear resistance.

However, there is currently no material constituting the upper layer that fully satisfies all of the above characteristics (■~■) as desired.
Currently, some of the characteristics of (2) are relaxed. That is, in the heat generating section 1゛07, ■, ■, and ■
Priority is given to the material selection, while the heat generating part 1
For example, in the electrode part other than 07, priority is given to ■, ■, and ■ in selecting materials, and the upper layer is formed on the surface of each corresponding area using the corresponding material. It is formed.

On the other hand, in the case of a multi-orifice type liquid jet recording head, in order to simultaneously form a large number of fine electrothermal transducers on the substrate, in the manufacturing process,
On the substrate, the formation of each layer and the removal of a portion of the formed layer are repeated, and at the stage where the upper layer is formed, the surface on which the upper layer is formed is located at the step wedge portion. Since the surface has a certain fine unevenness, the coverage of the upper layer (step COVerage) at this stepped portion is important. In other words, if the coverage of this stepped portion is poor, liquid will penetrate into that portion, causing electrolytic corrosion or electrical breakdown. In addition, if the upper layer to be formed has a small probability of having defects due to its manufacturing method, liquid may penetrate through the defects, which is a factor that significantly shortens the life of the electrothermal converter. It becomes.

For these reasons, the upper layer must have good coverage at the stepped portion, and the probability that defects such as pinholes will occur in the formed layer is low, and even if they occur, they can be ignored in practical terms. Or even less is required.

Conventionally, in order to meet these requirements, the upper layer is formed by laminating a first protective layer made of an inorganic insulating material and a second protective layer made of an organic material, or The first protective layer has a two-layer structure, the lower layer is made of an inorganic insulating material, and the upper layer is sticky and has relatively good mechanical strength, and has a strong structure with respect to the first protective layer and the second protective layer. It has been made of an inorganic material such as a metal that has adhesion and adhesive properties, or a third protective layer made of an inorganic material such as a metal has been disposed further above the second protective layer.

However, although the second protective layer made of an organic material has excellent covering properties, it is inferior in terms of heat resistance, so it is not provided on the heat generating resistive layer of the heat generating portion. On the other hand, the third protective layer made of an inorganic material such as metal may be provided on the entire surface of the substrate as the outermost layer, or may be provided only on the heat generating resistor layer of the heat generating portion. In the case where the third protective layer is provided in the latter manner, as shown in FIG. 1 (bl), the second protective layer 112
If the third protective layer 116 and the second protective layer 116 do not overlap, only the first protective layer will remain in that area, and a sufficient protective function cannot be achieved. Not only that, but the concentration of electric potential is biased in the area, and eventually the electrode layer dissolves. In other words, corrosion resistance deteriorates. Furthermore, even if the second protective layer and the third protective layer overlap, if the overlap width is small, the liquid will penetrate and the potential will concentrate as the liquid immersion time increases.
Again, electrode portion melting occurs. On the other hand, if the overlap width is too large, the following problems will occur. Figure 1 (
As shown in c), the third layer is made of inorganic material such as metal.
The protective layer 116 is placed below the second protective layer 112 made of an organic material in the vicinity of the heat generating part, and when it is placed on the first protective layer 111, the third protective layer 116 is placed below the second protective layer 112 made of an organic material. 11
This increases the probability of short-circuit occurrence between 6 and the electrodes 113 and 114, and the product yield is extremely reduced, which is undesirable. Further, as shown in FIG. 1(d), contrary to FIG. 1(c), the upper layer near the heat generating part is formed by forming a second protective layer 112 on top of the first protective layer 111, a third protective layer 112, and a third protective layer 112 on top of the first protective layer 111. When the protective layers 116 are laminated in this order, peeling of the organic material layer (second protective layer) progresses due to stress in the inorganic material layer (third protective layer) due to immersion in liquid from the liquid flow path. .

The present invention has been developed in view of the above points, and has excellent overall durability in frequent repeated use and long-term continuous use, and maintains good initial droplet formation characteristics over a long period of time. The main object of the present invention is to provide a liquid jet recording head that can be stably maintained.

Another object of the present invention is to provide a liquid jet recording head that is highly reliable in manufacturing and processing.

Another object of the present invention is to provide a liquid jet recording head that has a high production yield even when it has multiple orifices.

The liquid jet recording head of the present invention includes an orifice provided for ejecting liquid to form flying droplets, and a portion that communicates with the orifice and where thermal energy acts on the liquid to form the droplets. a liquid discharge part having a liquid flow path having a heat acting part as part of its structure; at least a pair of opposing electrodes electrically connected to a heat generating resistor layer provided on the substrate; and between these electrodes. an electrothermal converter in which a heat generating part is formed; a first protective layer made of at least an inorganic insulating material on at least a portion of the electrode below the liquid flow path; and a second protective layer made of an organic material. a first protective layer made of at least an inorganic insulating material and a third protective layer made of an inorganic material on at least the electrothermal converter; In the liquid jet recording head, the liquid jet recording head is provided with an upper layer formed by sequentially laminating layers, and the second protective layer and the third protective layer overlap each other on the electrode. The overlapping portion of the third protective layer has a width of 10 to 500 μm. The order in which the second protective layer and the third protective layer are overlapped may be the upper layer, as long as the width of the overlapping portion is within this range.

Further, the overlapping width does not have to be the same in all the peripheral parts of the electrothermal converter, but may be different as long as it is within this range.

The first protective layer 111 is made of an inorganic insulating material such as an inorganic oxide such as 5in2 or an inorganic nitride such as Si3N4, and the third protective layer 116 is sticky and has relatively good mechanical strength. , and has adhesion and adhesion to the first protective layer. For example, when the first protective layer is made of 5i02, it is preferably made of a metal material such as Ta. The fact that the third protective layer is made of an inorganic material such as metal that is relatively sticky and has mechanical strength prevents the cavitation effect that occurs when liquid is discharged, especially on the heat-active surface 108. Shocks can be sufficiently absorbed and the life of the electrothermal converter 101 can be significantly extended.

As a material constituting the first protective layer 111, an inorganic insulating material having relatively excellent thermal conductivity and heat resistance is suitable. For example, inorganic oxides such as 5in2, transition metal oxides such as titanium oxide, vanadium oxide, niobium oxide, molybdenum oxide, tantalum oxide, tungsten oxide, chromium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, yttrium oxide, manganese oxide, etc. metal oxides such as aluminum oxide, calcium oxide, strontium oxide, barium oxide, silicon oxide, and their composites, high-resistance nitrides such as silicon nitride, aluminum nitride, boron nitride, tantalum nitride, and oxides of these. , nitride composites, and even semiconductors such as amorphous silicon and amorphous selenium, which have low resistance in bulk, can become high in manufacturing processes such as sputtering, CVD, vapor deposition, gas phase reaction, and liquid coating. The thin film materials obtained can be mentioned.

As the abrasive material for forming the third protective layer 116, the above-mentioned T
In addition to a, elements of group 11a of the periodic table such as Sc and Yrz, elements of group TVa such as Ti, Zr, and Hf rx, and V.

Group Va elements such as Nb, Group Vi elements such as Cr, Mo, W, Fe, Co, Nir
xWhich group II element; Ti-Ni, Ta-W, T
a-Mo-Ni, Ni-Cr, Fe-Co, Ti
-W, Fe-Ti, Fe-Ni, Fe-Cr,
Fe-Ni-Cr. Alloys of any of the above metals; Ti-B
, Ta-B, Hf-B, W-B tx, and other borides of the above metals; Ti-C, Zr-C, V-C, Ta-C
, Mo-C, C1-C and other carbides of the above metals; Mo
Silicides of the above metals such as -5i, W-5i, Ta-8i; Ti-N, Nb-N, Ta-N'f
x Nitrides of any of the above metals may be mentioned. The third protective layer is formed using these materials by vapor deposition, sputtering, C
It can be formed by a method such as a VD method. The third protective layer may be made of the above-mentioned materials alone, but of course some of these materials may also be combined.

The second protective layer is composed of an organic insulating material with excellent liquid penetration prevention and liquid resistance properties, and also has good film formability.
■It has physical properties such as: ■Dense structure with few pinholes, ■Does not swell or dissolve in the ink used, ■Good insulation properties when formed into a film, and ■High heat resistance. This is desirable. Such organic materials include the following resins, such as silicone resins, fluororesins, aromatic polyamides, addition polymerization polyimides, polybenzimidazole, metal chelate polymers, titanate esters,
Epoxy resins, phthalic acid resins, thermosetting phenolic resins, P-vinylphenol resins, Zylock resins, triazine resins, BT resins (triazine resins and bismaleimide addition polymer resins), etc. The second protective layer can also be formed by vapor depositing polyxylylene resin and its derivatives.

Furthermore, various organic compounds such as thiourea,
Thioacetamide, vinylferrocene, 1.3.5-
) Lichlorobenzene, chlorobenzene, styrene, ferrocene, pyrroline, naphthalene, pentamethylbenzene, nitrotoluene, acrylonitrile, diphenylselenide, P-toluidine, P-xylene, N,N-dimethyl-P-)luidine, toluene, aniline, diphenyl Mercury, hexamethylbenzene, malononitrile, tetracyanoethylene, thiophene, benzene selenol, tetrafluoroethylene, ethylene, N-nitron diphenylamine, acetylene, 1°2.4-
to! The second protective layer can also be formed by forming a film using plasma polymerization using J-chlorobenzene, propane, or the like.

However, in order to create a high-density multi-orifice type recording head, it is necessary to use an organic material that is extremely easy to process using fine photolithography, in addition to the organic materials mentioned above, as the material for forming the second protective layer. is desirable. Specifically, such organic materials include, for example, polyimide isoindoquinazolinedione (product name: PIQ, manufactured by Hitachi Chemical), polyimide resin (product name: PYRALIN, manufactured by DuPont), cyclized polybutadiene (product name: PYRALIN, manufactured by DuPont), Name: JSR-CBR%CBR-M
2O3 (manufactured by Japan Synthetic Rubber Co., Ltd.), Photonice (trade name: Toshi Co., Ltd.), and other photosensitive polyimide resins are preferred.

The support body 115 is made of silicon, glass, ceramics, or the like.

The lower layer 109 is provided as a layer that mainly controls the flow of heat generated from the heat generating section 107 toward the support body 115, and when applying thermal energy to the liquid in the heat acting section 106, , so that more of the heat generated from the heat generating section 107 flows to the heat acting section 106 side, and when the electrothermal converter 101 is turned off, the heat remaining in the heat generating section 107 is The constituent materials are selected and the layer thickness is designed so that the material flows quickly toward the support 115. The material constituting the lower layer 109 is 5in2
Examples include inorganic materials represented by metal oxides such as zirconium oxide, tantalum oxide, and magnesium oxide.

As the material constituting the heat generating resistor layer 110, almost any material can be used as long as it generates desired heat when energized.

Specific examples of such materials include tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor,
Alternatively, metals such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium, alloys thereof, and borides thereof are preferable.

Among these materials constituting the heating resistance layer 110, metal borides can be cited as particularly excellent, and among them, hafnium boride has the most excellent properties.
This is followed by zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heat generating resistor layer 110 can be formed using the above-mentioned materials using techniques such as electron beam evaporation and sputtering.

As the material constituting the electrodes 113 and 114, many commonly used electrode materials can be effectively used.
Specifically, for example, metals such as AL AL "p PLCu are used, and these are used to provide a predetermined size, shape, and thickness at a predetermined position by a method such as vapor deposition.

The materials constituting the components of the grooved plate 103 and the common liquid chamber provided on the upstream side of the heat acting section 106 are materials whose shape is not affected by thermal effects during the construction of the recording head or under the environment during use. They do not undergo any susceptibility, or hardly any susceptibility, and can be easily applied with micro-precision machining, and can easily achieve the desired surface precision. Most things are effective as long as they can be processed so that the liquid can flow smoothly.

Typical examples of such materials include ceramics, glass, metals, plastics, silicon wafers, and the like. In particular, glass and silicon wafers are suitable materials because they are easy to process and have appropriate heat resistance, thermal expansion coefficient, and thermal conductivity.

The outer surface around the orifice 104 is treated with a water-repellent treatment if the liquid is aqueous, or an oil-repellent treatment if the liquid is non-aqueous, to prevent the liquid from leaking and getting around to the outside of the orifice 104. It's better to do so.

The liquid jet recording head of the present invention will be specifically explained below with reference to Examples.

EXAMPLE A liquid jet recording head of the present invention was manufactured as follows.

A 5 μm thick Si02 film was formed by thermal oxidation of the St wafer and used as a substrate. HfB was formed as a heating resistance layer on the substrate by sputtering to a thickness of 3000 mm, followed by a Ti layer of 50 mm and an Af1 layer of 100 mm by electron beam evaporation.

λ was deposited continuously.

The electrode part is patterned by a photolithography process, and electrode 1
13,114 were formed. The size of the heat acting surface is 50μm
The width is 150 μm and the length is 150 μm.

Next, as the first protective layer 111, a 5i02 layer was deposited to a thickness of 2.8 μm by high-rate sputtering.

Next, the third protective layer 116 was formed as follows.

As a Ta lift-off resist, polyimide resin was laminated to a thickness of 5 μm except for the window portion (400×300 μrn) around the heat-active surface, and then a Ta film was formed to a thickness of 0.5 μm by magnetron sputtering. After forming the Ta film,
By removing the polyimide resin with a stripping solution, T
Lift-off patterning was performed so that the a-film remained in the window portion.

Next, by applying a spinner, PhotoNice (manufactured by Toshi)
, and open a window/section (300 x 20
The second protective layer 112 was created by patterning and developing to form a layer (0 μm) jj -. The widths of the overlapping portions of the second protective layer and the third protective layer are all 50 μm. Further baking,
A substrate for a liquid jet recording head was created.

The electrothermal transducer of the recording head created in this way has a temperature of 10
When a pulsed voltage of 23 V in μs was applied at 800 Hz, the liquid was ejected as droplets in response to the applied signal, and flying droplets were stably formed.

Here, in order to clarify the relationship between the overlap width and the defective rate of the print head, the electrode of the print head was set to +40V into the ink liquid, and a Pt electrode was inserted so that the ink potential was GND, and the temperature of the ink liquid was adjusted. Defects were examined after the product was left at 80°C for 200 hours.

Figure 2 shows the results of investigating disconnections due to electrode melting that occur when the overlap width ranges from minus to around zero as shown in Figure 1 (bl). , the electrode melts from defects in the inorganic insulating layer (poor step coverage, pinholes), leading to disconnection.Also, liquid penetrates the overlapping boundary up to about 10 μm,
As expected, it will lead to a disconnection.

In addition, if the overlapping width is positive (overlapping) as shown in Figure 1(c) and (d), a third protective layer made of an inorganic material is applied as shown in Figure 1(C). When the third protective layer is below the second protective layer, a short circuit between the third protective layer and the electrode (defects in the inorganic insulating layer) becomes a problem, as shown in FIG. 3(a). In particular, if b is set to 500 μm or more, the yield of the product will be extremely reduced.Furthermore, if a heating potential immersion test is performed in the above-mentioned ink, the surface of the inorganic layer will be oxidized.
Stable discharge cannot be obtained.

If the third protective layer is above the second protective layer composed of an organic material, as shown in FIG.
As shown in Figure (b), the stress in the third protective layer, that is, the upper inorganic layer, the swelling of the second protective layer, that is, the lower organic layer, and the stress due to the difference in the thermal expansion coefficients of both layers. Film peeling becomes a problem due to such factors.This film peeling occurs when there are steps in the organic layer or defects in the inorganic layer.
This occurs to some extent even if the overlap width is small, but especially when the overlap width exceeds 500 μm, the entire surface of the inorganic layer peels off from the tip, which becomes a serious problem.

Therefore, by setting the overlap width to 10 to 500 μm, it is possible to provide a liquid jet recording head with high reliability, high yield, and excellent ink resistance.

[Brief explanation of drawings]

FIGS. 1(a), (b), (c), and (d) are for explaining the configuration of a conventional liquid jet recording head, respectively, and FIG. 1(a) is a schematic front partial view; Figure 1 (
b), (c), and (d) are partial cross-sectional views taken along the dashed-dotted line XY in FIG. 1(a). FIG. 1(b) shows that the second protective layer and the third protective layer do not overlap, and FIG. 1(c) shows that the second protective layer and the third protective layer overlap in the overlapping part. If the protective layer is on top of the third protective layer, Figure 1(d) shows that the second protective layer and the third protective layer
In the overlapping portion of the protective layers, the second protective layer is below the third protective layer. Figure 2 shows the overlap width (b) of the second protective layer and the third protective layer.
) and the wire breakage rate. 3) is the overlap width (b
) and the short rate. Figure 3 (b
l is in the overlapping part. 7 is a graph showing overlap (b) and film peeling rate in a liquid jet recording head in which the second protective layer is below the third protective layer. 100...Liquid jet recording head 101...
...Electrothermal converter 102...Substrate 103...Grooved plate 104...Orifice 105...Liquid discharge part 106...Heat Working part 107...Heat generating part 10B...Heat working surface 109...Lower layer 110...Heating resistance layer 111...First Protective layer (inorganic insulating material layer) 1
12...Second protective layer (organic material layer) 113.
...Common electrode 114...Selection electrode 115...Support 116...Third protective layer (inorganic material layer) b...
...Overlap width of second protective layer and third protective layer Patent applicant: Canon Co., Ltd. Figure 1 (b) Figure 1 (c) Figure 1 (d)

Claims (1)

[Claims] An orifice provided for ejecting a liquid to form flying droplets, and a heat acting part that communicates with the orifice and is a part where thermal energy acts on the liquid to form the droplets. a liquid discharge part having a liquid flow path, at least a pair of opposing electrodes electrically connected to a heat generating resistive layer provided on a substrate, and an electrical device having a heat generating part formed between these electrodes; A first protective layer made of at least an inorganic insulating material and a second protective layer made of an organic material are laminated in this order on at least a portion of the heat converter and the electrode below the liquid flow path. J4-Nt, comprising an upper layer in which at least a first protective layer made of an inorganic insulating material and a third protective layer made of an inorganic material are laminated in this order on at least the electrothermal converter. In the liquid jet recording head, the liquid jet recording head has a configuration in which the second protective layer and the third protective layer overlap on the electrode, wherein the second protective layer and the third protective layer overlap each other. A liquid jet recording head characterized in that the width of the portion is 10 to 500 μm.