JPH03169558A - Manufacture of ink 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 [Field of Industrial Application] The present invention relates to a method of manufacturing an inkjet recording head for performing recording by ejecting ink and forming ink droplets.

[Conventional technology]

An inkjet recording head generally includes an ink ejection port with a fine diameter, an ink path that communicates with the ejection port and supplies ink as it is ejected, and a part of this path that is installed to apply ejection pressure to the ink. It is equipped with an ejection energy generating element that provides ejection energy such as.

As one type of inkjet recording head, a substrate is provided with an ejection heater as an energy generating element, an electrode for supplying power to this heater, and an oxidation-resistant layer to prevent oxidation due to heat generated by the ejection heater. ,
Among the parts where this oxidation-resistant layer is provided, an anti-cavitation layer made of metal, for example, is provided to protect the oxidation-resistant layer from the so-called cavitation phenomenon, and an ink-resistant layer is provided on the part other than the upper part of the heater. An inkjet recording head has been proposed in which the ink liquid path is shaped by providing an organic layer on the substrate and patterning a cured resin film on the substrate (for example, JP-A-56-123869, JP-A-57- 438
76).

In this case, two layers, an anti-cavitation layer and an ink-resistant layer, or three layers, including an oxidation-resistant layer, are exposed on the substrate surface on which the cured resin film forming the ink liquid path is adhered. Therefore, due to the different light reflectances of these various films, the mode of exposure when patterning the cured resin film differs depending on these various films.

In other words, the cured resin film is exposed to light by direct irradiation from the patterning light source and reflection from the various films mentioned above due to this irradiation, and if the amount of reflection differs, the total amount of exposure on the resin film will differ. . For this reason, the dimensions of the ink channel formed by patterning vary depending on the surface of the substrate to which the cured resin film is applied, making it difficult to form a continuous ink channel according to the designed dimensions. There was a problem.

For example, the portion with the highest reflectance, such as the ink-resistant layer (organic material layer), then
The cured resin film was exposed to insufficient light as a whole, and sufficient polymerization could not be obtained, and the liquid channel wall sometimes peeled off from the substrate during development.

In addition, the amount of exposure along the direction in which the cured resin film layer is irradiated with light varies depending on the amount of light transmission and reflection, but if the reflectance of the adhered surface differs, this difference in exposure amount will change. The size of the ink liquid path may not be uniform, and as a result, it may not be possible to obtain a uniform ink liquid path size.

In order to solve these problems, a method has been proposed in which the amount of exposure given to the photosensitive resin layer is adjusted according to the difference in reflectance when patterning a photosensitive resin on an adhered surface with different reflectance. (Unexamined Japanese Patent Publication No. 80-2061i59
). According to this method, even when forming a liquid path made of a cured resin film over adhered surfaces with different reflectances,
A uniform and continuous ink liquid path size can be obtained regardless of the surface to which the liquid is adhered.

(Problem to be Solved by the Invention) However, although the above-mentioned method is effective in forming an ink liquid path with a uniform width across the adhered surfaces having different reflectances,
On the other hand, it does not provide a method for accurately forming a liquid path whose width is large or whose width changes in a step-like manner.

In other words, according to the above method, the relative exposure amount in the narrow part of the liquid channel or the liquid channel wall becomes excessive or insufficient in relation to the mask compared to other parts, and in the part where the liquid channel width is narrow, There was a problem that the liquid path was not completely formed and was partially blocked, and in the part where the partition wall of the liquid path was narrow, the partition wall itself was lost during development.

One way to solve this problem is to change the exposure amount depending on the width of the liquid path, but this requires preparing a large number of photomasks depending on the width of the liquid path, and Since the exposure amount must be adjusted depending on the mask, a problem arises in that the manufacturing cost increases as a result.

The present invention has been made in view of the above-mentioned problems, and provides an inkjet recording head that is capable of accurately determining the shape of an ink liquid path in which the ratio of the wide portion to the narrow portion of the ink liquid path is relatively large. The purpose is to provide

(Means for Solving the Problems) To this end, the present invention includes an ejection port provided for ejecting ink to form ink droplets by the action of thermal energy, an ink liquid path communicating with the ejection port, an ejection energy generating element that generates the thermal energy provided in the ink liquid path, and a wall forming the ink liquid path is shaped by patterning a photosensitive resin layer provided on a substrate. In the method for manufacturing an inkjet recording head, the reflectance in the patterning of the substrate is varied depending on the width of the wall.

More preferably, the reflectance of the substrate is low in the wide portions of the wall and high in the narrow portions.

[Function] According to the above configuration, in patterning C when defining the shape of the ink channel wall, more specifically, by changing the reflectance of the substrate according to the width of the ink channel wall, By setting the reflectance of the substrate to be low in areas where the wall width is wide and high in areas where the wall width is narrow, each area is exposed to just the right amount of light in relation to the patterning mask, and the ink liquid path is formed. It becomes possible to perform the process with good dimensional accuracy.

〔Example〕

The present invention will be explained in detail below with reference to the drawings.

Sequential steps in an embodiment of the method for manufacturing an inkjet recording head according to the present invention will be described with reference to FIGS. IA, IB to FIG. 8. As shown in FIG. 9, the ink liquid path of the inkjet recording head manufactured according to this embodiment is wide near the center of the ink liquid path 9, and wide in both directions toward the ejection port 92 and the supply port 93. The shape is narrower. As shown in FIG. 18 and FIG. 1B, first, a discharge heater 2 as a discharge energy generating element and an electrode 3 for supplying power to the heater 2 are formed on a substrate 1 by etching, screen printing, or the like.

Next, in the process shown in Figure 2, the heater 2
In order to prevent its own oxidation, for example, Sin. The oxidation-resistant layer 4 is formed by sputtering or the like.

In the steps shown in FIGS. 3A and 38, the oxidation-resistant layer 4 ruptures due to the so-called cavity condensation phenomenon that occurs when the ink is foamed during ejection in the ink liquid path formed as described later. In order to prevent this, a metal film of Ta, Nb, etc., for example, is formed on the discharge heater 2 as an anti-cavitation silicone layer 5. Furthermore, in this step, a wide part of the ink liquid path, that is, a liquid path is formed,
In order to increase the reflectance of the narrow portion of the wall separating adjacent liquid channels, a metal film 6 is formed on the upper layer of this portion. This metal film has a great effect on forming liquid channels with high precision, as will be described later.

Further, when metals such as Ta and Nb are used as the anti-cavitation layer, since these metals have high reflectance, they can be used as they are as the metal film 6, and there is no need to add a special process. FIG. 3B is a top view of FIG. 3A.

Next, in the steps shown in FIGS. 4A and 4B, an ink-resistant layer 7 is formed of an ink-resistant organic material, such as bolywood, in order to completely isolate the electrode 3 from ink. FIG. 4B is a top view of the substrate shown in FIG. 4A after the above steps.

Next, as shown in FIG. 5, a cured resin film 8, such as a dry film, for forming an ink channel wall is laminated.

Thereafter, as shown in FIG. 6A, in order to pattern the ink channel walls, a photomask 20, which is transparent only in the portion 20B that will become the ink channel walls, is placed on the cured resin film 8 as shown in FIG. 6B. They are aligned and placed using the method described above, and then exposed.

FIG. 7A and FIG. 7B are cross-sectional views corresponding to the A-A line and the B-B line in FIG. 6B, respectively, after the cured resin film 8 has been developed.

As shown in FIG. 7A, the cured resin film 8^ in the area where the metal film 6 is formed together with the metal film of the anti-cavitation layer.
Since the reflectance of the substrate during exposure is high, polymerization proceeds sufficiently and the width of the liquid channel wall hardly decreases after development. On the other hand, 3
As shown in FIGS. 47A and 7B, the reflectance is low in the areas where the metal film is not formed, so polymerization does not progress sufficiently and the width of the liquid channel wall becomes narrow, especially near the substrate. However, since this part is originally a wide part of the wall, there is no fear that the wall will be lost even if the width becomes slightly narrower.

FIG. 8 shows the external appearance of the liquid jet recording head manufactured through the above steps.

In FIG. 8, an ink liquid chamber 91 is connected to the ink liquid path 9. Further, the ink liquid path 9 communicates with a supply port 93 that forms a boundary between the ejection port 92 and the ink liquid chamber 9l. Furthermore, a cover 1o is formed as a top plate for the liquid path 9.

The manufacturing method according to the present invention can also be applied to manufacturing ink jet recording heads having ink liquid paths of other shapes.

FIG. 10 shows the structure of an ink liquid path in which a pariah as a fluid diode is arranged in one ink liquid path. When the barrier 15 shown in the figure is formed from a photosensitive resin, the distance between the barrier 15 and the liquid path wall and the width of the barrier itself are narrow, so in the conventional method, the barrier disappears during development due to underexposure or overexposure. Problems have arisen, such as the flow path between the barrier and the liquid path wall not opening properly.

Following the previous embodiment, the formation of the oxidation-resistant layer is carried out as shown in FIGS. IA to 2. Next, as shown in FIG. 11, a Ta film 5 for cavitation resistance is applied to the heater 2.
Formed in the upper layer of the At the same time, a Ta film 6 is formed on the narrow portion of the barrier to increase the reflectance so that the wall of the thin portion of the barrier is not lost due to development. The subsequent lamination and patterning of the cured resin film are the same as in the previous example.

According to this embodiment, barrier formation is relatively good (can be performed). Conventionally, the thin part of the barrier receives relatively insufficient light amount compared to other parts of the barrier. The maximum width ratio was 1.5:1, but the method according to this embodiment made it possible to achieve a ratio of 3:1.

Generally, the bright areas of a photomask (
The transmission area) should be larger than the width of the partition wall of the ink liquid path. In this way, in conjunction with the manufacturing method according to the present invention, it is also effective to use a photomask that takes into account the difference in thinning during development depending on the reflectance of the substrate, and has a difference in the finished size and the bright area size. be. In other words, in the thick part of the ink channel wall, the reflectance is made relatively low, so there is a large difference between the finished dimensions and the width of the photomask bright area, and in the small part of the ink channel wall, the reflectance is made high. Keep this difference small.

(Others) As described above, the present invention brings about excellent effects in a bubble jet recording head among ink jet recording systems. This method increases the recording density. It is possible to achieve high definition.

For its typical configuration and principle, see, for example, US Pat. No. 4,723,129. It is preferable to use the basic principle disclosed in the specification of the same No. 4740796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal, which is effective. The growth of this bubble. The contraction causes liquid (ink) to be ejected through the ejection opening to form at least one drop. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse-shaped drive signal is described in U.S. Pat. No. 4,463,359, U.S. Pat.
Those described in the specification are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head is a combination of an ejection port, an ink liquid path, and an electrothermal converter (ejection heater) as disclosed in the above specification (straight liquid flow path or right angle liquid flow path).
In addition, the present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the heat acting portion is disposed in a bending region. In addition, JP-A-59-123670 discloses a structure in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole absorbing pressure wave of thermal energy is disclosed. The effects of the present invention are also effective even with a configuration based on Japanese Patent Application Laid-open No. 138461/1983 which discloses a configuration in which a discharge portion corresponds to a discharge portion. In other words, regardless of the form of the recording head, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording head may have either 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 formed integrally. In addition, even if it is a serial type, it may be a replaceable chip type print head that can be attached to the main body of the device to enable electrical connection with the main body of the device or supply of ink from the main body of the device, or the print head itself. The present invention is also effective for a cartridge type recording head that is integrally provided with a cartridge type recording head.

(Effects of the Invention) As explained above, according to the present invention, in patterning when forming an ink channel wall, by changing the reflectance of the substrate according to the width of the ink channel wall, more specific patterns can be obtained. In order to achieve this, the reflectance of the substrate is low in the wide parts of the wall and high in the narrow parts, so that each part is exposed to just the right amount of light in relation to the patterning mask, and the ink path is adjusted. It becomes possible to perform formation with good dimensional accuracy.

As a result, the ink channel can be formed with high precision even if the partition walls of the ink channel have thin parts and thick parts.

Further, even when the height to width ratio of the liquid path is large, the partition wall is not lost during development and no liquid path remains, increasing the degree of freedom in designing the ink liquid path.

This makes it possible to form the ink liquid path as wide as possible within the predetermined liquid path bits, so it is possible to provide a high-performance inkjet recording head with low fluid resistance in the liquid path.

Furthermore, since the shape of the ink liquid path can be determined with one exposure, manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. IA to FIG. 9 show an embodiment of the manufacturing method according to the present invention, of which FIGS. 1A, 2, 3A,
Figures 4^, 5, and 6A are cross-sectional views showing the steps of the manufacturing method in this embodiment, Figure IB is a plan view corresponding to Figure 18, and Figure 3B is a sectional view corresponding to Figure 3.
FIG. 4B is a plan view corresponding to FIG. 4A, FIG. 6B is a plan view of the photomask used in this example, and FIGS. 7A and 7B are respectively FIG. 8 is a perspective view of the inkjet recording head created in this example. FIG. 9 is a plan view of the ink path formed in the above steps. 11 is a plan view showing the ink liquid path in the second embodiment of the invention. FIG. 11 is a plan view showing the process of forming the ink liquid path shown in FIG. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Heater 3... Electrode, 4... Antioxidation layer, 5... Anti-cavitation layer, 6... Metal film for increasing reflectance, 7... Ink-resistant layer, 8... Cured resin film, 9... Ink liquid path, IO... Ink liquid path cover, l5... Barrier, 20... Photomask, 9l... Ink liquid chamber , 92... Ink discharge port, 93... Ink supply port. Figure IB Figure 2 Figure 3A Figure 4A Figure 5 Figure 6A Figure 8

Claims (1)

[Scope of Claims] 1) An ejection port provided for ejecting ink to form ink droplets by the action of thermal energy, an ink liquid path communicating with the ejection port, and an ink liquid path provided in the ink liquid path. an ejection energy generating element that generates the thermal energy, and a wall forming the ink liquid path is formed by patterning a photosensitive resin layer provided on a substrate. . A method for manufacturing an inkjet recording head, characterized in that the reflectance in the patterning of the substrate is varied depending on the width of the wall. 2) The method of manufacturing an inkjet recording head according to claim 1, wherein the reflectance of the substrate is low in a wide portion of the wall and high in a narrow portion of the wall. 3) Manufacturing the inkjet recording head according to claim 1 or 2, wherein when patterning the photosensitive resin layer to form the wall of the ink liquid path, the exposure amount of the patterning is made uniform. Method.