JPH04158045A - Manufacture of ink jet recording head - Google Patents

Abstract

PURPOSE:To suppress heap of uppermost resin layer as low as possible by forming a thermosetting resin layer through patterning of a plurality of layers. CONSTITUTION:A heat accumulation layer 8 is provided on a heater substrate 1; a resistor layer 2 is formed thereon through deposition or sputtering and then subjected to patterning to form an individual electrode 3a and a common electrode 3b. Resistor protective layers 5, 6 and an electrode protective layer 7 are further formed thereon, followed by patterning to form bit layers 41a, 41b with thermosetting resin. Upon finish of exposure, the thermosetting resin 41b is removed from unexposed part thus forming a desired pattern. When prebake is performed, some degree of irregularities corresponding to the pattern of the thermosetting resin layer 41a are formed on the surface of a thermosetting resin layer 42b. Unexposed part 42b is then dissolved and removed and a desired pattern is formed of a thermosetting resin layer 42a. Thus formed pattern has a round profile. The thermosetting resin layers 41a, 42a are finally set through heat treatment.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method of manufacturing an inkjet recording head in which at least a portion of the ink flow path and other parts that come into contact with ink are made of a thermosetting resin. be.

(Prior Art) Conventionally, for inkjet recording heads, materials for forming parts that come in contact with ink, such as ink channels, have been used in terms of cost, productivity, and processability, as described in Japanese Patent Application Laid-Open No. 57-43876. A photosensitive solid film type mainly composed of acrylic resin has been widely used.

However, in inkjet recording heads whose ink flow path walls are formed using a cured film of photosensitive resin mainly composed of acrylic resin, when the recording time becomes long, ink may not be ejected from the nozzles or ejected ink droplets may occur. Recording media (paper, etc.)
There are many aspects that are unsatisfactory regarding the ejection durability of the recording head, such as deterioration of printing position accuracy.
This has been a major obstacle to achieving high reliability of inkjet recording heads and, by extension, inkjet recording methods.

In order to solve such problems, Japanese Patent Application Laid-Open No. 61-249
As described in Japanese Patent No. 767, polyimide resins, polyamide resins, etc. are used as materials for forming parts that come into contact with ink, such as ink flow paths, and as a result, the durability of the inkjet recording head is improved. High reliability can now be achieved.

On the other hand, as described in Japanese Patent Application Laid-Open No. 62-33648, a recess (the heating element is disposed within this recess) is used to limit the bubble growth area and to prevent air from being drawn in from the nozzle. Thermosetting resins are also effectively used to form the recesses (these recesses are called bits).

The method for forming such a thermosetting resin layer is usually to apply a desired resin varnish to a substrate such as a glass ceramic or Si wafer, form a desired pattern, and then harden it by heat treatment. A method has been adopted to

However, as a matter of course, by performing the heat treatment, the resin layer is thermally shrunk, and as a result, a phenomenon occurs in which the edges of the pattern formed by the resin layer after the heat treatment swell up into a picture frame shape.

FIG. 6 is a model diagram of the phenomenon. In the figure, 1 is a heater substrate, 4 is a resin layer as a bit layer, and 9 is a channel substrate. FIG. , shows the state after heat curing treatment. When the resin layer 4 in the state shown in FIG. 2A is heat-treated at, for example, 400° C., thermal contraction occurs not only in the film thickness direction but also in the planar direction. In addition, curing is
The edge part moves forward. Since the dimensions of the part where the resin layer 4 is in contact with the substrate 1 do not change, a large strain occurs inside the resin layer, and at the end of the resin layer, a raised part a as shown in FIG. It occurs like this.

An example of the degree of excitement will be explained with reference to FIG.

As the resin layer, Probimide (registered trademark) (C
(manufactured by iba-Geigy) and heated at 350° C. for 2 hours. The horizontal axis of the figure is the thickness of the resin layer before curing, and the vertical axis is the thickness D [μm] of the resin layer after curing,
On top of that, the height of the bulge d [μm] is added. It can be seen that the thicker the film, the larger the height d of the bulge, and the greater the tendency.

When such a phenomenon occurs, the following problems occur when assembling an inkjet recording head.

That is, as a method for forming the nozzles of an inkjet recording head, as shown in FIG.
A heat acting part (not shown) is formed thereon, and a bit layer 4 is formed thereon in a desired pattern using the resin described above, and then a channel board is formed in which a nozzle 10, a filter 11, and an ink supply port 12 are formed on this heater board. How to glue 9,
As shown in FIG. 5, a method is adopted in which a partition wall 14 is formed using the above-mentioned resin on a heater substrate 1 on which a heat acting part is formed, and a top plate 13 as an upper substrate is covered thereon to form a nozzle 10. However, in any case, as long as heat treatment is performed in a normal forming method, a phenomenon occurs in which the edges of the pattern are raised in the shape of a frame.

As mentioned above, it is known that the frame-like bulges at the edges of the pattern have a strong correlation with the resin film thickness, and become larger as the resin film becomes thicker. Therefore, if the film thickness is thin, this will not be much of a problem, but if practicality as an inkjet recording head is considered, a relatively thick resin layer of at least 5 to 100 μm is required. It is inevitable that the edges of the frame will bulge out like a picture frame. As a result, the inkjet recording head could not be completely adhered to the channel substrate and the top plate, which lowered the yield and significantly lowered the reliability of the inkjet recording head.

(Problems to be Solved by the Invention) The present invention provides a method for manufacturing an inkjet recording head comprising a substrate in which at least a portion of an ink flow path is formed with a thermosetting resin layer, and a substrate bonded to the substrate. By preventing frame-like bulges that occur at the edges of the pattern formed by thermosetting resin,
It is an object of the present invention to provide a manufacturing method by which a highly reliable inkjet recording head can be obtained.

(Means for Solving the Problems) In the first aspect of the invention, the present invention includes a substrate in which at least a part of an ink flow path is formed with a thermosetting resin layer, and a substrate bonded to the substrate. The method for manufacturing an inkjet recording head is characterized in that the thermosetting resin layer is formed by patterning and overlapping a plurality of layers, and in the second invention, the thermosetting resin layer of the plurality of layers in the first invention is When forming the thermoplastic resin layers by overlapping each other, the lower layer is patterned, and then the upper layer is patterned larger than the lower layer. When forming the curable resin layers by overlapping each other, the lower layer is patterned, and then the upper layer is patterned to be smaller than the lower layer. When forming thermosetting resin layers one on top of the other, the lower layer is patterned and cured, and then the upper layer is formed thinner than the lower layer and patterned.

(Function) According to the method for manufacturing an inkjet recording head according to the present invention, by patterning and overlapping a plurality of thermosetting resin layers, at least the uppermost thermosetting resin layer can be formed before the thermosetting treatment. The edge of the pattern is rounded, or after the lower layer is cured,
By forming the upper layer thinly, the swelling of the uppermost resin layer due to shrinkage during thermosetting can be suppressed to a slight degree.

(Example) In the method for manufacturing an inkjet recording head of the present invention, a thermosetting resin layer is laminated multiple times in a desired pattern to a predetermined thickness, thereby preventing frame-like bulges at the edges of the pattern. We have discovered that this can be done, and the process of one example will be described below.

(2) A desired pattern is formed in advance using a desired material on a substrate such as glass, ceramic, or Si wafer, and a thermosetting resin varnish is applied thereon by a method such as spin cord or roll coating.

■ Perform baking to dry the thermosetting resin varnish.

(2) Expose the thermosetting resin varnish through a mask corresponding to the desired pattern.

■ Develop using a method suitable for thermosetting resin varnish,
Form the desired pattern. When using a thermosetting resin that does not have photosensitivity, after step (1) above, a suitable resist is applied and then exposed and developed.

■ Baking is performed at an appropriate temperature for an appropriate time,
Curing the thermosetting resin.

■Furthermore, a thermosetting resin varnish is applied thereon again using a method such as spin cord or roll coating.

■ Perform baking to dry the thermosetting resin varnish.

■ Repeat the steps from ■ to ■ above. In this case, the exposure pattern is made to have an appropriate dimensional relationship in accordance with the pattern of the previous process.

■ After this, repeat steps from ■ to ■ as many times as necessary.

However, regarding the step (2), it is not necessarily necessary to perform it for each layer, and it may be sufficient to perform it once at the end.

In this way, the thermosetting resin layer obtained has a slight swell at least in the top layer,
This provides good adhesion to the substrate bonded thereto.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a bit part of an inkjet recording head of a type that performs recording by heating ink to generate bubbles and forming ink droplets. In the figure, 1 is a heater substrate, 2 is a resistor layer, 3a is an individual electrode,
3b is a common electrode, 41a, 41b, 42a, and 42b are thermosetting resin layers, 5.6 is a resistor protection layer, 7 is an electrode protection layer, and 8 is a heat storage layer.

First, a heat storage layer 8 is provided on a heater substrate 1 made of a Si wafer, ceramic, glass, etc., and a resistor layer 2 is deposited by vapor deposition, sputtering, etc., and patterned into a desired shape. Next, an electrode layer is deposited and patterned to form individual electrodes 3a,
A common electrode 3b is formed. Furthermore, resistor protection layers 5 and 6
is deposited and patterned. Next, an electrode protective layer 7 is deposited and patterned, and then a bit layer is formed using a thermosetting resin. The thickness of the bit layer is about 5 to 100 μm, more preferably about 20 to 40 μm.

Specific commercially available thermosetting resins suitable for the bit layer include, for example, PIMEL (registered trademark) 06000 (manufactured by Asahi Kasei Corporation), LITHOCOAT (registered trademark) PI-
400T, P knee 410 (manufactured by Ube Industries), 5ele
ctilux® HTR3-200 (Ci
ba-Geigy), Probimide (registered trademark) 337,348.349,412 (Ciba
-Geigy), Photoneece (registered trademark) UR3840, UR3600 (Toshisha), Py
Ralin® PI-2702D (Du
- Photosensitive polyimide varnish such as POnt), P
IQ-6700, PIQ-3200, PIX-3400
, PIX-3500, PIQ-3600゜PIX-81
03, PIX-8203 (manufactured by Hitachi Chemical) Semico
fine (registered trademark) 5p-480 (manufactured by Toshisha),
Pyralin® PI-2525, PI
-2611D, (manufactured by Du-Pont), LITHOC
OAT (registered trademark) 5I-100, 5I-110,
5I-500, 5I-510 (manufactured by Ube Industries), Pro
bimide (registration direction 1111) 293 (Cib
Polyimide varnish such as a-Geigy), LI
Photosensitive polyamide varnish such as THOCOATS (registered trademark) (7) PA-100 (manufactured by Ube Industries, Ltd.) and Pro
bimide (registered trademark) 10.32 (Ciba
- Polyimide amide varnish such as Geigy Co., Ltd.).

In this example, the photosensitive polyimide varnish Pro
We will explain the manufacturing method for the case where the bit layer is composed of two layers using bimide (registered trademark) 348, etc. However, it is noted that any material can be used depending on the type of thermosetting resin used, etc. Needless to say.

First, a photosensitive polyimide varnish is applied using a method such as spin cord or roll coating. The coating conditions at this time are:
The thickness is arbitrarily selected depending on the required thickness, taking into account the shrinkage after heat treatment and the two-layer structure. Note that an adhesion promoter such as aminosilane may be applied before applying the photosensitive polyimide varnish in order to improve the adhesion with the base material. Next, prebaking is performed as necessary. Prebaking conditions are not particularly limited, but in this example, they were set at 110°C for 925 minutes. After the prebaking is completed, exposure is performed through a mask having a desired pattern. The size of the mask was larger than the opening of the target bit. The exposure amount is not particularly limited, but in this example, it is 400 mJ/cm
2 (total exposure amount for wavelengths of 365 nm, 405 nm, and 436 nm). (Figure 1 (A)) After exposure, Probimide (registered trademark) 348
The unexposed portions of the thermosetting resin layer 41b are dissolved and removed using developer solution QZ3301 to form a desired pattern. (Figure 1 (B)) After this, Probi
Rinse liquid QZ331 for mide (registered trademark) 348
1. Rinse with QZ3312.

Next, again as described above, Probimid
e Apply (registered trademark) 348 and pre-bake. At this time, on the surface of the second thermosetting resin layer 42b,
A certain degree of unevenness is formed corresponding to the pattern formed by the first thermosetting resin layer 41a. (Fig. 1 (C)) Generally, polyimide or the like is used to flatten the unevenness of the base, but when the base has irregularities of approximately 5 μm or more as in this example, , unevenness clearly corresponding to the underlying pattern is formed. next,
Perform exposure. The mask used at this time is different from the mask used for the first layer, in which each non-exposed area 42b is smaller than the mask used for the first layer. It was made to be approximately the same size as the opening. This mask is aligned with the first layer pattern and exposed. (FIG. 1(D)) Next, as described above, the non-exposed portion 42b of the second layer is dissolved and removed to form a desired pattern of the thermosetting resin layer 42a. The cross section of the pattern thus obtained has a rounded shape with rounded corners, as shown in FIG. 1(E). Such a cross-sectional shape was obtained by making the surface unevenness caused by forming multiple layers as in this example and by making each unexposed area smaller in the upper layer than in the lower layer. It is.

Finally, the thermosetting resin layer 41a is formed by heat treatment.

42a is cured. The heat treatment conditions are not particularly limited, but in this example, heat treatment conditions range from room temperature to 40°C in vacuum.
The temperature was raised to 00C over 3 hours, heated at 400C for 2 hours, and then slowly lowered to room temperature. When we observed the cross-sectional shape after the heat treatment, we found that in the case where the cross-section before heat treatment was made by the usual method and had the shape as shown in Figure 6(A), when the total thickness of the two layers was approximately 40 μm, the shape after heat treatment was While the cross-sectional shape was raised by about 10 μm at the edge of the pattern (h in FIG. 6(B)), the cross-sectional shape was raised by about 0.5 μm in the case of this example. (Fig. 1 (F)) As shown in 2, the swelling at the edge of the pattern largely depends on the cross-sectional shape of the edge of the pattern before heat treatment. In this case, distortion due to film shrinkage during heat treatment does not occur, and no swelling occurs that would be an obstacle in the bonding process between the heater substrate and the channel substrate, which will be described later.

After the heater substrate 1 thus produced and the channel substrate 9 on which the nozzle 10 and ink reservoir (not shown) and ink supply port 12 for forming an ink flow path are attached are attached in a separate process, dicing is performed. An inkjet recording head as shown in FIG. 4 is manufactured by cutting out the inkjet recording head according to the process.

FIG. 2 is a process diagram for explaining another embodiment of the method for manufacturing an inkjet recording head of the present invention. The conditions for producing the thermosetting resin layer are the same as those explained in FIG. 1, so the explanation thereof will be omitted, and in particular, the patterning of the thermosetting resin will be explained. Further, the same parts as in FIG. 1 are given the same reference numerals and the description thereof will be omitted.

As in FIG. 1, the thermosetting resin is Probimici
e (registered trademark) 348 was used.

First, each layer is formed by a process similar to that described in FIG. 1(A), and then Probimide (registered trademark) 348 is applied as the first thermosetting resin layer, prebaked, exposed, and developed. Accordingly, the thermosetting resin layer 4
1a is formed. In this case, the mask used to form the unexposed portions had approximately the same size as the opening of the intended bit, and was smaller than that described with reference to FIG. 1(A). (FIG. 2(A)) Next, as the second thermosetting resin layer 42b, P
Robimide (registered trademark) 348 is applied, prebaked (FIG. 2(B)), and exposed. The mask used for this exposure is different from the first layer mask, and the unexposed area is one size larger than the mask used for the first layer, and it is aligned with the first layer pattern. and expose. (FIG. 2(C)) Next, development is performed to dissolve and remove the unexposed portion 42b, thereby forming a second thermosetting resin layer 42a. (FIG. 2(D)) The second thermosetting resin layer 42a obtained in this way
The cross section of the pattern is as shown in Figure 2(D).
Its edges are rounded and have a rounded shape. Such a cross-sectional shape was obtained due to the unevenness of the surface caused by forming multiple layers as in this example, and the fact that each unexposed area is set back in the upper layer compared to the lower layer. It is something.

Finally, the thermosetting resin layers 41a and 42a are cured by heat treatment in the same manner as in Example 1. (Fig. 5 (E)) When the cross-sectional shape of the obtained bit layer was observed, it was found that when the total thickness of the two layers was about 40 μm, the bulge was about 0.5 μm.
.mu.m, and no protrusions that would be a hindrance in the bonding process between the heater substrate and the channel substrate occurred.

FIG. 3 is a process diagram for explaining another embodiment of the method for manufacturing an inkjet recording head of the present invention. The conditions for producing the thermosetting resin layer are the same as those explained in FIG. 1, so the explanation thereof will be omitted, and in particular, the patterning of the thermosetting resin will be explained. Further, the same parts as in FIG. 1 are given the same reference numerals and the description thereof will be omitted.

As explained in FIG. 1, the thermosetting resin is Prob.
Imide (registered trademark) 348 was used.

First, after forming each layer in exactly the same manner as the steps explained in FIGS. 1(A) and (B), the first layer of Probimide
(registered trademark) 348 is coated, prebaked, exposed, and developed, but the mask for the unexposed area is approximately the same size as the opening of the target bit, as explained in Fig. 2 (A). Using.

Thereby, the first thermosetting resin layer 41a can be formed. (FIG. 2(A)) Next, heat treatment is performed to harden the thermosetting resin layer 41a. The heat treatment conditions are the same as those described in FIG. The thickness of the thermosetting resin layer 41a after thermosetting is approximately 18μ.
m, and the amount of swelling at the edge of the pattern was about 2 μm. (FIG. 3(A)) Then, again, the thermosetting resin layer 4
2b, Probimide® 348
Spin code and pre-bake.

The spin code conditions were set so that the thickness of the thermosetting resin layer 42b after prebaking was approximately 4 μm. When the surface of the thermosetting resin layer 42b after prebaking was examined, it was found that
Although irregularities were formed corresponding to the pattern of the first thermosetting resin layer 42a, the bulges at the edges of the pattern were absorbed by the flattening effect of the second thermosetting resin layer 42b. Not observed. (Figure 3 (B)) Next.

Perform exposure. The mask at this time may be one in which the size of the unexposed area is different between the first layer and the second layer, as explained in FIGS. , it may be exactly the same as the first layer. Here, align with the pattern of the first layer, and
It was exposed under the same conditions as the layers. (Figure 3(C)) Then,
Development, rinsing, and heat treatment are performed in the same manner as for the first thermosetting resin layer.

Thermosetting resin layers 41a, 41 formed in this way
When we observed B, we found that the film thickness was about 20 μm, and the protrusion at the edge of the pattern was about 0.5 μm (Figure 3 (D)).
), this level of swelling did not pose an obstacle in the bonding process between the heater substrate and the channel substrate. The reason why the swells at the ends of the pattern disappear in this way is that the swells at the ends of the pattern of the first thermosetting resin layer 41a are different from those of the second thermosetting resin layer 41a. 42b, and the heat shrinkage during the second heat treatment occurs only in the second thermosetting resin layer 42a, which has a thickness of about 4 μm. Despite its thickness,
This is because the swelling at the end of the pattern occurs only to the same extent as in the case of a film thickness of 4 μm.

The swelling at the edge of the pattern after heat treatment is shown in Figure 1.
As explained in FIG. 2, it depends not only on the cross-sectional shape before heat treatment, but also on the thickness of the thermosetting resin layer. Therefore, by providing a thin thermosetting resin layer on the heat-treated thermosetting resin layer and performing heat treatment again, the swelling at the pattern ends can be made sufficiently small.

Therefore, empirically speaking, if the thickness of the thermosetting resin layer resin to be heat-treated is 5 μm or less, no swelling will occur that will hinder the bonding process between the heater substrate and the channel substrate. can. However, although the thickness of the bit layer is preferably 20 μm or more, if you try to obtain this with a single layer, it is inevitable that swelling will occur at the edge of the pattern, which will be an obstacle in the above-mentioned bonding process. . However, as in this example,
By configuring the thermosetting resin layer with multiple layers, this swelling can be avoided.

In each of the embodiments described above, the thermosetting resin layer has a two-layer structure, but it is not necessarily limited to two layers, and even if it has three or more layers, it is completely different from the above embodiment You can get the same effect. In addition, although the formation of the thermosetting resin layer has been described with respect to the bit layer, it is not limited to this, and at least a part of the parts that come into contact with ink, such as the ink ejection nozzle and the ink flow path leading thereto, are formed using the thermosetting resin layer. It is clear that the present invention can be widely applied to the case where the structure is formed using:

(Effects of the Invention) As is clear from the above description, according to the present invention, by configuring the thermosetting resin layer with a plurality of layers, a frame-like shape is generated at the end of the pattern of the thermosetting resin layer. Eliminates swelling, improves adhesion between the thermosetting resin layer and top plate, grooved substrate, etc., significantly improves yield, and provides highly reliable inkjet recording with excellent ink ejection durability. There is an effect that can provide the head.

[Brief explanation of the drawing]

1 to 3 are process diagrams for explaining different embodiments of the method for manufacturing an inkjet recording head of the present invention,
4 and 5 are schematic configuration diagrams of an inkjet recording head using a thermosetting resin layer, and FIGS. 6 and 7 are explanatory diagrams of the cured state of the thermosetting resin layer. 1... Heater board, 2... Resistor layer, 3a...
Individual electrode, 3b... common electrode, 41a, 41b, 42
a. 42b...Thermosetting resin layer, 5, 6... Resistor protection layer, 7... Electrode protection layer, 8... Heat storage layer. Patent applicant Fuji Xerox Co., Ltd.

Claims (4)

[Claims] (1) A method for manufacturing an inkjet recording head comprising a substrate on which at least a part of an ink flow path is formed with a thermosetting resin layer, and a substrate bonded to the substrate, in which a plurality of the thermosetting resin layers are formed. A method for manufacturing an inkjet recording head characterized by forming layers by patterning and overlapping them. (2) Inkjet recording according to claim 1, characterized in that when forming a plurality of thermosetting resin layers by overlapping each other, the lower layer is patterned, and then the upper layer is patterned larger than the lower layer. Head manufacturing method. (3) Inkjet recording according to claim 1, characterized in that when forming a plurality of thermosetting resin layers by overlapping each other, the lower layer is patterned, and then the upper layer is patterned to be smaller than the lower layer. Head manufacturing method. (4) When forming a plurality of thermosetting resin layers by overlapping each other, the lower layer is patterned and cured, and then the upper layer is formed thinner than the lower layer and patterned. A method for manufacturing an inkjet recording head according to item 1.