JP2018144384A - Base plate and method of manufacturing liquid discharge head - Google Patents

Abstract

An adhesive is less likely to remain on a substrate when the substrate is peeled off from a protective substrate. A substrate 30 and a protective substrate 23 are bonded together through a foamable double-sided tape 31, and a predetermined process is performed on the substrate 30 to which the protective substrate 23 is bonded. After the predetermined processing is performed, the double-sided tape 31 is foamed to separate the protective substrate 23 and the double-sided tape 31, and the double-sided tape 31 and the substrate 30 from which the protective substrate 23 is separated are separated. The surface of the double-sided tape 31 that contacts the substrate 30 has a lower foamability than the surface that contacts the protective substrate 23. [Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a substrate, and more particularly to a method for manufacturing a liquid discharge head including a discharge port forming member in which discharge ports are formed.

In general, a liquid ejection head is joined to an ejection port forming member formed with a plurality of ejection ports for ejecting ink droplets, and a pressure chamber is formed between the ejection port forming member and the ejection port forming member. And a pressure chamber substrate. The discharge port forming member includes a through hole (hereinafter referred to as a discharge flow channel) in which one end communicates with the pressure chamber and the other end has a discharge port. A drive unit such as a piezoelectric element is formed on the pressure chamber substrate. By driving the drive unit to apply pressure to the ink in the pressure chamber, ink droplets are ejected from the selected ejection ports.
In recent years, the demand for the print quality of the liquid ejection head has increased further, and further improvement in ejection performance has been demanded. In order to improve the discharge performance, for example, it is desirable to adjust the flow path resistance of the discharge flow path of the discharge port forming member. Therefore, the thickness of the discharge port forming member is adjusted by grinding or polishing to optimize the channel length of the discharge channel (Patent Documents 1 and 2).

  In the manufacturing method of the liquid discharge head described in Patent Documents 1 and 2, a protective substrate is attached in advance to the discharge port forming member in order to protect the discharge port forming member that is thinned by grinding or polishing. After completion, the discharge port forming member is peeled from the protective substrate. The discharge port forming member is affixed to the protective substrate with a foamable double-sided tape so that the discharge port forming member is not cracked or cracked when the thinned discharge port forming member is peeled off from the protective substrate. The foamable double-sided tape has a self-peeling layer that foams at least on one side by light or heat. The self-peeling layer is also called a foamable adhesive layer. By irradiating the double-sided tape with light or heat and growing bubbles in the self-peeling layer, interfacial peeling occurs between the double-sided tape and the discharge port forming member. Accordingly, the discharge port forming member can be easily separated from the protective substrate with a slight external force. Therefore, defects such as wafer cracks and cracks due to releasability degradation due to re-adhesion at the interface of the release layer are less likely to occur, and productivity and yield can be improved at the same time. As double-sided foam tape, a double-sided UV (ultraviolet) foaming type (Patent Document 1), a single-sided thermal foaming type (Patent Document 2), and the like are known. Also known is a method (Patent Document 3) in which a foamable release layer and a resin layer are coated instead of a double-sided tape.

JP 2009-6501 A JP 2000-94695 A JP 2007-253608 A

  A substrate (referred to as a first substrate) that performs processing such as thinning with a protective substrate attached, such as a discharge port forming member, is attached to the protective substrate with foaming double-sided tape, It is easy to remove the protective substrate. However, there is a problem that the adhesive contained in the foamable adhesive layer tends to remain on the first substrate after the double-sided tape is peeled off. In the manufacturing methods described in Patent Documents 1 and 2, since the double-sided tape is pasted so that the foamable adhesive layer is in contact with the discharge port forming member, the adhesive is used when the first substrate is peeled from the protective substrate. Tends to remain on the first substrate.

  An object of the present invention is to provide a method for manufacturing a substrate in which an adhesive is unlikely to remain on the first substrate when the first substrate is peeled from the protective substrate.

  The substrate manufacturing method of the present invention includes bonding a first substrate and a protective substrate through a double-sided tape having foamability, and performing predetermined processing on the first substrate to which the protective substrate is bonded. After the predetermined processing, the double-sided tape is foamed to separate the protective substrate and the double-sided tape; and the double-sided tape from which the protective substrate is separated and the first substrate are separated. doing. The surface of the double-sided tape that contacts the first substrate is less foamable than the surface that contacts the protective substrate.

  According to the present invention, since the surface of the double-sided tape that contacts the first substrate has less foaming than the surface that contacts the protective substrate, the adhesive is applied to the first substrate when the first substrate is peeled off from the protective substrate. It is hard to remain.

It is a typical longitudinal cross-sectional view of an example of the liquid discharge head to which this invention is applied. It is a manufacturing process figure of the liquid discharge head concerning an example. FIG. 3 is a manufacturing process diagram showing a continuation of FIG. 2;

  FIG. 1 schematically shows an example of a liquid discharge head 1 manufactured by the manufacturing method according to the present invention in a longitudinal section. FIG. 1 shows a piezoelectric liquid ejection head using a piezoelectric piezoelectric body, but the present invention is not limited to the piezoelectric system, and can be widely applied to inkjet heads having the ejection port forming member 4. it can. The liquid ejection head 1 includes a pressure chamber substrate 2 on which a pressure chamber 11 in which ink is stored is formed, an actuator 3, and an ejection port forming member 4. The pressure chamber substrate 2 is located between the actuator 3 and the discharge port forming member 4. An ink-resistant protective film (not shown) is formed at a portion where the ink in the pressure chamber 11 contacts. The actuator 3 has a structure in which a lower electrode 13, a piezoelectric body 14, and an upper electrode 15 are laminated on a diaphragm 12. The discharge port forming member 4 is made of silicon. The discharge port forming member 4 is formed with a discharge channel 17 penetrating the discharge port forming member 4 at a position facing the pressure chamber 11. One end of the discharge channel 17 communicates with the pressure chamber 11, and the other end is a discharge port 17a for discharging ink. A first ink-resistant protective film 18 is formed on the surface of the discharge port forming member 4 facing the pressure chamber 11, and a second ink-resistant protective film 19 is formed on the back surface of this surface, that is, the surface where the discharge port 17 a is opened. A third ink-resistant protective film 20 is formed on the inner wall of the discharge channel 17. The first to third ink-resistant protective films 18, 19, and 20 can be formed of silicon oxide, silicon nitride, tantalum oxide, or the like that is resistant to alkaline ink. The second ink resistant protective film 19 is covered with a water repellent film 21. When a pulse voltage is applied between the upper electrode 15 and the lower electrode 13, the piezoelectric body 14 is deformed and the diaphragm 12 is bent. As a result, the pressure in the pressure chamber 11 changes, and ink is ejected from the ejection port 17a.

Next, with reference to FIGS. 2 and 3, a method for manufacturing the liquid discharge head 1 described above will be described based on an embodiment.
First, as shown in FIG. 2A, an SOI (Silicon on Insulator) substrate 5 was prepared. The SOI substrate 5 is inserted between the first silicon layer 16 that is the main part of the discharge port forming member 4, the second silicon layer 22 that is removed in a later step, and the pair of silicon layers 16 and 22. And a first silicon oxide layer 28 to be the first ink-resistant protective film 18. The second silicon layer 22 is a handle layer of the SOI substrate 5. The thickness of the first silicon layer 16 is 10 μm, the thickness of the second silicon layer 22 is 525 μm, and the thickness of the first silicon oxide layer 28 is 0.5 μm. The surface of the first silicon layer 16 opposite to the first silicon oxide layer 28 is a first surface 16a where the discharge port 17a is formed.

  Next, as shown in FIG. 2B, the first recess 24 that becomes the discharge flow path 17 in the subsequent process was formed in the first silicon layer 16. Specifically, a resist pattern was formed on the first surface 16a of the first silicon layer 16, and a through-hole was formed in the first silicon layer 16 by deep silicon RIE (deep-RIE). Subsequently, the first silicon oxide layer 28 was dry-etched to form the first recess 24, and the resist was removed. The diameter of the first recess 24 (that is, the discharge channel 17) was 20 μm. The dry-etched first silicon oxide layer 28 becomes the first ink-resistant protective film 18.

  Next, as shown in FIG. 2C, a second ink-resistant protective film 19 was formed on the first surface 16a. In this example, a silicon oxide layer having a thickness of 0.2 μm was formed by a thermal oxidation process. At the same time, a third ink-resistant protective film 20 made of silicon oxide was also formed on the side wall of the first recess 24, and a silicon oxide layer 29 was also formed on the bottom of the first recess 24.

  Next, as shown in FIG. 2D, a water repellent film 21 was formed on the second ink-resistant protective film 19. The water repellent film 21 is formed of a compound containing fluorine atoms by a film forming method such as spin coater, dipping, or vacuum deposition. In this example, a fluorine-containing film was formed by vacuum deposition. The water repellent film 21 also enters the first recess 24 and is also formed on the third ink-resistant protective film 20 and the silicon oxide layer 29. Through the above steps, the first concave portion 24 is formed in the SOI substrate 5, and the first substrate 30 in which the second ink-resistant protective film 19 and the water repellent film 21 are formed on the first surface 16a is formed. .

  Next, as shown in FIG. 2 (e), the first substrate 30 and the protective substrate 23 were attached using a foamable double-sided tape 31. The first surface 30 a (that is, the surface of the water repellent film 21) on which the first recess 24 of the first substrate 30 is formed faces the protective substrate 23. The protective substrate 23 is a glass substrate having a thickness of 525 μm. The foamable double-sided tape 31 generally has a foamable adhesive layer that foams by UV light or heat on one surface of a substrate (not shown), and a non-foamable material that does not have foamability on the other surface of the substrate. An adhesive layer is formed. As the non-foaming pressure-sensitive adhesive layer, a pressure-sensitive pressure-sensitive adhesive or a UV curable pressure-sensitive adhesive is used. In this embodiment, the foamable adhesive layer 32 is affixed so as to be in contact with the protective substrate 23, whereby the protective substrate 23 can be lifted and peeled off as described later. As the double-sided tape 31, Riva Alpha 3195V, which is a foamable heat-releasable double-sided tape manufactured by Nitto Denko Corporation, is used. The first substrate 30 was attached so as to be in contact with the substrate. That is, the non-foamable pressure-sensitive adhesive layer 33 has a non-foamable adhesive surface that is in contact with the first surface 30 a of the first substrate 30. Riva Alpha is composed of a base material, a heat-foaming foaming adhesive layer formed on one side of the base material, and a pressure-sensitive non-foaming adhesive layer formed on the other side of the base material. The thermal peeling temperature is 170 ° C. In addition, NWS-U228F manufactured by Nitto Denko Corporation, which includes a heat-foamable foamable adhesive layer and a UV curable nonfoamable adhesive layer, a UV foamable foamable adhesive layer and a UV curable nonfoamable adhesive layer SELFA manufactured by Sekisui Chemical Co., Ltd. can also be used.

  Instead of the double-sided tape 31, a resin layer and a foamable release layer can be coated. For example, in FIG. 2E, if the resin layer and the foaming release layer are applied in this order to the first surface 30a (the surface of the water repellent film 21) of the first substrate 30, the function equivalent to that of the double-sided tape 31 is achieved. An adhesive layer having is obtained. However, in this method, when the resin layer is peeled off, the peeled resin layer tends to remain on the first substrate 30, and an additional step for removal is required. Further, when the resin is applied to the water repellent film 21, the resin layer is repelled by the water repellent film 21, and it is difficult to apply the resin layer uniformly. Further, the resin layer flows into the discharge port, and a process for removing the resin layer is necessary. The double-sided tape 31 does not have these problems, and is particularly advantageous in that the adhesive of the non-foamable pressure-sensitive adhesive layer 33 does not easily remain on the first substrate 30 (the surface of the water-repellent film 21) after the double-sided tape 31 is peeled off. . If the water-repellent film 21 is omitted, the second ink-resistant protective film 19 comes into contact with the double-sided tape 31, but the same can be said in this case.

  Next, as shown in FIG. 2F, the second silicon layer 22 was removed. Specifically, in FIG. 2E, the entire substrate is inverted so that the protective substrate 23 faces downward, and the second silicon layer 22 is shaved by about 500 μm from the back surface 30b of the first surface 30a (reduction). Meat). Thereafter, the remaining second silicon layer 22 was removed by dry etching using the first ink-resistant protective film 18 (first silicon oxide layer 28) as an etch stop layer. The second silicon layer 22 may use a combination of a wet etching method and a grinder, or a combination of a wet etching method and a dry etching method. After this step, the first substrate 30 becomes thin with a thickness of about 10 μm. However, since it is bonded to the protective substrate 23, there is no problem in handling properties, and there is a possibility of damage during and after grinding. Is also low. At the end of this step, the silicon oxide layer 29 and the water-repellent film 21 formed in FIG. 2C remain at the bottom of the first recess 24, and the first recess 24 is in an unpenetrated state.

  Next, as shown in FIG. 2G, the silicon oxide layer 29 and the water-repellent film 21 at the bottom of the first recess 24 are removed, and the discharge channel 17 is formed through the first recess 24. . In order to prevent the third ink-resistant protective film 20 formed on the side wall of the first recess 24 from being removed by etching, the silicon oxide layer 29 was removed by anisotropic dry etching. Simultaneously with the silicon oxide layer 29, the first ink-resistant protective film 18 is also etched. For this reason, the silicon oxide layer 29 (second ink resistant protective film 19) is formed so that the first ink resistant protective film 18 remains on the first surface 30a when the silicon oxide layer 29 is removed. It is desirable to form it thinner than the one ink-resistant protective film 18. In order to remove the silicon oxide layer 29 and the water-repellent film 21 in the first recess 24, it is possible to perform anisotropic etching while protecting the portions other than the first recess 24 with a resist mask.

Next, as shown in FIG. 3 (h), the water repellent film 21 adhered to the side wall of the discharge channel 17 was removed. O ₂ plasma treatment was performed from the opening of the discharge channel 17 to decompose and remove the water-repellent film 21 adhering to the side wall of the discharge channel 17. The surface of the third ink-resistant protective film 20 appears on the side wall of the discharge flow path 17 so that the discharge flow path 17 can be protected from alkaline ink. The water repellent film 21 on the first surface 30 a is protected by a double-sided tape 31 and a second ink-resistant protective film 19. The discharge port forming member 4 is formed by the above process.

  Next, as shown in FIG. 3 (i), the second recess 26 and the flow path (not shown) forming the pressure chamber 11 are formed in a state where the discharge port forming member 4 is bonded to the protective substrate 23. The formed pressure chamber substrate (second substrate) 2 was bonded to the discharge port forming member 4 to form a bonded body 27. An actuator 3 is formed on the pressure chamber substrate 2 in advance. An epoxy adhesive 25 is applied to a portion of the pressure chamber substrate 2 facing the discharge port forming member 4, and the second recess 26 faces the back surface 30 b of the first substrate 30, that is, the first ink-resistant protective film 18. It was aligned with the discharge port forming member 4 in the direction, and heat-bonded at 100 ° C. for 1 hour. As a result, the second recess 26 is covered with the discharge port forming member 4 except for the discharge flow path 17, and the pressure chamber 11 in which ink stays is formed.

  Next, as shown in FIG. 3 (j), the joined body 27 was placed on a hot plate 35 at 170 ° C. Bubbles 321 are generated in the foamable adhesive layer 32, and the protective substrate 23 is in a floating state. Next, as shown in FIG. 3K, the protective substrate 23 and the double-sided tape 31 are separated. The double-sided tape 31 remains attached to the discharge port forming member 4 due to the adhesive force of the non-foaming adhesive layer 33. Since the discharge port forming member 4 is not in direct contact with the foamable adhesive layer 32, the foaming pressure is not directly applied to the discharge port forming member 4, but is only indirectly applied via the double-faced tape 31. Therefore, even if the discharge port forming member 4 is thin, the possibility of breakage due to foaming is reduced. Before foaming the foamable adhesive layer 32, the adhesion between the water repellent film 21 and the non-foamable adhesive layer 33 of the discharge port forming member 4 and the interface between the foamable adhesive layer 32 and the protective substrate 23 are high. , Almost no air bubbles. That is, these interfaces are in the same state as when the discharge port forming member 4 and the non-foaming adhesive layer 33 and the foaming adhesive layer 32 and the protective substrate 23 are adsorbed to each other in a vacuum state. It is in a state where it cannot be peeled off. However, since bubbles 321 are generated in the foamable adhesive layer 32 by heating, the vacuum state at the interface between the foamable adhesive layer 32 and the protective substrate 23 is broken, and the protective substrate 23 can be easily peeled from the double-sided tape 31. As can be understood from the above, it is difficult to peel the protective substrate 23 from the double-sided tape 31 when there is no foamable adhesive layer 32. This is because it is difficult to break the vacuum state at the interface of the double-sided tape in a state where the discharge port forming member 4 and the protective substrate 23 are joined by the non-foaming adhesive layer of the double-sided tape. This is because it cannot be peeled off while rolling.

  Next, as shown in FIG. 3L, the discharge port forming member 4 and the double-sided tape 31 are separated. As shown in FIG. 3 (m), the double-sided tape 31 and the discharge port forming member 4 are completely separated. Since the non-foaming pressure-sensitive adhesive layer 33 is in contact with the discharge port forming member 4 (water repellent film 21), the pressure-sensitive adhesive remaining on the discharge port forming member 4 is reduced. In addition, the interface between the discharge port forming member 4 and the non-foaming adhesive layer 33 is generally maintained in a vacuum state, but since the protective substrate 23 has already been peeled off, the double-sided tape 31 is attached from the end as shown in the figure. It can be easily peeled while being rolled.

  In the embodiment described above, the double-sided tape 31 is applied to the first substrate 30, but the present invention can also be applied to the case where the double-sided tape 31 is applied to another substrate and the substrate is subjected to predetermined processing. . Moreover, although the double-sided tape 31 provided with the non-foaming pressure-sensitive adhesive layer 33 on one side is used in this embodiment, a double-sided tape 31 having a difference in foamability on both sides may be used. In this case, the protective substrate 23 and the first substrate 30 are arranged such that the surface with low foamability contacts the substrate to be protected (for example, the first substrate 30 of the embodiment) and the surface with high foamability contacts the protective substrate 23. Can be bonded with a double-sided tape 31.

  The liquid discharge head manufactured according to this example was excellent in ink discharge stability and was capable of recording an image with high accuracy. The present invention can be widely used not only for recording images but also for industrial applications such as drawing a wiring pattern containing a conductive material to form a wiring pattern.

23 protective substrate 30 first substrate 31 double-sided tape 32 foaming adhesive layer 33 non-foaming adhesive layer

Claims (5)

Bonding the first substrate and the protective substrate through a double-sided tape having foamability, performing predetermined processing on the first substrate to which the protective substrate is bonded, and performing the predetermined processing And separating the protective substrate and the double-sided tape by foaming the double-sided tape, and separating the double-sided tape and the first substrate from which the protective substrate has been separated. And
The method of manufacturing a substrate, wherein a surface of the double-sided tape that contacts the first substrate has a lower foaming property than a surface that contacts the protective substrate.   The method for manufacturing a substrate according to claim 1, wherein a surface of the double-sided tape that is in contact with the first substrate is an adhesive surface having no foaming property.   A first recess is formed in the first surface of the first substrate before the predetermined processing is performed, and the double-sided tape is bonded to the first surface of the first substrate, and the predetermined surface 3. The substrate manufacturing method according to claim 1, wherein in the processing, the first substrate is thinned from a back surface of the first surface to form a through hole in the first substrate.   After the through-hole is formed, before the protective substrate is separated from the double-sided tape, the second substrate having the second recess is arranged in the direction in which the second recess faces the back surface. The method for manufacturing a substrate according to claim 3, wherein the substrate is bonded to one substrate. A method for manufacturing a liquid discharge head according to the method for manufacturing a substrate according to claim 4,
The first substrate includes an SOI substrate composed of a pair of silicon layers and a silicon oxide layer sandwiched between the pair of silicon layers, and the through hole is a discharge flow path having a discharge port for discharging a liquid. A method for manufacturing a liquid ejection head, wherein the second recess is a pressure chamber in which the liquid is stored.

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