JP5671967B2 - Method for manufacturing piezoelectric element - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric element.

  2. Description of the Related Art Conventionally, a piezoelectric element in which metal electrodes are formed on both surfaces and the exposed side surface of a piezoelectric ceramic is coated with a resin is known. As a manufacturing method of such a piezoelectric element, for example, a manufacturing method as in Patent Document 1 is known. In this manufacturing method, a piezoelectric element substrate is bonded to a base for dicing. After the piezoelectric element substrate is cut by the first dicing, the cut groove is filled with resin and cured. Thereafter, the dicing is performed a second time with a cutting width narrower than that of the first time, so that the piezoelectric element substrate is individualized. Thus, a piezoelectric element whose side surface is coated with a resin can be obtained.

US Pat. No. 6,393,681

  In the conventional manufacturing method, there is a problem that the resin filled in the kerf and the base are firmly bonded, and it is difficult to peel the piezoelectric element without destroying it. That is, when the kerf is filled with resin, the resin is adhered to the table, and if the piezoelectric element is peeled off from the table in such a state, there is a problem that a crack occurs in the piezoelectric element. Therefore, there has been a demand for a manufacturing method that can prevent the occurrence of cracks in the piezoelectric element.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for manufacturing a piezoelectric element capable of preventing the occurrence of cracks.

  The present invention provides a piezoelectric element substrate preparation step for preparing a piezoelectric element substrate having a first surface and a second surface facing each other, and a first tape preparation for preparing a first tape having a first adhesive layer that is cured with ultraviolet light on the surface. A first pasting step of pasting the first tape on the first surface of the piezoelectric element substrate, cutting the piezoelectric element substrate from the second surface side, and removing a part of the first tape from the first adhesive layer side A piezoelectric element substrate cutting step, a second tape preparation step of preparing a second tape having a second adhesive layer that is cured by ultraviolet light on the surface, and a second application for applying the second tape to the second surface of the piezoelectric element substrate An irradiation step of irradiating ultraviolet rays from the first tape side, a first peeling step of peeling the first tape from the piezoelectric element substrate, and a resin filling step of filling the kerf by the piezoelectric element substrate cutting step with a resin , Tree cutting resin from the first side A cutting step, characterized in that it comprises a second separation step of separating the second tape from the piezoelectric element substrate.

  In the manufacturing method according to the present invention, kerfs are formed in the piezoelectric element substrate and the first tape in the piezoelectric element substrate cutting step, and the second tape is attached to the second surface of the piezoelectric element substrate in the second attaching step. Therefore, when the ultraviolet ray is irradiated from the first tape side in the irradiation step, the ultraviolet ray passes through the kerf without being shielded by the piezoelectric element substrate and is irradiated to the second adhesive layer of the second tape. The portion of the second adhesive layer that has been irradiated with ultraviolet rays becomes an adhesive strength reduced portion in which the adhesive strength has decreased. When filling the kerf with resin in the resin filling step, the resin comes into contact with the side surface of the piezoelectric element substrate and the adhesive strength reducing portion. Since the surface of the adhesive strength reduction portion (that is, the interface with the resin) is not a portion processed in the piezoelectric element substrate cutting step, it is not rough and smooth, and the adhesive strength is also reduced. Therefore, in the second peeling step, the resin can be easily peeled from the second tape. This prevents cracks in the piezoelectric element.

  According to the present invention, the occurrence of cracks in the piezoelectric element can be prevented.

It is a perspective view which shows the piezoelectric element manufactured by the manufacturing method which concerns on 1st embodiment of this invention. It is a flowchart of the manufacturing method which concerns on 1st embodiment of this invention. It is the schematic which shows the content of the manufacturing method which concerns on 1st embodiment of this invention. It is the schematic which shows the content of the manufacturing method which concerns on 2nd embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

[First embodiment]
FIG. 1 is a perspective view showing a piezoelectric element 1 manufactured by the manufacturing method according to the first embodiment of the present invention. The piezoelectric element 1 is applied to, for example, a disk device provided with a magnetic disk. That is, in the dual actuator type disk device, the piezoelectric element 1 is used as the second actuator other than the voice coil motor.

As shown in FIG. 1, the piezoelectric element 1 includes a piezoelectric element substrate 2 having a first surface 2a and a second surface 2b facing each other. The piezoelectric element substrate 2 is configured by providing metal electrodes 4 on both surfaces of a piezoelectric ceramic 3. Examples of the material of the piezoelectric ceramic 3 include PZT [Pb (Zr, Ti) O ₃ ], PT (PbTiO ₃ ), PLZT [(Pb, La) (Zr, Ti) O ₃ ], barium titanate (BaTiO ₃ ), and the like. Can be mentioned.

  The first surface 2 a and the second surface 2 b of the piezoelectric element substrate 2 are covered with the metal electrode 4. The four side surfaces 2c of the piezoelectric element substrate 2 are not covered with the metal electrode 4, and the piezoelectric ceramic 3 is exposed. The side surface 2 c is covered with the resin 5. An epoxy resin is used as the material of the resin 5. In addition to the epoxy resin, a thermosetting resin such as a urethane resin can be used. Moreover, ultraviolet curable resin, such as an epoxy acrylate resin and a urethane acrylate resin, can also be used. A hot melt resin such as polyvinyl acetate may also be used.

  Next, with reference to FIG.2 and FIG.3, the manufacturing method of the piezoelectric element 1 which concerns on 1st embodiment of this invention is demonstrated.

  As shown in FIG. 2, the process is started from a piezoelectric element substrate preparation step (step S1) for preparing the piezoelectric element substrate 2 before cutting. The piezoelectric element substrate 2 in the piezoelectric element substrate preparation step S1 is a state in which a plurality of individual piezoelectric element substrates 2 are connected, and is formed in a plate shape. Metal electrodes 4 are formed on the first surface 2 a and the second surface 2 b of the piezoelectric element substrate 2 by sputtering or the like. Next, a first tape preparation step (step S2) for preparing the first tape 11 made of an ultraviolet curable dicing tape is executed. The 1st tape 11 has the 1st adhesion layer 11a hardened by ultraviolet rays on the surface.

  Next, the 1st sticking process (step S3) which affixes the 1st tape 11 on the 1st surface 2a of the piezoelectric element board | substrate 2 is performed. In the first attaching step S3, the first surface 2a of the piezoelectric element substrate 2 is attached to the first adhesive layer 11a of the first tape 11 (see FIG. 3A).

  Next, a piezoelectric element substrate cutting step (step S4) for cutting the piezoelectric element substrate 2 is performed. In the piezoelectric element substrate cutting step S4, dicing is performed by the blade W1 from the second surface 2b side of the piezoelectric element substrate 2 to form a cut groove CH1 (see FIG. 3B). By this dicing, the piezoelectric element substrate 2 is cut and the first tape 11 is also half cut, and a part of the first tape 11 is removed from the first adhesive layer 11a side. A side surface 2 c is formed on the piezoelectric element substrate 2. The thickness of the blade W1 (that is, the width of the cut groove CH1) is set to 40 to 200 μm, for example. The depth of the half cut of the first tape 11 is not particularly limited, and in the subsequent ultraviolet irradiation step S7, the ultraviolet light can pass through the first tape 11 to cure the second adhesive layer 12a of the second tape 12. Any depth can be used. More preferably, the depth is such that the first adhesive layer 11a is completely removed at the kerf CH1.

  Next, a second tape preparation step (step S5) for preparing the second tape 12 made of an ultraviolet curable dicing tape is executed. The 2nd tape 12 has the 2nd adhesion layer 12a hardened by ultraviolet rays on the surface. Next, the 2nd sticking process (step S6) which sticks the 2nd tape 12 on the 2nd surface 2b of the piezoelectric element substrate 2 is performed. In the second attaching step S6, the second surface 2b of the piezoelectric element substrate 2 is attached to the second adhesive layer 12a of the second tape 12 (see FIG. 3C).

  Next, an ultraviolet irradiation process (step S7) is performed in which ultraviolet light is irradiated from the first tape 11 side to the piezoelectric element substrate 2 to which the tapes 11 and 12 are attached. In the ultraviolet irradiation step S7, ultraviolet rays are irradiated from the back side of the first tape 11 (see FIG. 3C). As a result, the first adhesive layer 11a of the first tape 11 has a reduced adhesive force and can be peeled off. Further, since the ultraviolet rays are not shielded by the piezoelectric element substrate 2 at the position of the kerf CH1, the ultraviolet rays reach the second adhesive layer 12a of the second tape 12. At a position corresponding to the kerf CH1, an adhesive strength reduction portion 12b in which the adhesive strength of the second adhesive layer 12a is reduced by ultraviolet irradiation is formed. After the ultraviolet irradiation step S7, a first peeling step (step S8) for peeling the first tape 11 from the piezoelectric element substrate 2 is performed.

  Next, a resin filling step (step S9) for filling the kerf CH1 with the resin 5 is performed. As a filling method, a method using printing or a dispenser is employed. After covering the side surface 2c of the piezoelectric element substrate 2 by filling the entire cut groove CH1 with the resin 5, the resin 5 is cured (see FIG. 3D). The resin 5 also comes into contact with the adhesive strength reduction portion 12 b of the second tape 12.

  Next, a resin cutting step (step S10) for cutting the resin 5 from the first surface 2a side is performed. In the resin cutting step S10, dicing is performed by the blade W2 from the first surface 2a side of the piezoelectric element substrate 2 to form a cut groove CH2 (see FIG. 3E). By this dicing, the resin 5 is cut and the piezoelectric element substrate 2 is individualized with the side surface 2 c covered with the resin 5. At this time, the second tape 12 is also half-cut. The thickness of the blade W2 (that is, the width of the cut groove CH2) is smaller than that of the blade W1, and is set to 20 to 100 μm, for example. Thereby, the thickness of the resin 5 covering the side surface 2c of the piezoelectric element substrate 2 becomes 10 to 50 μm.

  Next, the 2nd peeling process (step S11) which peels the 2nd tape 12 from the piezoelectric element board | substrate 2 is performed. At this time, the surface of the adhesive strength reduction part 12b which is a part which contacts the resin 5 among the 2nd tape 12 is flat, and the adhesive force is also falling by ultraviolet irradiation. Therefore, the individualized piezoelectric element substrate 2 can be easily peeled from the second tape 12. By separating the second tape 12, the individualized piezoelectric element 1 is completed (see FIG. 3F), and the process shown in FIG. 2 is completed.

  As described above, in the manufacturing method according to the first embodiment, the kerf CH1 is formed in the piezoelectric element substrate 2 and the first tape 11 in the piezoelectric element substrate cutting step S4, and the second of the piezoelectric element substrate 2 in the second pasting step S6. The 2nd tape 12 is affixed on the surface 2b. Therefore, when the ultraviolet ray is irradiated from the first tape 11 side in the ultraviolet ray irradiation step S7, the ultraviolet ray passes through the kerf CH1 without being shielded by the piezoelectric element substrate 2, and is irradiated to the second adhesive layer 12a of the second tape 12. Is done. The portion of the second adhesive layer 12a that has been irradiated with ultraviolet rays becomes the adhesive strength reduced portion 12b in which the adhesive strength has decreased. When filling the kerf CH1 with the resin 5 in the resin filling step S9, the resin 5 comes into contact with the side surface 2c of the piezoelectric element substrate 2 and the adhesive strength reduction portion 12b. Since the surface of the adhesive strength reduction portion 12b (that is, the interface with the resin 5) is not a portion processed in the piezoelectric element substrate cutting step S4, it is not rough and smooth, and the adhesive strength is also reduced. Therefore, the resin 5 can be easily peeled from the second tape 12 in the second peeling step S11. As a result, the occurrence of cracks in the piezoelectric element 1 is prevented.

[Second Embodiment]
Next, with reference to FIG. 4, the manufacturing method which concerns on 2nd embodiment of this invention is demonstrated. The manufacturing method according to the second embodiment is mainly different from the first embodiment in that a release agent 20 is applied to the first surface 2 a of the piezoelectric element substrate 2.

  In the piezoelectric element substrate preparation step S <b> 1, the release agent 20 is applied to the first surface 2 a of the piezoelectric element substrate 2. As the release agent 20, fluorine type or silicone type can be used. However, since the silicone type release agent may contaminate the disk due to volatilization of low molecular weight siloxane, the use of the fluorine type release agent is required. Is preferred. The solvent for the release agent can be either organic or aqueous. The release agent 20 is applied by a method such as spraying or brushing. In the step after the piezoelectric element substrate preparation step S1, as shown in FIG. 4, the same steps as in the first embodiment are performed in a state where the release agent 20 exists on the first surface 2a of the piezoelectric element substrate 2. Is done.

  In the first embodiment, as shown in FIGS. 3D to 3F, when the resin 5 is filled into the kerf CH1, a part of the resin 5 crawls up to the first surface 2a of the piezoelectric element substrate 2. A part of the metal electrode on the first surface 2 a is covered with the resin 5. On the other hand, in 2nd embodiment, as shown in FIG.4 (d), since the mold release agent 20 exists in the 1st surface 2a, the resin 5 cannot adhere to the 1st surface 2a. Therefore, as shown in FIGS. 4D to 4F, the resin 5 can cover only the side surface 2c without covering the metal electrode of the first surface 2a.

  The present invention is not limited to the embodiment described above. For example, the shape of the piezoelectric element manufactured by the manufacturing method of the present invention is not limited to that shown in FIG. 1, and can be appropriately changed according to the location to which the piezoelectric element is applied.

[First embodiment]
Gold electrodes are formed on both sides of a piezoelectric element substrate (using PZT [Pb (Zr, Ti) O ₃ ]) having a thickness of 0.1 mm and 10 cm square by sputtering. A first tape made of an ultraviolet curable dicing tape is attached to the first surface of the piezoelectric element substrate. The piezoelectric element substrate is diced to a size of 1.1 mm × 1.4 mm with a blade having a thickness of 100 μm. A second tape made of an ultraviolet curable dicing tape is attached to the second surface of the piezoelectric element substrate, and ultraviolet rays are irradiated from the first surface side. The first tape is peeled off, and the one-part epoxy resin is filled into the kerf formed by dicing by printing. Curing is performed at 100 ° C. for 1 hour. After that, dicing is again performed with a blade having a thickness of 50 μm to make individual pieces. When trying to peel the piezoelectric element created by the manufacturing method according to the first embodiment from the second tape, the epoxy resin and the second tape are not firmly bonded, without causing cracks in the piezoelectric element, It was easily peeled off.

[Second Example]
Gold electrodes are formed on both sides of a piezoelectric element substrate (using PZT [Pb (Zr, Ti) O ₃ ]) having a thickness of 0.1 mm and 10 cm square by sputtering. A fluorine release agent is applied to the first surface of the piezoelectric element substrate by spraying and dried. A first tape made of an ultraviolet curable dicing tape is attached to the first surface of the piezoelectric element substrate. The piezoelectric element substrate is diced to a size of 1.1 mm × 1.4 mm with a blade having a thickness of 100 μm. A second tape made of an ultraviolet curable dicing tape is attached to the second surface of the piezoelectric element substrate, and ultraviolet rays are irradiated from the first surface side. The first tape is peeled off, and the one-part epoxy resin is filled with a dispenser into the kerf formed by dicing. Curing is performed at 100 ° C. for 1 hour. The mold release agent is removed by cleaning the first surface of the piezoelectric element substrate with an organic solvent. After that, dicing is again performed with a blade having a thickness of 50 μm to make individual pieces. When trying to peel the piezoelectric element created by the manufacturing method according to the second embodiment from the second tape, the epoxy resin and the second tape are not firmly bonded, without causing cracks in the piezoelectric element, It was easily peeled off.

[Comparative example]
A piezoelectric element substrate (using PZT [Pb (Zr, Ti) O ₃ ]) having a thickness of 100 μm and having gold electrodes formed on both sides is attached to a dicing tape. The piezoelectric element substrate is diced to a size of 1.1 mm × 1.4 mm with a blade having a thickness of 100 μm. The one-component epoxy resin is printed so as to cover the kerf formed by dicing, and the one-component epoxy resin is filled. Curing is performed at 100 ° C. for 1 hour. The product is diced with a blade having a thickness of 50 μm. When an attempt was made to peel off the piezoelectric element created by the manufacturing method according to the comparative example from the dicing tape, the epoxy resin and the dicing tape were firmly adhered to each other, so that the piezoelectric element was cracked and destroyed.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element, 2 ... Piezoelectric element board | substrate, 2a ... 1st surface, 2b ... 2nd surface, 2c ... Side surface, 5 ... Resin, 11 ... 1st tape, 11a ... 1st adhesion layer, 12 ... 2nd tape, 12a ... 2nd adhesion layer.

Claims (1)

Preparing a piezoelectric element substrate having a first surface and a second surface facing each other and having a metal electrode formed thereon;
A first tape preparation step of preparing a first tape having a first adhesive layer that is cured by ultraviolet rays on the surface;
A first attaching step of attaching the first tape to the first surface of the piezoelectric element substrate;
Cutting the piezoelectric element substrate from the second surface side, and removing a part of the first tape from the first adhesive layer side; and
A second tape preparation step of preparing a second tape having a second adhesive layer that is cured by ultraviolet rays on the surface;
A second attaching step of attaching the second tape to the second surface of the piezoelectric element substrate;
An irradiation step of irradiating ultraviolet rays from the first tape side,
A first peeling step of peeling the first tape from the piezoelectric element substrate;
A resin filling step of filling a resin into a kerf by the piezoelectric element substrate cutting step;
A resin cutting step of cutting the resin from the first surface side;
A second peeling step of peeling the second tape from the piezoelectric element substrate.

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