JP5795272B2 - Method for manufacturing ceramic element - Google Patents

Description

  The technology disclosed in this specification relates to a method of manufacturing a ceramic element.

  In the manufacturing process of ceramic elements such as piezoelectric elements, it is generally known to handle a plurality of ceramic substrates by attaching them to an adhesive sheet. In addition, a plurality of ceramic substrates may be transferred from the adhesive sheet to another adhesive sheet. For example, Patent Document 1 discloses a technique for transferring an electronic component from an adhesive sheet to another adhesive sheet.

JP 2004-080868 A

  In a conventional technique for transferring a ceramic substrate from an adhesive sheet (hereinafter referred to as a first adhesive sheet) to another adhesive sheet (hereinafter referred to as a second adhesive sheet), transfer is performed as follows. In the conventional technique, a pressure-sensitive adhesive sheet whose adhesive strength is reduced by heating, such as a thermal foam sheet, is used as the first pressure-sensitive adhesive sheet. Various adhesive sheets are used for the second adhesive sheet. Similarly to the first pressure-sensitive adhesive sheet, the second pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet whose adhesive force is reduced by heating. In the conventional technique, the second pressure-sensitive adhesive sheet is bonded to the surface opposite to the first pressure-sensitive adhesive sheets of the plurality of ceramic substrates bonded to the first pressure-sensitive adhesive sheet. And a 1st adhesive sheet is heated. Thereby, the adhesive force of a 1st adhesive sheet is reduced. Thereafter, the first pressure-sensitive adhesive sheet is peeled from the ceramic substrate. Thereby, a plurality of ceramic substrates are transferred from the first adhesive sheet to the second adhesive sheet.

  However, in recent years, ceramic substrates have become extremely thin. When the thin ceramic substrate is transferred from the first adhesive sheet to the second adhesive sheet by the above-described conventional technique, the ceramic substrate is thin, so that heat is transmitted to the second adhesive sheet when the first adhesive sheet is heated. As a result, the second adhesive sheet is thermally deformed, and a plurality of ceramic substrates cannot be accurately transferred to the second adhesive sheet. That is, the arrangement (pitch, etc.) of the plurality of ceramic substrates changes before and after the transfer.

  There is also a transfer method in which an adhesive sheet whose adhesive strength is reduced by irradiation with ultraviolet rays is used as the first adhesive sheet in place of the adhesive sheet whose adhesive strength is reduced by heating. However, this type of pressure-sensitive adhesive sheet does not lose its adhesive strength even after being irradiated with ultraviolet rays, and a certain level of adhesive strength remains. Therefore, when the first adhesive sheet is peeled off, the ceramic substrate is pushed up from the first adhesive sheet side and pushed up by a pin, so that the contact area between the first adhesive sheet and the ceramic substrate is reduced. Peel off the ceramic substrate. At this time, the push-up pins deform the second adhesive sheet, and the arrangement of the plurality of ceramic substrates changes before and after the transfer. In addition, there is a problem that cracks occur in the ceramic substrate. When a thin ceramic substrate is used, it is difficult to use an adhesive sheet whose adhesive strength is reduced by irradiation with ultraviolet rays as the first adhesive sheet.

  Therefore, the present specification provides a technique capable of accurately transferring a plurality of ceramic substrates using an adhesive sheet whose adhesive strength is reduced by heating.

  The method for manufacturing a ceramic element disclosed in the present specification includes a heating step, a pasting step, and a peeling step. In the heating step, a plurality of ceramic substrates bonded to the first pressure-sensitive adhesive sheet, in which a plurality of through-holes are formed and whose adhesive strength is reduced by heating, are sealed through the through-holes. The first pressure-sensitive adhesive sheet is heated while sucking. In the sticking step, the second pressure-sensitive adhesive sheet is stuck to the surface of each ceramic substrate opposite to the first pressure-sensitive adhesive sheet while sucking each ceramic substrate through each through hole continuously from the heating step. In the peeling step, after the suction of each ceramic substrate is stopped, the first adhesive sheet is peeled from each ceramic substrate.

  The ceramic substrate means a substrate having a ceramic base material. Therefore, the ceramic substrate may be constituted only by a ceramic base material, or a member made of another material (for example, an electrode, a protective film, etc.) is added to the ceramic base material. There may be. The ceramic substrate may be a ceramic element itself.

  In this manufacturing method, in the heating step, the first pressure-sensitive adhesive sheet is heated while sucking each ceramic substrate through each through hole. Although the adhesive force of the first pressure-sensitive adhesive sheet is reduced by heating, the ceramic substrate is not peeled from the first pressure-sensitive adhesive sheet in the heating step because each ceramic substrate is fixed by suction through each through-hole. In the affixing step, the ceramic substrate is sucked through each through-hole continuously from the heating step (that is, while the ceramic substrate is being fixed), and the first adhesive sheet of each ceramic substrate is maintained. A 2nd adhesive sheet is affixed on the surface on the opposite side. Thereafter, the suction of each ceramic substrate is stopped, and the first adhesive sheet is peeled from each ceramic substrate. Thereby, each ceramic substrate is transferred from the first adhesive sheet to the second adhesive sheet. In this method, the second pressure-sensitive adhesive sheet is not attached to the ceramic substrate when the first pressure-sensitive adhesive sheet is heated. Therefore, the second pressure-sensitive adhesive sheet is prevented from being thermally deformed. For this reason, according to this method, it is possible to transfer from the first pressure-sensitive adhesive sheet to the second pressure-sensitive adhesive sheet in a batch with high accuracy while maintaining the arrangement (pitch, etc.) of the plurality of ceramic substrates.

FIG. 3 is a cross-sectional view of the ceramic element 20 attached to the first adhesive sheet 10. The top view of the ceramic element 20 affixed on the 1st adhesive sheet 10. FIG. The flowchart which shows a transcription | transfer process. Explanatory drawing of a suction process. Explanatory drawing of the process which affixes the 2nd adhesive sheet 40. FIG. Sectional drawing of the ceramic element 20 affixed on the 2nd adhesive sheet 40. FIG. The graph which shows the relationship between area ratio A2 / A1 and the positional accuracy of transcription | transfer. The figure which shows the dimension of element B1-B4. Explanatory drawing of the dimension L, W, and H. FIG. The longitudinal cross-sectional view of the ceramic element of a modification. The longitudinal cross-sectional view of the ceramic element of a modification.

  First, the features of the embodiments described below are listed. Note that the features listed here are all independently effective.

(Characteristic 1) When one ceramic substrate attached to the first pressure-sensitive adhesive sheet is viewed perpendicularly to the first pressure-sensitive adhesive sheet, the ceramic substrate is closed with respect to the area of the ceramic substrate. The ratio of the area of the hole is 15% or more and 35% or less.

  According to the feature 1, the ceramic substrate can be transferred with higher accuracy.

(Feature 2) The thickness of the thinnest portion of the ceramic substrate is 0.2 mm or less.

  In the prior art, when the thickness of the ceramic substrate is thin, the accuracy during transfer is extremely poor. Therefore, the technique of the embodiment is particularly useful when handling a thin ceramic substrate as in feature 2.

(Feature 3) In the heating step and the pasting step, the porous suction pad is brought into contact with the first pressure-sensitive adhesive sheet so as to cover the plurality of through holes, and each ceramic substrate is sucked through the pores inside the suction pad.

  According to the feature 3, a plurality of ceramic substrates can be sucked and fixed at a time by the porous suction pad without fine alignment.

(Feature 4) The second pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet whose adhesive strength is reduced by heating.

  In the prior art, heat is applied to the second adhesive sheet when the first adhesive sheet is heated. For this reason, when the adhesive sheet whose adhesive force falls by heating is used as the second adhesive sheet, the adhesive force of the second adhesive sheet is reduced when the first adhesive sheet is heated. Therefore, when the first adhesive sheet is peeled off, the ceramic substrate may fall off from the second adhesive sheet. On the other hand, in the method of an Example, since the heating of a 2nd adhesive sheet can be suppressed, even if it uses the adhesive sheet which adhesive force falls by heating as a 2nd adhesive sheet, a problem does not arise.

  The method for producing a ceramic element of the embodiment is characterized by a step of transferring the ceramic element 20 from the first adhesive sheet 10 shown in FIG. 1 to the second adhesive sheet 40 shown in FIG. First, the first adhesive sheet 10 and the ceramic element 20 of FIG. 1 will be described.

  A first pressure-sensitive adhesive sheet 10 shown in FIG. 1 has an adhesive layer 12 and a resin film 14. The adhesive layer 12 is formed on one surface of the resin film 14. The adhesive layer 12 is made of an adhesive that foams when heated and has extremely low adhesive strength. That is, the 1st adhesive sheet 10 is a thermal foam sheet. The first pressure-sensitive adhesive sheet 10 is formed with a plurality of through holes 16 that communicate the front surface and the back surface.

  The ceramic element 20 includes a piezoelectric ceramic substrate and electrodes (not shown) formed on both surfaces of the substrate. Each ceramic element 20 is affixed to the adhesive layer 12 of the first pressure-sensitive adhesive sheet 10. FIG. 2 shows a plan view of the ceramic element 20 attached to the first adhesive sheet 10 as viewed from above. As illustrated, each ceramic element 20 is affixed to the first adhesive sheet 10 such that each ceramic element 20 closes each through hole 16. That is, one ceramic element 20 closes one corresponding through hole 16. The center of gravity 20 a of each ceramic element 20 exists at a position overlapping the through hole 16 when viewed perpendicularly to the first adhesive sheet 10.

  The structure of FIG. 1 in which a plurality of ceramic elements 20 are attached to the first adhesive sheet 10 is formed as follows. First, a ceramic wafer that is a material of the ceramic element 20 is fixed on a glass plate. The ceramic wafer is composed of a wafer made of piezoelectric ceramics and electrodes formed on both surfaces thereof. Next, the ceramic wafer is diced on a glass plate. As a result, the ceramic wafer is divided into a plurality of ceramic elements 20. At this stage, each ceramic element 20 is fixed on a glass plate. Next, the 1st adhesive sheet 10 is affixed on the surface on the opposite side with respect to the glass plate of each ceramic element 20. FIG. At this time, each through hole 16 of the first pressure-sensitive adhesive sheet 10 is closed by each ceramic element 20. Next, each ceramic element 20 is separated from the glass plate. Thereby, the structure shown in FIG. 1 is obtained.

  The method for forming the structure shown in FIG. 1 is not limited to the above method. For example, the ceramic wafer may be attached to the first adhesive sheet 10 and the ceramic wafer may be diced on the first adhesive sheet 10. By performing dicing so that the dicing line does not overlap with the through holes 16 of the first pressure-sensitive adhesive sheet 10, the divided ceramic elements 20 can be disposed on the through holes 16 as shown in FIG. 1.

  Next, a method for transferring the ceramic element 20 from the first adhesive sheet 10 to the second adhesive sheet 40 will be described. The transfer of the ceramic element 20 is executed according to the flowchart shown in FIG. In step S2, the suction pad 30 is first arranged as shown in FIG. The suction pad 30 has a plate 32 made of a porous material. A large number of holes are formed in the plate 32. The holes are connected to each other. For this reason, air can flow through the plate 32. Here, the suction pad 30 is set so that the plate 32 contacts the entire region of the first adhesive sheet 10 where the through-holes 16 are formed. That is, all the through holes 16 are covered with the plate 32. Next, suction is performed by the suction pad 30. That is, as shown by the arrow 100 in FIG. 4, the air in the suction pad 30 is discharged. Then, the air in each through-hole 16 is discharged to the outside through the air holes inside the plate 32. Thereby, the inside of each through hole 16 is decompressed, and each ceramic element 20 is sucked (adsorbed) by the through hole 16. Next, the 1st adhesive sheet 10 is heated, maintaining the state which attracted | sucked each ceramic element 20. FIG. Here, the 1st adhesive sheet 10 is heated at about 120 degreeC. The 1st adhesive sheet 10 may be heated with the heating apparatus provided in the plate 32, and may be heated with another heating apparatus. When the first pressure-sensitive adhesive sheet 10 is heated, the adhesive layer 12 substantially loses the adhesive force. In addition, since each ceramic element 20 is attracted | sucked by each through-hole 16, even if the adhesive force of the adhesive bond layer 12 falls, the state by which each ceramic element 20 is being fixed to the surface of the 1st adhesive sheet 10 is the state. Maintained.

  In step S4, first, the heating device is stopped. Thereby, each ceramic element 20 is cooled to room temperature. In step S4, the suction pad 30 continues to perform suction from step S2. Therefore, also in step S4, the state where each ceramic element 20 is fixed to the surface of the first adhesive sheet 10 is maintained. When each ceramic element 20 is cooled to room temperature, the second adhesive sheet 40 is attached to the surface of each ceramic element 20 (surface opposite to the first adhesive sheet 10), as shown in FIG. The second pressure-sensitive adhesive sheet 40 has an adhesive layer 42 and a resin film 44. The adhesive layer 42 is formed on one surface of the resin film 44. The adhesive layer 42 is made of an adhesive that foams when heated and has extremely low adhesive strength. That is, the second adhesive sheet 40 is a thermal foam sheet. Here, the adhesive layer 42 is brought into contact with each ceramic element 20, and the second adhesive sheet 40 is attached to each ceramic element 20.

  As described above, since the second adhesive sheet 40 is attached to each ceramic element 20 after each ceramic element 20 is cooled to room temperature, the second adhesive sheet 40 is not heated during attachment. This prevents the second pressure-sensitive adhesive sheet 40 from being thermally deformed (for example, thermal expansion) and prevents the adhesive force of the adhesive layer 42 of the second pressure-sensitive adhesive sheet 40 from being lowered.

  In step S6, first, suction of the suction pad 30 is stopped. Next, the suction pad 30 is pulled away from the first adhesive sheet 10. Next, the first adhesive sheet 10 is peeled from each ceramic element 20. Since the adhesive force of the adhesive layer 12 of the first pressure-sensitive adhesive sheet 10 is almost lost, the first pressure-sensitive adhesive sheet 10 can be easily peeled from each ceramic element 20. Thereby, as shown in FIG. 6, a state in which each ceramic element 20 is attached to the second adhesive sheet 40 is obtained. That is, the process of transferring each ceramic element 20 from the first adhesive sheet 10 to the second adhesive sheet 40 is completed.

  As described above, in this manufacturing method, the second adhesive sheet 40 is attached to each ceramic element 20 after the heating of the first adhesive sheet 10 is completed. Therefore, heat is not applied to the second adhesive sheet 40. For this reason, the thermal deformation of the 2nd adhesive sheet 40 is suppressed. Therefore, these ceramic elements 20 can be transferred to the second pressure-sensitive adhesive sheet 40 while substantially maintaining the arrangement of the ceramic elements 20 when attached to the first pressure-sensitive adhesive sheet 10. That is, according to this method, highly accurate transfer is possible.

  Moreover, even if the 2nd adhesive sheet 40 is a thermal foam sheet as mentioned above, according to the technique of an Example, the fall of the adhesive force of the 2nd adhesive sheet 40 can be prevented in a transfer process. Therefore, the ceramic element 20 can be prevented from falling off from the second adhesive sheet 40 when the first adhesive sheet 10 is peeled off.

  In the above embodiment, after the heating device is stopped, the second adhesive sheet 40 is attached to each ceramic element 20 after waiting for each ceramic element 20 to cool to room temperature. However, it is not always necessary to cool to room temperature. If the temperature of each ceramic element 20 is lowered to a temperature at which the second adhesive sheet is not substantially thermally deformed, the second adhesive sheet 40 may be attached to each ceramic element 20 at any time.

  It has been found that the accuracy of transfer correlates with the ratio between the area of the ceramic element and the area of the through hole. The horizontal axis of FIG. 7 shows the through hole 16 with respect to the area A1 of the ceramic element 20 when the ceramic element 20 attached to the first adhesive sheet 10 is viewed perpendicularly to the first adhesive sheet 10. The ratio A2 / A1 of the area A2 is shown. The vertical axis in FIG. 7 indicates the variation in the position of each ceramic element 20 on the second adhesive sheet 40 after being transferred to the second adhesive sheet 40. The positional variation was evaluated as follows. The center coordinates of the plurality of ceramic elements 20 after being transferred to the second adhesive sheet 40 were measured using a tool microscope. Next, the pitch between the centers of the ceramic elements 20 was calculated, and the difference between the calculated pitch and the design value of the pitch was defined as position variation. The experiment of FIG. 7 was performed using ceramic elements 20 having four sizes of element B1 to element B4. FIG. 8 shows the sizes of the elements B1 to B4. FIG. 9 shows the dimensions L, W, and H of FIG. Note that the lower surface of the ceramic element 20 in FIG. 9 is a surface that is attached to the first adhesive sheet 10, and the upper surface is a surface that is attached to the second adhesive sheet 40. In FIG. 7, the data when the ratio A2 / A1 is 0% indicates the result when the through hole 16 is not formed. As shown in FIG. 7, if the through hole 16 is formed except for the element B1, the positional accuracy can be improved as compared with the case where the through hole 16 is not formed regardless of the value of the ratio A2 / A1. I understood. In addition, in the element B1, it was found that when the ratio A2 / A1 is 65% or less, the position accuracy can be improved by forming the through hole 16 as compared with the case where the through hole 16 is not formed. In any element, if the ratio A2 / A1 is too large, the positional accuracy tends to deteriorate. This is because if the through hole 16 is made too large with respect to the ceramic element 20, the ceramic element 20 fits into the through hole 16 at the time of suction, or cracks at a portion where the ceramic element 20 is applied to the through hole 16 at the attaching step. This is because there are cases. From FIG. 7, it can be seen that when the ratio A2 / A1 is 5% or more and 65% or less, the positional accuracy is clearly improved. In particular, it can be seen that the positional accuracy is remarkably improved when the ratio A2 / A1 is 15% or more and 50% or less.

  In the above-described embodiment, the method of transferring the ceramic element has been described. However, a transfer method similar to that of the embodiment may be used for a semi-finished product in the process of manufacturing the ceramic element.

  In the above-described embodiments, the ceramic element (that is, the ceramic substrate) has a substantially constant thickness. However, as shown in FIGS. 10 and 11, the thickness of the ceramic element may vary depending on the position. In this case, the thickness H of the thinnest part of the ceramic element is preferably 0.2 mm or less.

  Moreover, in the Example mentioned above, although the thermally foamed sheet was used as the 2nd adhesive sheet 40, even if another adhesive sheet (for example, adhesive sheet in which adhesive force falls by irradiation of an ultraviolet-ray) is used as a 2nd adhesive sheet. Good.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10: Adhesive sheet 12: Adhesive layer 14: Resin film 16: Through hole 20: Ceramic element 30: Adsorption pad 32: Plate 40: Adhesive sheet 42: Adhesive layer 44: Resin film

Claims (4)

A method for manufacturing a ceramic element, comprising:
While sucking through the through-holes a plurality of ceramic substrates bonded to the first pressure-sensitive adhesive sheet in which the through-holes are formed and the adhesive strength of the first adhesive sheet is reduced by heating A heating step for heating the first adhesive sheet;
An affixing step of adhering the second adhesive sheet to the surface opposite to the first adhesive sheet of each ceramic substrate while sucking each ceramic substrate through each through hole continuously from the heating step;
A peeling step of peeling the first adhesive sheet from each ceramic substrate after stopping the suction of each ceramic substrate;
A manufacturing method comprising:   When one ceramic substrate attached to the first pressure-sensitive adhesive sheet is viewed perpendicularly to the first pressure-sensitive adhesive sheet, the area of the through hole blocked by the ceramic substrate relative to the area of the ceramic substrate The method according to claim 1, wherein the ratio is 15% or more and 50% or less.   The manufacturing method according to claim 1 or 2, wherein the thickness of the thinnest portion of the ceramic substrate is 0.2 mm or less.   In the heating step and the pasting step, the porous suction pad is brought into contact with the first pressure-sensitive adhesive sheet so as to cover the plurality of through holes, and each ceramic substrate is sucked through the pores inside the suction pad. The manufacturing method as described in any one of these.

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