JP4091558B2 - Manufacturing method of ceramic element - Google Patents

Description

  The present invention relates to a method for manufacturing a ceramic element such as a multilayer piezoelectric element, a piezoelectric sensor, or a multilayer capacitor, and more specifically, an electrical connection between one end surface side and the other end surface side of a ceramic layer through a through hole. The present invention relates to a method of manufacturing a ceramic element that has been smoothly connected.

  In recent years, technological development of a multilayer piezoelectric element which is one of ceramic elements has been actively performed. This type of laminated piezoelectric element is disclosed, for example, in Patent Document 1 below.

The multilayer piezoelectric element described in Patent Document 1 is formed by alternately stacking piezoelectric layers patterned with a large number of individual electrodes and piezoelectric layers patterned with common electrodes in the thickness direction of the multilayer piezoelectric element. The aligned individual electrodes are connected by a conductive member through through holes formed in the piezoelectric layer. In such a multilayered piezoelectric element, by applying a voltage between a predetermined individual electrode and a common electrode, an active portion corresponding to the predetermined individual electrode (a portion in which distortion occurs due to the piezoelectric effect) in the piezoelectric layer. ) Can be selectively displaced.
JP 2002-254634 A

  In ceramic elements such as the multilayer piezoelectric element as described above, between the one end surface side and the other end surface side of the ceramic layer due to the miniaturization of the element itself and the high integration of the electrodes formed on the element. Therefore, a technique capable of reliably achieving electrical connection through a through hole has been desired.

  Therefore, the present invention has been made in view of such circumstances, and a ceramic element in which electrical connection between the one end surface side and the other end surface side of the ceramic layer is reliably made through a through hole. An object is to provide a manufacturing method.

In order to achieve the above object, according to the method for manufacturing a ceramic element of the present invention, electrical connection between one end surface side and the other end surface side of the ceramic layer is performed through a through hole formed in the ceramic layer. A method for producing a ceramic element, the method comprising forcibly shrinking the ceramic material together with the carrier film by heating the ceramic material containing a lead-containing compound and forming a ceramic layer on the upper surface of the carrier film ; , After forcibly shrinking the ceramic material together with the carrier film , forming a position reference hole in at least one of the ceramic material and the carrier film ; and after forming the position reference hole, a second YAG laser is applied to the ceramic material. Through holes in ceramic materials by irradiating laser light of higher harmonics or third harmonics Forming, characterized in that it comprises a.

Further, the method for manufacturing a ceramic element according to the present invention is a method for manufacturing a ceramic element in which electrical connection is made between one end surface side and the other end surface side of the ceramic layer through a through hole formed in the ceramic layer. A step of forcibly shrinking the ceramic material together with the carrier film by heating the ceramic material that has a powder density of 5000 kg / m ³ or more and is formed on the upper surface of the carrier film to be a ceramic layer; A step of forming a position reference hole in at least one of the ceramic material and the carrier film after forcibly shrinking together with the carrier film ; and after forming the position reference hole, the second harmonic or the second harmonic of the YAG laser is applied to the ceramic material. A process that forms a through hole in a ceramic material by irradiating a third harmonic laser beam. And a step.

The present inventor has determined that the second harmonic of the YAG laser is applied to a ceramic material containing a lead-containing compound (such as lead titanate or lead zirconate titanate) or a ceramic material having a powder density of 5000 kg / m ³ or more. It has been found that the following good through-holes can be formed by irradiating a laser beam of a wave or a third harmonic. That is, when laser light irradiation by a conventional CO ₂ laser is performed, a large amount of scattered matter is deposited around the through hole, whereas the second harmonic or third harmonic laser beam of the YAG laser is accumulated. When irradiation is performed, it is possible to eliminate the accumulation of scattered matter around the through hole. This prevents clogging of the through-holes due to scattered objects. For example, by conducting screen printing with a conductive paste filling the through-holes, it is possible to reliably form the conductive member in the through-holes. Become. Therefore, electrical connection between the one end surface side and the other end surface side of the ceramic layer can be reliably performed through the through hole.

  Here, the ceramic element means an element having a ceramic layer formed of a ceramic material, and includes a multilayer piezoelectric element, a piezoelectric sensor, a capacitor, an inductor, a transformer, a filter, and a combination of these. .

  Further, it is preferable to oscillate the laser beam, for example, to oscillate the laser beam repeatedly by Q switching. Generally, when a through hole is formed by laser light irradiation, if it is not pulse oscillation (for example, repetitive oscillation due to Q switching), it is difficult to manage the processing, and the shape of the through hole is tapered toward the laser light incident surface side. In addition, the scattered matter generated by the processing does not scatter and becomes processing waste and accumulates around the through hole. However, it is possible to easily obtain a large peak output by pulsating the laser beam, for example, by repeatedly oscillating the laser beam by Q switching, and the through-hole shape expands in a taper shape and scattered matter accumulates. Can be suppressed. Thus, for example, when a through hole is formed by irradiating a laser beam from one end surface side of a ceramic material, and an electrode is patterned on one end surface so as to include this through hole, the through hole for the electrode is formed. The relative size can be reduced. Therefore, it becomes possible to further miniaturize the electrode, and as a result, high integration of the electrode or miniaturization of the ceramic element can be achieved.

  According to the present invention, it is possible to manufacture a ceramic element in which electrical connection between the one end surface side and the other end surface side of the ceramic material is reliably performed through the through hole.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, a ceramic element manufactured by the method for manufacturing a ceramic element according to this embodiment will be described.

  As shown in FIG. 1, the ceramic element according to the present embodiment is a multilayer piezoelectric element 1, which includes a piezoelectric layer (ceramic layer) 3 on which individual electrodes 2 are formed, and a common electrode. 4 piezoelectric layers (ceramic layers) 5 each having 4 formed thereon are alternately laminated, and further sandwiched from above and below by the piezoelectric layers 7 on which the terminal electrodes are formed and the piezoelectric layer 9 serving as a base. Configured.

Each of the piezoelectric layers 3, 5, 7, and 9 is made of a piezoelectric material mainly composed of lead zirconate titanate and having a powder density of 8000 kg / m ³ , and has a rectangular shape of “10 mm × 30 mm, thickness 30 μm”. It is formed in a thin plate shape. The individual electrode 2 and the common electrode 4 are mainly composed of silver and palladium, and are formed by patterning by screen printing. The same applies to each electrode described below.

  A large number of individual electrodes 2 are arranged in a matrix on the upper surface of each piezoelectric layer 3. The individual electrodes 2 are separated from each other by a predetermined distance, thereby achieving electrical independence and preventing the influence of mutual vibration. Each individual electrode 2 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 3 immediately below the outer end portion thereof (excluding the lowermost piezoelectric layer 3).

  Furthermore, an intermediate electrode 6 for electrically connecting the common electrodes 4 and 4 of the piezoelectric layer 5 positioned above and below is formed on the edge of the upper surface of the piezoelectric layer 3. The intermediate electrode 6 is connected to a conductive member in a through hole 8 formed in the piezoelectric layer 3 immediately below the intermediate electrode 6.

  An intermediate electrode 16 is formed on the upper surface of each piezoelectric layer 5 so as to face the outer end of each individual electrode 2 of the piezoelectric layer 3 in the thickness direction of the multilayer piezoelectric element 1. (Hereinafter, “the thickness direction of the laminated piezoelectric element 1”, that is, “the thickness direction of the piezoelectric layers 3 and 5” is simply referred to as the “thickness direction”). Each intermediate electrode 16 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 5 immediately below.

  Further, a rectangular common electrode 4 is formed on the upper surface of the piezoelectric layer 5. The common electrode 4 is formed in a solid shape so as to overlap with a portion of the piezoelectric layer 3 other than the outer end portion of each individual electrode 2 when viewed from the thickness direction. The common electrode 4 is connected to a conductive member in the through hole 8 formed in the piezoelectric layer 5 so as to face the intermediate electrode 6 of the piezoelectric layer 3 in the thickness direction.

  An outer electrode 17 is formed on the upper surface of the uppermost piezoelectric layer 7 so as to face each intermediate electrode 16 of the piezoelectric layer 5 in the thickness direction, and the intermediate electrode 6 of the piezoelectric layer 3 in the thickness direction. An external electrode 18 is formed so as to oppose to. Each external electrode 17 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 7 immediately below it, and the external electrode 18 is connected to the inside of the through hole 8 formed in the piezoelectric layer 7 immediately below it. Connected to the conductive member. A rectangular common electrode 19 is formed on the upper surface of the lowermost piezoelectric layer 9 in a solid shape with a predetermined interval from the outer peripheral portion of the piezoelectric layer 9.

  The outermost electrodes 17 and 18 in the uppermost layer are provided with a silver baking electrode so as to attach a lead wire for electrical connection to a drive power supply, and function as terminal electrodes of the multilayer piezoelectric element 1.

  By laminating the piezoelectric layers 3, 5, 7, 9 having the electrode patterns as described above, four individual electrodes 2 are intermediate electrodes in the thickness direction with respect to the outermost electrodes 17 of the uppermost layer. The electrodes 2, 16, and 17 that are aligned with the interposition of 16 are electrically connected by a conductive member in the through hole 13. More specifically, as shown in FIG. 2, the individual electrodes 2 and 2 adjacent to each other in the thickness direction are electrically connected by the conductive member 14 in the through hole 13 with the intermediate electrode 16 interposed therebetween. Become.

  On the other hand, with respect to the uppermost external electrode 18, the four common electrodes 4 and the lowermost common electrode 19 are aligned with the intermediate electrode 6 interposed in the thickness direction, and the aligned electrodes 4, 6, 18 are arranged. , 19 are electrically connected by the conductive member 14 in the through hole 8.

  When a voltage is applied between the predetermined external electrode 17 and the external electrode 18 by such electrical connection in the multilayer piezoelectric element 1, the individual electrode 2 and the common electrodes 4 and 19 aligned under the predetermined external electrode 17. A voltage is applied between the two. Thereby, in the piezoelectric layers 3 and 5, as shown in FIG. 2, an electric field is generated in the portion sandwiched between the portions other than the outer end portion of the individual electrode 2 and the common electrodes 4 and 19. The active part 21 is displaced. Therefore, by selecting the external electrode 17 to which the voltage is applied, among the active portions 21 corresponding to the individual electrodes 2 arranged in a matrix, the active portions 21 aligned under the selected external electrode 17 are arranged in the thickness direction. Can be displaced. Such a laminated piezoelectric element 1 is applied to a drive source of various devices that require minute displacement, such as valve control of a micropump.

  Next, a method for manufacturing the multilayer piezoelectric element 1 described above will be described as a method for manufacturing a ceramic element according to the present embodiment.

First, as shown in FIG. 3, a paste is prepared by mixing an organic binder, an organic solvent, etc. with a piezoelectric material mainly composed of lead zirconate titanate and having a powder density of 8000 kg / m ^3. Store in 31. Then, while winding the carrier film (holding member) 32 from the reel 33 to the other reel 33, the green sheet (ceramic material) 34 to be the piezoelectric layers 3, 5, 7, 9 is carried by the doctor blade method. It forms on the upper surface of the film 32 (sheet forming process). As the carrier film 32, a transparent PET film having a thickness of 54 μm and a width of 100 mm was used. The thickness of the green sheet 34 formed on the upper surface of the carrier film 32 is 40 μm.

  After the sheet forming step, as shown in FIG. 4, while the carrier film 32 on which the green sheet 34 is formed is wound from the reel 33 to another reel 33, the carrier film 32 and the green sheet are used using the heating furnace 36. 34 is heated and these are forcibly contracted (heat treatment process). Thereby, the thermal contraction of the carrier film 32 and the green sheet 34 in the subsequent steps can be prevented, and the formation of through holes and the pattern of electrodes can be performed with high positional accuracy.

  After the heat treatment step, as shown in FIG. 5, a position reference hole is formed using a punching device 37 while winding the carrier film 32 on which the green sheet 34 is formed from the reel 33 to another reel 33. Through holes 8 and 13 (not shown) are formed at a predetermined position of the green sheet 34 with reference to the position reference hole using a laser processing device 38 (through hole forming step). Note that the position reference hole is formed in the outer edge portion of the green sheet 34 which is a remaining material in a later cutting process, or when there is a blank portion where the green sheet 34 is not formed in the outer edge portion of the carrier film 32. It may be formed in the part.

  After the through-hole forming step, as shown in FIG. 6, the screen printing device 39 is used to screen-fill the through-holes 8 and 13 with the conductive paste from the upper surface side of the green sheet 34 (first screen). Printing process). Subsequently, the carrier film 32 and the green sheet 34 are placed in a dryer to dry and solidify the conductive paste in the through holes 8 and 13 to form the conductive member 14 (first drying step). Before the drying step, the carrier film 32 and the green sheet 34 are heated for a predetermined time at a temperature lower than the drying temperature (heating step). By this heating, the conductive paste is softened, and the conductive paste is reliably spread to the lower end portions in the through holes 8 and 13.

  After the first drying step, screen printing of the conductive paste is performed on a predetermined position on the upper surface of the green sheet 34 (second printing step). Subsequently, the carrier film 32 and the green sheet 34 are put in a dryer, and the conductive paste is dried and solidified to form the electrodes 2, 4, 17, 19 and the like (second drying step). The conductive paste used in the first and second printing steps was prepared by mixing an organic binder, an organic solvent, or the like with a metal material composed of silver and palladium in a predetermined ratio.

  After the second drying step, as shown in FIG. 7, the green sheet 34 a having a predetermined length is peeled off from the carrier film 32 using the pickup device 41, and the same stacking order as that of the multilayer piezoelectric element 1 described above is obtained. Thus, the green sheets 34a are laminated and temporarily pressed (lamination process).

  After the laminating step, each green sheet 34a is thermocompression-bonded by pressing in the laminating direction while heating to produce a laminate green. Subsequently, a plurality of laminated green elements having a predetermined size are cut out from the laminated green, and the cut-out laminated green elements are degreased and fired, and then the laminated piezoelectric element 1 is completed through terminal electrode formation, polarization treatment, and the like. Let

  Next, the through hole forming process described above will be described in more detail.

  As shown in FIG. 8, in the through-hole forming step, the carrier film 32 on which the green sheet 34 is formed is vacuum-sucked on a stage 43 disposed between the reels 33 and 33. When the carrier film 32 and the green sheet 34 are sucked and fixed on the stage 43, the laser beam focusing point P of the laser light L is aligned with a predetermined position of the green sheet 34 by the laser processing device 38. Is irradiated with laser light L.

  At this time, the position of the condensing point P with respect to the green sheet 34 is determined based on the image data obtained by imaging a plurality of position reference holes (position reference portions) formed by the punching device 37 with a CCD camera (imaging means). Positioned at a predetermined position with respect to the reference hole.

The laser beam L is a laser beam obtained by pulsing the third harmonic of an Nd: YAG laser (for example, a laser beam repeatedly oscillated by Q switching), having a repetition frequency of 30 kHz, a pulse width of 210 nsec, and an output of 5 W. Irradiated under conditions. Then, depending on the thickness and composition of the green sheet 34, the green sheet 34 is formed so that the through hole 13 is formed in the green sheet 34 and the hole formed in the carrier film 32 by melting or the like is below a predetermined depth. The number of shots irradiated to a predetermined position 34 (that is, the number of pulses irradiated (in the case of repeated oscillation by Q switching, the number of repeated irradiations of the laser beam L)) is set. In this embodiment, the thickness is 40 μm, and (Pb0.97 Sr0.03) [Ti0.465 Zr0.535] O ₃ is the main component and Nb ₂ O ₅ is used as a subcomponent for 1 mol of the main component. The green sheet 34 having a composition added with 0.5% by mass was irradiated with the laser beam L with the number of shots set to 30.

  As shown in FIG. 9, the irradiated portion of the laser light L in the green sheet 34 melts and evaporates to form the through hole 13 as a result of such irradiation of the laser light L, but the scattered matter around the through hole 13 There was almost no sedimentation. Therefore, clogging of the through hole 13 due to scattered objects is prevented, so that the conductive member 14 can be reliably formed in the through hole 13 by performing screen printing with filling of the conductive paste into the through hole 13. become.

  In general, when a through-hole is formed by laser light irradiation, the shape of the through-hole becomes a tapered shape spreading toward the laser light incident surface side. For example, the laser light L is repeatedly oscillated by Q switching. By causing the laser beam L to oscillate, it is possible to suppress the through hole from spreading in a tapered shape. In the present embodiment, the spread on the upper surface side of the through hole 13 is suppressed such that the diameter on the lower surface side of the through hole 13 is 40 μm while the diameter on the upper surface side is about 50 μm.

  As a result, the individual electrode 2 formed on the upper surface so as to include the through hole 13 can be made to have a narrower shape, and as a result, the individual electrode 2 can be highly integrated or the stacked piezoelectric element 1 can be miniaturized. Can be planned. In addition, the conductive paste filled in the through hole 13 from the upper surface side of the green sheet 34 easily flows to the lower surface side, and the conductive paste can be reliably spread to the lower end portion in the through hole 13.

  Further, as described above, the number of shots is set and irradiation with the laser light L is performed, thereby preventing the carrier film 32 from being damaged as shown in FIG. In the present embodiment, the damage depth of the carrier film 32 is suppressed to 18 μm or less.

  Thereby, it is possible to prevent the conductive paste filled in the through hole 13 from oozing out from between the green sheet 34 and the carrier film 32 to the lower surface of the green sheet 34. In addition, since the damage to the carrier film 32 is extremely small, the carrier film 32 can be surely vacuum-sucked in other processes after the through-hole forming process. Can prevent such a situation.

  Then, when the multilayer piezoelectric element 1 having 300 individual electrodes 2 (4 rows and 75 columns) formed on the upper surface of the piezoelectric layer 3 of “10 mm × 30 mm, thickness 30 μm” was manufactured and the yield was calculated, The following results were obtained. That is, the yield when the through hole was formed in the carrier film 32 by laser light irradiation was less than 20%, and the yield when the damage depth of the carrier film 32 was 18 to 48 μm was about 50%. On the other hand, the yield when the damage depth of the carrier film 32 was 0 to 18 μm exceeded 90%. The yield was calculated by assuming that 140 laminated piezoelectric elements 1 were tested and only 300 locations corresponding to the individual electrodes 2 were normally obtained.

  Next, a comparison result between the laser beam irradiation and the other laser beam irradiation in the above-described through hole forming step will be described.

As shown in FIG. 10, in the case of a CO ₂ laser (wavelength 10.6 μm), a large amount of scattered matter due to laser light irradiation was deposited around the through hole. In addition, when the fundamental wave (wavelength 1064 nm) of the YAG laser was oscillated continuously (CW), the through hole was greatly spread on the laser light incident surface side. Further, when the fundamental wave (wavelength 1064 nm) of the YAG laser is repeatedly oscillated by Q switching, the thermal effect is large, the control of the diameter of the through hole is extremely difficult, and there are many processed deposits. .

  In contrast, when the third harmonic (wavelength 355 nm) of the YAG laser is repeatedly oscillated by Q switching (this embodiment), there is almost no accumulation of scattered matter around the through hole, and the laser of the through hole The spread on the light incident surface side was also suppressed. Further, when the second harmonic (wavelength 532 nm) of the YAG laser was repeatedly oscillated by Q switching, the same effect as that obtained when the third harmonic of the YAG laser was pulsated was obtained. From the above comparison results, it can be said that laser light oscillated from the YAG laser and whose wavelength is converted to a wavelength of 532 nm or less is preferable.

  As described above, according to the method for manufacturing a ceramic element according to the present embodiment, good through holes 8 and 13 can be formed in the green sheet 34 in the through hole forming step. Thus, the conductive member 14 can be reliably formed. Thereby, for example, in each piezoelectric layer 3, the individual electrode 2 on the upper surface side and the intermediate electrode 16 on the lower surface side can be reliably connected by the conductive member 14 in the through hole 13. In each piezoelectric layer 5, the common electrode 4 on the upper surface side and the individual electrode 2 on the lower surface side can be reliably connected by the conductive member 14 in the through hole 8. Therefore, it is possible to manufacture the multilayer piezoelectric element 1 in which the electrical connection between the upper surface side and the lower surface side of the piezoelectric layers 3 and 5 is reliably made through the through holes 8 and 13.

The present invention is not limited to the above embodiment. For example, by irradiating a green sheet (ceramic material) having a powder density of 5000 kg / m ³ or more with a second harmonic or third harmonic laser beam of a YAG laser, a through hole is formed in the green sheet. It may be formed.

Here, for a green sheet made of a piezoelectric material having a composition of (Na0.25 K0.25 Bi0.5) [Ti0.97 In0.01 Nb0.02] O ₈ and a powder density of 5500 kg / m ³ , Nd : A through hole was formed by irradiating a laser beam obtained by repeatedly oscillating the third harmonic of the YAG laser by Q switching. At this time, the laser light irradiation conditions were a repetition frequency of 30 kHz, a pulse width of 210 nsec, an output of 5 W, and a shot count of 20 times. Then, a laminated piezoelectric element having the same configuration as that of the above embodiment was manufactured by the same manufacturing method as that of the above embodiment (however, platinum was used as a material for the internal electrode and the conductive member).

  When the yield of the multilayer piezoelectric element produced in this way was calculated, the yield exceeded 90% when the damage depth of the carrier film was 0 to 18 μm. In addition, when a through hole is formed by irradiating a laser beam in which the second harmonic or the third harmonic of an Nd: YAG laser is repeatedly oscillated by Q switching, the scattered matter around the through hole is generated. There was almost no deposition, and the spread of the through hole on the laser light incident surface side was suppressed, and the through hole was in a state satisfying the desired quality.

  The powder density is measured by, for example, a so-called gas phase substitution method. That is, the finely pulverized ceramic powder before making it into a paint for forming a green sheet is the object of measurement, and the volume and pressure of the gas (eg, He gas) are changed at a constant temperature according to Boyle's law. Ask. And after calculating | requiring the volume of a measuring object, weight is measured and the density of a measuring object is calculated | required.

It is a disassembled perspective view of the multilayer piezoelectric element of this embodiment. It is the expanded sectional view seen from the direction orthogonal to the longitudinal direction of the lamination type piezoelectric element shown in FIG. It is a conceptual diagram which shows the sheet forming process of this embodiment. It is a conceptual diagram which shows the heat processing process of this embodiment. It is a conceptual diagram which shows the through-hole formation process of this embodiment. It is a conceptual diagram which shows the 1st printing process of this embodiment. It is a conceptual diagram which shows the lamination process of this embodiment. It is a conceptual diagram which shows the state during the laser beam irradiation in the through-hole formation process of this embodiment. It is a conceptual diagram which shows the state after the laser beam irradiation in the through-hole formation process of this embodiment. It is a figure which shows the comparison result of the through-hole formation state by laser beam irradiation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element (ceramic element), 3, 5 ... Piezoelectric layer (ceramic layer), 8, 13 ... Through hole, 34 ... Green sheet (ceramic material), L ... Laser beam.

Claims (5)

A method of manufacturing a ceramic element in which electrical connection is made between one end surface side and the other end surface side of the ceramic layer through a through hole formed in the ceramic layer,
A step of forcibly shrinking the ceramic material together with the carrier film by heating a ceramic material that contains a lead-containing compound and is formed on the upper surface of the carrier film and becomes the ceramic layer;
Forming the position reference hole in at least one of the ceramic material and the carrier film after forcibly shrinking the ceramic material together with the carrier film ;
Forming the through hole in the ceramic material by irradiating the ceramic material with a laser beam of the second harmonic or the third harmonic of the YAG laser after forming the position reference hole; A method for producing a ceramic element, comprising: A method of manufacturing a ceramic element in which electrical connection is made between one end surface side and the other end surface side of the ceramic layer through a through hole formed in the ceramic layer,
A step of forcibly shrinking the ceramic material together with the carrier film by heating a ceramic material that has a powder density of 5000 kg / m ³ or more and is formed on the upper surface of the carrier film and serves as the ceramic layer;
Forming the position reference hole in at least one of the ceramic material and the carrier film after forcibly shrinking the ceramic material together with the carrier film ;
Forming the through hole in the ceramic material by irradiating the ceramic material with a laser beam of the second harmonic or the third harmonic of the YAG laser after forming the position reference hole; A method for producing a ceramic element, comprising:   2. The method of manufacturing a ceramic element according to claim 1, wherein the compound is lead zirconate titanate.   The method for manufacturing a ceramic element according to claim 1, wherein the laser light is pulse-oscillated. 5. The method of manufacturing a ceramic element according to claim 4, wherein the laser light is repeatedly oscillated by Q switching.

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