JP4655117B2 - Manufacturing method of chip parts - Google Patents

Description

  The present invention relates to a chip part manufacturing method, and more particularly to a chip part manufacturing method including a step of barrel polishing the chip part.

  In a method of manufacturing a chip component such as a ceramic electronic component, when a ridge line portion or a corner portion of the chip component is sharp, a phenomenon called chipping, in which the ridge line portion or the like is chipped or cracked, is a problem. It was.

  As a conventional technique for solving the above problems, for example, a manufacturing method is known in which, after obtaining a ceramic fired body, the ceramic fired body is barrel-polished to round the ridge line portion of the chip component. (Refer to patent document 1 etc.).

However, in the manufacturing method according to the prior art, since barrel polishing is performed after firing, there is a problem that chipping is likely to occur in the step before firing the chip component. Further, in the manufacturing method according to the prior art, when the rotational speed increase rate is large, the load applied to the chip component becomes too large and chipping is likely to occur during polishing, while the rotational speed increase rate is small, There was a problem that barrel polishing took a long time.
JP-A-8-316088

  An object of the present invention is to provide a method of manufacturing a chip component that prevents chipping and cracking of the chip component.

In order to solve the above object, a method for manufacturing a chip component according to the present invention includes:
Preparing a plurality of pre-fired chip parts;
Introducing the plurality of pre-fired chip parts into a barrel container;
A first stage of increasing the rotational speed of the barrel container at a first speed; and a second stage of increasing the rotational speed of the barrel container at a second speed smaller than the first speed after the first stage. A polishing step for controlling the number of rotations of the barrel container in a plurality of stages including, and barrel-polishing the chip part before firing, and
Firing the pre-fired chip component.

  In the chip part manufacturing method according to the present invention, the rotational speed of the barrel container is controlled at a plurality of stages in which the rotational speed of the barrel container is increased at different speeds, and the chip part before firing is barrel-polished. By appropriately adjusting the number of rotations of the barrel container according to the polishing state of the chip before firing, it is possible to suppress an excessive load from being applied to the chip during polishing and to prevent chipping. In addition, since the chip part manufacturing method according to the present invention barrel-polls the chip part before firing, chipping before the firing process can be prevented after the chip part before firing is manufactured.

  Moreover, in the chip component manufacturing method according to the present invention, in the polishing step, the chip component before firing may be dry-type and barrel-polished.

  Chips with good electrical characteristics can be obtained by performing dry barrel polishing, compared to when wet barrel polishing is performed, because liquid components and the like are prevented from entering the chip components during barrel polishing. Parts can be obtained. In addition, since the chip container manufacturing method according to the present invention can appropriately adjust the number of rotations of the barrel container in accordance with the polishing state of the chip before firing, the friction pressure applied to the chip before firing is adequate even when dry polishing is performed. To prevent chipping during polishing.

  In the chip component manufacturing method according to the present invention, in the polishing step, the pre-fired chip component may be barrel-polished without a medium.

  By barrel-polishing without using a medium, it is possible to omit the step of separating the media and the chip component after the polishing, so that the production of the chip component can be made more efficient. Further, it is possible to prevent a substance constituting the medium from entering the inside of the chip during polishing and adversely affecting the characteristics of the chip component.

  The first speed in the first stage may be a speed that increases the number of revolutions at a rate of 750 revolutions per minute or less. In particular, the occurrence of chipping and the like can be more effectively prevented by setting the speed of increase in the rotational speed of the barrel container immediately after the start of barrel polishing to a predetermined value or less.

  Further, in the polishing step, a constant speed stage for keeping the rotational speed of the barrel container constant after the second stage, and a deceleration stage for lowering the rotational speed of the barrel container after the constant speed stage; The number of rotations of the barrel container may be controlled in a plurality of stages further including: By controlling the number of rotations of the barrel container in a plurality of stages including a constant speed stage and a deceleration stage, the friction pressure applied to the chip part can be adjusted more appropriately.

  Further, in the polishing step, after the second stage, the barrel container is controlled in a plurality of stages further including one or more speed increasing stages for increasing the number of rotations of the barrel container, and in the speed increasing stage, The rotational speed of the barrel container is reduced at a speed smaller than any speed at which the rotational speed of the barrel container is increased in a stage performed before the speed increasing stage including the first stage and the second stage. It may be raised. The friction pressure applied to the tip can be adjusted more appropriately by controlling the number of rotations of the barrel container in multiple stages set so that the ascending speed gradually decreases with each stage.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a ceramic capacitor manufactured by a chip component manufacturing method according to an embodiment of the present invention.
FIG. 2A is a perspective view of a green chip before the barrel polishing step used in the chip component manufacturing method according to one embodiment of the present invention,
FIG. 2B is a schematic cross-sectional view of the green chip before the barrel polishing step shown in FIG.
FIG. 3A is a cross-sectional view showing a green sheet used for a chip component manufacturing method according to an embodiment of the present invention,
FIG. 3B is a cross-sectional view showing a green sheet having an internal electrode pattern layer used in the chip component manufacturing method according to the embodiment of the present invention.
FIG. 4A is a perspective view of a green chip after a barrel polishing step used for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention.
4B is a schematic cross-sectional view of the green chip after the barrel polishing step shown in FIG. 3A cut along the line IVB-IVB.
FIG. 5 is a schematic view of a barrel polishing apparatus used in a chip component manufacturing method according to an embodiment of the present invention.
FIG. 6 is a graph showing the change over time in the number of rotations of the barrel container in the polishing step performed in the chip component manufacturing method according to the first embodiment and Example 1.
FIG. 7 is a graph showing the change over time in the number of rotations of the barrel container in the polishing process performed in the method for manufacturing a chip part according to Example 2,
FIG. 8 is a graph showing the change over time in the number of rotations of the barrel container in the polishing step performed in the method of manufacturing a chip part according to Reference Example 1.
FIG. 9 is a graph showing the result of a polishing process simulation performed for the chip part manufacturing method according to Example 3,
FIG. 10 is a graph showing the results of a polishing process simulation performed for the chip component manufacturing method according to Reference Example 2.
First embodiment

  FIG. 1 is a schematic cross-sectional view showing an example of a ceramic capacitor 2 manufactured by a chip component manufacturing method according to an embodiment of the present invention. However, the chip component manufactured by the method according to the embodiment is not limited to the multilayer ceramic electronic component such as a ceramic capacitor, and may be other chip components.

  As shown in FIG. 1, the multilayer ceramic capacitor 2 manufactured by the manufacturing method according to the present embodiment includes a capacitor body 4, a first external electrode 6, and a second external electrode 8. The capacitor body 4 has inner dielectric layers 10 and internal electrode layers 12, and the internal electrode layers 12 are alternately stacked between the inner dielectric layers 10. The capacitor body 4 has outer dielectric layers 11 on both end faces in the stacking direction. One internal electrode layer 12 that is alternately stacked is electrically connected to the inside of the first external electrode 6 that is formed outside the first end of the capacitor body 4. The other internal electrode layers 12 that are alternately stacked are electrically connected to the inside of the second external electrode 8 formed outside the second end of the capacitor body 4.

  The material of the inner dielectric layer 10 and the outer dielectric layer 11 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. The thickness of each inner dielectric layer 10 is not particularly limited, but is generally several μm to several hundred μm. Further, the thickness of the outer layer portion made of the outer dielectric layer 11 is not particularly limited, but can be in the range of 10 to 200 μm.

  The material of the external electrodes 6 and 8 is not particularly limited, but usually at least one of Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, Ir, or an alloy thereof can be used. Usually, Cu, Cu alloy, Ni, Ni alloy, etc., Ag, Ag—Pd alloy, In—Ga alloy, etc. are used. The thickness of the external electrodes 6 and 8 is not particularly limited, but is usually about 10 to 50 μm. The shape and size of the multilayer ceramic capacitor 2 may be appropriately determined according to the purpose and application.

  Next, the manufacturing method of the multilayer ceramic capacitor as one embodiment of the present invention will be described.

  In the method for manufacturing a ceramic capacitor according to the present embodiment, first, as shown in FIGS. 2A and 2B, a green chip 42 in which a green laminate is cut to a predetermined size is prepared. Although it does not specifically limit as a manufacturing method of the green chip 42, For example, it can manufacture by the following methods.

   In the step of preparing the green chip 42, first, as shown in FIG. 3A, an inner green sheet paste is applied on a carrier sheet 20 as a support by a doctor blade method or the like. Form. The formed inner green sheet 10a is appropriately dried.

  The inner green sheet paste is usually composed of an organic solvent-based paste obtained by kneading ceramic powder and an organic vehicle, or an aqueous paste. The raw material for the ceramic powder is appropriately selected from various compounds to be composite oxides and oxides, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, and can be used as a mixture. An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral.

  Next, as shown in FIG. 3 (B), the internal electrode pattern layer 12a is formed on the surface of the inner green sheet 10a formed above using the internal electrode pattern layer paste, and the internal electrode pattern layer 12a is formed. The inner green sheet 10a is obtained. A method for forming the internal electrode pattern layer 12a is not particularly limited, and examples thereof include a printing method and a transfer method.

  The internal electrode pattern layer paste is obtained by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare. The internal electrode pattern layer paste may contain a ceramic powder as a co-material, if necessary.

  Next, the inner green sheets 10a having the obtained internal electrode pattern layers 12a are alternately stacked to obtain the internal stacked body 30 (FIG. 2B). And the obtained inner laminated body 30 is laminated | stacked on the outer side green sheet 11a, and also the outer side green sheet 11a is laminated | stacked also on the inner laminated body 30, and a green laminated body is obtained. Instead of laminating the inner laminate 30 on the outer green sheet 11a, a predetermined number of inner green sheets 10a and inner electrode pattern layers 12a may be alternately laminated on the outer green sheet 11a. Alternatively, a laminate unit in which a plurality of inner green sheets 10a and a plurality of internal electrode pattern layers 12a are alternately stacked may be prepared in advance, and a predetermined number of them may be stacked on the outer green sheet 11a.

  Similar to the inner green sheet 10a, the outer green sheet 11a is obtained by applying an outer green sheet paste on the carrier sheet 20 and then performing an appropriate drying process. Similar to the inner green sheet paste, the outer green sheet paste is composed of an organic solvent-based paste obtained by kneading ceramic powder and an organic vehicle, or an aqueous paste.

  The obtained green laminate is cut into a predetermined size to obtain a green chip 42 shown in FIG. At this stage, as shown in FIG. 2A, the green chip 42 has a substantially rectangular parallelepiped shape in which the ridge line portion 42a and the corner portion 42b are pointed. In the step of preparing the green chip 42, each of the green sheets 10a, 11a, the inner laminate 30 and the green chip 42 is dried as necessary.

  Next, in the method for manufacturing a ceramic capacitor according to the present embodiment, the plurality of green chips 42 obtained as described above are put into the pot 52 in the barrel apparatus 50 shown in FIG.

  As shown in FIG. 5, the barrel device 50 has a barrel device main body portion including a pot 52 and a support portion 53, and the barrel main body portion is housed inside a barrel device exterior 54. The barrel device 50 used in the manufacturing method according to the present embodiment is a centrifugal barrel device, and has four pots 52 that are rotated around a revolution shaft 58. The pots 52 are arranged at substantially equal intervals (90-degree intervals) on the circumference around the revolution axis 58 (however, only two pots 52 are shown in FIG. 5).

  The shape of the pot 52 is usually a cylindrical shape or a polygonal column shape, and may be appropriately changed depending on the polishing conditions. In the present embodiment, the shape is a hexagonal column shape. The pot 52 is provided with a lid 60 for sealing a green chip or the like put into the pot. In addition, as the barrel apparatus 50 used for the manufacturing method which concerns on this invention, it is not limited to a centrifugal barrel apparatus, You may use other barrel apparatuses, such as a rotation barrel apparatus.

  A revolving shaft 58 whose rotational speed can be controlled by a control unit (not shown) is attached to the support unit 53 of the barrel device 50. A revolution plate 55 that rotates integrally with the revolution shaft 58 is fixed to the revolution shaft 58. Further, a pot holder 56 is attached to the upper surface of the revolution plate 55 via a rotation shaft 51.

  The pot 52 into which the green chip 42 is inserted is attached to the pot holder 56 and is rotated about the revolution shaft 58 together with the pot holder 56, so that centrifugal force is applied to the green chip 42. Further, the pot 52 shown in FIG. 5 is rotatable around a rotation shaft 51 attached to the revolution plate 55.

  That is, a control unit (not shown) can independently control the rotation speed of the revolution shaft 58 and the rotation speed of the rotation shaft 51 as necessary. Therefore, the barrel device 50 can perform barrel polishing by controlling the number of rotations to apply an appropriate centrifugal force to the green chip 42 put in the pot 52. In the present specification and claims, the rotation of the pot 52 includes the rotation of the pot 52 around the rotation axis 51 and the revolution of the pot 52 around the revolution axis 58.

  In the present embodiment, liquid such as water is not poured into the pot 52, and barrel polishing is performed in a dry manner. By performing barrel polishing in a dry manner, it is possible to prevent liquid components such as moisture from entering the green chip 42 during polishing and deteriorating electrical characteristics after firing.

  In the barrel polishing according to the present embodiment, a medium (polishing medium) may be input together with the green chip 42. As the media, alumina balls, silica balls, zirconia balls, or the like can be used. However, in barrel polishing according to the present embodiment, media may be polished without putting media into the pot 52.

  By performing medialess polishing, it is possible to prevent substances constituting the media from entering the green chip 42 and deteriorating electrical characteristics after firing. Moreover, since the process of separating the green chip 42 and the media after polishing can be omitted, the manufacturing process can be simplified and the productivity can be improved.

  In the method for manufacturing a ceramic capacitor according to the present embodiment, after putting a plurality of green chips 42 into the pot 52 of the barrel apparatus 50 shown in FIG. 5, the pot 52 is rotated to perform barrel polishing. The ridgeline part 42a and the corner part 42b shown in FIG. In the barrel apparatus 50 shown in FIG. 5, barrel polishing may be performed by rotating only one of the revolution shaft 58 and the rotation shaft 51, or barrel polishing while rotating both the revolution shaft 58 and the rotation shaft 51. You may do.

  In the present embodiment, barrel polishing is performed by rotating only the revolution shaft 58 while the rotation shaft 51 is fixed. FIG. 6 shows the change over time of the rotational speed of the pot 52 attached to the revolution shaft 58 shown in FIG. In the polishing process in the present embodiment, the rotational speed of the revolution shaft 58 is increased while controlling the rotational speed of the revolution shaft 58 (pot 52) in the first to fourth stages, which are different from each other. Since the pot 52 is fixed to the revolution shaft 58 via the revolution plate 55 and the pot holder 56 shown in FIG. 5, the pot 52 rotates around the revolution shaft 58 at the same rotational speed as the revolution shaft 58.

  That is, in the first stage 61 from the start of rotation to 3 minutes after the start of rotation, the control unit of the barrel device 50 increases the rotation speed of the pot 52 (revolution shaft 58) at the first speed. The first speed is a speed at which the number of rotations of the pot 52 is increased at a rate of approximately 27 rotations per minute. By the first step 61, the rotation speed of the pot 52 reaches 80 rpm.

  In the second stage 62 from 3 minutes to 10 minutes after the start of rotation, the control unit of the barrel device 50 increases the rotation speed of the pot 52 at the second speed. The second speed is a speed at which the number of rotations of the pot 52 is increased at a rate of about 9 rotations per minute. By the second stage 62, the rotational speed of the pot 52 reaches 140 rpm.

  In the third stage 63 from 10 minutes to 15 minutes after the start of rotation, the control unit of the barrel device 50 increases the rotation speed of the pot 52 at the third speed. The third speed is a speed at which the number of rotations of the pot 52 is increased at a rate of about 4 rotations per minute. According to the third stage 63, the rotational speed of the pot 52 reaches 160 rpm.

  In the fourth stage 64 from 15 minutes to 25 minutes after the start of rotation, the control unit of the barrel device 50 increases the rotational speed of the pot 52 at the fourth speed. The fourth speed is a speed at which the number of rotations of the pot 52 is increased at a rate of approximately two rotations per minute. According to the fourth stage 64, the rotational speed of the pot 52 reaches 180 rpm.

  In the constant speed phase 65 from 25 to 45 minutes after the start of rotation, the rotation speed of the pot 52 is maintained at 180 rpm, and in the deceleration phase 66 from 45 to 50 minutes after the rotation starts, the rotation speed of the pot 52 is set to the seventh speed. Lower at speed. The seventh speed is a speed at which the number of rotations of the pot 52 is decreased at a rate of about 36 rotations per minute. The rotation of the pot 52 is stopped by the deceleration stage 66, and the barrel polishing process is completed.

  FIG. 4 is a perspective view showing a polished green chip 43 obtained by polishing the green chip 42 shown in FIG. 2 by the above-described polishing process. The ridge line portion 43a and the corner portion 43b of the green chip 43 are rounded by barrel polishing.

  As described above, in the manufacturing method according to the present embodiment, since the ridge line portion 43a and the corner portion 43b of the green chip 43 are rounded, in the subsequent process of firing the green chip 42 or the like, It is possible to prevent cracks, chips, cracks and the like from occurring. In addition, it can prevent effectively that a chipping etc. generate | occur | produce in a subsequent process by making the radius dimension of the roundness R formed in the ridgeline part 43a and the corner part 43b of the green chip 43 into about 20 micrometers-40 micrometers.

  In the polishing process according to the present embodiment, the first stage 61 for increasing the rotational speed of the pot 52 at the first speed and the second rotational speed of the pot 52 that is smaller than the first speed after the first stage 61 are second. The number of rotations of the barrel is controlled in a plurality of stages including a second stage 62 that increases at a speed of. By performing such control, the manufacturing method according to the present embodiment can effectively prevent the chipping of the green chip 42 during polishing and can perform polishing in a short time.

  That is, the polishing process according to the present embodiment controls the rotation speed of the pot 52 at a plurality of stages in which the rotation speed of the pot 52 is increased at different speeds. (Centrifugal force) can be applied. By increasing the rotation speed of the pot 52 at an appropriate speed, it is possible to suppress a sudden increase in load on the green chip 42 due to a rapid increase in the rotation speed and prevent chipping. Furthermore, by changing the increasing speed of the rotational speed, it is possible to prevent a state in which sufficient centrifugal force is not applied to the polishing state of the green chip 42 from continuing, and to shorten the polishing time.

  Further, the rotation speed of the pot 52 is sandwiched between a rising stage for increasing the rotation speed of the pot 52 (for example, the first stage 61 and the second stage 62) with a constant speed stage for holding the rotation speed of the pot 52 for a certain time. Can be raised step by step. However, since the polishing of the green chip 42 proceeds even at a constant speed stage, it is preferable to increase the rotation speed of the barrel continuously rather than intermittently. That is, in the barrel polishing step, it is preferable to continuously increase the rotation speed of the pot 52 until a predetermined rotation speed is reached from the viewpoint of applying an appropriate load to the green chip 42 in accordance with the polishing state.

  Further, by making the second speed smaller than the first speed, an appropriate load (centrifugal force) can be applied to the green chip 42 in accordance with the polishing state. This is because, in the first stage 61, it is preferable to quickly increase the rotational speed of the pot 52 until the flow of the green chip 42 is started inside the pot 52 and the polishing is substantially started.

  Accordingly, in the first stage 61, the rotational speed of the pot 52 is quickly increased, and in the second stage 62, the speed of increase of the rotational speed of the pot 52 is made smaller than that in the first stage 61, thereby providing an appropriate load on the green chip 42. (Centrifugal force) can be applied. Therefore, the polishing process according to the present embodiment can reduce the time required for polishing while preventing chipping. Thus, in the barrel polishing step, the rotational speed of the pot 52 can be continuously increased while controlling the rotational speed of the pot 52 to gradually decrease until the predetermined rotational speed is reached. This is preferable from the viewpoint of applying an appropriate load to the green chip 42.

  Furthermore, according to the polishing step according to the present embodiment, when the green chips 42 in the pot 52 collide with each other, chipping is suppressed even in dry polishing that does not add water that has a function of relaxing the impact. Polishing can be performed. This is because the polishing process according to the present embodiment can perform barrel polishing while maintaining the load applied to the green chip 42 at an appropriate size according to the polishing state. It should be noted that the speed of increase in the rotational speed of the pot 52 may be changed in finer steps, or may be controlled so as to make the speed of increase in the rotational speed of the pot 52 small in a transitional manner. In this way, by performing barrel polishing in a dry manner, it is possible to prevent liquid components such as moisture from entering the green chip 42 during polishing and deteriorating electrical characteristics after firing.

  Further, according to the polishing step according to the present embodiment, polishing can be performed without putting a medium (polishing medium) into the pot 52. This is because the polishing process according to the present embodiment can perform barrel polishing while maintaining the load applied to the green chip 42 at an appropriate size according to the polishing state, and therefore it is efficient even if polishing is performed without media. This is because an effective polishing is possible.

  Further, by performing polishing without a medium, it is possible to prevent substances constituting the medium from entering the green chip 42 and deteriorating electrical characteristics after firing. Moreover, since the process of separating the green chip 42 and the media after polishing can be omitted, the manufacturing process can be simplified and the productivity can be improved.

  In the method for manufacturing a ceramic capacitor according to the present embodiment after the polishing process, the green chip 43 is subjected to a binder removal process, a firing process, an annealing process performed as necessary, and the like, so that the capacitor shown in FIG. An element body 4 is obtained. In the manufacturing method according to the present embodiment, since the green chip 42 before firing is barrel-polished, chipping can be prevented until the green chip 42 is produced and then fired.

Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.
Example 1

  In the manufacturing method according to Example 1 of the present invention, a green chip 42 as shown in FIG. 2A was prepared. As described in the embodiment, the green chip 42 is formed by laminating the inner green sheet 10a having the internal electrode pattern layer 12a on the surface on the outer green sheet 11a, and further laminating the outer green sheet 11a. A laminate was formed and the resulting green laminate was cut.

As the inner green sheet paste used for the inner green sheet 10a shown in FIG. 2B, an organic solvent-based paste obtained by kneading BaTiO ₃ -based powder as a ceramic powder and an organic vehicle was used. Polyvinyl butyral resin was used as the binder used in the organic vehicle, and terpineol was used as the solvent.

The internal electrode paste for forming the internal electrode pattern layer was prepared by kneading Ni particles as a conductive agent and an organic vehicle. Further, as the outer green sheet paste used for the outer green sheet 11a, an organic solvent-based paste obtained by kneading BaTiO ₃ -based powder, which is a ceramic powder, and an organic vehicle is used in the same manner as the inner green sheet paste. It was.

  The green chip 42 obtained by cutting the green laminate has a width of 1.0 mm, a length of 0.5 mm, in a state where the external electrodes 6 and 8 shown in FIG. The dimensions were such that a ceramic capacitor with a height of 0.5 mm could be obtained.

  In the manufacturing method according to Example 1 of the present invention, the plurality of green chips 42 obtained as described above were put into the pot 52 of the barrel apparatus 50 shown in FIG. The volume of the pot 52 used in Example 1 was 2 liters, and the input amount of the green chip 42 into the pot 52 was 50% of the volume of the pot 52.

  Further, in the manufacturing method according to the first embodiment of the present invention, the liquids such as water, solvent, and dispersing material are not put into the pot 52, and these liquids are not substantially present in the pot 52, that is, Barrel polishing was performed dry. Further, media was not put into the pot 52, and barrel polishing was performed without using media.

  Next, in the manufacturing method according to the first embodiment of the present invention, the pot 52 in which the green chip 42 is inserted is rotated to perform barrel polishing, and the ridge line portion 42a and the corner portion 42b shown in FIG. Wearing.

  FIG. 6 shows the change over time of the rotational speed of the pot 52 shown in FIG. In the polishing process in Example 1, the number of revolutions of the revolution shaft 58 (pot 52) was increased while being controlled in the first to fourth stages in which the ascent speed of the revolution shaft 58 was different from each other. In the manufacturing method according to Example 1, barrel polishing was performed by rotating only the revolution shaft 58 while the rotation shaft 51 was fixed. Also in the first embodiment, since the pot 52 is fixed to the revolution shaft 58 via the revolution plate 55 and the pot holder 56 shown in FIG. 5, the pot 52 rotates around the revolution shaft 58 at the same rotational speed as the revolution shaft 58. Rotate.

  That is, as shown in FIG. 6, in the first stage 61 from the start of rotation to 3 minutes after the start of rotation, the rotation speed of the pot 52 is set to the first speed (the rotation speed of the pot 52 is approximately 27 rotations per minute). The rate was increased at a rate). By the first step 61, the rotation speed of the pot 52 reached 80 rpm.

  In the second stage 62 from 3 minutes to 10 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the second speed (the rotation speed of the pot 52 is approximately 9 rotations per minute). ). By the second stage 62, the rotation speed of the pot 52 reached 140 rpm.

  In the third stage 63 from 10 minutes to 15 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the third speed (the rotation speed of the pot 52 is approximately 4 rotations per minute). The speed was raised at (). By the third stage 63, the rotation speed of the pot 52 reached 160 rpm.

  In the fourth stage 64 from 15 minutes to 25 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the fourth speed (the rotation speed of the pot 52 is approximately two rotations per minute). Increase the speed at (). By the fourth stage 64, the rotation speed of the pot 52 reached 180 rpm.

  In the constant speed phase 65 from 25 to 45 minutes after the start of rotation, the rotation speed of the pot 52 is maintained at 180 rpm, and in the deceleration phase 66 from 45 to 50 minutes after the rotation starts, the rotation speed of the pot 52 is set to the seventh speed. The speed was lowered at a speed (speed at which the number of revolutions of the pot 52 was lowered at a rate of about 36 revolutions per minute). The rotation of the pot 52 was stopped by the deceleration stage 66, and the barrel polishing process was completed.

  In the first embodiment, the above-described polishing process is performed, and the green chip 42 shown in FIG. 2 is barrel-polished so that the ridge line portion 43a and the corner portion 43b are formed as shown in FIGS. 4 (A) and 4 (B). A rounded green chip 43 was obtained. The radius dimension of the roundness R formed in the ridge line portion 43a and the corner portion 43b of the green chip 43 was 10 μm to 50 μm.

  Furthermore, in Example 1, the capacitor body 4 shown in FIG. 1 was obtained by performing the binder removal step and the firing step on the green chip 43. Further, 500 pieces of the obtained ceramic body 4 were examined for cracks and chips. The results are shown in Table 1.

As shown in Table 1, in Example 1, none of the 500 ceramic bodies 4 investigated had cracks or chips, and the chipping rate was 0%.
Example 2

  In the manufacturing method according to Example 2, the capacitor element body 4 was manufactured in the same manner as in the manufacturing method according to Example 1, except that the control (time change) of the rotation speed of the pot 52 in the polishing process was different. FIG. 7 shows a change over time in the number of rotations of the pot 52 in the polishing step of the manufacturing method according to the second embodiment. In the polishing process in Example 2, the number of revolutions of the revolution shaft 58 (pot 52) shown in FIG. 5 was increased while controlling the revolution speed of the revolution shaft 58 in the first to fifth stages different from each other.

  That is, in the first stage 67 from the start of rotation to 0.2 minutes after the start of rotation, the rotation speed of the pot 52 is increased to the first speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 750 rotations per minute. ). By the first stage 67, the number of rotations of the pot 52 reached 150 rpm.

  In the second stage 68 from 0.2 to 10 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the second speed (the rotation speed of the pot 52 is approximately two rotations per minute). )). By the second stage 68, the rotation speed of the pot 52 reached 170 rpm.

  In the third stage 69 from 10 minutes to 15 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the third speed (the rotation speed of the pot 52 is approximately 1 rotation per minute). The speed was raised at (). By the third stage 69, the rotation speed of the pot 52 reached 175 rpm.

  In the fourth stage 70 from 15 minutes to 20 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the fourth speed (the rotation speed of the pot 52 is a rate of approximately 3 rotations in 5 minutes). The speed was raised at (). By the fourth stage 70, the rotation speed of the pot 52 reached 178 rpm.

  In the fifth stage 71 from 20 minutes to 25 minutes after the start of rotation, the control unit of the barrel device 50 sets the rotation speed of the pot 52 to the fifth speed (the rotation speed of the pot 52 is a rate of approximately two rotations in five minutes). The speed was raised at (). By the fifth stage 71, the rotation speed of the pot 52 reached 180 rpm.

  In the constant velocity stage 72 from the start of rotation to 45 minutes after the start of rotation, the rotation speed of the pot 52 is maintained at 180 rpm, and in the deceleration stage 73 from 45 minutes to 50 minutes after the start of rotation, the rotation speed of the pot 52 is changed to the seventh speed. The speed was lowered at a speed (speed at which the number of revolutions of the pot 52 was lowered at a rate of about 36 revolutions per minute). The rotation of the pot 52 was stopped by the deceleration stage 73, and the barrel polishing process was completed.

In Example 2, as in Example 1, the green chip 43 was fired and 500 of the ceramic body 4 were examined for cracks and chips. The results are shown in Table 1. In Example 2, five of the 500 ceramic bodies 4 were cracked or chipped, and the chipping rate was 1%.
Reference example 1

  In the manufacturing method according to Reference Example 1, the capacitor element body 4 was manufactured in the same manner as the manufacturing method according to Example 1, except that the control (time change) of the rotational speed of the pot 52 in the polishing process was different. FIG. 8 shows a change over time in the number of rotations of the pot 52 in the polishing process of the manufacturing method according to Reference Example 1. In the polishing process in Reference Example 1, the number of revolutions of the revolution shaft 58 (pot 52) was increased in one step. In Reference Example 1 as well, the pot 52 rotates around the revolution shaft 58 at the same rotational speed as the revolution shaft 58.

  That is, in the first stage 74 from the start of rotation to 0.1 minutes after the start of rotation, the rotation speed of the pot 52 is increased to the first speed (the rotation speed of the pot 52 is increased at a rate of approximately 1500 rotations per minute. ). By the first stage 74, the rotation speed of the pot 52 reached 150 rpm.

  In the constant speed stage 75 from the start of rotation to 0.1 to 60 minutes, the rotation speed of the pot 52 is maintained at 150 rpm, and in the deceleration stage 76 from the start of rotation to 60.1 minutes, the rotation speed of the pot 52 is reached. Was lowered at a seventh speed (the speed at which the rotational speed of the pot 52 was lowered at a rate of approximately 1500 revolutions per minute). The rotation of the pot 52 was stopped by the deceleration stage 76, and the barrel polishing process was completed.

In Reference Example 1, as in Examples 1 and 2, 500 of the ceramic body 4 obtained by firing the green chip 43 was examined for cracks and chips. The results are shown in Table 1. In the reference example, among the 500 ceramic body 4, there were 20 that were cracked or chipped, and the chipping rate was 4%.
Comprehensive evaluation

  As shown in Table 1, the manufacturing method according to Examples 1 and 2 has a lower chipping occurrence rate than that of Reference Example 1. That is, in the manufacturing methods according to the first and second embodiments, when the rotation speed of the pot 52 is increased, the increase speed of the rotation speed is controlled in multiple stages and while decreasing with time. It is effectively prevented that an excessive load is applied to the chip 42. Therefore, in the manufacturing methods according to Examples 1 and 2, it is considered that an excessive load is not applied to the green chip 42 during polishing, and the chipping occurrence rate is reduced.

  Further, in Example 1 where the chipping occurrence rate was 0%, even in the first stage 61 where the rotational speed increase rate was the highest, the rotational speed increase speed of the pot 52 was approximately 26.7 rotations per minute. It is. For this reason, the ridge line portion 42a of the green chip 42 is sharpest during polishing, and even immediately after the start of polishing when a sudden load is easily applied to the green chip 42, the load related to the green chip 42 is appropriately adjusted to prevent chipping. It is thought that.

  On the other hand, in Example 2 where the chipping occurrence rate was 1%, the increase speed of the pot 52 in the first stage 67 was approximately 750 rotations per minute, and the increase speed of the rotation speed was further increased. When it is raised, the chipping occurrence rate is considered to deteriorate. Therefore, it is considered that the rate of increase in the rotation speed of the pot 52 in the first stage is preferably 750 rotations or less.

  In Reference Example 1 in which the chipping occurrence rate was 4%, the number of rotations of the pot 52 was increased at a one-step rising speed. At this time, an excessive load was applied to the green chip 42 and chipping occurred during polishing. It is thought that it occurred. Since the polishing process of the example and the reference example is performed by a dry method in which the impact mitigating action by the liquid does not work, in the first and second examples, the load on the green chip 42 is appropriately adjusted as described above. It is considered that the remarkable effect appears remarkably.

In Example 3 and Reference Example 2 described below, how the friction pressure applied to the green chip 42 changes during barrel polishing performed in each Example and Reference Example was simulated.
Example 3

  In Example 3, except that the control (rotational change) of the number of rotations of the pot 52 in the polishing process is different, the capacitor element body 4 is manufactured in the same manner as in the manufacturing method according to Example 1, and during barrel polishing. The friction pressure was simulated. The results are shown in FIG.

  FIG. 9 shows the change in the rotation speed of the pot 52 (that is, the rotation speed of the revolution shaft 58) with respect to the time change and the change in the friction pressure polished in the pot 52. In FIG. 9, the change in the rotational speed of the pot 52 is represented by a dotted line, and the change in the friction pressure is represented by a solid line.

  In Example 3, the simulation was performed under the condition that barrel polishing is performed while controlling the rotational speed of the pot 52 in the first to sixth stages in which the increasing speed of the rotational speed of the pot 52 is different from each other. That is, in the first stage 77 from the start of rotation to 2 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a first speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 40 rotations per minute). 2 minutes after the start of rotation, the rotation speed of the pot 52 reaches 80 rpm.

  Further, in the second stage 78 from 2 minutes to 6 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a second speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 15 rotations per minute). 6 minutes after the start of rotation, the rotation speed of the pot 52 reaches 140 rpm. In the third stage 79 from 6 minutes to 10 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a third speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 5 rotations per minute), 10 minutes after the start of rotation, the rotation speed of the pot 52 reaches 160 rpm.

  Similarly, in the fourth stage 80 from 10 minutes to 15 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a fourth speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 4 rotations per minute). After 15 minutes from the start of rotation, the rotational speed of the pot 52 reaches 180 rpm. In the fifth stage 81 from 15 to 25 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a fifth speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 2 rotations per minute), The rotation speed of the pot 52 reaches 200 rpm 25 minutes after the start of rotation.

  In the sixth stage 82 from 25 minutes to 45 minutes after the start of rotation, the rotation speed of the pot 52 is increased at a sixth speed (speed at which the rotation speed of the pot 52 is increased at a rate of approximately one rotation per minute) After 45 minutes from the start of rotation, the rotation speed of the pot 52 reaches 220 rpm. In the deceleration stage 83 from 45 minutes to 50 minutes after the start of rotation, the rotational speed of the pot 52 is decreased at a seventh speed (the rotational speed of the pot 52 is decreased at a rate of approximately 44 rotations per minute), The rotation of the pot 52 was stopped 50 minutes after the start of rotation.

Here, the friction pressure P applied to the green chip 42 put into the pot 52 during barrel polishing is a contact area S (t) that is a function of the centrifugal force F generated by the rotation of the pot 52 and the time t. Can be generally expressed as in equation (1).
P = F / S (t) (1)

Further, the centrifugal force F is expressed as in Expression (2) using the mass m of the green chip 42, the rotation radius r of the pot 52, and the angular velocity ω proportional to the rotation speed of the pot 52.
F = mrω ² (2)

When the formula (2) is substituted into the formula (1), the friction pressure P can be expressed by the formula (3).
P = mrω ² / S (t) (3)
That is, the friction pressure P is inversely proportional to the contact area S and proportional to the square of the rotation speed (angular velocity ω).

  The friction pressure indicated by the solid line in FIG. 9 was calculated based on the equation (3). In Example 3, as shown in FIG. 9, it can be seen that there is no rapid fluctuation of the friction pressure, and a stable friction pressure is applied to the green chip 42. That is, in the third embodiment, the number of rotations of the barrel container is controlled in multiple stages that are set so that the ascending speed gradually decreases for each stage. Accordingly, the rotation speed of the pot 52 (the angular velocity ω in the expression (3)) increases corresponding to the increase in the contact area S in the expression (3) as the polishing progresses, and the green chip 42 is stabilized. A friction pressure P is applied.

As shown in FIG. 9, according to the manufacturing method according to the third embodiment, the friction pressure is stable without a steep change, so that the load applied to the green chip 42 is set to an appropriate size according to the polishing state. It can be seen that barrel polishing can be performed while keeping. Therefore, by performing barrel polishing while increasing the number of rotations of the barrel in multiple stages with different rising speeds, it is possible to reduce the polishing time while suppressing rapid fluctuations in friction pressure and preventing chipping. It is.
Reference example 2

  In Reference Example 2, the friction pressure during barrel polishing was simulated in the same manner as in Example 3 except that the control (time change) of the rotation speed of the pot 52 in the polishing process was different. The results are shown in FIG.

  In the polishing process in Reference Example 1, as indicated by the dotted line in FIG. 10, the number of revolutions of the revolution shaft 58 was increased in one step. That is, in the first stage 84 from the start of rotation to 0.1 minutes after the start of rotation, the rotation speed of the revolution shaft 58 is increased to the first speed (the speed at which the rotation speed of the pot 52 is increased at a rate of approximately 1500 rotations per minute. ), And the rotational speed of the pot 52 reaches 150 rpm 0.1 minutes after the start of the rotation.

  In the constant speed stage 85 from 0.1 minute to 60 minutes after the start of rotation, the rotation speed of the pot 52 is maintained at 150 rpm, and then in the deceleration stage 86 from 60 minutes to 60.1 minutes after the rotation starts, the rotation speed of the pot 52. Was lowered at a seventh speed (the speed at which the rotational speed of the pot 52 was lowered at a rate of approximately 1500 revolutions per minute). The rotation of the pot 52 was stopped by the deceleration stage 86, and the barrel polishing process was completed.

  In Reference Example 2, as shown in FIG. 10, the friction pressure indicated by the solid line increases rapidly immediately after the start of polishing, and then decreases rapidly. When the number of rotations of the pot 52 is increased in one stage as in Reference Example 2, a very large frictional pressure is applied to the green chip 42 in the first stage 84, so that the green chip 42 is cracked and chipped. It can be seen that there is a high risk of

FIG. 1 is a schematic cross-sectional view showing an example of a ceramic capacitor manufactured by a chip component manufacturing method according to an embodiment of the present invention. 2A is a perspective view of the green chip before the barrel polishing process used in the chip part manufacturing method according to the embodiment of the present invention, and FIG. 2B is the barrel polishing process shown in FIG. It is the schematic sectional drawing which cut | disconnected the front green chip along the II-II line. FIG. 3A is a cross-sectional view showing a green sheet used in a method for manufacturing a chip component according to an embodiment of the present invention, and FIG. 3B shows a green sheet having an internal electrode pattern layer in FIG. It is sectional drawing to represent. 4A is a perspective view of a green chip after a barrel polishing process used for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention, and FIG. 4B is a barrel polishing process shown in FIG. 3A. It is the schematic sectional drawing which cut | disconnected the subsequent green chip along the III-IIIB line. FIG. 5 is a schematic view of a barrel polishing apparatus used in a chip part manufacturing method according to an embodiment of the present invention. FIG. 6 is a graph showing temporal changes in the number of rotations of the barrel in the polishing process performed in the chip component manufacturing method according to the first embodiment and Example 1. FIG. 7 is a graph showing a temporal change in the number of rotations of the barrel in the polishing process performed in the chip component manufacturing method according to the second embodiment. FIG. 8 is a graph showing temporal changes in the number of rotations of the barrel in the polishing process performed in the method of manufacturing the chip part according to Reference Example 1. FIG. 9 is a graph showing a result of a polishing process simulation performed for the chip part manufacturing method according to the third embodiment. FIG. 10 is a graph showing the results of a polishing process simulation performed for the chip component manufacturing method according to Reference Example 2.

Explanation of symbols

2 ... Ceramic capacitor 4 ... Capacitor body 42, 43 ... Green chip 50 ... Barrel device 51 ... Spindle shaft 52 ... Pot 58 ... Revolving shaft 61, 67, 77 ... First stage 62, 68, 78 ... Second stage

Claims (7)

Preparing a plurality of pre-fired chip parts;
Introducing the plurality of pre-fired chip parts into a barrel container;
A first stage of increasing the rotational speed of the barrel container at a first speed; and a second stage of increasing the rotational speed of the barrel container at a second speed smaller than the first speed after the first stage. A polishing step for controlling the number of rotations of the barrel container in a plurality of stages including, and barrel-polishing the chip part before firing, and
And a step of firing the pre-fired chip component.   2. The chip part manufacturing method according to claim 1, wherein in the polishing step, the pre-firing chip part is dry-type and barrel-polished.   3. The chip part manufacturing method according to claim 1, wherein in the polishing step, the pre-fired chip part is barrel-polished without a medium.   Of the plurality of steps for controlling the number of revolutions of the barrel container, all of the steps for increasing the number of revolutions of the barrel container increase the number of revolutions at a rate of 750 revolutions per minute or less. A method for manufacturing a chip part according to any one of claims 1 to 3.   5. The chip part manufacturing method according to claim 1, wherein in the polishing step, in the first stage, a friction pressure equal to or lower than the second stage is applied to the chip part before firing. 6.   The polishing step further includes a constant speed step for keeping the rotational speed of the barrel container constant after the second stage, and a deceleration stage for lowering the rotational speed of the barrel container after the constant speed stage. 6. The method of manufacturing a chip part according to claim 1, wherein the number of rotations of the barrel container is controlled in a plurality of stages.   In the polishing step, after the second stage, the barrel container is controlled in a plurality of stages further including one or more speed increasing stages for increasing the number of rotations of the barrel container. In the speed increasing stage, The rotation speed of the barrel container is increased at a speed smaller than any speed at which the rotation speed of the barrel container is increased in a stage performed before the speed increase stage including the first stage and the second stage. The method for manufacturing a chip part according to claim 1, wherein:

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