JP2005327929A - Method for manufacturing semiconductor ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor ceramic electronic component capable of surely suppressing a growth of an undesired plating film on the surface of a ceramic sintered compact other than the surface of an external electrode, when forming a plating film by an electrolytic plating method after forming the external electrode on the outer surface of the ceramic sintered compact. <P>SOLUTION: The method for manufacturing the semiconductor ceramic electronic component comprises the step of preparing the ceramic sintered compact, barrel polishing the ceramic sintered compact with the use of a barrel and a polishing powder, then removing the polishing powder adhered to the surface of the ceramic sintered compact by the step of removing the polishing powder, and then forming the external electrode on the surface by applying and baking a conductive paste on the end face of the ceramic sintered compact, and forming a plating film by the electrolytic plating method after forming the external electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a semiconductor ceramic electronic component using semiconductor ceramics such as a varistor or a thermistor. More specifically, an internal electrode is drawn out to an end surface of a ceramic sintered body, and the external electrode is electrically connected to the end surface. The present invention relates to a method for manufacturing a semiconductor ceramic electronic component having a structure connected to the.

  Conventionally, varistors, thermistors, and the like are known as ceramic electronic parts using semiconductor ceramics. A varistor is widely used as an element for protecting a circuit from electrostatic discharge or surge current, for example.

  With the miniaturization of electronic components, multilayer ceramic varistors using semiconductor ceramics are also widely used in varistors. The multilayer varistor includes a ceramic sintered body in which semiconductor ceramics and internal electrodes are alternately stacked, and external electrodes formed on both end faces of the ceramic sintered body.

  The external electrode is usually formed by baking a conductive paste. In many cases, a Ni plating film and a Sn plating film are formed on the surface of the external electrode by a wet electrolytic plating method. The Sn plating film improves solderability and achieves high-density mounting, and the Ni plating film can prevent the underlying internal electrode from being eroded by solder.

  By the way, in the multilayer varistor, the ceramic layer is made of semiconductor ceramics. Therefore, when the plating film is formed by electrolytic plating, the electric field during plating is partially concentrated on the surface of the ceramic sintered body, current flows on the surface of the ceramic sintered body, and Ni and Sn are deposited. It was. For this reason, the deposited Ni or Sn tends to grow, and the plating film tends to precipitate in the ceramic sintered body portion other than the surface of the external electrode.

  When a plated film is formed on the surface of the ceramic sintered body other than the region where the external electrode is formed, a short circuit problem occurs in the multilayer varistor.

  Therefore, Patent Document 1 below discloses a method for reducing the irregularities on the surface of the ceramic sintered body in order to solve the above-described problems. In other words, when manufacturing a multilayer varistor, barrel polishing is performed after obtaining a ceramic sintered body so that the internal electrodes are exposed to the end face of the ceramic sintered body and the corners of the ceramic sintered body are chamfered. It has been broken. In the method described in Patent Document 1, in this barrel polishing, a ceramic ball or glass ball having a diameter of 0.2 to 0.3 mm, an alumina compound or silicon carbide compound having a diameter of 0.1 to 1.0 μm, water, and the like A method is disclosed in which a surface roughness Ra value of a ceramic sintered body is set to 0.01 to 0.04 μm by barrel-polishing the ceramic sintered body for 30 to 120 minutes using a solvent.

Here, it is possible to reduce the unevenness of the ceramic sintered body surface as described above, thereby suppressing the growth of the plating film due to the electric field concentration described above.
JP 2000-3805 A

  However, in the method described in Patent Document 1, the surface roughness Ra value of the ceramic sintered body surface is reduced to 0.01 to 0.04 μm to reduce unevenness. However, there is a problem that the insulator powder made of alumina compound or silicon carbide compound used for barrel polishing adheres to the surface of the ceramic sintered body and remains. Therefore, during plating, electric field concentration occurs around the attached insulator, the resistance of the semiconductor ceramic is lowered, and the plating film may grow with the insulator as a core. That is, in the method described in Patent Document 1, it is not always possible to reliably prevent the plating film from being deposited on the surface of the ceramic sintered body when the plating film is formed by electrolytic plating.

  In addition, it is actually difficult to make the outer surface of the ceramic sintered body have a uniform surface roughness due to the nature of barrel polishing, and there are portions with large irregularities, regardless of the presence or absence of insulating powder. There was a portion where the plating film grew.

  The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and in the production of ceramic electronic parts using semiconductor ceramics, when a plating film is formed on the surface of the external electrode by the electrolytic plating method, An object of the present invention is to provide a method for manufacturing a ceramic electronic component in which undesired plating film growth is unlikely to occur on the surface portion of the bonded body.

  1st invention of this application is a semiconductor provided with the ceramic sintered compact which consists of semiconductor ceramics, the external electrode formed in the end surface of a ceramic sintered compact, and the plating film formed in the said external electrode surface by the electroplating method A method of manufacturing a ceramic electronic component, comprising: preparing a green chip made of unsintered semiconductor ceramics; firing the green chip to obtain a ceramic sintered body; and crushing and polishing the ceramic sintered body A barrel polishing step for barrel polishing using powder, a polishing powder removal step for removing polishing powder adhering to the surface of the ceramic sintered body after the barrel polishing step, and applying a conductive paste to the end face of the ceramic sintered body A step of forming an external electrode by baking, and after forming the external electrode, a plating film is formed on the surface of the external electrode by electrolytic plating. Characterized in that it comprises a step.

  The second invention is a ceramic sintered body made of semiconductor ceramics, disposed in the ceramic sintered body, and an internal electrode drawn out on an end face of the ceramic sintered body and electrically connected to the internal electrode. A method for manufacturing a semiconductor ceramic electronic component comprising an external electrode formed on an end face of a ceramic sintered body and a plating film formed on the surface of the external electrode by an electrolytic plating method. A step of preparing a green chip having at least one internal electrode drawn out to an end face, a step of firing the green chip to obtain a ceramic sintered body, and crushing the ceramic sintered body with cobblestone and polishing powder. A barrel polishing process using barrel polishing, and a polishing powder for removing polishing powder adhering to the surface of the ceramic sintered body after the barrel polishing process And a step of forming an external electrode by applying and baking a conductive paste on an end face of the ceramic sintered body, and a step of forming a plating film on the surface of the external electrode by electrolytic plating after the formation of the external electrode. It is characterized by that.

On the specific situation with the manufacturing method of the semiconductor ceramic electronic component of this invention (1st, 2nd invention), the specific surface area of the abrasive powder used in the said barrel grinding | polishing process is 0.5-10 m < ² > / g.

  In another specific aspect of the method for producing a semiconductor ceramic electronic component according to the present invention, in the polishing powder removing step, a diameter smaller than the shortest side among the sides defining the outer shape of the ceramic sintered body is set. Abrasive powder is removed by polishing and purifying with a polishing material containing spherical beads and a solvent.

  In still another specific aspect of the method for manufacturing a semiconductor ceramic electronic component according to the present invention, ultrasonic cleaning is performed in the polishing powder removing step.

  In the method for manufacturing a semiconductor ceramic electronic component according to the first and second inventions, after the ceramic sintered body is barrel-polished using boulders and abrasive powder, the abrasive powder adhering to the surface of the ceramic sintered body is removed by the abrasive powder. Is removed. Therefore, when an external electrode is formed on the end face of the ceramic sintered body by applying and baking an electrically conductive paste and then a plating film is formed on the surface of the external electrode by electrolytic plating, there is almost no abrasive powder residue on the surface of the ceramic sintered body. Therefore, it is difficult for the plating film to grow on the surface of the ceramic sintered body other than the surface of the external electrode.

  Therefore, according to the first and second inventions, undesired plating film growth can be reliably suppressed on the outer surface of the ceramic sintered body, whereby short circuit and undesired conduction with other electronic components can be prevented. It is possible to provide a semiconductor ceramic electronic component that is unlikely to occur and excellent in reliability. In particular, according to the second invention, it is possible to provide a semiconductor ceramic electronic component of the type having an internal electrode that is excellent in such reliability.

In the manufacturing method according to the present invention, when the specific surface area of the polishing powder used in the barrel polishing step is in the range of 0.5 to 10 m ² / g, the internal electrode is further formed on the end surface of the ceramic sintered body by barrel polishing. Polishing can be performed so as to be surely exposed, and a plating film can be reliably attached to the surface of the external electrode.

  In the above polishing powder removal step, when the outer shape of the ceramic sintered body is defined, when polishing is performed using a polishing material containing a spherical bead having a diameter smaller than the shortest side and a solvent, and purified, Thus, the polishing powder residue can be removed more reliably, thereby preventing the growth of the plating film on the surface of the ceramic sintered body more desirably.

  In the manufacturing method according to the present invention, when ultrasonic cleaning is performed in the polishing powder removing step, the ceramic sintered body and water as a solvent are placed in an ultrasonic cleaner, and ultrasonic waves are applied to the water. By virtue of vibrating, the polishing powder residue can be washed and removed more reliably.

  Preferably, in addition to polishing with a polishing material containing the spherical beads and a solvent, the ultrasonic cleaning is used in combination, and in that case, the polishing powder residue can be more reliably removed.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a diagram showing each step of a method for manufacturing a semiconductor ceramic electronic component according to an embodiment of the present invention.

  As shown in FIG. 1, in this embodiment, first, a green chip is manufactured. As the green chip, an appropriate green chip made of unsintered semiconductor ceramics and having at least one internal electrode drawn out to the end face is prepared.

  The method for manufacturing the green chip as described above is not particularly limited, and a method conventionally used in the manufacturing process of semiconductor ceramic electronic components can be employed. In this embodiment, when manufacturing a laminated semiconductor ceramic electronic component, a plurality of mother semiconductor ceramic green sheets are prepared. Then, an internal electrode pattern is formed on the semiconductor ceramic green sheet by screen printing or the like. A plurality of mother semiconductor ceramic green sheets on which the internal electrode patterns are printed are laminated, and if necessary, a plain mother semiconductor ceramic green sheet on which no internal electrode patterns are formed is laminated to obtain a mother laminate. The mother laminate is cut into green chips in units of individual semiconductor ceramic green sheets. In this way, a green chip can be prepared.

  In this embodiment, a mother semiconductor ceramic green sheet is used to obtain a green chip for each semiconductor ceramic electronic component unit after obtaining a mother laminate. In the present invention, the mother semiconductor ceramic green sheet is used. It is not always necessary to use. That is, a plurality of semiconductor ceramic green sheets for obtaining one semiconductor ceramic electronic component may be laminated with at least one internal electrode interposed therebetween to obtain a green chip.

  Next, as shown in FIG. 1, the green chip is fired to obtain a ceramic sintered body. Also in the step of firing the green chip to obtain a ceramic sintered body, firing may be performed according to appropriate firing conditions used in the conventional method for manufacturing a semiconductor ceramic electronic component.

  A ceramic sintered body is obtained as described above. FIG. 2 is a schematic front sectional view showing a ceramic sintered body used in the multilayer varistor obtained in the present embodiment. Here, the ceramic sintered body 1 made of semiconductor ceramic has a rectangular parallelepiped shape. The ceramic sintered body 1 has first and second end faces 1a and 1b facing each other. In the ceramic sintered body 1, first internal electrodes 2a and 2b and second internal electrodes 3a and 3b are alternately arranged. The first internal electrodes 2a and 2b and the second internal electrodes 3a and 3b are arranged so as to overlap with each other through the semiconductor ceramic layer in the thickness direction.

  The first inner electrodes 2a and 2b are drawn out to the first end face 1a, and the second inner electrodes 3a and 3b are drawn out to the second end face 1b.

  In the present embodiment, the internal electrodes 2a, 2b, 3a, 3b are screen-printed with a conductive paste mainly composed of platinum on a mother semiconductor ceramic green sheet, and baked in a firing step for obtaining the ceramic sintered body 1 described above. Is formed.

  Next, in the manufacturing method of the present embodiment, the ceramic sintered body 1 is barrel-polished. For barrel polishing, for example, a large number of ceramic sintered bodies 1, boulders that are polishing media, polishing powder, and polishing liquid are put into a cylindrical barrel, and the barrel is rotated around its axial direction. To do. As the cobblestone, for example, a spherical body made of ceramic beads, glass beads or the like can be used. In addition, about the diameter of the said cobblestone, it selects suitably according to the dimension of the ceramic sintered compact 1 thrown in.

  Examples of the abrasive powder include ceramic powders such as alumina and silicon carbide. The average particle size of the abrasive powder also constitutes the dimensions of the ceramic sintered body 1 to be charged and the ceramic sintered body. It is appropriately selected according to the type of semiconductor ceramic material.

However, in the present invention, the specific surface area of the polishing powder used in the barrel polishing is preferably 0.5 to 10 m ² / g. When it exceeds 10 m ² / g, particularly when an internal electrode is provided, the first and second end faces 1a and 1b cannot be sufficiently polished during barrel polishing, and the internal electrodes 2a, 2b, 3a, and 3b are not polished. In the case of less than 0.5 m ² / g, the surface of the ceramic sintered body 1 becomes rough or the particle size of the abrasive powder is large. It may be difficult to remove from the surface of the ceramic sintered body.

  An appropriate liquid such as water is used as the liquid charged together with the cobblestone and the abrasive powder.

  The barrel polishing is usually performed by rotating the cylindrical barrel at a speed of about 150 to 360 rotations / minute for about 30 to 180 minutes, although it varies depending on the size and configuration of the ceramic sintered body 1 to be charged.

  By the barrel polishing, the ceramic sintered body 1 is polished, and the internal electrodes 2a, 2b, 3a, 3b are reliably exposed on the first and second end faces 1a, 1b of the ceramic sintered body 1. In addition, chamfering is performed so that the corners of the ceramic sintered body 1 are rounded by the barrel polishing.

  Next, after the barrel polishing, a polishing powder removing step is performed. In the present embodiment, in the polishing powder removing step, after polishing, an abrasive material containing the ceramic sintered body 1 and spherical beads and a solvent is put into the container, and the container is rotated or vibrated, or the container is vibrated. This is performed by purifying the surface of the ceramic sintered body.

  In the purification step performed in the polishing powder removing step, preferably, as the spherical beads, spherical beads having a diameter smaller than the shortest side among the sides defining the outer shape of the ceramic sintered body 1 are used. It is done. The material which comprises such a spherical bead is not specifically limited, For example, PSZ, a glass bead, etc. are mentioned. By using spherical beads having a diameter smaller than the shortest side among the sides defining the outer shape of the ceramic sintered body, the abrasive powder adhering to the surface of the ceramic sintered body can be reliably removed. If the diameter of the spherical beads is larger than the shortest of the sides that define the outer shape of the ceramic sintered body 1, the contact efficiency with the ceramic sintered body is reduced and the abrasive powder is reliably removed. There are things you can't do.

  In addition, it does not specifically limit about the solvent used with the said spherical bead, For example, liquids, such as water, are used.

  Purification in the polishing powder removing step is performed by rotating, vibrating, or applying vibration to the container. However, the purification time varies depending on the state of the ceramic sintered body 1 to be charged. However, the rotation speed of the barrel may be about 150 to 360 rotations / minute.

  In the present embodiment, the polishing powder is removed by the purification. However, ultrasonic cleaning may be continued, and the polishing powder adhering to the surface of the ceramic sintered body 1 can be more reliably removed. it can. This ultrasonic cleaning can be performed using a known ultrasonic cleaning apparatus as long as it has a cleaning tank into which a large number of ceramic sintered bodies 1 can be put. The ultrasonic cleaning time may be about 30 to 180 minutes. Since the ultrasonic cleaning time varies depending on the size and amount of the ceramic sintered body 1 to be introduced, the cleaning time is appropriately set according to the size and amount of the ceramic sintered body 1 and the material of the semiconductor ceramic. That's fine.

  In this embodiment, in the polishing powder removing step, the purification step and the ultrasonic cleaning step are performed. However, the purification and ultrasonic cleaning may be performed at the same time. That is, ultrasonic cleaning may be applied in the purification step, and ultrasonic cleaning and purification using an abrasive material may be performed simultaneously.

  Furthermore, in the present invention, the step of removing the polishing powder may be only the purification step using the polishing material, or may be only the ultrasonic cleaning step. Furthermore, you may remove polishing powder by methods other than the purification | cleaning process by the said abrasive material, and an ultrasonic cleaning process.

  In the present embodiment, following the above-described polishing powder removing step, the first and second external electrodes shown in FIG. 3 are applied by applying and baking a conductive paste on the end faces 1a and 1b of the ceramic sintered body 1. 4 and 5 are formed. In this embodiment, an Ag paste is used as the conductive paste.

  Next, Ni plating films 6 and 7 and Sn plating films 8 and 9 are sequentially formed on the outer surfaces of the external electrodes 4 and 5 by a wet method. The external electrodes 4 and 5, the Ni plating films 6 and 7, and the Sn plating films 8 and 9 can be formed according to a known electrolytic plating method.

  In this embodiment, even if the polishing powder adheres to the surface of the ceramic sintered body 1 after barrel polishing, the polishing powder residue attached by the polishing powder removing step is removed. Therefore, even if the Ni plating films 6 and 7 and the Sn plating films 8 and 9 are formed by the electrolytic plating method after the external electrodes 4 and 5 are formed, the abrasive powder is almost adhered to the outer surface of the ceramic sintered body 1. Therefore, the growth of an undesired plating film can be reliably prevented, and the multilayer varistor 10 as a semiconductor ceramic electronic component having excellent reliability can be provided.

  In the present embodiment, the multilayer varistor 10 as the multilayer semiconductor ceramic electronic component shown in FIG. 3 is obtained. However, the present invention is not limited to the method for manufacturing the multilayer semiconductor ceramic electronic component. Absent.

  That is, the present invention can be applied to the manufacture of the thermistor 21 shown in FIG. The thermistor 21 has a ceramic sintered body 22 as a semiconductor ceramic. The ceramic sintered body 22 is configured using a semiconductor ceramic having positive or negative resistance temperature characteristics. First and second internal electrodes 23 and 24 are extended from the first and second end faces 22a and 22b facing each other of the ceramic sintered body 22 toward the center. The first and second internal electrodes 23 and 24 are formed at the same height position, and their inner ends are opposed to each other with a predetermined gap therebetween. External electrodes 25 and 26 are formed so as to cover the first and second end faces 22a and 22b. First and second plating films 27, 28 and 29, 30 are formed by electrolytic plating so as to cover the external electrodes 25, 26.

  Like the thermistor 21, in the semiconductor ceramic electronic component to which the present invention is applied, the first and second internal electrodes do not have to overlap in the thickness direction via the semiconductor ceramic layer.

  Further, in the multilayer varistor 10 or thermistor 21 as the semiconductor ceramic electronic component shown in FIGS. 3 and 4, the first and second internal electrodes are drawn out to the first and second end surfaces, respectively. In the semiconductor electronic component to which the present invention is applied, the first and second internal electrodes may not be formed. Further, only at least one of the first internal electrode and the second internal electrode may be formed. That is, it may be an electronic component having a structure in which at least one internal electrode is drawn out to any end face.

  The semiconductor ceramic constituting the semiconductor ceramic electronic component is not limited to the semiconductor ceramic having the varistor characteristics and the semiconductor ceramic having thermistor characteristics, and various semiconductor ceramics can be used.

  Also, the plating film formed on the surface of the external electrode is not particularly limited with respect to the material constituting the plating film and the number of laminated plating films as long as it is formed by an electrolytic plating method.

  Next, specific experimental examples will be described.

(Experimental example 1)
A mother semiconductor ceramic green sheet was formed using a slurry containing ceramic particles obtained by using a composition containing ZnO as a main component and Pr ₆ O ₁₁ and CoCO ₃ as subcomponents.

  On the obtained semiconductor ceramic green sheet, Pt paste was screen-printed to form an internal electrode pattern. A plurality of mother semiconductor ceramic green sheets on which the internal electrode patterns were printed were laminated, and a plain semiconductor ceramic green sheet was laminated on the top and bottom, and pressed in the thickness direction to obtain a mother laminate.

  The mother laminate was cut into individual multilayer varistor unit green chips to obtain green chips.

  The green chip obtained as described above was heated and fired at 1165 ° C. in the air to obtain a ceramic sintered body.

  Thus, a rectangular parallelepiped ceramic sintered body having a length of 1.0 mm, a width of 0.5 mm and a thickness of 0.5 mm was obtained. In the ceramic sintered body, like the multilayer varistor shown in FIG. 3, a plurality of first and second internal electrodes are alternately laminated, and the number of laminated internal electrodes is six. .

A large number of ceramic sintered bodies prepared in this way were combined with PSZ spheres having a diameter of 1.0 mm as cobblestones, alumina polishing powder (specific surface area of 0.56 m ² / g), water as liquid, and cylinders. The barrel was polished into a cylindrical barrel. In the barrel polishing, about 100 to 200,000, that is, about 200 mL of the total volume of the ceramic sintered body 1, the alumina polishing powder is about 5 to 20% by volume, and the PSZ sphere is about 30 to 50% by volume. The amount of water was 350 mL. The rotational speed during barrel polishing was 256 rpm, and the polishing time was 60 minutes.

  When the ceramic sintered body was taken out after the barrel polishing, the internal electrode was reliably exposed on the end face. Thereafter, the ceramic sintered body was once washed with running water to remove the alumina powder as the abrasive powder adhering to the surface of the ceramic sintered body. However, the alumina powder could not be reliably removed only by washing with running water.

  Next, put 100,000 to 200,000 ceramic sintered bodies, 150 mL of PSZ beads having a diameter of 0.3 mm, and 100 mL of water in a 300 mL container, rotate the container at 360 rpm with a planetary mill, and polish the alumina. The powder residue was washed away. The rotation speed was 360 rpm, and the rotation time for cleaning and removal was 30 minutes.

  Thereafter, Ag paste was applied to the first and second end faces and baked at 800 ° C., thereby forming the first and second external electrodes. Furthermore, the excessive glass component which protruded on the external electrode surface was removed by ultrasonic cleaning. Finally, a Ni plating film and a Sn plating film were formed by electrolytic plating.

  In the above manufacturing method, the ceramic sintered body before barrel polishing obtained by the firing step, the ceramic sintered body after barrel polishing, and the surface of the ceramic sintered body after the polishing powder removing step using PSZ beads have a diameter of 100 μm. For these regions, the atomic concentration of the element was measured using XPS. XPS is an atomic concentration measurement method using high electron spectroscopy, and the apparatus used is Quantum 2000 manufactured by PHYSICAL ELECTRONICS. The results are shown in Table 1 below.

表１から明らかなように、焼成直後のセラミック焼結体の外表面では、Ａｌ、すなわちアルミナ研磨粉由来のＡｌは存在していなかった。これに対して、バレル研磨後には、Ａｌの濃度は２９％と高かったのに対し、研磨粉残渣を洗浄により除去した後には、１３％と低かった。すなわち、バレル研磨直後には、原子濃度比Ｚｎ／Ａｌは０．０５８だったのに対し、上記研磨粉除去工程後には０．５５と飛躍的に高められ、言い換えればバレル研磨に際して用いられたアルミナ研磨粉由来のＡｌをセラミック焼結体表面から除去し得たことがわかる。

As is apparent from Table 1, Al, that is, Al derived from the alumina polishing powder was not present on the outer surface of the ceramic sintered body immediately after firing. On the other hand, after barrel polishing, the Al concentration was as high as 29%, but after the polishing powder residue was removed by washing, it was as low as 13%. That is, immediately after barrel polishing, the atomic concentration ratio Zn / Al was 0.058, but after the polishing powder removal step, it was dramatically increased to 0.55, in other words, alumina used for barrel polishing. It can be seen that Al derived from the abrasive powder could be removed from the surface of the ceramic sintered body.

  Further, after forming the Ni plating film and the Sn plating film, the surface of the sintered ceramic body of the multilayer varistor obtained above was observed using a metal microscope (VHX100, manufactured by Keyence Corporation). No undesired plating film growth was observed. This is considered to be because the above-mentioned alumina polishing powder was sufficiently removed from the outer surface of the ceramic sintered body, and thus the phenomenon that the electric field concentrated on the polishing powder during electrolytic plating and the plating film grew effectively could be suppressed. .

  Therefore, as is clear also in Experimental Example 1 described above, an undesired plating film on the surface of the ceramic sintered body is obtained by removing the polishing powder adhering to the surface of the ceramic sintered body after the barrel polishing step according to the present invention. It can be seen that the growth of can be reliably suppressed.

(Experimental example 2)
Green chips were prepared in the same manner as in Experimental Example 1, and barrel polishing was performed. Thereafter, in the cleaning process as the abrasive powder removing process in Experimental Example 1, the diameter of the PSZ beads was changed to 0 (not used), 0.1 mm, 0.3 mm, and 1.0 mm, and the abrasive powder removing process was performed. went. The cleaning time in the polishing powder removing step was 30 minutes, and the total volume of the PSZ beads was 150 ml. Others were the same as in Experimental Example 1.

  On the other hand, instead of the above-described cleaning step for removing polishing powder performed in Experimental Example 1, 150 ml of PSZ beads having a diameter of 0.3 mm and water were used, and an ultrasonic cleaning machine (manufactured by SND Co., US- 4 and a frequency of 38 kHz), the polishing powder removal process was performed by performing ultrasonic cleaning for 60 minutes.

  In this way, the polishing powder removing step was performed under various conditions, and the external electrode and the plating film were formed and evaluated in the same manner as in Experimental Example 1 below. The results are shown in Table 2 below. In Table 2, in addition to the plating defect rate, the value of capacitance variation 3cv is also shown.

表２から明らかなように、バレル研磨に際しての研磨粉の比表面積が０．５ｍ²／ｇ以上であれば、めっき不良率を０％とし得ることがわかる。また、比表面積が１３．６ｍ²／ｇの研磨粉を用いてバレル研磨を行った場合には、めっき不良率は低減し得るものの、内部電極部の端面に対する露出が不十分であるため、静電容量のばらつきが生じがちとなった。従って、バレル研磨に際しての研磨粉の比表面積は、０．５〜１０ｍ²／ｇの範囲であることが望ましいことがわかる。

As is apparent from Table 2, it can be seen that if the specific surface area of the polishing powder during barrel polishing is 0.5 m ² / g or more, the plating defect rate can be 0%. In addition, when barrel polishing is performed using a polishing powder having a specific surface area of 13.6 m ² / g, although the plating defect rate can be reduced, the exposure to the end face of the internal electrode portion is insufficient. Variations in capacitance tend to occur. Therefore, it can be seen that the specific surface area of the polishing powder during barrel polishing is desirably in the range of 0.5 to 10 m ² / g.

  Further, as apparent from Table 2, in the polishing powder removing step, when spherical beads having a diameter of 0.3 mm or less were used, the plating defect rate could be reduced to 0%. Therefore, it can be seen that by using spherical beads having a diameter of 0.5 mm or less which is the dimension of the shortest side among the sides defining the outer shape of the ceramic sintered body, the plating defect rate can be surely lowered. As apparent from Table 2, conversely, when the diameter of the spherical beads is larger than the shortest side of the sides defining the outer shape of the sintered body, that is, a spherical bead having a diameter of 1.0 mm is used. When the polishing powder removal step was performed using Zn / Al, the ratio of Zn / Al was 0.24, and the plating defect rate was 12%.

  Therefore, it can be seen that the diameter of the spherical beads is preferably smaller than the shortest side defining the outer shape of the ceramic sintered body.

  In addition, as a result of performing Al mapping analysis by WDX (wavelength dispersive X-ray spectrometer), it was confirmed that a large amount of Al residue remained in a portion where undesired plating film growth occurred. Therefore, it is supported that the alumina residue as the polishing powder affects the growth of the plating film.

  Further, as is apparent from Table 2, in the polishing powder removing step, the plating defect rate is also obtained when ultrasonic cleaning is performed instead of polishing the spherical beads with a polishing material containing a solvent or the like. It can be seen that can be 0%. It can also be seen that the defective plating rate can be similarly reduced to 0% by using the spherical beads and ultrasonic cleaning together.

The schematic diagram which shows each process of one Embodiment of the manufacturing method of the semiconductor ceramic electronic component of this invention. The front sectional view showing the ceramic sintered compact prepared for one embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view showing a multilayer varistor as a semiconductor ceramic electronic component obtained in an embodiment of the present invention. The typical front sectional view showing other semiconductor ceramic electronic parts obtained with the manufacturing method of the semiconductor ceramic electronic parts of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic sintered compact 1a, 1b ... End surface 2a, 2b ... 1st internal electrode 3a, 3b ... 2nd internal electrode 4, 5 ... External electrode 6, 7 ... Ni plating film 8, 9 ... Sn plating film 10 ... Laminated varistor 21 ... Thermistor 22 ... Ceramic sintered body 22a, 22b ... End face 23,24 ... Internal electrode 25,26 ... External electrode 27,28 ... Plating film 29,30 ... Plating film

Claims (5)

A method of manufacturing a semiconductor ceramic electronic component comprising: a ceramic sintered body made of semiconductor ceramics; an external electrode formed on an end surface of the ceramic sintered body; and a plating film formed on the surface of the external electrode by electrolytic plating. And
Preparing a green chip made of unsintered semiconductor ceramics;
Firing the green chip to obtain a ceramic sintered body;
A barrel polishing step of barrel-polishing the ceramic sintered body using cobblestone and polishing powder;
After the barrel polishing step, a polishing powder removing step for removing the polishing powder adhering to the ceramic sintered body surface,
Forming an external electrode by applying and baking a conductive paste on the end face of the ceramic sintered body;
And a step of forming a plating film on the surface of the external electrode by electrolytic plating after the formation of the external electrode. A ceramic sintered body made of semiconductor ceramics, disposed in the ceramic sintered body, an internal electrode drawn out on an end face of the ceramic sintered body, and a ceramic sintered so as to be electrically connected to the internal electrode A method of manufacturing a semiconductor ceramic electronic component comprising an external electrode formed on an end surface of a body and a plating film formed on the surface of the external electrode by an electrolytic plating method,
A step of preparing a green chip made of unsintered semiconductor ceramics and having at least one internal electrode drawn to an end face;
Firing the green chip to obtain a ceramic sintered body;
A barrel polishing step of barrel-polishing the ceramic sintered body using cobblestone and polishing powder;
After the barrel polishing step, a polishing powder removing step for removing the polishing powder adhering to the ceramic sintered body surface,
Forming an external electrode by applying and baking a conductive paste on the end face of the ceramic sintered body;
And a step of forming a plating film on the surface of the external electrode by electrolytic plating after the formation of the external electrode. The manufacturing method of the semiconductor ceramic electronic component of Claim 1 or 2 whose specific surface area of the abrasive powder used in the said barrel grinding | polishing process is 0.5-10 m < ² > / g.   In the polishing powder removal step, by polishing with a polishing material containing a spherical bead having a diameter smaller than the shortest side among the sides defining the outer shape of the ceramic sintered body and a solvent, and purifying it. The manufacturing method of the semiconductor ceramic electronic component of any one of Claims 1-3 in which polishing powder is removed. The manufacturing method of the semiconductor ceramic electronic component of any one of Claims 1-4 with which ultrasonic cleaning is performed in the said grinding | polishing powder removal process.

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