JP2005286002A - Manufacturing method of electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of electronic component which is capable of preventing the generation of variation in the electric characteristics of semiconductor porcelain, by effectively dissipating heat from sintering porcelain in the temperature lowering process of sintering process. <P>SOLUTION: Under the condition that supporting fixtures 10, in which a multitude of ceramic forms MP are retained, are seen from fore-and-rear direction and left-and-right direction, the lower ends of all of the ceramic forms MP positioned at the fore and rear ends of the fixtures 10 are hidden by supporting bars 12 at the fore and rear ends thereof. However, almost all parts of the ceramic forms MP or the parts more than 3/4 of them materially are exposed. Further, the lower ends of all ceramic forms MP positioned at the left and right ends are hidden by the other side bars 11. However, almost all parts of all ceramic forms MP or more than 3/4 of them materially are exposed whereby elements which preclude the dissipation of heat from the semiconductor porcelain after sintering do not exist substantially at the fore and rear ends and the left and right ends of the supporting fixtures 10, under the process of lowering temperature in the sintering process wherein the ceramic forms MP are sintered and the temperature of them is lowered to change them into semiconductors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic component manufacturing method including a step of firing a ceramic molded body having a predetermined shape.

  An electronic component including a step of firing a ceramic molded body as one of the manufacturing processes, for example, a ring varistor having a predetermined inner and outer diameter and wall thickness, is formed by placing raw material granules in a mold having a ring-shaped cavity. A ring-shaped ceramic molded body, and a refractory support holding a large number of ceramic molded bodies in a predetermined posture is passed through a tunnel-like firing furnace using a conveying means such as a conveyor. It is manufactured through a process of sintering the body in a lump to make a semiconductor and a process of forming an electrode on a semiconductor ceramic obtained by firing.

  The support shown in FIG. 1 is generally known as the support used in the firing step. The support 100 has a rectangular container shape with an open upper surface, and has a rectangular recess 100a for holding a large number of ceramic molded bodies in a predetermined posture, and has gas flow in the upper part of two opposing wall surfaces. A notch 100b.

  When a large number of ring-shaped ceramic molded bodies MP are held by the support tool 100, the ceramic molded bodies MP are stacked side by side so that their annular surfaces are in contact with each other and arranged side by side in parallel with the bottom surface of the recess 100a. (See FIG. 1) or placed in a predetermined arrangement in the recess 100a in a vertical orientation (see FIG. 2).

  When firing a large number of ceramic molded bodies MP held on the support tool 100, the support tools 100 holding a large number of ceramic molded bodies MP are stacked in multiple stages as shown in FIG. 1 and placed on a conveyor of a firing furnace. The desired firing is performed while moving in the direction of the white arrow in FIG.

  A support 110 shown in FIGS. 3 to 5 is also known as a support having a configuration different from the above (see Japanese Patent Application Laid-Open No. 2002-343609). The support 110 includes a rectangular frame 111 and a plurality of round bars 112. The support frame 111 has a plurality of grooves 111a that support both ends of the round bar 112 at equal intervals on the upper surface of two opposing side portions. There are notches 111b for gas distribution on the two sides.

  When a large number of ring-shaped ceramic molded bodies MP are held by the support tool 110, the round bars 112 are inserted into the inner holes of the stacked ceramic molded bodies MP so that their annular surfaces are in contact with each other. The operation of placing both ends of 112 in the groove 111a of the support frame 111 is repeated.

When firing a large number of ceramic molded bodies MP held by the support 110, the supports 110 holding the ceramic molded bodies MP are stacked in multiple stages as shown in FIG. 6 and placed on a conveyor of a firing furnace. The desired firing is performed while moving in the direction of the white arrow in FIG.
JP 2002-343609 A

  In a method of manufacturing an electronic component such as a ring varistor having a firing process in which a ceramic molded body is sintered and cooled to become a semiconductor, in order to stabilize the electrical characteristics of semiconductor ceramics obtained by firing, It is important to quickly cool in the temperature lowering process. When the cooling rate is slow, the semiconductor is not uniform, and the electrical characteristics of the semiconductor ceramic are likely to vary.

  The cooling rate in the temperature lowering process mainly depends on the heat dissipation efficiency from the sintered porcelain. In the support tool 100 shown in FIGS. 1 and 2, the ceramic molded body MP is placed on the bottom surface of the recess 100a. In addition, since the periphery of the ceramic molded body MP accommodated in the recess 100a is surrounded by the wall surface, the cooling rate is different for each stage in a multi-layered state, and the heat radiation from the sintered porcelain It is obstructed by the surrounding wall surface and causes a decrease in cooling rate.

  3 to 6 does not have a bottom surface like the support 100 shown in FIGS. 1 and 2, the periphery of the ceramic molded body MP is surrounded by a rectangular frame 111. Therefore, heat radiation from the sintered porcelain is blocked by the rectangular frame, and it is difficult to increase the cooling rate.

  The present invention was created in view of the above circumstances, and its purpose is to prevent heat from being efficiently dissipated from the sintered porcelain during the temperature-decreasing process of the firing process, thereby preventing variations in the electrical characteristics of the semiconductor porcelain. An object of the present invention is to provide a method for manufacturing an electronic component.

  In order to achieve the above object, the present invention provides a semiconductor in which a large number of ceramic compacts are sintered together by passing a fire-resistant support holding a large number of ceramic compacts in a predetermined posture through a tunnel-like firing furnace. In the electronic component manufacturing method including the firing step, the large number of ceramic molded bodies are formed of all ceramic molded bodies positioned at the front and rear ends and the left and right ends when the support is viewed from the front and rear directions and the left and right directions. It is characterized in that it is held by a support so that most of the portion is exposed and passes through a tunnel-like firing furnace while maintaining the holding state.

  According to this method of manufacturing an electronic component, a large number of ceramic molded bodies are exposed so that most of the ceramic molded bodies located at the front and rear ends and the left and right ends thereof are exposed in a state in which the support is viewed from the front and rear directions and the left and right directions. Since the ceramic molded body is sintered and cooled to lower the temperature in the firing process, the elements that hinder heat dissipation from the sintered porcelain are the front and rear ends and the left and right ends of the support tool. It will hardly exist. In other words, it is possible to efficiently perform heat dissipation from the sintered porcelain in the temperature lowering process and quickly cool down, so that the semiconductorization becomes non-uniform due to the slow cooling rate and the electrical characteristics of the semiconductor porcelain. Variations can be prevented from occurring.

  According to the present invention, it is possible to efficiently dissipate heat from the sintered porcelain during the temperature lowering process of the firing process to prevent variation in the electrical characteristics of the semiconductor porcelain, and to obtain a high-quality electronic component.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

[First Embodiment]
Below, with reference to FIGS. 7-15, 1st Embodiment of the manufacturing method which concerns on this invention is described, taking manufacture of a ring varistor as an example.

First, (SrxBayCaz) _A TiO ₃ (0.2 <x <0.8 / 0.2 <y <0.8 / 0.2 <z <0.8) x + y + z = 1 A = 0.800 to 1.200 (x, y in the formula) , z, and A are molar ratios), and the second component contains Nb, Ta, W and rare earth elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb). , Dy, Ho, Er, Tm , Yb, Lu, Sc, at least one member selected from the oxides of Y) containing a predetermined mol%, the SiO ₂ comprises a predetermined mol% as a third component, a fourth component A mixture containing a predetermined mol% of at least one selected from transition oxides of Cu, Co, Mn, Fe, and Ni is obtained.

  Next, this mixture is dried and calcined at 1000 to 1500 ° C. for 1 to 3 hours in the air. After calcination, the calcined product is pulverized and weighed, and then added with a solvent and pulverized. Then, a binder such as polyvinyl alcohol is added to this powder and granulated by a spray dryer or the like.

  Next, this granule is put into a mold having a ring-shaped cavity and molded to obtain a ring-shaped ceramic molded body 3 (see FIGS. 7 to 11). This ceramic molded body MP has a predetermined inner and outer diameter (D2, D1) and wall thickness (t).

  Next, a large number of ceramic molded bodies MP are held in a predetermined posture on the support 10 shown in FIGS.

  The support 10 includes two side pieces 11 arranged in parallel and a plurality of support rods 12 having a circular cross section arranged in parallel in the left-right direction at equal intervals in FIG. Each side piece 11 has a plurality of fixing grooves 11a formed at equal intervals in the left-right direction in FIG. 7 on the upper surface, and leg pieces 11b used when stacking the support 10 in multiple stages are arranged on the left and right sides in FIG. Have at both ends. Each support rod 12 is fitted into the fixing groove 11a at both ends, and both ends are fixed to each side piece 11 by a method such as screwing or press fitting.

  The side piece 11 and the support rod 12 of the support 10 and the later-described weight rod 13 are formed of a refractory material, preferably alumina, mullite, silicon carbide, zirconia, magnesia or the like. Further, since the support bar 12 and the weight bar 13 are in contact with the ceramic molded body MP, in order to prevent an unnecessary chemical reaction from occurring at the contact point in the firing process, reaction prevention composed of zirconia or the like on each surface is performed. It is desirable to form the film with a thickness of about 100 to 400 μm.

  Furthermore, if a hollow thing (cylindrical thing) is used as the support bar 12, it can suppress that the support bar 12 itself bends by repeated baking. If the support rod 12 having at least one flat surface at both ends is used, the support rod 12 can be prevented from rotating, and if both ends have a plane larger than MP (polygonal cross section). Even when the support rod 12 itself bends, it is possible to correct the bend by changing the direction of the support rod 12.

  Further, in the drawing, each side piece 11 and each support bar 12 are configured as separate parts, and these are combined to form the support 10. However, each side piece 11 and each support bar 12 are formed as one part. You may make it comprise the support tool 10. FIG.

  When a large number of ceramic molded bodies MP are held in a predetermined posture by the support 10, a large number of ceramic molded bodies MP stacked such that their annular surfaces are in contact with each other are turned sideways, and each ceramic molded body MP is placed. A plurality of rows are formed by placing each of the arc-shaped outer surfaces MPa so as to be in contact with the outer surfaces of the two adjacent support rods 12, and the inner holes of the ceramic molded bodies MP in each row have a diameter larger than that of the inner holes. Are inserted so that they are in contact with the arc-shaped inner surface MPb of the ceramic molded body MP (see FIGS. 7 to 10).

  Alternatively, a large number of ceramic molded bodies MP are mounted on the spindle 13 and a large number of ceramic molded bodies MP are stacked so that their annular surfaces are in contact with each other, and the arc-shaped outer surface MPa of each ceramic molded body MP. Are placed together in each row so as to be in contact with the outer surfaces of the two adjacent support rods 12, and the weight bar 13 inserted in the inner hole of the ceramic molded body MP in each row is placed in a circle of the ceramic molded body MP. It mounts so that it may contact arc-shaped inner surface MPb (refer FIGS. 7-10).

  Accordingly, as shown in FIGS. 10 (A) and 10 (B), each of a large number of ceramic molded bodies MP placed so that the arc-shaped outer surface MPa is in contact with the outer surfaces of two adjacent support rods 12. The weight of the weight bar 13 is acted on, and a large number of ceramic molded bodies MP constituting each row are held in an upright state in a direction in which the annular surface is substantially perpendicular to the length direction of the two adjacent support bars 12. The

  A large number of ceramic molded bodies MP constituting each row are supported by two contact points SP at positions lower than the center of gravity of the ceramic molded body MP having the arc-shaped outer surface MPa, and the ceramic molded bodies MP having the arc-shaped inner surface MPb are supported. Since the weight bar 13 that is in contact with a position lower than the center of gravity is pressed against the two contact points SP by the weight of the weight bar 13, a large number of ceramic molded bodies MP constituting each row are held in a more stable state. It will be.

  Here, with reference to FIG. 11, the supplementary description regarding the setting of the space | interval A of the two support rods 12 which the support tool 10 adjoins is demonstrated.

The outer diameter of the ceramic molded body MP is D1, the inner diameter is D2, the wall thickness is t, the diameter of the weight bar 13 is DMP, and the ceramic molded body MP in the state where the ceramic molded body MP is most inclined with respect to the weight bar 13 When the angle formed by the weight bar 13 is θ and the distance between the support bar 12 and the weight bar 13 is A1, the ceramic molded body MP through which the weight bar 13 is inserted does not fall from the two adjacent support bars 12. To achieve this, it is necessary to satisfy A <2A1 + DMP. In this case, since A1 = ((D1 + D2) / 2) cos θ−DMP, θ = arctan (1 / DMP × √ (D2 ² + t ² + DMP ² )) − arctan (t / D2), A < 2A1 + DMP is A <2 × (D1 + D2) / 2 × cos θ−DMP = 2 × (D1 + D2) / 2 × cos (arctan (1 / DMP × √ (D2 ² + t ² + DMP ² )) − arctan (t / D2)) −DMP, and the distance A between two adjacent support rods 12 can be determined from the outer diameter D1 and inner diameter D2 of the ceramic molded body MP and the diameter DMP of the spindle 13. By setting the distance A to be smaller within a range where adjacent rows of ceramic molded bodies MP do not interfere with each other, the number of ceramic molded bodies MP held can be increased.

  When the support 10 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 7) and the left-right direction (up-down direction in FIG. 7), all the ceramic molded bodies positioned at the front-rear ends. Although the lower end portion of the MP is concealed by the support rods 12 at the front and rear ends, most portions of all the ceramic molded bodies MP, specifically, more than 3/4 portions are exposed, and all the portions located at the left and right ends thereof are exposed. Although the lower end portion of the ceramic molded body MP is hidden by the side 11, most of the ceramic molded body MP, specifically 3/4 or more, is exposed.

  Next, in a state where a large number of ceramic molded bodies MP are held by the support tool 10 and the spindle bar 13 and the support tool 10 is stacked in multiple stages as shown in FIG. It passes through a tunnel-like reduction firing furnace having a high temperature holding region and a temperature decreasing region in order. Incidentally, the white arrow in FIG. 12 indicates the moving direction of the support 10 in the reduction firing furnace.

In this passing process, first the ceramic binder MP is decomposed and removed by heating the ceramic molded body MP in the binder removal region, then the ceramic molded body MP after the binder removal is heated in the temperature rising region, and then In the high temperature holding region, the ceramic molded body MP is sintered by holding at about 1350 ° C. for about 4 hours under a reducing atmosphere of N ₂ + H ₂ (H ₂ = 1.0 to 5.0%). Cool the sintered porcelain.

  Next, the semiconductor ceramic obtained by the firing process is subjected to re-oxidation heat treatment in air or in an oxidizing atmosphere at 700 to 1000 ° C. for about 4 hours.

  Next, an electrode paste containing a metal powder such as Ag is applied to a predetermined region of one side surface or arcuate outer surface of the semiconductor porcelain after the reoxidation heat treatment, followed by baking at 400 to 900 ° C. for about 50 minutes. Form.

  As described above, when the support 10 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 7) and the left-right direction (up-down direction in FIG. 7), Although all the ceramic molded bodies MP positioned are concealed at the lower end portions by the support rods 12 at the front and rear ends, most of all the ceramic molded bodies MP, specifically, 3/4 or more are exposed, Although all the ceramic molded bodies MP located at the left and right ends are concealed at the lower end portion 11 by the side 11, most of all the ceramic molded bodies MP, specifically 3/4 or more are exposed. .

  In other words, in the temperature lowering process in the firing step, there are almost no elements hindering heat radiation from the sintered porcelain at the front and rear ends and the left and right ends of the support 10. In other words, heat can be efficiently radiated from the sintered porcelain during the temperature-falling process, and cooling can be performed quickly. Therefore, the semiconductor becomes non-uniform due to the slow cooling rate, and the electrical characteristics of the semiconductor porcelain vary. It is possible to obtain a ring varistor having a high quality and an improved α value.

  Incidentally, the α value is expressed by α = 1 / (log () when a voltage when a current of 1 mA flows through the electrode of the manufactured ring varistor is E1 and a voltage when a current of 10 mA flows is E10. E10 / E1)) is a nonlinear coefficient calculated.

  Further, according to experiments, the cooling rate is a ratio of “the heat capacity of the support 10 (including the weight bar 13)” and “the heat capacity of the all ceramic molded body MP held on the support 10”, alternatively Is related to the ratio of the respective weights. Specifically, “weight of all ceramic molded body MP” / “weight of support 10 (including weight bar 13)” ≧ 0.3, preferably “weight of all ceramic molded body MP” / “support 10 If the respective weights are set in advance such that the weight of the weight bar 13 (including the weight bar 13) is equal to or greater than 1.0, it is possible to obtain a higher-quality ring varistor by speeding up the cooling rate. .

  In the above-described embodiment, the one using a plurality of independent weight bars 13 is shown. However, as shown in FIG. 13, the plurality of weight bars 13 are integrated by a connecting piece 14 provided on one end side thereof. Also good. 14A and 14B, when a light weight bar 13 is used, the weight 15 or the weight 16 may be detachably attached to both ends thereof. . Each of the weights 15 and 16 has attachment holes 15a and 16a in the upper part, and can be detachably attached by inserting the ends of the weight bar 13 into the attachment holes 15a and 16a and screwing them. The latter weight 16 is of a low center of gravity type having a weight portion 16b below the mounting hole 16a.

  Moreover, in the above-mentioned embodiment, although the ring-shaped thing was shown as the ceramic molded body MP, the C-shaped thing (MP1) shown to FIG. 15 (A) and the U-shaped thing shown to FIG. 15 (B). (MP2) can also be used as a ceramic molded body. When the C-shaped ceramic molded body MP1 is held by the support 10, as shown in FIG. 15A, a large number of ceramic molded bodies MP1 are stacked so that their C-shaped surfaces are in contact with each other. A plurality of rows are formed by placing them sideways so that the arcuate outer surface MP1a of each ceramic molded body MP1 is in contact with the outer surfaces of the two adjacent support rods 1d, and the ceramic molded bodies MP1 of each row. Each of the weights 2 may be inserted into the inner side of the ceramic body, and the weights 2 may be placed in contact with the arcuate inner surface MP1b of the ceramic molded body MP1. Further, when the U-shaped ceramic molded body MP2 is held by the support 10, as shown in FIG. 15B, a large number of ceramic molded bodies MP2 are stacked so that their U-shaped surfaces are in contact with each other. A plurality of rows are formed by placing the product in a horizontal direction so that the arc-shaped outer surface MP2a of each ceramic molded body MP2 is in contact with the outer surfaces of two adjacent support rods 1d, and ceramic molding of each row. The weights 2 may be inserted inside the body MP2, and the weights 2 may be placed in contact with the arcuate inner surface MP2b of the ceramic molded body MP2.

[Second Embodiment]
Below, with reference to FIGS. 16-22, 2nd Embodiment of the manufacturing method which concerns on this invention is described, taking manufacture of a ring varistor as an example.

  First, a mixture is obtained in the same manner as in the first embodiment. Next, granulation is performed in the same manner as in the first embodiment. Next, predetermined inner and outer diameters and wall thicknesses are obtained in the same manner as in the first embodiment. A ceramic molded body MP is obtained.

  Next, a large number of ceramic molded bodies MP are held in a predetermined posture by the support 20 shown in FIGS.

  The support 20 includes a rectangular base plate 21 and a plurality of comb-shaped supports 22 attached to the base plate 21. The base plate 21 has mounting holes 21a formed at equal intervals in the left-right direction in FIG. Each comb-shaped support 22 is formed on a vertically long plate-like portion 22a, a plurality of support rods 22b having a circular cross section provided at equal intervals in the vertical direction on one surface of the plate-like portion 22a, and a lower end of the plate-like portion 22a. And the insertion piece 22c. Each support rod 22b is formed integrally with the plate-like portion 22a, and one end of each support rod 22b formed separately from the plate-like portion 22a is fitted into a hole provided in the plate-like portion 22a and fixed. May be.

  As shown in FIG. 19, the support 20 has two comb-shaped support bodies 22 stacked on each other so that the other surfaces of the plate-like portions 22 a face each other. It is assembled by repeating the work of inserting it in and attaching it by techniques such as press fitting and screwing. As shown in FIGS. 16-18, in the state which attached the several comb-shaped support body 22 to the base plate 21, the surface of the side in which the support bar 22b of the adjacent comb-shaped support body 22 does not exist substantially touches. If wobbling occurs in the plurality of comb-shaped supports 22 attached to the base plate 21, a cap (not shown) that restricts the movement of each plate-like portion 22a covers the upper ends of all the plate-like portions 22a. You may make it cover.

  The base plate 21 and the comb-shaped support 22 of the support 20 are formed of a refractory material, preferably alumina, mullite, silicon carbide, zirconia, magnesia or the like. Further, since the plate-like portion 22a and the support rod 22b constituting the comb-shaped support body 22 and the cap 23 which will be described later are in contact with the ceramic molded body MP, an unnecessary chemical reaction is prevented from occurring at the contact portion in the firing process. Therefore, it is desirable to form a reaction prevention film made of zirconia or the like with a thickness of about 100 to 400 μm on each surface. Furthermore, if a hollow thing (cylindrical thing) is used as the support bar 22b, it can suppress that bending will arise in support bar 22b itself by repeated baking.

  When a large number of ceramic molded bodies MP are held in the support tool 20 in a predetermined posture, a large number of ceramic molded bodies MP stacked such that their annular surfaces are in contact with each other are turned sideways and support rods 22b are formed in the inner holes thereof. The operation of attaching the support rods 22b so as to be inserted is repeated. After the attachment, caps 23 for preventing the drop-off are fitted to the open ends of the support rods 22b (see FIGS. 16 to 20).

  As a result, as shown in FIGS. 20A and 20B, a large number of ceramic molded bodies MP mounted on the support rods 22 are hung on the support rods 22, that is, one of the arc-shaped inner surfaces MPb. It is held in a state supported by two contact points SP.

  When the support 20 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 16) and the front-rear direction (up-down direction in FIG. 16), all ceramic molded bodies positioned at the front-rear ends. Since MP does not hide anything, 100% of the portion is exposed, and all ceramic molded bodies MP located on the left and right ends of all ceramic molded bodies MP whose upper end portions are hidden by the cap 23 Most parts, specifically 7/8 or more, are exposed.

  Next, while holding a large number of ceramic molded bodies MP by the support 20, a tunnel-like shape including a binder removal region, a temperature rising region, a high temperature holding region, and a temperature decreasing region in that order without being stacked in multiple stages. Pass through the reduction firing furnace. Incidentally, the white arrow in FIG. 18 indicates the moving direction of the support 20 in the reduction firing furnace.

In this passing process, first the ceramic binder MP is decomposed and removed by heating the ceramic molded body MP in the binder removal region, then the ceramic molded body MP after the binder removal is heated in the temperature rising region, and then In the high temperature holding region, the ceramic molded body MP is sintered by holding at about 1350 ° C. for about 4 hours under a reducing atmosphere of N ₂ + H ₂ (H ₂ = 1.0 to 5.0%). Cool the sintered porcelain.

  Next, the re-acid heat treatment is performed on the semiconductor ceramic obtained by the firing process in air or in an oxidizing atmosphere at 700 to 1000 ° C. for about 4 hours.

  Next, an electrode paste containing a metal powder such as Ag is applied to a predetermined region of one side surface or arcuate outer surface of the semiconductor porcelain after the reoxidation heat treatment, followed by baking at 400 to 900 ° C. for about 50 minutes. Form.

  As described above, when the support 20 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 16) and the front-rear direction (up-down direction in FIG. 16), Since all the ceramic molded bodies MP that are positioned do not have anything to hide, 100% of the parts are exposed, and all the ceramic molded bodies MP that are positioned at the left and right ends of the ceramic molded bodies MP are hidden by the cap 23. Most parts of all the ceramic molded bodies MP, specifically, 7/8 or more are exposed.

  In other words, in the temperature lowering process in the firing step, there are almost no elements hindering heat radiation from the sintered porcelain at the front and rear ends and the left and right ends of the support tool 20. In other words, heat can be efficiently radiated from the sintered porcelain during the temperature-falling process, and cooling can be performed quickly. Therefore, the semiconductor becomes non-uniform due to the slow cooling rate, and the electrical characteristics of the semiconductor porcelain vary. It is possible to obtain a ring varistor having a high quality and an improved α value. Since the α value is as described in the first embodiment, description thereof is omitted here.

  Further, according to experiments, the cooling rate is a ratio of “the heat capacity of the support 20 (including the cap 23)” and “the heat capacity of the all ceramic molded body MP held by the support 20”, alternatively It has been confirmed that it is related to the ratio of each weight. Specifically, “weight of all ceramic molded body MP” / “weight of support 20 (including cap 23)” ≧ 0.3, preferably “weight of all ceramic molded body MP” / “support 20 ( If the respective weights are set in advance so that the "weight of the cap 23 (including the cap 23)" ≧ 1.0, the cooling rate can be further increased to obtain a ring varistor with higher quality.

  In the above-described embodiment, the plate-like portion 22a and the one provided with a plurality of support rods 22b are shown as the comb-shaped support body 22, but the two comb-shaped support bodies 22 are combined. 21 has a comb-shaped support 22 ′, that is, a plate-like portion 22a ′, a plurality of support bars 22b provided on both sides thereof, and a plug 22c ′ formed at the lower end of the plate-like portion 22a ′. A comb support 22 a ′ may be used instead of the comb support 22.

  Moreover, in the above-mentioned embodiment, although the ring-shaped thing was shown as the ceramic molded body MP, the C-shaped thing (MP1) shown in FIG. 22 (A) and the U-shaped thing shown in FIG. 22 (B). (MP2) can also be used as a ceramic molded body. When the C-shaped ceramic molded body MP1 is held by the support 20, as shown in FIG. 22 (A), a large number of ceramic molded bodies MP1 stacked so that their C-shaped surfaces are in contact with each other. What is necessary is just to mount in the horizontal direction so that the arc-shaped inner surface MP1b of each ceramic molded body MP1 contacts the outer surface of the support rod 22b. When the U-shaped ceramic molded body MP2 is held by the support 20, as shown in FIG. 22B, a large number of ceramic molded bodies MP2 are stacked so that their U-shaped surfaces are in contact with each other. What is necessary is just to mount a thing sideways and this so that the circular arc-shaped inner surface MP2b of each ceramic molded body MP2 may contact the outer surface of the support bar 22b.

[Third Embodiment]
Below, with reference to FIGS. 23-25, 3rd Embodiment of the manufacturing method based on this invention is described, taking manufacture of a ring varistor as an example.

  First, a mixture is obtained in the same manner as in the first embodiment. Next, granulation is performed in the same manner as in the first embodiment. Next, predetermined inner and outer diameters and wall thicknesses are obtained in the same manner as in the first embodiment. A ceramic molded body MP is obtained.

  Next, a large number of ceramic molded bodies MP are held in a predetermined posture on the support 20 shown in FIGS.

  The support 30 includes a rectangular base plate 31 and a plurality of support bars 32 having a circular cross section provided on the base plate 31. Each support bar 32 has a large-diameter portion 32a at the lower portion, and an annular support surface 32b at the upper end of the large-diameter portion 32a. Each support bar 32 may be formed integrally with the base plate 31 or may be fixed by inserting the lower end of each support bar 32 into a hole provided in the base plate 31. Each support bar 32 is formed by surrounding the ceramic molded body MP with three support bars 32 in a vertically oriented manner so that their annular surfaces are in contact with each other, and the lowermost ceramic molded body MP is surrounded by three support bars. It has an arrangement which is supported by 32 support surfaces 32b.

  The base plate 31 and the support bar 32 of the support 30 are formed of a refractory material, preferably alumina, mullite, silicon carbide, zirconia, magnesia or the like. Further, since the support bar 32 is in contact with the ceramic molded body MP, in order to prevent an unnecessary chemical reaction from occurring at the contact portion in the firing process, a reaction preventing film made of zirconia or the like is formed on each surface 100 to 100. It is desirable to form with a thickness of about 400 μm. Furthermore, if a hollow thing (cylindrical thing) is used as the support bar 32, it can suppress that the support bar 32 itself bends by repeated baking.

  When holding a large number of ceramic molded bodies MP on the support 30 in a predetermined posture, the three support rods 32 are arranged in a vertical orientation in which a large number of ceramic molded bodies MP are stacked so that their annular surfaces are in contact with each other. It inserts in between and repeats the operation | work which mounts the lowest ceramic molded object MP on the support surface 32b of the three support rods 32 (refer FIGS. 23-24).

  As a result, a large number of ceramic molded bodies MP inserted between the three support rods 32 are supported at three locations of the lowest ceramic molded body MP by the support surfaces 32b of the three support rods 32, and 3 It is held in a vertical state by the support rod 32 of the book and is prevented from tilting or falling.

  When the support 30 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 23) and the front-rear direction (up-down direction in FIG. 23), all ceramic molded bodies positioned at the front-rear ends. Although the MP is partially hidden by the support rod 32, most of the ceramic molded body MP, specifically, more than half of the ceramic molded body is exposed, and all the ceramic molded bodies located at the left and right ends are exposed. Although part of the MP is hidden by the support bar 32, most part of all the ceramic molded bodies MP, specifically, a part of 1/2 or more is exposed.

  Next, while holding a large number of ceramic molded bodies MP by the support 30, without removing them in multiple stages, the tunnel-like structure is provided with a binder removal region, a temperature rising region, a high temperature holding region, and a temperature decreasing region in this order. Pass through the reduction firing furnace. Incidentally, the white arrow in FIG. 25 indicates the moving direction of the support 30 in the reduction firing furnace.

In this passing process, first the ceramic binder MP is decomposed and removed by heating the ceramic molded body MP in the binder removal region, then the ceramic molded body MP after the binder removal is heated in the temperature rising region, and then In the high temperature holding region, the ceramic molded body MP is sintered by holding at about 1350 ° C. for about 4 hours under a reducing atmosphere of N ₂ + H ₂ (H ₂ = 1.0 to 5.0%). Cool the sintered porcelain.

  Next, the semiconductor ceramic obtained by the firing process is subjected to re-oxidation heat treatment in air or in an oxidizing atmosphere at 700 to 1000 ° C. for about 4 hours.

  Next, an electrode paste containing a metal powder such as Ag is applied to a predetermined region of one side surface or arcuate outer surface of the semiconductor porcelain after the reoxidation heat treatment, followed by baking at 400 to 900 ° C. for about 50 minutes. Form.

  As described above, when the support 30 holding a large number of ceramic molded bodies MP is viewed from the front-rear direction (left-right direction in FIG. 23) and the front-rear direction (up-down direction in FIG. 23), Although all the ceramic molded bodies MP located are partially hidden by the support rod 32, most of the ceramic molded bodies MP, specifically, more than 1/2 are exposed, and the left and right ends are exposed. Although all of the ceramic molded bodies MP that are positioned are partially hidden by the support rod 32, most of all the ceramic molded bodies MP, specifically, more than half of the ceramic molded bodies MP are exposed.

  In other words, in the temperature lowering process in the firing step, there are almost no elements that obstruct heat dissipation from the sintered porcelain at the front and rear ends and the left and right ends of the support 30. In other words, heat can be efficiently radiated from the sintered porcelain during the temperature-falling process, and cooling can be performed quickly. Therefore, the semiconductor becomes non-uniform due to the slow cooling rate, and the electrical characteristics of the semiconductor porcelain vary. It is possible to obtain a ring varistor having a high quality and an improved α value. Since the α value is as described in the first embodiment, description thereof is omitted here.

  Further, according to experiments, the cooling rate is a ratio of “the heat capacity of the support tool 30” and “the heat capacity of the entire ceramic molded body MP held by the support tool 30”, alternatively, the ratio of the respective weights. It has been confirmed that it is related. Specifically, “weight of all ceramic molded body MP” / “weight of support tool 30” ≧ 0.3, preferably “weight of all ceramic molded body MP” / “weight of support tool 30” ≧ 1.0. If the respective weights are set so as to satisfy the above, it is possible to obtain a ring varistor with higher quality by further increasing the cooling rate.

It is a side view of the stacking state of the conventional support tool used at a baking process. It is a figure which shows the other holding | maintenance form of the ceramic molded body by the support tool shown in FIG. It is a top view of the other conventional support tool used at a baking process. It is the a1-a1 sectional view taken on the line of FIG. It is an a2-a2 line arrow directional view of FIG. It is a side view of the stacked state of the support shown in FIG. It is a top view of the support tool concerning a 1st embodiment of the present invention. It is the b1-b1 sectional view taken on the line of FIG. It is a b2-b2 line arrow line view of FIG. It is explanatory drawing of the holding state of the ceramic molded body by the support tool shown in FIG. It is a supplementary explanatory drawing regarding the space | interval setting of two support rods adjacent to the support tool shown in FIG. It is a side view of the stacked state of the support shown in FIG. FIG. 8 is a perspective view showing a modified example of the weight bar shown in FIG. 7. It is a perspective view which shows the other modification of the weight bar shown in FIG. It is a figure which shows the other example of a shape and holding | maintenance state of a ceramic molded body. It is a top view of the support tool concerning a 2nd embodiment of the present invention. It is the c1-c1 sectional view taken on the line of FIG. It is a c2-c2 arrow directional view of FIG. It is a perspective view which shows the structure of the support tool shown in FIG. It is explanatory drawing of the holding state of the ceramic molded body by the support tool shown in FIG. It is a perspective view which shows the modification of the comb-shaped support body shown in FIG. It is a figure which shows the other example of a shape and holding | maintenance state of a ceramic molded body. It is a top view of the support tool concerning a 3rd embodiment of the present invention. FIG. 24 is a sectional view taken along line d1-d1 of FIG. It is a d2-d2 line arrow directional view of FIG.

Explanation of symbols

MP, MP1, MP2 ... ceramic molded body, 10 ... support, 11 ... side piece, 12 ... support bar, 13 ... weight bar, 20 ... support, 21 ... base plate, 22, 22 '... comb support, 22b ... support rod, 23 ... cap, 30 ... support, 31 ... base plate, 32 ... support rod, 32b ... support surface.

Claims (5)

An electronic component manufacturing method comprising a firing step in which a large number of ceramic compacts are sintered together to form a semiconductor by passing a fireproof support holding a large number of ceramic compacts in a predetermined posture through a tunnel-like firing furnace. Because
The large number of ceramic molded bodies are held by the support so that most of the ceramic molded bodies located at the front and rear ends and the left and right ends thereof are exposed when the support is viewed from the front-rear direction and the left-right direction. , Passing through the tunnel-like firing furnace while maintaining the holding state,
An electronic component manufacturing method characterized by the above. All ceramic molded bodies located at the front and rear ends and the left and right ends are exposed at a half or more when viewed from each direction.
The electronic component manufacturing method according to claim 1. The support is provided with a plurality of support bars capable of holding the ceramic molded body in an upright state by supporting the arc-shaped outer surface of the ceramic molded body having an arc-shaped outer surface at two locations, and the support is stacked in multiple stages. Passed through the firing furnace in a
The electronic component manufacturing method according to claim 1, wherein the electronic component manufacturing method is an electronic component manufacturing method. The support is provided with a plurality of support bars in a predetermined arrangement in the vertical direction and the front-rear direction that can be held in a state where the ceramic molded body is suspended by supporting the arc-shaped inner surface of the ceramic molded body having an arc-shaped inner surface in one place. The support passes through the firing furnace as it is,
The electronic component manufacturing method according to claim 1, wherein the electronic component manufacturing method is an electronic component manufacturing method. The support is capable of holding the ceramic molded body in a vertical state by supporting three places of the lowest ceramic molded body of the vertical one in which the ring-shaped ceramic molded bodies are overlapped so that their annular surfaces are in contact with each other. A plurality of support rods are provided in a predetermined arrangement in the front-rear direction and the left-right direction, and the support passes through the firing furnace as it is.
The electronic component manufacturing method according to claim 1, wherein the electronic component manufacturing method is an electronic component manufacturing method.

Images