JP4480438B2 - Electronic component manufacturing method - Google Patents

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 includes a step of holding a large number of ceramic molded bodies in a predetermined posture on a support, and a large number of ceramic molded bodies collectively by passing the support through a tunnel-shaped firing furnace. A method of manufacturing an electronic component comprising a firing step of sintering into a semiconductor and holding a large number of ceramic molded bodies in a predetermined posture on a support is a ring shape having an arc-shaped outer surface and an arc-shaped inner surface, C A large number of ceramic compacts are stacked in the same direction using a letter-shaped or U-shaped ceramic compact, a support with a plurality of support bars arranged in parallel at equal intervals, and a plurality of weight bars A plurality of rows are formed so that each arc-shaped outer surface is in contact with the outer surfaces of two adjacent support rods, and weights are formed so as to be in contact with the arc-shaped inner surfaces of the ceramic molded bodies in each row. Put each stick on each row A ceramic molded body carried out by the action of the weight of the Tsumubo respectively, and its characterized by.

A large number of ceramic molded bodies held by the support are supported at two contact points with each of the two arcing outer surfaces on each arc-shaped outer surface, and the weight bar placed on each arc-shaped inner surface. It will be in the state pressed against these two contact locations by weight. In short, since many ceramic molded bodies held by the support are held so that most of the ceramic molded body is exposed from the support, the ceramic molded body is sintered and cooled to lower the temperature in the firing process. support again and again will be the element to inhibit heat radiation from the sintered ceramic hardly resides. 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.

Below, with reference to FIGS. 7-15, one 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. It Using those having at least one plane at both ends as the support rods 12 support bar 12 can be prevented from rotating, the support rod 12 Using the cross-sectional surface of the both ends as the supporting rod 12 that the polygon be of Even when bending occurs in itself, it is possible to correct the bending 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. In order 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 the 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 this 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 inside each of the two and placed so that the weights 2 come into 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.

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 one 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 the two support rods which the support tool shown in FIG. 7 adjoins. 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.

MP, MP1, MP2 ... ceramic molded body, 10 ... support, 11 ... side piece, 12 ... support bar, 13 ... weight bar .

Claims (4)

A step of holding a large number of ceramic molded bodies in a predetermined posture on a support, and a firing step of sintering the plurality of ceramic molded bodies in a lump by passing the support through a tunnel-shaped firing furnace. Electronic component manufacturing method,
The step of holding a large number of ceramic molded bodies in a predetermined posture on a support tool,
A ring-shaped, C-shaped or U-shaped ceramic molded body having an arc-shaped outer surface and an arc-shaped inner surface, a support tool including a plurality of support bars arranged in parallel at equal intervals, and a plurality of weight bars make use of,
A plurality of ceramic molded bodies stacked in the same direction are placed so that each arc-shaped outer surface is in contact with the outer surfaces of two adjacent support rods to form a plurality of rows, and the ceramic molded bodies in each row The weight rods are placed so as to be in contact with the arc-shaped inner surface of each of them, and the weights of the weight rods are applied to the ceramic molded bodies in each row, respectively.
An electronic component manufacturing method characterized by the above. The portion of the support rod that contacts the ceramic molded body of the support rod has a circular cross section, and the portion of the spindle that contacts the ceramic molded body has a circular cross section.
The electronic component manufacturing method according to claim 1. The weight bar consists of a weighted bar,
The electronic component manufacturing method according to claim 1, wherein the electronic component manufacturing method is an electronic component manufacturing method. The weight bar consists of a bar and weights provided at both ends thereof.
The electronic component manufacturing method according to claim 1, wherein the electronic component manufacturing method is an electronic component manufacturing method.

Images