JP5019629B2 - Capacitor element manufacturing method and manufacturing apparatus thereof - Google Patents

Description

  The present invention relates to a method of manufacturing a capacitor element used for a solid electrolytic capacitor and a manufacturing apparatus thereof.

  Solid electrolytic capacitors using tantalum, niobium or the like as a valve action metal are small, have a large capacitance, have excellent frequency characteristics, and have been widely used in CPU decoupling circuits or power supply circuits. With the development of portable electronic devices, various technologies have been developed for the purpose of low ESR (equivalent series resistance) and low ESL (equivalent series inductance) particularly in a high frequency range.

  For example, Patent Document 1 discloses a technique for reducing ESR by a shape in which an anode lead wire of a capacitor element sintered body is planted at a position close to the cathode terminal side.

  On the other hand, Patent Document 2 discloses a lead frameless chip-type solid electrolytic capacitor in which the anode lead wire is planted at a position higher or lower than the center line of the capacitor element, thereby reducing the rising mounting failure when mounting the substrate. ing.

  Further, in Patent Document 3, as a bottom electrode type solid electrolytic capacitor element, a lead wire led so as to be eccentric in a direction substantially orthogonal to the lead direction is used, and currents between the anode terminal, the cathode terminal, and the external circuit board are used. A technique for reducing ESL and ESR in a high frequency range by shortening the distance of the path is disclosed.

  As described above, ESR and ESL are reduced and mounting defects are improved by planting the anode lead wire in the vicinity of the outer periphery instead of the center of the capacitor element. FIG. 4 shows a perspective view of an example of a capacitor element in which such a lead wire is eccentric, that is, an eccentric pellet. The eccentric pellet 40 having the eccentric lead wire 2 is produced from a molded body obtained by pressure-molding a valve metal powder. There are two methods for forming such a molded body: vertical push molding in which a pressure punch is pressed and molded from the lead wire drawing direction, that is, the vertical direction, and the direction perpendicular to the lead wire drawing direction, that is, the horizontal direction. There is a lateral press molding in which a pressure punch is used for pressure molding.

  Here, a general method for manufacturing a solid electrolytic capacitor element is described. After a binder is added to and mixed with a valve metal powder such as tantalum or niobium, in the case of vertical press molding, the upper punch and lower Pressed from above and below with a punch and compression molded into a square or cylindrical shape to form a molded body. At this time, an anode lead wire of the same type as that of the valve action metal powder is used, one end is embedded in the powder and pressure-molded together, and the other end is drawn from the molded body. Then, the compact is vacuum-sintered, anodized to form an oxide film layer, impregnated with a manganese nitrate aqueous solution, a manganese dioxide layer formed by a thermal decomposition method that repeats thermal decomposition multiple times, or impregnated with a monomer solution After forming a solid electrolyte layer by forming a conductive polymer by polymerization, a cathode lead layer composed of a carbon layer and a silver layer is sequentially formed to obtain a capacitor element. Subsequently, the lead wire and the anode lead frame are welded, the cathode lead layer and the cathode lead frame are connected to each other through a conductive adhesive, and then resin-coated with a transfer mold or the like. Thereafter, unnecessary anode and cathode lead frames are cut and then bent to one side of the capacitor exterior to complete a chip-type solid electrolytic capacitor as anode and cathode terminals.

  FIG. 5 is a schematic cross-sectional view showing a pressure molding process by vertical press molding. In FIG. 5, the upper punch 7 is provided with a lead wire insertion hole for passing the lead wire 2 as an anode lead wire, and a die 6 processed into a molded shape (for example, round shape, square, rectangle, etc.) is provided. 5A, the lead wire 2 is inserted into the upper punch 7 having the same cross-sectional pressure surface as that shown in FIG. 5A, and the lower punch 8 processed into the same shape as the die 6 is positioned on the lower surface of the die 6. The valve action metal powder 1 is filled in the through hole of the die 6. Thereafter, as shown in FIG. 5B, the upper punch 7 protruding the lead wire 2 is lowered into the die 6. Further, the upper punch 7 and the lower punch 8 are moved in synchronism toward the center of the filled valve action metal powder, and the lead wire 2 is pressure-formed to a predetermined size while being planted. Thereafter, as shown in FIG. 5 (c), the upper punch 7 is retracted above the die 6 in a state where the lead wire 2 is planted. 51 is pushed upward in the die 6 to perform die cutting, and the lead wire 2 of the molded body 51 is cut to a predetermined length to complete the molded body 51 shown in FIG.

  FIG. 6 is a perspective view showing the arrangement of the pressure punch and the mold base in the pressure molding process by horizontal pressing, and FIG. 7 (a) is a schematic top sectional view of the mold, FIG. 7 (b), FIG. 7 (c) is a schematic cross-sectional view. In FIG. 6, a mold base 4 having a U-shaped base groove disposed upward, two pressure punches 5 (L), 5 (R) inserted into the base groove and moving to the left and right, and leads A lead wire insertion hole through which the wire 2 is inserted is provided, and an upper die 3 that seals the base groove of the die base from above is used. As shown in FIG. 7 (b), the valve metal powder 1 is filled in the space provided between the pressure surfaces of the pressure punches 5 (L) and 5 (R) in the center of the base groove, and the upper mold 3 Covers the base groove of the mold base with the lead wire 2 protruding, and seals the base groove as shown in FIG. Thereafter, the pressure punches 5 (L) and 5 (R) move in the base groove from the left and right to pressurize the valve metal powder 1 to produce a molded body. Thereafter, the lead wire 2 is cut and die-cut.

JP 09-237743 A JP 2007-088387 A JP 2007-142161 A

  When pressing the molded body of the eccentric pellet by vertical pressing, the shape of the upper punch lead wire insertion hole is decentered and installed, resulting in a complicated shape and increasing the number of manufacturing steps. When inserting into the die with the wire protruding, there is a problem that the lead wire is caught by the punch and the die due to the bending of the lead wire protruding from the upper punch, and the mold is easily damaged.

  On the other hand, in the horizontal pressing, the left and right pressure punches 5 (L), with the lead wire 2 positioned near the side wall of the base groove of the mold base 4 as shown in FIG. When pressure molding is performed with 5 (R), the middle point of the pressed metal powder pressed between the pressing surfaces and the center of the width of the base groove comes, and the lead wire 2 is close to the side wall of the base groove. There may be unfilled parts (nests) in the molded body, lead wire exposure, or cracking of the molded body after sintering, and sufficient connection strength between the lead wire and the molded body. There is a problem that it is difficult to obtain. If the bonding between the lead wire and the molded body is not sufficient, the oxide film is destroyed by thermal and mechanical stress, leading to an increase in short-circuit failure rate and deterioration in leakage current characteristics.

  Further, in the side press molding, as shown in FIG. 8, the lead wire 2 from the press surface of the left and right press punches 5 (L) and 5 (R) in the press direction at the center in the width direction of the base groove. If the left and right pressure punches are simultaneously moved to a predetermined position to form a formed body when the distances are different, the lead wire 2 inserted into the upper mold 3 starts from the root protruding into the base groove. It will be bent toward the center of the compact. FIG. 9 is a side view of the molded body showing the state of the lead wire bent in the molded body. The greater the amount of eccentricity of the lead wire, the greater the lead wire is bent in the shearing direction, and the lead wire insertion hole of the upper die 3 is worn into an ellipse. In addition, since the base portion of the lead wire of the molded body is not subjected to sufficient pressure molding, coating peeling or the like is likely to occur during the subsequent processing steps, which causes a failure in leakage current characteristics.

  Accordingly, an object of the present invention is to obtain a sufficient connection strength between a molded body and a lead wire in the production of a molded body of an eccentric pellet, which is a capacitor element with an eccentric lead wire, and to sinter the molded body. An object of the present invention is to provide a capacitor element manufacturing method and a manufacturing apparatus therefor that do not cause short-circuit defects or deterioration of leakage current characteristics in later manufacturing processes.

  In order to solve the above-described problems, a method for manufacturing a capacitor element according to the present invention includes a valve-acting metal powder in which one end of an anode lead wire is exposed and embedded in an upright manner, and the valve-acting metal powder is pressure-molded. In the method of manufacturing a capacitor element including the step of performing, the pressing direction of the pressure forming and the planting direction of the lead wire are orthogonal to each other, and the pressure forming is opposed to the pressing direction across the powder of the valve metal The two lead punches are arranged at different positions from the pressure surface of the two pressure punches, and the two pressure punches are arranged at different positions. The moving distance is set to be different depending on the distance between the pressing surface and the lead wire.

  Specifically, an upper mold through which the lead wire is inserted, a mold base having a U-shaped base groove filled with the valve metal powder, and a left and right inserted into the base groove to move left and right. Two pressure punches are used, the valve action metal powder is filled between the pressure surfaces of the two pressure punches, and the upper die protrudes from the lower surface by a length for embedding the lead wire. The base groove of the mold base is sealed, and the protruding portion of the lead wire is located substantially in the center in the direction perpendicular to the pressing direction in the base groove, and from the pressing surfaces of the two pressing punches The two pressure punches may be simultaneously moved and pressure-molded.

  Further, the capacitor element manufacturing apparatus according to the present invention is a capacitor having a function of pressure-molding the valve action metal powder by embedding the valve action metal powder in an upright position by exposing one end of the lead wire for anodic extraction to the valve action metal powder. In the element manufacturing apparatus, an upper mold through which the lead wire is inserted, a mold base having a U-shaped base groove filled with the powder of the valve metal, and a left and right insertion inserted into the base groove. The pressure metal surfaces of the two pressure punches are filled with valve action metal powder, and the upper die protrudes from the lower surface by a length for embedding the lead wire. When the base groove of the mold base is sealed, the projecting portion of the lead wire is positioned substantially at the center in the direction perpendicular to the pressing direction in the base groove, and the two pressing punches Distance from pressure surface Are set to be different from each other, the two pressure punches are moved simultaneously, and the movement distance is set to be different according to the distance between the pressure surface and the lead wire. To do.

  As described above, in the present invention, in the press molding of the lateral press molding, the lead wire is erected in an eccentric manner in the position where the distance from the pressing surface of the two pressing punches is different, that is, in the pressing direction. The moving distance of the two left and right pressure punches is set to be different depending on the distance between the pressure surface and the lead wire. Thereby, in the production of a molded body of an eccentric pellet, which is a capacitor element with an eccentric lead wire, sufficient connection strength between the molded body and the lead wire is obtained, and in the manufacturing process after sintering the molded body In addition, a capacitor element manufacturing method and a manufacturing apparatus thereof that do not cause short-circuit defects or leakage current characteristics can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram for explaining an embodiment of a capacitor element manufacturing method and manufacturing apparatus according to the present invention, and is a view showing a mold used for pressure forming of valve action metal particles in the present embodiment. . FIG. 1A is a schematic upper cross-sectional view, and FIGS. 1B and 1C are schematic cross-sectional views. The basic configuration of the mold used in the present embodiment is the same as that of the lateral push mold shown in FIG. 6, and a mold base 4 having a U-shaped base groove disposed upward, and a base groove Two pressure punches 5 (L), 5 (R) that are inserted and moved to the left and right, and an upper die 3 that has a lead wire insertion hole through which the lead wire 2 is inserted and seals the base groove of the die base from above. Is used. Further, as shown in FIG. 1A, the lead wire 2 is disposed so as to be substantially at the center in the width direction of the base groove, and as shown in FIG. The pressure punches 5 (L) and 5 (R) are arranged such that the distances from the pressure surface are different from t1 and t2. The arrangement before the pressure molding is the same as that in FIG. 8, but in this embodiment, the moving distances of the left and right pressure punches 5 (L) and 5 (R) that move simultaneously correspond to the distances t1 and t2, respectively. Are set differently.

  As shown in FIG. 1 (b), a valve action metal powder such as tantalum, aluminum, or niobium is provided in a space provided between the pressure surfaces of the pressure punches 5 (L), 5 (R) in the center of the base groove. 1, the upper mold 3 covers the base groove of the mold base with the lead wire 2 protruding, and seals the base groove. Thereafter, as shown in FIG. 1 (c), the pressure punches 5 (L) and 5 (R) simultaneously pass through the base groove from the left and right, and the distances between the respective pressure surfaces and the lead wires 2 are t1 ′ and t2 ′. It moves to this position, pressurizes the valve action metal powder 1, and produces a molded object.

  The above molded body is sintered in a vacuum atmosphere of about 1200 ° C., an anodized film layer is formed on the surface of the metal powder, and the manganese dioxide layer formed by thermal decomposition is repeatedly impregnated with a manganese nitrate aqueous solution and thermally decomposed a plurality of times. A solid electrolyte layer is formed by formation, impregnation into a monomer solution, or formation of a conductive polymer layer by polymerization, and then a cathode lead layer composed of a carbon layer and a silver layer is sequentially formed to form a capacitor element.

  As an example of the capacitor element manufactured according to the present embodiment, it can have a substantially rectangular parallelepiped shape as in the capacitor element shown in FIG. 4, and the width, depth, and height are from 0.5 mm to 2 mm. In the range of about 0 mm, one end of the lead wire with the same material as the valve action metal powder from 0.1 mm to 0.3 mm in diameter is exposed from one side, and the other end is planted in the molded body. Can do.

  Here, as an example of the amount of eccentricity of the lead wire, for example, when the width in the pressing direction of the molded body is 2.0 mm and the lead wire is eccentric from the center of the molded body by 0.5 mm to the right, Since the distance to the center is 1.5 mm and 0.5 mm, respectively, from the end face of the molded body, the ratio of the movement distances of the pressure punches 5 (L) and 5 (R) in the present embodiment is 3: Set to 1.

  FIG. 2 is a diagram showing a specific example of the capacitor element manufacturing apparatus used in the present embodiment, and is a side view of the left and right pressure punch driving units in pressure molding. In FIG. 2, when the motor 11 is driven up and down, the left and right plate cams 10 (L) and 10 (R) move up and down, and the left and right levers 9 (L) and 9 (R) respectively move to the plate cam 10 (L ) Following 10 (R), the fulcrum points 90 (L) and 90 (R) at the center portions of the levers 9 (L) and 9 (R), respectively, The follower action point swings in a circular orbit. Further, since the follower action point of the left and right levers and the left and right pressure punches are engaged with each other, the left and right pressure punches 25 (L) and 25 (R) are linked to the vertical movement of the plate cam, and lead wires It is opened and closed to the left and right with 2 being the midpoint.

  The angles θ (L) and θ (R) of the plate cams 10 (L) and 10 (R) are calculated based on the lead wire planting positions, and the plate cams having angles according to the eccentric state are arranged. . For example, when the width of the molded body is 2.0 mm as described above and the lead wire is decentered by 0.5 mm in the right direction from the center of the element, θ (R) = 30 degrees and θ (L) = 60 degrees. By doing so, a ratio of the moving distance of 3: 1, that is, a pressurizing ratio is obtained.

  In the above example, as shown in FIG. 2, the angle of the plate cam is determined by the shape of the molded body and the eccentric amount of the lead wire position, and the plate cam fixed to the angle is used. By adopting a structure in which the angle θ of the plate cam can be varied, a pressure punch drive unit that can flexibly cope with changes in the dimensions of the molded body and the eccentricity of the lead wire is obtained.

  FIG. 3 is a diagram showing another specific example of the capacitor element manufacturing apparatus used in the present embodiment, and is a schematic cross-sectional view showing a mold and a pressure punch driving unit used for pressure molding. In FIG. 3, motors 31 (L) and 31 (R) are directly connected to the left and right pressure punches 35 (L) and 35 (R), respectively. Similarly to the above example, the left and right pressure punches are moved by the motors directly connected to each other at the same distance of movement corresponding to the shape of the molded body and the amount of eccentricity of the lead wire position.

  2 and FIG. 3 as another specific example, the left and right plate cams in FIG. 2 have the same angle, and the left and right plate cams are driven by two independent motors. good. Further, any method and structure other than those described above can be used in the manufacturing method and manufacturing apparatus of the present embodiment as long as the pressure punches on the left and right move and pressurize at different distances in synchronization. .

  After the lead wire and the sleeper lead frame are welded, the molded body manufactured in the present embodiment is connected to a substrate provided with an anode and a cathode terminal using a conductive adhesive or high-temperature solder, and is resin-coated. . Thereafter, unnecessary exterior parts are cut by dicing or the like to complete a solid electrolytic capacitor.

  As described above, the manufacturing method and the manufacturing apparatus according to the present invention provide a sufficient connection strength between the molded body and the lead wire, and even in the manufacturing process after sintering the molded body, short circuit failure and deterioration of leakage current characteristics. Thus, a capacitor element that does not cause the problem can be obtained.

  Needless to say, the present invention is not limited to the above-described embodiment, and the structure and shape of a mold, a pressure punch, and the like according to requirements for the shape and performance of the target capacitor element. Moreover, the driving method of the pressure punch can be changed.

The figure which shows the metal mold | die used for the pressure molding of one Embodiment of the manufacturing method and manufacturing apparatus of the capacitor | condenser element by this invention, FIG.1 (a) is a top cross-sectional schematic diagram, FIG.1 (b), FIG.1 (c) Is a schematic cross-sectional view. The figure which shows a specific example of the manufacturing apparatus used for this Embodiment, The side view of the pressure punch drive part on either side in pressure molding. The figure which shows the other specific example of the manufacturing apparatus used for this Embodiment, the cross-sectional schematic diagram which shows the metal mold | die used for pressure molding, and a pressure punch drive part. The perspective view of an example of the capacitor element (eccentric pellet) which made the lead wire eccentric. The cross-sectional schematic diagram which shows the press molding process by the conventional vertical press molding. The perspective view which shows the arrangement | positioning of the pressure punch of the pressure forming process by the conventional horizontal pressing, and a metal mold | die base. FIG. 7A is a schematic diagram showing a conventional pressure molding process by lateral pressing, FIG. 7A is a schematic top sectional view of a mold, and FIG. 7B and FIG. The upper cross-section schematic diagram of a metal mold | die at the time of arrange | positioning by decentering a lead wire to a pressurization direction by horizontal pressing. The side view of the molded object which shows the mode of the lead wire bent in the molded object.

Explanation of symbols

1 Valve Action Metal Powder 2 Lead Wire 3 Upper Die 4 Mold Base 5 (L), 5 (R), 25 (L), 25 (R), 35 (L), 35 (R) Pressure Punch 6 Die 7 Upper punch 8 Lower punch 9 (L), 9 (R) Lever 10 (L), 10 (R) Plate cam 11, 31 (L), 31 (R) Motor 40 Eccentric pellet 51, 91 Molded body 90 (L ), 90 (R) Center fulcrum

Claims (3)

In the method of manufacturing a capacitor element, including a step of exposing and embedding one end of the lead wire for anode extraction in the valve action metal powder, and embedding the valve action metal powder under pressure,
The pressurization direction of the press molding is orthogonal to the direction in which the lead wire is laid, and the press molding is arranged opposite to the pressurization direction with the valve metal powder sandwiched therebetween and moves in the pressurization direction. It is performed by two pressure punches, and the lead wire is erected at a position where the distance from the pressure surface of the two pressure punches is different, and the movement distance of the two pressure punches is the distance between the pressure surface and the lead wire. The capacitor element manufacturing method is characterized in that the capacitor element is set differently according to a distance between the capacitor element and the capacitor element.   An upper mold through which the lead wire is inserted, a die base having a U-shaped base groove filled with the powder of the valve action metal, and two pressure punches which are inserted into the base groove and move left and right The metal base is filled with the valve action metal powder between the pressure surfaces of the two pressure punches, and the upper die protrudes from the lower surface by a length for embedding the lead wire. The groove is sealed, and the protruding portion of the lead wire is located substantially in the center in the direction perpendicular to the pressing direction in the base groove, and the distance from the pressing surface of the two pressing punches is different. 2. The method of manufacturing a capacitor element according to claim 1, wherein the two pressure punches are simultaneously moved and pressure-molded. In an apparatus for manufacturing a capacitor element having a function of exposing one end of a lead wire for anode extraction to a valve metal powder and embedding it in an upright manner, and pressure-molding the valve metal powder,
An upper mold through which the lead wire is inserted, a mold base having a U-shaped base groove filled with the valve metal powder, and two pressure punches inserted in the base groove and moving to the left and right The metal base is filled with valve metal powder between the pressure surfaces of the two pressure punches, and the upper die protrudes from the lower surface by a length for embedding the lead wire. When the base groove is sealed, the protruding portion of the lead wire is located substantially in the center in the direction perpendicular to the pressing direction in the base groove, and the distance from the pressing surface of the two pressing punches is It is set to be different, and the two pressure punches move at the same time, and the movement distance is set to be different depending on the distance between the pressure surface and the lead wire. Capacitor element manufacturing equipment.

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