JP2007095820A - Manufacturing method of solid-state electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of solid-state electrolytic capacitor for adhering conductive paste to the predetermined part of an element intermediate material in higher accuracy. <P>SOLUTION: In this manufacturing method of solid-state electrolytic capacitor, a valve metal foil 28 is swayed, for example, for one stroke in the direction orthogonally crossing the front surface 27b and rear surface 27c of a comb tooth 27 under the condition that each comb tooth 27 is soaked into the carbon paste 25 within a paste tank 26. Accordingly, swell generated on the front surface 25a of the carbon paste 25 is controlled and the comb tooth 27 is surely soaked into the carbon paste 25 until the upper end 13a of a resist layer 13. Therefore, the carbon paste 25 can be coated in higher accuracy to the predetermined part 27a of the comb tooth 27. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor.

As a conventional method for producing a solid electrolytic capacitor, an element intermediate comprising a valve metal substrate, a dielectric layer formed on the valve metal substrate, and a solid electrolyte layer formed on the dielectric layer is obtained as a predetermined intermediate body. What includes a step of immersing in a conductive paste so that the conductive paste adheres to the portion is known (for example, see Patent Document 1).
JP-A-6-77097

  However, in the above-described prior art, the familiarity between the element intermediate and the conductive paste may be poor due to the influence of the wettability of the conductive paste with respect to the element intermediate and the surface tension of the conductive paste. In such a case, when the element intermediate is immersed in the conductive paste, the surface of the conductive paste may follow the element intermediate, and a concave undulation may occur on the surface of the conductive paste around the element intermediate. is there. When such waviness occurs on the surface of the conductive paste, the conductive paste does not adhere to the upper end of a predetermined portion of the element intermediate. If the conductive paste does not adhere to a predetermined part of the element intermediate with high accuracy, the conductive paste becomes a conductive layer that forms a counter electrode with the valve metal substrate in the solid electrolytic capacitor, so the frequency characteristics of the capacitance of the solid electrolytic capacitor Will deteriorate.

  Accordingly, the present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a solid electrolytic capacitor capable of accurately attaching a conductive paste to a predetermined portion of an element intermediate. And

  In order to achieve the above object, a method of manufacturing a solid electrolytic capacitor according to the present invention includes a valve metal base, a dielectric layer formed on the valve metal base, a solid electrolyte layer formed on the dielectric layer, A method of manufacturing a solid electrolytic capacitor including a step of immersing an element intermediate including the element intermediate in a conductive paste so that the conductive paste adheres to a predetermined portion thereof, wherein the element intermediate is immersed in the conductive paste Is characterized in that at least one of the element intermediate and the paste tank storing the conductive paste is swung while the element intermediate is immersed in the conductive paste.

  In this method of manufacturing a solid electrolytic capacitor, at least one of the element intermediate and the paste tank is swung while the element intermediate is immersed in a conductive paste. As a result, the fluidity of the conductive paste around the element intermediate increases, and even if the familiarity between the element intermediate and the conductive paste is poor, the undulation is suppressed and the surface of the conductive paste is flattened. be able to. Therefore, it is possible to attach the conductive paste to a predetermined portion of the element intermediate with high accuracy.

  The direction in which at least one of the element intermediate and the paste tank is swung is preferably a direction intersecting the main surface of the element intermediate. When the compatibility between the element intermediate and the conductive paste is poor, the surface of the conductive paste tends to easily follow the main surface of the element intermediate. Therefore, by swinging at least one of the element intermediate and the paste tank in a direction intersecting with the main surface of the element intermediate, a predetermined portion of the element intermediate is positively brought into contact with the conductive paste, so that it is reliable and easy. The surface of the conductive paste can be flattened.

  According to the present invention, the conductive paste can be attached to a predetermined portion of the element intermediate with high accuracy.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, terms such as “upper” and “lower” are based on the state shown in the drawings and are for convenience.

  As shown in FIG. 1, the solid electrolytic capacitor 1 includes a printed circuit board 2. The printed circuit board 2 has a substrate 3 made of an epoxy resin or the like. On the upper surface of the substrate 3, anode wiring 4 and cathode wiring 5 are patterned with copper or the like, and on the lower surface of the substrate 3, anode terminals 6 are formed. The cathode terminal 7 is patterned with copper or the like. The anode wiring 4 and the anode terminal 6 are electrically connected by a plating layer 9 formed on the inner wall surface of the through hole 8 provided in the substrate 3. Similarly, the cathode wiring 5 and the cathode terminal 7 are connected to the substrate. 3 are electrically connected by a plating layer 9 formed on the inner wall surface of a through hole 8 provided in 3.

  A capacitor element laminate 10 is fixed on the printed board 2. The capacitor element laminate 10 is configured by laminating four layers of capacitor elements 11.

  The capacitor element 11 has a foil-like valve metal substrate 12 made of a valve metal such as aluminum, tantalum, or niobium. The valve metal base 12 includes a capacitor portion 12 a located on the cathode wiring 5 of the printed board 2 and an electrode portion 12 b extending from the capacitor section 12 a to the anode wiring 4 of the printed board 2. A resist layer 13 made of an epoxy resin or the like is formed on the outer surface of a portion of the valve metal base 12 located between the capacitor portion 12a and the electrode portion 12b. The valve metal base 12 functions as an anode in the capacitor element 11.

  As shown in FIG. 2, the outer surface of the valve metal base 12 is roughened and widened by etching. A dielectric layer 15 made of a valve metal oxide is formed on the outer surface of the capacitor portion 12a of the valve metal base 12, and a solid electrolyte layer made of a conductive polymer is formed on the outer surface of the dielectric layer 15. 16 is formed. Further, an inner conductor layer 17 made of a conductive material containing carbon is formed on the outer surface of the solid electrolyte layer 16, and an outer surface of the inner conductor layer 17 is made of a conductive material containing silver. An outer conductor layer 18 is formed. The solid electrolyte layer 16, the inner conductor layer 17, and the outer conductor layer 18 function as a cathode in the capacitor element 11.

  As shown in FIG. 1, in the capacitor element laminate 10, the outer conductor layers 18 and 18 of adjacent capacitor elements 11 and 11 are bonded to each other with a conductive adhesive 21, and The outer conductor layer 18 is bonded to the cathode wiring 5 of the printed board 2 with a conductive adhesive 21. Further, in the capacitor element laminate 10, the electrode portions 12 b of the valve metal base 12 of each capacitor element 11 are laminated on the anode wiring 4 of the printed circuit board 2 and welded to the anode wiring 4 by laser light irradiation. . Note that the capacitor element laminate 10 fixed on the printed circuit board 2 is covered with a resin mold 22.

  Next, a method for manufacturing the above-described solid electrolytic capacitor 1 will be described.

  First, a valve metal foil having an enlarged outer surface is prepared and punched into a comb shape. Each comb tooth portion of the valve metal foil corresponds to the valve metal base 12 of the capacitor element 11. Subsequently, a resist layer 13 is formed on a predetermined portion on the outer surface of the comb tooth portion by screen printing. As a result, in the comb tooth portion, the portion on the distal end side from the resist layer 13 corresponds to the capacitor portion 12a, and the portion on the proximal end side from the resist layer 13 corresponds to the electrode portion 12b.

  Subsequently, the dielectric layer 15 is formed on the outer surface of the comb tooth portion by anodizing. Then, the solid electrolyte layer 16 is formed on the outer surface of the dielectric layer 15 so as not to exceed the resist layer 13 by chemical oxidation polymerization treatment or electrolytic oxidation polymerization treatment. Thereafter, an inner conductor layer 17 is formed on the outer surface of the solid electrolyte layer 16 by an immersion method (dip method) so as not to exceed the resist layer 13, and further, an outer conductor is formed on the outer surface of the inner conductor layer 17. Layer 18 is formed.

  Subsequently, four pieces of valve metal foil punched out in a comb shape are overlapped, and the outer conductor layers 18 and 18 of the comb tooth portions adjacent to each other in the stacking direction are bonded to each other by the conductive adhesive 21. And the comb-tooth part is cut out from the laminated valve metal foil, and the capacitor | condenser element laminated body 10 is obtained.

  Subsequently, the capacitor element laminate 10 is fixed on the printed circuit board 2. Specifically, the outer conductor layer 18 of the lowermost capacitor element 11 is bonded to the cathode wiring 5 of the printed circuit board 2 by the conductive adhesive 21, and the electrode portion 12 b of the valve metal base 12 of each capacitor element 11 is attached. It is laminated on the anode wiring 4 of the printed circuit board 2 and welded to the anode wiring 4 by laser light irradiation.

  Finally, the resin mold 22 is formed by casting mold, injection or transformer mold, and the solid electrolytic capacitor 1 is completed.

  Next, the immersion method for forming the inner conductor layer 17 on the outer surface of the solid electrolyte layer 16 will be described in more detail.

  First, as shown in FIG. 3, a paste tank 26 storing a carbon paste (conductive paste) 25 is prepared. The carbon paste 25 is a mixture of carbon particles, a resin, and a solvent, and has a viscosity of, for example, 200 mPa · s or less.

  Subsequently, the valve metal foil 28 having a plurality of comb tooth portions (element intermediate bodies) 27 on which the resist layer 13, the dielectric layer 15, and the solid electrolyte layer 16 are formed is lowered, and the resist layer 13 is formed in each comb tooth portion 27. Each comb tooth portion 27 is immersed in the carbon paste 25 in the paste tank 26 so that the carbon paste 25 is applied to a predetermined portion 27a on the tip side from the upper end 13a. The carbon paste 25 applied to the predetermined portion 27 a of the comb tooth portion 27 becomes the inner conductor layer 17.

  However, when the familiarity between the carbon paste 25 and the comb tooth portion 27 is poor, the surface 25 a of the carbon paste 25 is driven to the comb tooth portion 27. In particular, the surface 25a of the carbon paste 25 is easy to follow the surface (main surface) 27b and the back surface (main surface) 27c of the comb tooth portion 27, and as shown in FIG. A concave undulation centering on the comb tooth portion 27 occurs in 25a. Due to the concave undulation, the carbon paste 25 does not reach the upper end 13a of the resist layer 13.

  Therefore, as shown in FIG. 4B, the valve metal foil 28 is swung only once in a direction orthogonal to the front surface 27b and the back surface 27c of the comb tooth portion 27. Thereby, the fluidity of the carbon paste 25 around the comb tooth portion 27 is enhanced, and the undulation generated on the surface 25a of the carbon paste 25 is suppressed as shown in FIG. 25a is flattened. Then, the comb tooth portion 27 is surely immersed in the carbon paste 25 up to the upper end 13 a of the resist layer 13.

  As described above, in the method of manufacturing the solid electrolytic capacitor 1 described above, the undulation of the surface 25 a of the carbon paste 25 can be suppressed, and the predetermined portion 27 a of each comb tooth portion 27 can be surely immersed in the carbon paste 25. . Further, since the surface 25a of the carbon paste 25 easily follows the front surface 27b and the back surface 27c of the comb tooth portion 27, the valve metal foil 28 is swung in a direction orthogonal to the front surface 27b and the back surface 27c of the comb tooth portion 27. By positively contacting the predetermined portion 27a of the comb tooth portion 27 with the carbon paste 25, the surface 25a of the carbon paste 25 can be flattened reliably and easily. Accordingly, the carbon paste 25 can be applied to the predetermined portion 27a of the comb tooth portion 27 with high accuracy. As a result, the frequency characteristic of the capacity of the solid electrolytic capacitor 1 can be improved, and consequently the yield of the solid electrolytic capacitor 1 can be improved.

  The present invention is not limited to the embodiment described above.

  For example, in the above embodiment, the solid electrolytic capacitor 1 has the four-layer capacitor element 11, but is not limited thereto. In the present invention, the solid electrolytic capacitor may have one layer or a plurality of layers of capacitor elements other than four layers.

  In the above embodiment, the valve metal foil 28 having a plurality of comb teeth portions 27 is swung in the dipping method for forming the inner conductor layer 17 on the outer surface of the solid electrolyte layer 16, but the present invention is not limited to this. Instead, the valve metal foil 28 may be swung in a dipping method for forming the outer conductor layer 18 on the outer surface of the inner conductor layer 17. In this case, the comb tooth portion on which the resist layer 13, the dielectric layer 15, the solid electrolyte layer 16, and the inner conductor layer 17 are formed becomes an element intermediate. Further, the swinging is not limited to the valve metal foil 28, and may be the paste tank 26, or both the valve metal foil 28 and the paste tank 26.

  Moreover, in the said embodiment, although the valve metal foil 28 was rock | swiveled only once in the direction orthogonal to the surface 27b and the back surface 27c of the comb-tooth part 27, it is not limited to this. In the present invention, the swinging direction does not necessarily have to be a direction orthogonal to the front surface 27b and the back surface 27c of the comb tooth portion 27, and the swinging may be one or more reciprocating movements, There may be. Further, the rocking may be rocking so as to draw a circle.

  Examples of the present invention will be described below.

  First, an aluminum valve metal foil having an enlarged outer surface was prepared, and punched into a comb shape to form six rectangular comb teeth of 3.5 mm × 6.5 mm. And the resist layer was formed in the predetermined part in the outer surface of a comb-tooth part by screen printing.

  Subsequently, after a predetermined portion of the valve metal foil is immersed in an aqueous solution of ammonium adipate as a chemical conversion solution, a voltage of 6 V is applied to the valve metal foil to advance an anodic oxidation reaction, and a dielectric made of aluminum oxide The layer was formed on the surface layer of the valve metal foil.

  Subsequently, a mixed solution consisting of 0.9 g of 3,4-ethylenedioxythiophene (BAYTRONM manufactured by Bayel), 10.81 g of iron paratoluenesulfonate (BAYTRON CB 50 manufactured by Bayel) and 2.63 g of butanol was prepared. . Then, a predetermined portion of the valve metal foil was immersed in this mixed solution and pulled up, and after heat treatment in a furnace at a temperature of 150 ° C. for about 5 minutes, it was washed with water and dried. This process was repeated several times to form a solid electrolyte layer made of 3,4-ethylenedioxythiophene on the outer surface of the dielectric layer.

  Subsequently, a paste tank in which a carbon paste with a viscosity of 100 mPa · s is stored is prepared, and the carbon paste in the paste tank is applied to the outer surface of the solid electrolyte layer by an immersion method, and an inner conductor layer having a thickness of about 3 μm is applied. Formed. At this time, the valve metal foil was swung only once in a direction orthogonal to the front and back surfaces of the comb tooth portion while the comb tooth portion was immersed in the carbon paste. Furthermore, a paste tank storing silver paste was prepared, and the silver paste in the paste tank was applied to the outer surface of the inner conductor layer by a dipping method to form an outer conductor layer having a thickness of about 20 μm.

  Subsequently, the comb tooth portion on which the dielectric layer, the solid electrolyte layer, the inner conductor layer, and the outer conductor layer were formed was cut from the valve metal foil to obtain a capacitor element. Then, after connecting the iron anode lead and cathode lead to the capacitor element, the capacitor element is covered with epoxy resin so that the anode lead and cathode lead are partially exposed, and a resin mold is formed to complete the solid electrolytic capacitor. It was.

  Here, the solid electrolytic capacitor according to Example 1 described above manufactured by swinging the valve metal foil when the comb tooth portion was immersed in the carbon paste in the paste tank, and the paste tank instead of the valve metal foil was shaken. 100 of each of the solid electrolytic capacitor according to Example 2 manufactured by moving and the solid electrolytic capacitor according to the comparative example manufactured without swinging any of the paste tank and the valve metal foil, up to a predetermined portion. It was visually determined whether or not the paste was adhered. As a result, the solid electrolytic capacitor according to the comparative example was 71% within the standard range, whereas the solid electrolytic capacitor according to Example 1 was 94% within the standard range. In the solid electrolytic capacitor according to Example 2, 96% was within the standard range. From this result, the effect of the manufacturing method of the solid electrolytic capacitor according to the present invention that the yield of the solid electrolytic capacitor can be improved was confirmed.

It is sectional drawing of the solid electrolytic capacitor manufactured by one Embodiment of the manufacturing method of the solid electrolytic capacitor which concerns on this invention. It is an expanded sectional view of the capacitor | condenser element of the solid electrolytic capacitor shown by FIG. It is a figure which shows the one part process of one Embodiment of the manufacturing method of the solid electrolytic capacitor which concerns on this invention. FIG. 4 is a sectional view taken along line IV-IV shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid electrolytic capacitor, 12 ... Valve metal base | substrate, 15 ... Dielectric layer, 16 ... Solid electrolyte layer, 25 ... Carbon paste (electroconductive paste), 26 ... Paste tank, 27 ... Comb tooth part (element intermediate body), 27a ... predetermined portion, 27b ... front surface (main surface), 27b ... rear surface (main surface).

Claims (2)

A conductive paste adheres to a predetermined portion of an element intermediate comprising a valve metal substrate, a dielectric layer formed on the valve metal substrate, and a solid electrolyte layer formed on the dielectric layer. A method of manufacturing a solid electrolytic capacitor including a step of immersing in the conductive paste,
In the step of immersing the element intermediate in the conductive paste, at least one of the element intermediate and the paste tank storing the conductive paste in a state where the element intermediate is immersed in the conductive paste. A method of manufacturing a solid electrolytic capacitor, wherein The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein a direction in which at least one of the element intermediate and the paste tank is swung is a direction intersecting a main surface of the element intermediate.

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