JP2004207686A - Chip-type solid-state electrolytic capacitor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method at a low cost for a chip-type solid-state electrolytic capacitor having a low ESR and mass storage by using the existing facilities without modifications as much as possible. <P>SOLUTION: Two capacitor elements 110, 120 having solid electrolytes are piled on the upper and lower sides arranging the respective anode lead rods 112, 122 thereof in the same direction. Each of anode lead rods 112, 122 are welded to each surface of an anode lead frame 130 via electric conductive spacers 161, 162 and therewith a cathode lead frame 140 is arranged between cathode extraction layers 118, 128 of the respective capacitor elements 110, 120 via a conductive adhesive material 170. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a chip-type solid electrolytic capacitor and a method of manufacturing the same, and more particularly, to a chip-type solid electrolytic capacitor having a structure capable of significantly reducing ESR (equivalent series resistance).

  First, a typical conventional example of a chip-type solid electrolytic capacitor will be described with reference to FIG. In the chip-type solid electrolytic capacitor 1, a capacitor element 4 is mounted between an anode lead frame 2 and a cathode lead frame 3, and an exterior body 5 made of, for example, an epoxy-based heat-resistant synthetic resin is molded therearound. The ends of the lead frames 2 and 3 protruding from the body 5 are bent in a crab-foot shape along the bottom surface of the exterior body 5 to form legs 2a and 3a for a circuit board (not shown). In some cases, the legs 2a and 3a may be bent toward the outside of the exterior body 5 instead of the bottom side.

  Capacitor element 4 includes an anode body 4a obtained by sintering powder of valve metal such as tantalum, aluminum, niobium, or titanium into a columnar or prismatic shape, and has an anode lead rod 6 on one end surface. It has been planted. Usually, the anode lead rod 6 is made of the same material as the anode body 4a.

  A dielectric oxide film 4b is formed on the peripheral surface of the anode body 4a by, for example, electrolytic oxidation treatment in a phosphoric acid aqueous solution, and an inorganic oxide or a conductive organic compound represented by, for example, manganese dioxide (for example; A cathode layer 4c made of a solid electrolyte such as polypyrrole, polythiophene) is formed.

  It should be noted that a washer 6a is inserted through the base of the anode lead bar 6 to prevent the solid electrolyte from crawling up on the anode lead bar 6 when the cathode layer 4c is formed. On the cathode layer 4c, a cathode extraction layer 4f including a carbon layer 4d and a silver paste layer 4e is formed.

  The anode lead bar 6 is attached to the anode lead frame 2 by welding, and the cathode lead layer 4f is attached to the cathode lead frame 3 via a conductive adhesive 7 such as adhesive silver. Normally, the end of the cathode lead frame 3 (the end opposite to the leg 3a) is formed from the bottom of the capacitor element 4 (the end face on the side opposite to the anode lead rod) in order to increase the bonding area to the capacitor element 4. An element receiving portion 3b is formed substantially in an L-shape along the surface.

  By the way, with the recent miniaturization and higher frequency of electronic devices, chip-type solid electrolytic capacitors used for them are required to have a low ESR and a large capacity especially in a high frequency region.

  It is known to use a conductive polymer such as polypyrrole, polythiophene, polyaniline, or polyfuran as a solid electrolyte as one of the techniques for reducing the ESR, but at present, a solid electrolyte using manganese dioxide is used. There is a problem that it is not easily accepted by the market because the cost is considerably higher than that of.

  In order to increase the capacity, for example, to obtain a capacity required for backup of a CPU, a plurality of (for example, about 5 to 10) chip-type solid electrolytic capacitors are connected in parallel to a circuit board. Since it is necessary to mount the device, the occupied space required for the mounting is widened, which hinders miniaturization of the device.

  As another method for reducing the ESR, there is a method of connecting a plurality of capacitors in parallel. Therefore, some proposals have been made to apply this method to achieve a low ESR and also to realize a large capacity and a small mounting space (see Patent Documents 1 to 3).

  That is, in Patent Document 1, a plurality of chip-type solid electrolytic capacitors having substantially the same bottom size are stacked in contact with each other, and the corresponding terminal portions are electrically connected in parallel by welding to form one product.

  In Patent Document 2, a plurality of unit capacitor bodies (capacitor elements) are stacked so that their cathode lead layers are in contact with each other, one of the cathode lead layers is connected to a cathode lead frame, and each anode lead rod is connected. After forming and welding each of them to the anode lead frame, an exterior body made of synthetic resin is formed around a plurality of unit capacitor bodies.

  Also, in Patent Document 3, two chip-type solid electrolytic capacitors are stacked, and the corresponding lead frames are connected to each other by welding to obtain a stacked capacitor.

JP-A-11-26304 JP 2001-284192 A JP-A-2002-280263

  Patent Literature 1 and Patent Literature 3 each have a structure in which, for example, two chip-type solid electrolytic capacitors that are commonly used as products are stacked, so that the configuration looks simple at first glance. A terminal connecting component for connecting the terminals of the solid electrolytic capacitor is required separately. Therefore, in addition to the existing production equipment, a terminal part mounting jig and a welding machine must be newly introduced, and the number of processes increases accordingly.

  Further, in Patent Document 3, the anode lead frame and the cathode lead frame of the chip-type solid electrolytic capacitor disposed above are lengthened, and they are bent so that the corresponding anode lead of the chip-type solid electrolytic capacitor disposed below is bent. Since the connection is made to the frame and the cathode lead frame, no separate terminal connection component is required as in Patent Document 1, but this also has the following problems.

  That is, since the length of the lead frame used is different between the chip-type solid electrolytic capacitor arranged above and the chip-type solid electrolytic capacitor arranged below, the production line is divided into two systems. Therefore, the burden on equipment and the number of processes increase.

  Further, in order to weld the lead frame of the chip-type solid electrolytic capacitor arranged above to the lead frame of the chip-type solid electrolytic capacitor arranged below, it is necessary to prepare a new welding machine as in Patent Document 1. . Also, in any of Patent Documents 1 and 3, since the chip type solid electrolytic capacitors having the outer package are stacked, the bulk is inevitably increased.

  On the other hand, in Patent Literature 2, for example, two capacitor elements are stacked and an outer package is formed around the two capacitor elements, so that the external appearance looks like one chip-type solid electrolytic capacitor. , 3 and the existing lead frame can be used as it is.

  However, when welding the anode lead rod of the capacitor element to the anode lead frame, the anode lead rod of the capacitor element arranged above is made longer than the anode lead rod of the capacitor element arranged below, and moreover, The tip must be L-shaped. Therefore, a new forming process is required, and the existing equipment cannot be used.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to use a chip-type solid electrolytic capacitor having a low ESR and a large capacity at a low cost by using existing facilities as much as possible. To be able to be manufactured.

  In order to achieve the above object, the first invention of the present application is directed to a first aspect of the present invention, wherein a cathode layer is formed on a peripheral surface of an anode body made of a valve metal having an anode lead rod implanted on one end surface via a dielectric film. A capacitor element having a cathode lead layer containing silver paste thereon, an anode lead frame welded to the anode lead rod and a cathode lead frame connected to the cathode lead layer via a conductive adhesive, and the capacitor element And an end body of the anode lead frame and the cathode lead frame protruding from the exterior body are bent toward the bottom surface side of the exterior body. A chip-type solid electrolytic capacitor, comprising at least two capacitor elements, wherein each of the capacitor elements has the same anode lead rod in the outer package. Each of the anode lead bars is welded to each surface of the anode lead frame via a conductive spacer, and the cathode lead frame is connected to the cathode lead layer of each of the capacitor elements. It is characterized by being arranged between them.

  According to this configuration, one of the two capacitor elements is disposed above and the other is disposed below the anode lead frame and the cathode lead frame. By simply adding new components, a chip-type solid electrolytic capacitor having a low ESR and a large capacity can be obtained by using the existing production equipment for chip-type solid electrolytic capacitors as they are. Also, by forming a conductive spacer between the anode lead bar and the anode lead frame, it is not necessary to form the anode lead bar.

  In the present invention, it is preferable that the two capacitor elements have substantially the same shape and the same size. According to this, the two capacitor elements are almost completely separated by the anode lead frame and the cathode lead frame. Since the arrangement is symmetrical, there is almost no difference in characteristics between the capacitor elements arranged above and below, and the matching of the characteristics is excellent. Therefore, the ESR can be further reduced, and the current does not flow to one of the capacitor elements, so that no short circuit occurs.

  In order to reduce the height, it is preferable that both of the two capacitor elements are flat prismatic bodies. Further, the conductive spacer welded to the upper surface side of the anode lead frame, and the conductive spacer welded to the lower surface side of the anode lead frame are positioned so that they do not overlap in the vertical direction. Preferably, the positions are relatively shifted, and according to this, the anode lead can be welded to the anode lead frame by a resistance welding method which is inexpensive in terms of equipment.

  As the conductive spacer, one formed in a rod-like body such as a round bar or a square bar is used, and the conductive spacer is disposed along the width direction of the anode lead frame. The length of the conductive spacer does not need to be the entire length of the anode lead frame, and the length of the conductive spacer is equal to the width of the anode lead frame. At least 1/2 or more. Preferably, the conductive spacer is made of the same material as the anode lead rod in order to reduce the contact resistance with the anode lead rod.

  According to the present invention, the cathode lead frame is disposed between the cathode lead layers of the respective capacitor elements with a conductive adhesive interposed therebetween. A first bent piece bent along the side surface of the one capacitor element is continuously provided on the side edge of the capacitor element, and is bent along the side surface of the other capacitor element on the other side edge of the cathode lead frame. It is preferable that the second bent pieces are continuously provided.

  In the case where the exterior body has a box shape including a top surface and a bottom surface parallel to each other, if the capacitor element is inclined, the cathode extraction layer side may appear on the surface of the exterior body, resulting in a defective product. In order to prevent this, the inclination angle of the axis of the anode lead rod is preferably less than ± 5 ° with respect to the reference plane, with the top and bottom surfaces as the reference plane, which is also included in the features of the present invention. It is.

  The present invention includes an embodiment in which the number of capacitor elements is four for lowering the ESR. That is, it comprises first to fourth four capacitor elements having the same shape and the same size, and the respective capacitor elements are vertically stacked in the outer casing with the anode lead rod in the same direction, and the upper two Each anode lead rod of the second capacitor element is welded to one surface of the anode lead frame via the conductive spacer, and the cathode lead layers of the first and second capacitor elements are fixed to each other by a predetermined distance. The anode lead bars of the lower two third and fourth capacitor elements are electrically connected to each other via conductive bonding means, and are each welded to the other surface of the anode lead frame via the conductive spacer. The cathode lead-out layers of the third and fourth capacitor elements are electrically connected to each other via a predetermined conductive bonding means; By chromatography arm is disposed between the respective cathodes lead layer of the second capacitor element and the third capacitor element located inside, it can be more low ESR.

  In the above aspect, the first capacitor element and the fourth capacitor element located on the outside are welded to the anode lead frame via the large-diameter conductive spacer, respectively, and the second capacitor element located on the inside is provided. And the third capacitor element are preferably welded to the anode lead frame via the small-diameter conductive spacer.

  The ESR can be further reduced by using a conductive organic compound as the solid electrolyte contained in the cathode layer. Therefore, the most preferable embodiment for lowering the ESR is to use four capacitor elements and to use a solid electrolyte made of polypyrrole by electrolytic polymerization or polythiophene by chemical polymerization.

  The second invention of the present application relates to a method for manufacturing a chip-type solid electrolytic capacitor as defined in the first invention, and in particular, connects the anode lead rod through the conductive spacer by a resistance welding method which is inexpensive in terms of equipment. It defines a preferred mode for welding to the anode lead frame.

  That is, in the second invention of the present application, the first and second two capacitor elements, both of the same shape and the same size, and the anode lead frame and the cathode lead frame are both formed in the same shape and the same size rod-shaped body. First and second conductive spacers are prepared, and each anode lead rod of the capacitor element is welded to the anode lead frame via the conductive spacer by a resistance welding method. After the first conductive spacer is welded to the surface side, the second conductive spacer is attached to the other surface of the anode lead frame from the welding position of the first conductive spacer to the outer diameter of the conductive spacer. The anode lead frame of the first capacitor element and the anode lead rod of the second capacitor element are welded to each other at a position closer to the leg side of the anode lead frame at a distance of at least one minute. In addition, after shortening by at least the outer diameter of the conductive spacer and welding on the first conductive spacer, the anode lead rod of the second capacitor element is welded on the second conductive spacer. And

  In the second invention of the present application, the anode lead rod of the first capacitor element is welded onto the first conductive spacer in order to make the chip-type solid electrolytic capacitor defined in the first invention into a final product form. As a result, the cathode lead layer of the first capacitor element is connected to one surface of the cathode lead frame via a conductive adhesive, and the anode lead bar of the second capacitor element is connected to the second conductive spacer. After welding, the cathode lead layer of the second capacitor element is connected to the other surface of the cathode lead frame via a conductive adhesive, and then heat-resistant around the first and second capacitor elements. Forming an exterior body made of a conductive synthetic resin, and bending each end of the anode lead frame and the cathode lead frame projecting from the exterior body toward a bottom surface side of the exterior body. Each step of the legs Te is further included.

  According to the present invention, two or four capacitor elements having a solid electrolyte are vertically stacked with their respective anode lead bars in the same direction, and each of the anode lead bars is connected to each of the anode lead frames via conductive spacers. Welded to each surface and the cathode lead frame is placed between the cathode lead layers of each capacitor element via a conductive adhesive, resulting in a low-ESR and large-capacity chip-type solid electrolytic capacitor. It can be manufactured at low cost by using existing equipment as much as possible.

  In addition, by making the length of the anode lead rod of one capacitor element shorter than the anode lead rod of the other capacitor element, each anode lead rod is connected to each anode lead frame with a resistance welding machine that is inexpensive in terms of equipment. Can be welded to the surface.

  Next, some embodiments of the present invention will be described with reference to FIGS. 1 to 12, and the present invention will be described in more detail. However, the present invention is not limited thereto.

  FIG. 1 shows a cross section of a chip-type solid electrolytic capacitor 100 according to a first embodiment of the present invention. The chip-type solid electrolytic capacitor 100 includes first and second two capacitor elements 110 and 120. The first capacitor element 110 and the second capacitor element 120 are mounted vertically symmetrically with respect to the anode lead frame 130 and the cathode lead frame 140, and an outer body 150 made of a heat-resistant synthetic resin is formed around them. .

  In this example, the first capacitor element 110 and the second capacitor element 120 have the same configuration including the shape, size, and characteristics. Therefore, the configuration of one of the first capacitor elements 110 will be described, and the reference number of the other second capacitor element 120 will be described in parentheses.

  In the present invention, the capacitor element 110 (120) may have the configuration described in the conventional example. That is, an anode body 111 (121) obtained by sintering valve metal powder into a columnar or prismatic shape is provided, and an anode lead rod 112 (122) is implanted on one end surface thereof. Examples of the valve metal include tantalum, aluminum, niobium, and titanium. The anode lead rod 112 (122) is preferably made of the same material as the anode body 111 (121).

  A dielectric oxide film 113 (123) is formed on the peripheral surface of the anode body 111 (121) by, for example, electrolytic oxidation treatment in a phosphoric acid aqueous solution, and a cathode layer 114 (124) made of a solid electrolyte is formed thereon. Have been. The solid electrolyte constituting the cathode layer 114 (124) may be any of inorganic oxides typified by manganese dioxide or conductive organic compounds such as polypyrrole by electrolytic polymerization and polythiophene by chemical polymerization. Is preferably an inorganic oxide which can be formed at low cost, for example, manganese dioxide.

  At the base of the anode lead rod 112 (122), a washer 115 (125) for preventing the solid electrolyte from crawling up on the anode lead rod 112 (122) when forming the cathode layer 114 (124). ) Is inserted. On the cathode layer 114 (124), a cathode extraction layer 118 (128) including a carbon layer 116 (126) and a silver paste layer 117 (127) is formed.

  The shape of the capacitor element 110 (120) may be any of a columnar body and a prismatic body. However, in order to reduce the mounting height of the chip-type solid electrolytic capacitor 100 on a circuit board (not shown), It is preferably a body.

  As the anode lead frame 130 and the cathode lead frame 140, a conventionally used lead frame made of, for example, stainless steel can be used as it is without changing its shape or the like.

  The anode lead rod 112 of the first capacitor element 110 is welded to one surface (upper surface in this example) of the anode lead frame 130, and the anode lead rod 122 of the second capacitor element 120 is welded to the other surface of the anode lead frame 130. (In this example, the lower surface is welded.) In the present invention, in order to eliminate the need for forming (bending) the anode lead bars 112 and 122 in the present invention, rod-shaped conductive spacers 161 and 162 are newly provided. Used for

  That is, the anode lead rod 112 of the first capacitor element 110 and the anode lead rod 122 of the second capacitor element 120 are welded to the anode lead frame 130 via the conductive spacers 161 and 162 in a state where they are straightened, respectively. You.

  The conductive spacers 161 and 162 are not particularly limited as long as they can be welded, but are preferably made of the same material as the anode lead bars 112 and 122 in order to reduce the contact resistance. Also, the shape may be a round bar, a square bar or the like except for the triangular bar.

  The cathode lead frame 140 is disposed between the cathode lead-out layer 118 of the first capacitor element 110 and the cathode lead-out layer 128 of the second capacitor element 120, and these layers are electrically and electrically connected via the conductive adhesive 170. Connected mechanically. As the conductive adhesive 170, for example, adhesive silver is used.

  The first capacitor element 110 and the second capacitor element 120 are attached to the anode lead frame 130 and the cathode lead frame 140 in a straightened state, as shown by the imaginary line in FIG. Then, an outer package 150 made of, for example, epoxy resin is formed around each of the capacitor elements 110 and 120 by a transfer molding method.

  After forming the exterior body 150, the portions of the anode lead frame 130 and the cathode lead frame 140 projecting from the exterior body 150 are cut to a predetermined length, and the ends thereof are bent along the bottom surface of the exterior body 150, These are legs 131 and 141 for a circuit board (not shown). In this example, the legs 131 and 141 are bent in a crab-foot shape so as to be located within the bottom surface of the exterior body 150, but may be bent in the opposite direction.

  According to this chip-type solid electrolytic capacitor 100, since the first and second capacitor elements 110 and 120 are connected in parallel, the capacitor element shown as a conventional example in FIG. In comparison, the ESR can be reduced to about half.

  In addition, since the two capacitor elements 110 and 120 are arranged almost completely symmetrically in the vertical direction with the anode lead frame 130 and the cathode lead frame 140 as boundaries, there is a difference in characteristics between the capacitor elements 110 and 120. With little conformity and excellent property matching. Therefore, the ESR can be further reduced, and the current does not flow to one of the capacitor elements, so that no short circuit occurs.

  In addition, since the cathode lead frame 140 is arranged between the cathode lead layers 118 and 128 of the capacitor elements 110 and 120, the cathode lead frame 140 has a substantially L shape as in the above-described conventional example. There is no need to form the bent element receiving portion 3b (see FIG. 13).

  Therefore, the capacitor element can be made larger (about 8%) by the absence of the element receiving portion 3b. This means that when the size of the capacitor element is the same as that of the related art, the size of the exterior body can be relatively reduced.

  The present invention includes a modification of the cathode lead frame 140 shown in FIG. FIG. 2 is a schematic view of the cathode lead frame 140 viewed from the right side of FIG. 1. According to this modification, one side edge of the cathode lead frame 140 is bent along the side surface of the first capacitor element 110. One bent piece 142 is continuously provided, and a second bent piece 143 bent along the side surface of the second capacitor element 120 is provided on the other side edge. By doing so, higher adhesive strength can be obtained.

  In this chip-type solid electrolytic capacitor 100, the only newly adopted components are the conductive spacers 161 and 162, and therefore, the capacitor can be manufactured using existing production equipment including a welding machine as it is.

  By the way, laser welding, resistance welding, ultrasonic welding, etc. can be applied to the welding between the anode lead and the lead frame. However, ultrasonic welding has a weaker adhesive force than laser welding and resistance welding, and furthermore, the capacitor element This is not preferable because the anodic oxide films 113 and 123 of 110 and 120 may be broken.

  In laser welding, a laser beam may be applied to a butt portion of a member to be welded. Therefore, as shown in FIG. 3, anode lead rods 112 and 122 of each of capacitor elements 110 and 120 have the same length and a conductive spacer. 161 and 162 can be arranged and welded in a position overlapping vertically.

  An example of the welding procedure will be described. First, after one conductive spacer 161 is welded to one surface of the anode lead frame 130, the anode lead frame 130 is turned 180 °, and the other conductive spacer 162 is connected to the anode lead frame 130. It is welded to the other surface of the lead frame 130.

  Next, the anode lead frame 130 is further inverted by 180 °, and the anode lead bar 112 of the first capacitor element 110 is welded to the conductive spacer 161 with one of the conductive spacers 161 facing upward. Is again inverted by 180 °, and the anode lead rod 122 of the second capacitor element 120 is welded to the conductive spacer 162 with the other conductive spacer 162 facing upward.

  After the conductive spacer 161 and the anode lead bar 112 of the first capacitor element 110 are sequentially welded on one surface of the anode lead frame 130, the anode lead frame 130 is turned 180 ° and the other surface is turned. Alternatively, the conductive spacer 162 and the anode lead rod 122 of the second capacitor element 120 may be sequentially welded.

  Since the laser welding machine is expensive, the resistance welding method is preferable from the viewpoint of burden on equipment costs. However, in the case of resistance welding, it is necessary to press the workpiece (work) with a pair of electrodes, so that welding cannot be performed with the arrangement of FIG. For this reason, in the present invention, resistance welding can be performed by the following measures.

  That is, as shown in FIG. 4, for example, the anode lead rod 112 of the first capacitor 110 is made shorter than the anode lead rod 122 of the second capacitor 120, and the positions of the conductive spacers 161 and 162 are also relatively reduced. Stagger. The dimension for shortening the anode lead rod 112 is at least the outer diameter dimension of the conductive spacer.

  Next, an example of a welding procedure in the case of the resistance welding method will be described with reference to FIGS. In each drawing, (a) is a front view of the welded portion as viewed from the near side of the drawing, and (b) is a left side view thereof. Further, a pair of upper and lower arrows shown in the figure are welding electrodes.

  First, as shown in FIG. 5, after a conductive spacer 161 is welded to one surface of the anode lead frame 130, the anode lead frame 130 is inverted by 180 °, and as shown in FIG. The conductive spacer 162 is welded to the other surface of the. The conductive spacers 161 and 162 are arranged along the width direction of the anode lead frame 130 (the direction orthogonal to the length direction of the anode lead frame).

  In this case, the conductive spacer 162 is shifted to the outside of the welding position of the conductive spacer 161 (to the left in the drawing, that is, the leg 131 side). In the case of resistance welding, a slight dent is formed in the nugget portion. In order to prevent the dent from overlapping with the welding position of the anode lead rod (the central portion of the conductive spacer), FIGS. As shown in FIG. 6B, it is preferable to shift the welding position of the conductive spacers 161 and 162 to the anode lead frame 130 to one side.

  Next, the anode lead frame 130 is turned again by 180 ° so that the conductive spacer 161 faces upward and the length dimension of the first capacitor element 110 is substantially at the center of the conductive spacer 161 as shown in FIG. Is welded to the shortened anode lead rod 112.

  Then, the anode lead frame 130 is again turned by 180 °, and the conductive spacer 162 is turned upward as shown in FIG. 8 so that the anode lead rod 122 of the second capacitor element 120 is placed almost at the center of the conductive spacer 162. To weld. At this time, since the anode lead rod 112 is shorter than the anode lead rod 122, the lower welding electrode can be pressed against the anode lead frame 130.

  At least until the outer package 150 is formed, the cathode lead frame 140 is integrated with the anode lead frame 130 via an outer frame (not shown). The cathode lead layer 118 of the element 110 is attached to the cathode lead frame 140 via the conductive adhesive 170, and the cathode lead layer 128 of the second capacitor element 120 becomes conductive when the anode lead rod 122 of FIG. 8 is welded. It is attached to the cathode lead frame 140 via the adhesive 170.

  The length of the conductive spacers 161 and 162 does not necessarily have to be the same as the width of the anode lead frame 130. As long as the anode lead bars 112 and 122 have a length enough to be located substantially at the center of the anode lead frame 130, that is, at least a length equal to or more than half the width of the anode lead frame 130, the anode lead frame 130 May be shorter than the width, and the amount of conductive spacers used can be reduced accordingly. FIG. 9 (a drawing corresponding to FIG. 8B) shows an example in which the length of the conductive spacers 161 and 162 is ２ of the width of the anode lead frame 130.

  When the anode lead bars 112 and 122 of the first capacitor element 110 and the second capacitor element 120 are welded to the respective surfaces of the anode lead frame 130 via the conductive spacers 161 and 162 as described above, each anode lead is Depending on the diameter of the rods 112 and 122 and the diameter of the conductive spacers 161 and 162, the capacitor elements 110 and 120 are inclined as shown by the dashed lines in FIG. 10, whereby the cathode extraction layers 118 and 128 of the capacitor elements 110 and 120 are covered. It may appear on the surface of the body 150 and become defective. In the present specification, this is referred to as an element output failure.

  This defective device appearance does not easily occur when the size of the outer package 150 is increased, but occurs because the size of the package 150 is restricted due to a demand for reduction in size and thickness. As an example, when the depth L1 of the capacitor elements 110 and 120 is 4.4 mm, the width W1 is 3.5 mm, and the height is 1.1 mm as shown in FIG. At the request, for example, it is designed in a box shape having a depth width L2 of 7.3 mm, a width W2 of 4.3 mm and a height of about 2.8 mm. In the case of a normal chip component, each of the upper surface 150a and the bottom surface 150b of the outer package 150 is parallel.

  Therefore, when the two capacitor elements 110 and 120 are stacked and accommodated in the outer casing 150 having such a size, even if the thickness of the cathode lead frame 140 is not included, the upper surface 150 a of the outer casing 150 and the first The thickness between the cathode lead layer 118 of the capacitor element 110 and the distance between the bottom surface 150b of the exterior body 150 and the cathode lead layer 128 of the second capacitor element 120 is 0.3 mm. Including the thickness, the thickness is further reduced to less than 0.3 mm.

  The chip-type solid electrolytic capacitors having the actual dimensions described above were actually produced by changing the wire diameters of the anode lead bars 112 and 122 and the conductive spacers 161 and 162. The incidence was examined, and the results are shown in Table 1. The inclination angle of the anode lead rods 112 and 122 is an angle θ with respect to a reference plane X parallel to the upper surface 150a and the bottom surface 150b of the exterior body 150, as shown in FIG. 10, + θ is an elevation angle, and −θ is a depression angle. .

  In Table 1 above, the wire diameter of the conductive spacers 161 and 162 is fixed at 0.3 mm, whereas the wire diameter of the anode lead rods 112 and 122 is changed from 0.2 to 1.0 mm in units of 0.1 mm. In this case, the wire diameters of the anode lead rods 112 and 122 are fixed at 0.3 mm, and the wire diameters of the conductive spacers 161 and 162 are 0.1 mm from 0.2 to 1.0 mm. 10 to 18 cases in which the number is changed in units are included, and the production number in each example is 1000 pieces.

  As can be seen from this, when the inclination angle θ of the anode lead rods 112, 122 becomes −5 °, −6 °, + 5 °, + 6 °, as in the examples of 1, 2, 8 to 11, 17, and 18, the element emerges. When the defect occurrence rate reaches about 6 to 20%, the inclination angle θ of the anode lead rods 112 and 122 is + 4 ° to −4 ° as in 3 to 7 examples and 12 to 16 examples. Indicates that the rate of occurrence of defective elements is reduced to 1% or less. Therefore, it is preferable that the inclination angle θ of the anode lead bars 112 and 122 be less than ± 5 ° with respect to the reference plane X.

  Next, a chip type solid electrolytic capacitor 200 according to a second embodiment of the present invention will be described with reference to FIG. The chip-type solid electrolytic capacitor 200 includes first to fourth four capacitor elements for further reducing the ESR. Each capacitor element may have the same configuration as the capacitor elements 110 and 120 of the first embodiment. However, in the second embodiment, the first capacitor element is 210, the second capacitor element is 220, and the third capacitor element is 230. , The fourth capacitor element is denoted by 240, and the anode lead rods of the respective capacitor elements are denoted by 211, 221, 231, 241.

  The first to fourth four capacitor elements 210, 220, 230, and 240 are vertically oriented with their anode lead rods facing 211, 221, 21, and 241 in the same direction, that is, toward the anode lead frame 130 side. The upper two first and second capacitor elements 210 and 220 are electrically and mechanically connected between their respective cathode lead layers by a conductive adhesive 251 such as adhesive silver.

  The lower two third and fourth capacitor elements 230 and 240 are also electrically and mechanically connected between their respective cathode lead layers by a conductive adhesive 252 such as adhesive silver. A cathode lead frame 140 is disposed between the second capacitor element 220 and the third capacitor element 230 located inside, and conductive adhesive such as adhesive silver is attached to each of the cathode lead layers as in the first embodiment. They are electrically and mechanically connected via a member 170 (see FIG. 1).

  As for the anode lead rods, the second capacitor element 220 and the third capacitor element 230 located inside correspond to the first and second capacitor elements 110 and 120 in the first embodiment, respectively, so that their respective anode lead rods 221 are provided. , 231 are welded to the upper and lower surfaces of anode lead frame 130 via conductive spacers 161 and 162 of small diameter, respectively.

  On the other hand, the anode lead rods 211 and 241 of the first capacitor element 210 and the fourth capacitor element 240 located outside are connected to the upper and lower surfaces of the anode lead frame 130 via the large-diameter conductive spacers 163 and 164, respectively. Respectively. Also in this example, the wire diameters of the conductive spacers 161 to 164 are selected such that the anode lead rods 211, 221, 231, and 241 do not tilt ± 5 ° or more with respect to the upper surface 150a and the bottom surface 150b of the exterior body 150. Is preferred.

  In this way, the anode lead bars 211 and 221 of the first and second capacitor elements 210 and 220 are connected to the upper surface of the anode lead frame 130, and the anode lead bars 231 and 231 of the third and fourth capacitor elements 230 and 240 are connected. By connecting 241 to the lower surface of the anode lead frame 130, the four capacitor elements 210, 220, 230, and 240 are connected in parallel between the anode lead frame 130 and the cathode lead frame 140, so that the ESR is further reduced. can do.

  As a modification, the anode lead rod 211 of the first capacitor element 210 is welded to the anode lead rod 221 of the second capacitor element 220 via a conductive spacer (not shown). May be welded to the anode lead rod 231 of the third capacitor element 230 via a conductive spacer (not shown).

  Actually, the chip-type solid electrolytic capacitors according to the first embodiment (an example including two capacitor elements) and the second embodiment (an example including four capacitor elements) of the present invention, and the structure shown in FIG. A chip-type solid electrolytic capacitor (comparative example) was manufactured, and the ESR at 100 kHz was measured. The following results were obtained. In each of the examples and comparative examples, the solid electrolyte was manganese dioxide.

[Rated 10V, 100μF]
ESR of the first embodiment (two elements): 26 mΩ
ESR of the second embodiment (4 elements); 12 mΩ
ESR of comparative example (one element); 55 mΩ
[Rated 10V, 150μF]
ESR of the first embodiment (two elements); 21 mΩ
ESR of the second embodiment (4 elements); 10 mΩ
ESR of comparative example (one element): 45 mΩ
[Rating 6.3V, 220μF]
ESR of the first embodiment (two elements): 18 mΩ
ESR of the second embodiment (4 elements); 8 mΩ
ESR of comparative example (one element): 40 mΩ
[Rating 6.3V, 330μF]
ESR of the first embodiment (two elements); 17 mΩ
ESR of the second embodiment (4 elements); 7 mΩ
ESR of comparative example (one element): 38 mΩ

  Further, in order to reduce the ESR, the solid electrolyte of the capacitor element may be a conductive organic compound (conductive polymer) such as polypyrrole formed by electrolytic polymerization and polythiophene formed by chemical polymerization. For a method of forming the conductive organic compound, see, for example, JP-A-3-214719.

  In order to verify how much the ESR is reduced by the conductive organic compound, the solid electrolytes of the capacitor elements of the first embodiment, the second embodiment, and the comparative example were used as polypyrrole and polythiophene, respectively. As a result, the following results were obtained. In each case, the rating is 6.3V330μF.

First embodiment (two elements)
ESR with polypyrrole; 8 mΩ
ESR with polythiophene; 8mΩ
Second embodiment (4 elements)
ESR with polypyrrole; 3 mΩ
ESR with polythiophene; 3mΩ
Comparative example (1 element)
ESR with polypyrrole; 18 mΩ
ESR with polythiophene; 19 mΩ

  A low-ESR, large-capacity chip-type solid electrolytic capacitor can be manufactured at low cost using existing equipment as much as possible, and can be made even smaller and thinner. It is possible to provide a chip-type solid electrolytic capacitor suitable for use and in-vehicle equipment.

FIG. 2 is a cross-sectional view schematically showing the internal structure of the chip-type solid electrolytic capacitor according to the first embodiment of the present invention. FIG. 9 is a side view showing a modified example of the cathode lead frame used in the chip-type solid electrolytic capacitor. FIG. 4 is a front view of a welded portion for explaining an example of a procedure for welding the anode lead rod by laser welding in the chip-type solid electrolytic capacitor. FIG. 4 is a front view of a welded portion showing a configuration in which the anode lead rod can be welded by a resistance welding method in the chip-type solid electrolytic capacitor. The (a) front view which shows an example of the procedure (1st process) of welding the said anode lead bar by a resistance welding method, (b) The left view. The (a) front view which shows an example of the procedure (2nd process) which welds the said anode lead bar by a resistance welding method, (b) The left view. The (a) front view which shows an example of the procedure (3rd process) of welding the said anode lead bar by a resistance welding method, (b) The left view. The (a) front view and (b) the left side view which show an example of the procedure (4th process) which welds the said anode lead bar by a resistance welding method. FIG. 9 is a left side view corresponding to FIG. 8B showing a modified example of a welded portion by a resistance welding method. FIG. 3 is a cross-sectional view schematically showing the internal structure of the chip-type solid electrolytic capacitor according to the first embodiment. FIG. 3 is a perspective view showing the capacitor element of the chip-type solid electrolytic capacitor according to the first embodiment and an exterior body in comparison. FIG. 6 is a cross-sectional view schematically illustrating an internal structure of a chip-type solid electrolytic capacitor according to a second embodiment of the present invention. Sectional drawing which shows typically the internal structure of the conventional typical chip type solid electrolytic capacitor.

Explanation of reference numerals

100, 200 Chip type solid electrolytic capacitor 110, 120, 210, 220, 230, 240 Capacitor element 111, 121 Anode body 112, 122, 211, 21, 21, 23, 241 Anode lead rod 113, 123 Anodic oxide film 114, 124 Cathode Layers 115, 125 Washers 116, 126 for preventing solid electrolyte from rising 116, 126 Carbon layers 117, 127 Silver paste layers 118, 128 Cathode extraction layer 130 Anode lead frame 140 Cathode lead frame 131, 141 Legs 142, 143 Folded pieces 150 Exterior body 161,162,163,164 Conductive spacer 170,251,252 Conductive adhesive

Claims (13)

A capacitor element having a cathode layer formed on a peripheral surface of an anode body made of a valve metal having an anode lead rod implanted on one end surface via a dielectric film, and having a cathode extraction layer containing silver paste on the cathode layer; An anode lead frame welded to the anode lead rod, a cathode lead frame connected to the cathode lead-out layer via a conductive adhesive, and an outer package made of a heat-resistant synthetic resin formed around the capacitor element In the chip solid electrolytic capacitor wherein each end of the anode lead frame and the cathode lead frame projecting from the exterior body is bent toward the bottom side of the exterior body,
At least two capacitor elements are provided, and the respective capacitor elements are vertically stacked with the anode lead bars in the same direction within the outer package, and each of the anode lead rods is a respective one of the anode lead frames via a conductive spacer. A chip-type solid electrolytic capacitor, which is welded to a surface thereof, and wherein the cathode lead frame is disposed between the cathode lead layers of the capacitor elements.   The chip-type solid electrolytic capacitor according to claim 1, wherein each of the capacitor elements has substantially the same shape and size.   The chip-type solid electrolytic capacitor according to claim 1, wherein each of the capacitor elements is a flat prism.   The conductive spacers to be welded to the upper surface of the anode lead frame and the conductive spacers to be welded to the lower surface of the anode lead frame are positioned so that they do not overlap in the vertical direction. The chip-type solid electrolytic capacitor according to any one of claims 1 to 3, which is relatively shifted.   The chip-type solid electrolytic capacitor according to any one of claims 1 to 4, wherein the conductive spacer is formed of a rod-shaped body having a length of at least half the width of the anode lead frame.   The chip-type solid electrolytic capacitor according to any one of claims 1 to 5, wherein the conductive spacer is made of the same material as the anode lead rod.   On one side edge of the cathode lead frame, a first bent piece bent along the side surface of the one capacitor element is continuously provided, and on the other side edge of the cathode lead frame, 7. The chip-type solid electrolytic capacitor according to claim 1, wherein a second bent piece bent along a side surface of the other capacitor element is continuously provided.   The exterior body has a box shape including an upper surface and a bottom surface that are parallel to each other, and an inclination angle of an axis of the anode lead rod is less than ± 5 ° with respect to the reference surface, with the upper surface and the bottom surface being a reference surface. The chip-type solid electrolytic capacitor according to any one of claims 1 to 7.   It comprises first to fourth four capacitor elements of the same shape and the same size, wherein each of the capacitor elements is vertically stacked in the exterior body with the anode lead rod in the same direction, and the two upper and lower first and second capacitor elements are provided. Each anode lead rod of the capacitor element is welded to one surface of the anode lead frame via the conductive spacer, and the cathode lead layers of the first and second capacitor elements are bonded to each other by a predetermined conductive adhesive. The anode lead bars of the lower two third and fourth capacitor elements are welded to the other surface of the anode lead frame via the conductive spacers, respectively. The cathode lead layers of the third and fourth capacitor elements are electrically connected to each other via a predetermined conductive bonding means, and the cathode lead frame is Chip type solid electrolytic capacitor according to any one of the second capacitor element and the third claims 1 are disposed between the respective cathodes lead layer of the capacitor element 8 located.   The first capacitor element and the fourth capacitor element located on the outside are welded to the anode lead frame via the large-diameter conductive spacer, respectively, and the second capacitor element and the third capacitor located on the inside are welded to each other. The chip-type solid electrolytic capacitor according to claim 9, wherein each of the elements is welded to the anode lead frame via the small-diameter conductive spacer.   The chip-type solid electrolytic capacitor according to any one of claims 1 to 10, wherein the solid electrolyte contained in the cathode layer comprises a conductive organic compound. 2. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 1, wherein the first and second two capacitor elements, both of the same shape and the same size, have the same shape as the anode lead frame and the cathode lead frame. When preparing first and second conductive spacers forming a rod-like body of the same size, and welding each anode lead rod of the capacitor element to the anode lead frame by a resistance welding method via the conductive spacer,
After the first conductive spacer is welded to one surface of the anode lead frame, the second conductive spacer is welded to the other surface of the anode lead frame from the welding position of the first conductive spacer. Welded to the position closer to the leg side of the anode lead frame separated by the outer diameter of the conductive spacer or more,
After the anode lead rod of the first capacitor element is shorter than the anode lead rod of the second capacitor element by at least the outer diameter of the conductive spacer and welded to the first conductive spacer, the second capacitor A method of manufacturing a chip-type solid electrolytic capacitor, comprising welding an anode lead rod of an element onto the second conductive spacer.   As the anode lead rod of the first capacitor element is welded on the first conductive spacer, the cathode lead layer of the first capacitor element is connected to one surface of the cathode lead frame via a conductive adhesive. Connecting the anode lead bar of the second capacitor element to the second conductive spacer, and connecting the cathode lead-out layer of the second capacitor element to the other surface of the cathode lead frame. After that, an exterior body made of a heat-resistant synthetic resin is formed around the first and second capacitor elements, and each end of the anode lead frame and the cathode lead frame protruding from the exterior body. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 12, wherein the portion is bent toward the bottom surface side of the exterior body to form a leg.

Images