JP2010056118A - Solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable solid electrolytic capacitor and its manufacturing method. <P>SOLUTION: The cathode loading part of a lead frame has a recess, a hole or a notch along the outer periphery of the cathode loading part. Thereafter, the cathode of a capacitor element is bonded to the cathode loading part using a conductive adhesive. Thus, the recess, the hole or the notch allows the excess conductive adhesive to stay and prevents the conductive adhesive from projecting from the bonding interface of the cathode of the capacitor element and the cathode loading part of the cathode lead frame. As a result, since the thickness of an exterior resin can be sufficiently secured, reliability is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a solid electrolytic capacitor.

  The structure of a conventional solid electrolytic capacitor is shown in FIGS. As shown in FIG. 11, the solid electrolytic capacitor is composed of a plurality of capacitor elements 6 covered with an exterior resin 18, and anode lead frames 9a and cathode lead frames 9b made of metal (see Patent Document 1).

  As shown in FIG. 12, in the capacitor element 6, a dielectric acid film 2, a solid electrolyte layer 3, a conductive carbon layer 4, and a silver paste layer 5 are formed on the surface of the anode body 1 using a valve action metal foil. Is. Here, the valve metal refers to a metal on which a very dense and durable dielectric film is formed by oxidation treatment, and specifically refers to tantalum, niobium, aluminum, titanium, and the like. For the solid electrolyte 3, a conductive polymer such as a TCNQ complex, polypyrrole, polythiophene, polyfuran, or polyaniline is used.

  Among the capacitor elements 6, the anode portion 7 made of the anode body 1 is connected to the 9 a anode mounting portion 10 of the lead frame, and the cathode portion 8 made of the solid electrolyte layer 3, the conductive carbon layer 4, and the silver paste layer 5 is the lead frame. It is connected to the cathode mounting part 11 of 9b. At this time, the anode part 7 and the anode mounting part 10 of the capacitor element 6 are joined by spot welding, and the cathode part 8 and the cathode mounting part 11 of the capacitor element 6 are joined via the conductive adhesive 14. Also, the anode part 7 of the capacitor element 6 and the anode part 7 of another capacitor element 6 are joined by spot welding, and the cathode part 8 of the capacitor element 6 and the cathode part 8 of the other capacitor element 6 are conductively bonded. It is joined and laminated via the agent 14.

  The laminated body of the capacitor element and the lead frame laminated as described above is sealed with the exterior resin 18 so as to expose a part of the anode terminal portion 12 and the cathode terminal portion 13 of the lead frame serving as external terminals. The exposed portions of the anode terminal portion 12 and the cathode terminal portion 13 are bent along the exterior resin 18 to complete the solid electrolytic capacitor.

  Such a capacitor has a large capacitance and excellent frequency characteristics, and is widely used in a CPU decoupling circuit or a power supply circuit. However, with the development of portable electronic devices, it is necessary to respond to many demands such as higher capacity, smaller size, lower ESR (Equivalent Series Resistance) in the high frequency range, higher reliability, etc. I came.

JP2007-294495A

  The stacking of capacitor elements according to the conventional method will be described with reference to FIGS. FIG. 13 is a perspective view showing a positional relationship before the capacitor elements are stacked, and FIG. 14 is a perspective view after the capacitor elements are stacked.

  First, the anode portion 7a and the cathode portion 8a of the capacitor element 6a are joined to the anode mounting portion 10 and the cathode mounting portion 11 of the lead frame, respectively. At this time, a conductive adhesive 14a is applied to one surface of the cathode portion 8a, and this coated surface is bonded to the cathode mounting portion 11 so as to face it. The anode part 7a is joined to the anode mounting part 10 by spot welding.

  Subsequently, another capacitor element 6b is joined so as to face the capacitor element 6a. At this time, the conductive adhesive 14b is applied to one surface of the cathode portion 8b, and the coated surface is bonded to face the cathode portion 8a. The anode part 7b is joined to the anode part 7a by spot welding.

  By repeating the above steps, the capacitor elements 6c and 6d are also bonded to the back surface of the lead frame, and finally the conductive adhesive is cured by heat to complete the capacitor element laminate.

  In general, in the manufacturing process, capacitor elements are fixed to a plurality of units on a fixing jig such as a carrier bar and collectively processed in order to simplify the transportation and loading of the capacitor elements into the apparatus. Also in the step of applying the conductive adhesive, a plurality of capacitor elements are fixed to the fixing jig and collectively processed. Therefore, all the capacitor elements are laminated after being applied with a conductive adhesive whose application amount is adjusted to a constant amount.

  However, the surface properties of the cathode portions 8a, 8b, 8c, and 8d of the capacitor element and the surface of the cathode mounting portion 11 of the lead frame are different, so that it is necessary to connect the cathode portion of the capacitor element and the cathode mounting portion of the lead frame. The optimum amount of the conductive adhesives 14a and 14c is different from the optimum amount of the conductive adhesives 14b and 14d necessary for joining the cathode portions of the capacitor elements. The cathode part of the capacitor element has a rough surface and requires a large amount of conductive adhesive, but the cathode mounting part of the lead frame has a smooth surface and does not require a large amount of conductive adhesive. .

  When the coating amount of the conductive adhesive is constant at an optimum amount for joining the cathode parts, the conductive adhesives 14a and 14c become excessive in joining the cathode part and the cathode mounting part, as shown in FIG. Excess conductive adhesives 14a1 and 14c1 protrude from the joint between the cathode and the cathode mounting portion. As described above, when the capacitor element laminate having the protruding portion of the conductive adhesive is covered with the exterior resin, there is a problem that the exterior resin in the vicinity of the protruding portion becomes thin and reliability is lowered.

  The exterior resin must have a certain thickness to ensure reliability. Reliability decreases mainly due to penetration of oxygen and moisture into the exterior resin. Oxygen causes deterioration of ESR and the like, and moisture causes deterioration of moisture resistance and reflow resistance. However, when there is a portion where the exterior resin is thin as described above, oxygen and moisture easily penetrate into the inside, and the reliability is significantly lowered.

  Note that if the amount of conductive adhesive applied is constant at an optimum amount for joining the cathode part and the cathode mounting part, the conductive adhesive will be insufficient in joining the cathode parts, resulting in poor bonding and poor characteristics. ， Conductive adhesive could not be reduced.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid electrolytic capacitor capable of achieving an improvement in reliability while avoiding a decrease in productivity.

The present invention relates to a capacitor element comprising an anode part, a cathode part, and a dielectric film layer formed between the anode part and the cathode part, and an anode lead frame comprising an anode mounting part and an anode terminal part. And a cathode lead frame comprising a cathode mounting portion and a cathode terminal portion, wherein the capacitor element is covered with an exterior resin, and a part of the lead frame is exposed from the exterior resin. The cathode mounting portion of the cathode lead frame to which the cathode portion of the element is joined has at least one of a recess, a hole, and a notch along the outer periphery of the cathode mounting portion, and the cathode portion and the cathode mounting portion Is a solid electrolytic capacitor characterized by being bonded via a conductive adhesive.

  The cutout portion of the cathode mounting portion preferably has a shape constricted at the central portion of the side end of the cathode mounting portion.

  The solid electrolytic capacitor is preferably laminated with a plurality of capacitor elements.

  In the solid electrolytic capacitor, the cathode terminal portion of the cathode lead frame has a reinforcing hole that is at least partially filled with an exterior resin, and a corridor portion on both sides of the reinforcing hole. It is preferable that at least one of a concave portion or a hole portion is provided at a position facing the corridor portion in the outer peripheral portion.

Embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
1 to 3 show the structure of the solid electrolytic capacitor according to the first embodiment. FIG. 1 is a cross-sectional view of a capacitor element, FIG. 2 is a cross-sectional view of a solid electrolytic capacitor, and FIG. 3 is a perspective view showing the positional relationship of each component when the capacitor elements are stacked.

  First, an aluminum foil, which is a valve metal, is cut into a plate shape to form an anode body 1, and a dielectric coating layer 2 and a cathode portion 9 are sequentially formed to produce a capacitor element 6. Here, the cathode portion 9 is specifically composed of the solid electrolyte layer 3, the conductive carbon layer 4, and the silver paste layer 5.

  The dielectric coating layer 2 is formed by subjecting the anode body 1 to electrolytic conversion treatment in a phosphoric acid aqueous solution.

  The anode body 1 formed up to the dielectric film layer 2 as the solid electrolyte layer 3 is immersed in a chemical polymerization solution composed of 3,3-ethylenedioxythiophene, iron (III) P-toluenesulfonate, 1-butanol. By doing so, a polythiophene layer is formed.

  Next, as shown in FIG. 3, the anode portion 7a and the cathode portion 8a of the capacitor element 6a are connected to the anode mounting portion 10 of the anode lead frame 9a and the cathode mounting portion 11 of the cathode lead frame 9b, respectively. The cathode mounting portion 11 is provided with a recess 15 along the outer periphery of the cathode mounting portion 11. The anode portion 7a and the anode mounting portion 10 are joined by spot welding, and the cathode portion 8a and the cathode mounting portion 11 are joined by a conductive adhesive 14a.

  Next, the anode portion 7 b of the capacitor element 6 b is joined by spot welding, and the cathode portion 8 a of the capacitor element 6 a and the cathode portion 8 b of the capacitor element 6 b are joined via the conductive adhesive 14. At this time, the coating amount of the conductive adhesive used for joining the cathode part and the cathode mounting part was the same as the conductive adhesive used for joining the cathode parts.

  By repeating this process, four capacitor elements 6a, 6b, 6c and 6d are laminated, and the conductive adhesive 14 is cured by heat.

  The capacitor element is sealed with the exterior resin 18 so that a part of the anode terminal portion 12 of the anode lead frame 9a and the cathode terminal portion 13 of the cathode lead frame 9b of the capacitor element laminated as described above is exposed. The exposed portions of the anode terminal portion 12 and the cathode terminal portion 13 are bent along the exterior resin 18 to complete the solid electrolytic capacitor of the present invention.

  By having the concave portion 15 as described above, when the capacitor elements 6a and 6c are joined to the cathode portions 8a and 8c, excess conductive adhesive 14 stays in the concave portion 15 and the cathode as shown in FIG. The protrusions 14a1 and 14b1 of the conductive adhesive from the bonding interface between the mounting portion 11 and the cathode portions 8a and 8c did not occur. Moreover, since the conductive adhesive was applied in a sufficient amount for bonding, no bonding failure occurred at the bonding portion between the cathode mounting portion and the cathode portion and at the bonding portion between the cathode portions.

  The anode body 1 may be made of a valve metal such as tantalum, niobium or titanium in addition to aluminum, or a sintered body.

In addition to polythiophene, a conductive polymer such as TCNQ complex, polypyrrole, polyfuran, or polyaniline may be used for the solid electrolyte layer 3. The recess 15 is not limited to the shape shown in FIG. The design can be appropriately changed depending on the shape, the shape of the lead frame, the surplus amount of the conductive adhesive, the protruding direction, and the like. FIG. 4 is a diagram illustrating the shape of the recess 15 formed in the cathode mounting portion. In FIG. 4A, the recess 15 is formed in parallel with the arrangement direction of the lead frames 9a and 9b along the outer periphery of the cathode mounting portion. In FIG. 4B, the recess 15 is formed perpendicular to the arrangement direction of the lead frames 9a and 9b along the outer periphery of the cathode mounting portion.

The recesses are processed by chemical etching, but can also be formed by mechanical processing such as press molding.
(Embodiment 2)
In the second and subsequent embodiments, the same parts and members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The first embodiment is different from the first embodiment in that a concave portion is provided in the cathode mounting portion of the lead frame, whereas the second embodiment is different from the first embodiment in that a through hole is provided in the cathode mounting portion of the lead frame. FIG. 5 is a perspective view showing the positional relationship of each component when the capacitor elements are stacked, and the hole portion 16 is parallel to the arrangement direction of the lead frames 10a and 10b along the outer periphery of the cathode mounting portion 11. positioned.

  By having the hole portion 16 as described above, when the capacitor elements 6a and 6c are joined to the cathode portions 8a and 8c, excess conductive adhesive stays in the hole portion 16, and as shown in FIG. The protrusions 14a1 and 14b1 of the conductive adhesive did not occur from the bonding interface between the cathode mounting portion 11 and the cathode portions 8a and 8c. In addition, since the conductive adhesive was applied in a sufficient amount for bonding, no bonding failure occurred at the bonding portion between the cathode mounting portion 11 and the cathode portion and between the cathode portions.

  The hole 16 is not limited to the shape shown in FIG. 5 and can be appropriately changed in design depending on the shape of the capacitor element, the surplus amount of the conductive adhesive, the protruding direction, and the like. FIG. 6 is a diagram illustrating the shape of the hole 16 formed in the cathode mounting portion. In FIG. 6A, the hole is formed perpendicular to the arrangement direction of the lead frames 9a and 9b along the outer periphery of the cathode mounting portion. In FIG.6 (b), it forms so that the outer periphery of a cathode mounting part may be enclosed. In FIG. 6C, a plurality of circular holes are formed so as to surround the outer periphery of the cathode mounting portion.

The hole is drilled by punching, but may be drilled by mechanical techniques such as laser processing or chemical etching.
(Embodiment 3)
In the first embodiment, a recess is provided in the cathode mounting portion of the lead frame, and in the second embodiment, a hole is provided in the cathode mounting portion of the lead frame, whereas in the third embodiment, a notch is formed in the cathode mounting portion of the lead frame. The point which provided the part differs from the said Embodiment 1 and 2.

  As shown in FIG. 7, the notch portion 17 of the cathode mounting portion is located in parallel to the arrangement direction of the lead frames 9a and 9b along the outer periphery of the cathode mounting portion. The cutout portion 17 forms the most constricted shape at the center in the extending direction of the cathode mounting portion 11.

  By having the notch portion 17 having the above-described structure, excess conductive adhesive 14 stays in the notch portion 17 of the cathode portion 8 when the capacitor elements 6a and 6c are joined to the cathode portions 8a and 8c. However, the protrusions 14a1 and 14b1 of the conductive adhesive did not occur from the junction between the cathode mounting portion 11 and the cathode portions 8a and 8c as shown in FIG. Further, since the conductive adhesive was applied in a sufficient amount for bonding, no bonding failure occurred at the bonding portion between the cathode mounting portion 11 and the cathode portion and between the cathode portions.

  The notch 17 is not limited to the shape shown in FIG. 7, and can be appropriately changed in design depending on the shape of the capacitor element, the surplus amount of the conductive adhesive, the protruding direction, and the like. FIG. 8 is a diagram illustrating the shape of the cutout portion 17 formed in the cathode mounting portion, and the left side of the drawing is the anode mounting portion side. FIG. 8A shows an arc-shaped cutout formed on the outer periphery of the cathode mounting portion. FIG. 8B shows a rectangular cutout formed in parallel with the direction in which the lead frames 9a and 9b are arranged along the outer periphery of the cathode mounting portion. These cutouts have a shape in which the central portion in the extending direction of the cathode mounting portion is most narrowed, and the above-described effect can be obtained more.

The notch may be formed by a mechanical method such as pressing or laser processing, or may be formed by chemical etching or the like.
(Embodiment 4)
In the first embodiment, four capacitor elements are stacked, whereas in the fourth embodiment, two capacitor elements are stacked, which is different from the first embodiment. As shown in FIG. 9, capacitor elements 6a and 6c coated with a conductive adhesive 12 were bonded to the upper and lower surfaces of the cathode mounting part 11 having the recess 15, respectively.

  In the case of a structure in which the capacitor elements are not bonded to each other and only the capacitor elements are bonded to the lead frame, the conductive adhesive can be applied in an amount optimal for bonding the cathode portion and the cathode mounting portion. The viscosity of conductive adhesive varies depending on the temperature, and the amount of coating varies frequently.

  In this embodiment, since the cathode mounting portion has a recess, excess conductive adhesive can be retained in the recess 15 with respect to the variation in the amount of conductive adhesive applied as described above. , The conductive adhesive protrusions 14a1 and 14b1 as shown in FIG. 14 did not occur. Further, no joint failure occurred at the joint between the cathode mounting portion 11 and the cathode portion.

In this embodiment, two capacitor elements are stacked. However, the number of stacked capacitor elements may be one.
(Embodiment 5)
In the fifth embodiment, as shown in FIG. 10, in order to increase the adhesion effect with the exterior resin, reinforcement holes 19a and 19b in which at least part of the anode terminal portion 12 and the cathode terminal portion 13 of the lead frame are filled with the exterior resin. And corridors 20a and 20b on both sides of the reinforcing hole, and a recess 15 is provided at a position facing the corridor 20b in the outer periphery of the cathode mounting portion 11 of the cathode lead frame. This is different from the first to fourth embodiments.

  In the present embodiment, when the capacitor element is bonded to the cathode mounting portion by providing the recess 15, excess conductive adhesive is retained in the recess 15, and the conductive adhesive moves toward the corridor 20 b. Protruding could be suppressed.

  When the lead frame having the reinforcing hole as described above is not provided with the concave portion as described above, the conductive adhesive reaches the corridor so that the interface between the exterior resin and the lead frame is covered with the exterior resin. Adhesion deteriorates, oxygen and moisture easily penetrate into the interior, and reliability is significantly reduced. On the other hand, in this Embodiment, protrusion of the conductive adhesive to the said corridor part 20b can be prevented, As a result, reliability could be improved.

  The concave portion is not limited to a square shape but may be a circular shape, and is not limited to a concave shape and may be a hole shape. Moreover, although the said recessed part was processed by chemical etching, you may form by mechanical methods, such as press processing or laser processing, chemical etching, etc. to others.

  The above embodiments are merely illustrative of the present invention and should not be construed as limiting the invention described in the claims. The present invention can be freely modified within the scope of the claims and the scope of equivalent meanings. For example, one or more capacitor elements may be stacked, and the number is not particularly limited.

It is sectional drawing of the capacitor | condenser element which concerns on Embodiment 1 of this invention. It is sectional drawing of the solid electrolytic capacitor which concerns on Embodiment 1 of this invention. It is a perspective view which shows the positional relationship of each structure part at the time of capacitor element lamination | stacking based on Embodiment 1 of this invention. 1 is a top view of a lead frame according to a first embodiment of the present invention. It is a perspective view which shows the positional relationship of each structure part at the time of the capacitor | condenser element lamination which concerns on Embodiment 2 of this invention. FIG. 6 is a top view of a lead frame according to a second embodiment of the present invention. It is a perspective view which shows the positional relationship of each structure part at the time of the capacitor | condenser element lamination | stacking which concerns on Embodiment 3 of this invention. FIG. 6 is a top view of a lead frame according to a third embodiment of the present invention. It is a perspective view which shows the positional relationship of each structure part at the time of the capacitor | condenser element lamination based on the 4th Embodiment of this invention. FIG. 9 is a top view of a lead frame according to a fifth embodiment of the present invention. It is sectional drawing of the solid electrolytic capacitor by a prior art. It is sectional drawing of the capacitor | condenser element by a prior art. It is a perspective view which shows the positional relationship of each structure part before laminating | stacking a capacitor | condenser element with a prior art. It is a perspective view after laminating | stacking a capacitor | condenser element by a prior art.

Explanation of symbols

・ Anode body ・ Dielectric film layer ・ Solid electrolytic layer ・ Conductive carbon layer ・ Silver paste layer ・ Capacitor element ・ Anode part ・ Cathode part ・ Lead frame ・ Anode mounting part ・ Cathode mounting part ・ Anode terminal part ・ Cathode terminal part ・Conductive adhesive, recess, hole, notch, exterior resin, reinforcement hole, corridor

Claims (4)

A capacitor element comprising an anode part, a cathode part, and a dielectric film layer formed between the anode part and the cathode part;
An anode lead frame comprising an anode mounting portion and an anode terminal portion;
A cathode lead frame comprising a cathode mounting portion and a cathode terminal portion;
The anode part of the capacitor element is connected to the anode terminal part of the anode lead frame, and the cathode part is connected to the cathode terminal part of the cathode lead frame,
In the solid electrolytic capacitor in which the capacitor element is covered with an exterior resin, and a part of the anode terminal portion and the cathode terminal portion are exposed from the exterior resin,
The cathode mounting portion of the cathode lead frame to which the cathode portion of the capacitor element is joined has at least one of a recess, a hole, and a notch along the outer periphery of the cathode mounting portion, and the cathode portion and the cathode mounting A solid electrolytic capacitor characterized in that the portions are joined via a conductive adhesive. 2. The solid electrolytic capacitor according to claim 1, wherein in the solid electrolytic capacitor, the cutout portion of the cathode mounting portion is bundled at a central portion in the extending direction of the cathode lead frame of the cathode mounting portion. 3. The solid electrolytic capacitor according to claim 1, wherein a plurality of capacitor elements each having an anode body made of a foil body are laminated. In the solid electrolytic capacitor, the cathode terminal portion of the cathode lead frame has a reinforcing hole that is at least partially filled with an exterior resin, and a corridor portion on both sides of the reinforcing hole,
The outer periphery of the cathode mounting portion of the cathode lead frame has at least one of a recess or a hole at a position facing the corridor, according to any one of claims 1 to 3. The solid electrolytic capacitor as described.