JP3388934B2 - Structure of package type solid electrolytic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor made of tantalum, aluminum or the like which has been reduced in size and capacity.
The present invention relates to a structure of a solid electrolytic capacitor in which a capacitor element is packaged in a synthetic resin mold. 2. Description of the Related Art Conventionally, a package type solid electrolytic capacitor of this type is, as described in, for example, Japanese Patent Application Laid-Open No. 60-220922, an anode lead terminal made of a metal plate and a metal A plate-shaped cathode lead end is disposed on the same plane so as to face each other, and a capacitor element is provided between the two lead terminals with an anode rod projecting from one end surface of a chip piece of the capacitor element. The lead terminal is disposed so as to be joined to the anode lead terminal by welding or the like, and the tip end of the cathode lead terminal is largely bent along the upper surface or the lower surface of the other end of the chip piece of the capacitor element. Then, this tip is joined to the cathode-side electrode film on the surface of the chip piece with a conductive paste such as a solder paste or a silver paste. It was configured to be packaged in a fat mold part. However, in this conventional solid electrolytic capacitor, a bent portion must be formed in the middle of the cathode lead terminal so as to greatly bend the tip so as to be in close contact with the upper or lower surface of the chip piece. The total length of the electrolytic capacitor is increased by the length of the bent portion, resulting in an increase in size and an increase in weight. Therefore, the present inventor has proposed the above-mentioned patent application (Japanese Patent Application No. 5-66610, Japanese Unexamined Patent Application Publication No.
9-103392), as shown in FIGS. 9 and 10, an anode lead terminal 11 made of a metal plate and a cathode lead end 12 also made of a metal plate are disposed so as to face each other on substantially the same plane. Between the lead terminals 11 and 12, the capacitor element 3 is joined to the anode lead terminal 11 by welding an anode rod 5 protruding from one end face 4 'of the chip piece 4 of the capacitor element 3. In a solid electrolytic capacitor which is packaged in a synthetic resin molded part 16, the tip of the cathode lead terminal 12 is abutted against the other end face 4 ″ of the chip piece 4. The conventional solid is bonded to the cathode-side electrode film 7 formed on the surface of the piece 4 with a conductive paste 18 such as a silver paste or by soldering or welding. Abolished the large bent portion to be formed in the middle of the cathode lead terminal in solutions capacitor, compact,
It was proposed to reduce the weight. [0004] However, it has been found that the solid electrolytic capacitor of the prior application has the following problems. When manufacturing the capacitor element 3, first, a metal powder such as tantalum is applied to a porous chip piece 4, and one end face 4 ′ of the chip piece 4 is applied.
The anode chip 5 is solidified so as to protrude therefrom, and then sintered. The porous chip piece 4 is immersed in a chemical conversion solution in a state of being substantially vertically downward, and anodizing treatment is performed.
A dielectric film such as tantalum pentoxide is formed on the surface of each metal powder and at the base of the anode bar 5.
By immersing in an aqueous solution of manganese nitrate in the state of being directed substantially vertically downward, and then raising and firing a plurality of times, a solid electrolyte layer such as manganese dioxide is formed on the surface of the dielectric film. By forming a metal film such as silver or nickel on the surface of the solid electrolyte layer using a graphite film as a base, the entire surface of the chip piece 4 except for one end face 4 'is shown in FIG. As described above, a method of forming the cathode-side electrode film 7 using the solid electrolyte layer, the graphite film, and the metal film is generally adopted. In this manufacturing method, when the solid electrolyte layer in the cathode-side electrode film 7 is formed on the chip piece 4, when the chip piece 4 is pulled up from the aqueous solution of manganese nitrate, the chip piece 4 The permeated manganese nitrate aqueous solution hangs down toward the other end face 4 ″ of the chip piece 4 and is solidified by firing in this state. By forming a graphite film and a metal film on the solid electrolyte layer, As shown in FIG. 11, the thickness of the formed cathode-side electrode film 7 gradually increases from one end face 4 ′ to the other end face 4 ″ of the chip piece 4. In the other end face 4 ″ of the chip piece 4, the periphery protrudes and the central part is depressed. That is, when manufacturing the capacitor element 3, the chip piece is formed. The cathode-side electrode film 7 formed on the surface of the chip 4 cannot avoid a situation in which the periphery protrudes and the center portion is depressed at the other end face 4 ″ of the chip piece 4. On the other hand, the width W of the two lead terminals 11 and 12 cannot be reduced in order to secure a soldering area when the two lead terminals 11 and 12 are soldered to a printed circuit board or the like. As a result, as shown by a two-dot chain line in FIG. 11, the cathode side electrode film 7 on the other end face 4 ″ of the chip piece 4 of the capacitor element 3
When the tips of the cathode lead terminals 12 are abutted, a considerably large gap is formed between the tip of the cathode lead terminals 12 and the cathode-side electrode film 7. Therefore, when the tip of the cathode lead terminal 12 is joined to the cathode-side electrode film 7 with the conductive paste 18, bubbles are involved in the conductive paste 18.
A problem that a predetermined joint strength cannot be obtained, and a problem that a predetermined joint strength cannot be obtained due to the presence of the gap also occurs when connecting by soldering or welding. There is. In addition, since the tip of the cathode lead terminal 12 locally contacts the surrounding protruding portion of the cathode electrode film 7 of the chip piece 4, the tip piece 4 and its cathode electrode Since there is a high possibility that the film 7 is partially damaged, the occurrence rate of defective products during the production is high in combination with the decrease in the bonding strength. In particular,
When the anode bar 5 protruding from the chip piece 4 of the capacitor element 3 is fixed to the anode-side lead terminal 11 by welding or the like, the chip piece 4 of the capacitor element 3 is As shown by the dashed line, there is an attachment error such that the anode rod 5 bends by an appropriate angle θ1 or θ2 in the horizontal direction due to bending or the like, and the gap increases due to the attachment error. At the same time, the local contact increases, which further promotes a decrease in bonding strength and a possibility of damaging the chip piece 4 and its cathode-side electrode film 7. The present invention has a technical object to solve the above-mentioned problems of the prior application, although the idea of the prior application is followed. [0010] In order to achieve this technical object, the present invention provides a method of forming an anode lead terminal made of a metal plate and a cathode lead terminal also made of a metal plate on substantially the same plane. A capacitor element is disposed between the two lead terminals so that an anode bar projecting from one end surface of a chip piece of the capacitor element is joined to the anode lead terminal. In a solid electrolytic capacitor which is entirely packaged in a synthetic resin molded part, the width dimension of the cathode lead terminal is narrowed at the tip of the cathode lead terminal, and the tip is formed of a chip piece in the capacitor element. Butt against the other end,
It is bonded to the cathode-side electrode film formed on the surface of the chip piece. ". As described above, by narrowing the width of the cathode lead terminal at the tip end of the cathode lead terminal, the width of the cathode lead terminal and the anode lead terminal in the portion protruding from the molded portion is reduced. Can be brought into contact with only the depressed portion of the cathode-side electrode film on the other end surface of the chip piece while maintaining a predetermined width dimension. Can be reduced, and the tip of the cathode lead terminal can be prevented from locally colliding with the cathode-side electrode film. In addition, when the chip piece of the capacitor element is tilted in the left-right direction due to a mounting error or the like. In addition, it is possible to reduce the increase in the gap and the local contact. Therefore, according to the present invention, it is possible to reliably ensure the bonding strength when the cathode lead terminal is bonded to the cathode-side electrode film in the chip piece of the capacitor element, and to secure the capacitor element. Since the occurrence of breakage of the chip piece can be reliably reduced, the incidence of defective products can be greatly reduced as compared with the case of the above-mentioned prior invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIGS. 1 and 2 show a solid electrolytic capacitor according to a first embodiment, in which an anode lead terminal 1 formed of a metal plate and having an appropriate width W, and an anode lead terminal also formed of an appropriate width of a metal plate The cathode lead terminal 2 formed on the W is disposed facing each other on substantially the same plane, and the capacitor element 3 manufactured by the conventional manufacturing method is interposed between the lead terminals 1 and 2. , The capacitor element 3
Anode rod 5 protruding from one end face 4 'of chip piece 4
Are arranged on the upper surface of the anode lead terminal 1 so as to be joined by welding or the like, while the tip 2a of the cathode lead terminal 2 is provided.
Is partially formed to have a narrow width dimension W ′, and this tip 2a
Against the recessed portion of the cathode-side electrode film 7 formed on the other end face 4 ″ of the chip piece 4 in the capacitor element 3, and a conductive paste 8 such as a silver paste is applied to the cathode-side electrode film 7. Or by soldering, welding, or the like, and then packaging the entirety with a synthetic resin mold 6 such as an epoxy resin. The portion of the molds 1 and 2 that protrudes from the mold portion 6 is bent toward the lower surface of the mold portion 6 to form a surface mount type.
Further, it is preferable that the narrow width W ′ at the tip 2 a of the cathode lead terminal 2 is about half the width W of the cathode lead terminal 2. As described above, the width W of the cathode lead terminal 2 is partially reduced to the width W ′ at the front end 2 a of the cathode lead terminal 2. 6, the tip 2a of the cathode lead terminal 2 is depressed in the cathode-side electrode film 7 on the other end face 4 "of the chip piece 4 while maintaining the width W of the portion protruding from the predetermined width. Therefore, the gap therebetween can be reduced, and the tip 2a of the cathode lead terminal 2 can be prevented from locally contacting the cathode-side electrode film 7. Further, in FIG. 2, the chip piece 4 of the capacitor element 3 is shifted right and left with respect to the line connecting the two lead terminals 1 and 2 due to an attachment error or the like. When the tip of the cathode lead terminal 2 is formed to have a narrow width dimension W ′, the gap and the local contact can be reduced when the tip is inclined by an appropriate angle. As shown in the figure, the left and right sides at the tip of the cathode lead terminal 2 are not limited to be inclined surfaces, and the left and right sides at the tip of the cathode lead terminal 2 are formed as stepped surfaces as in the second embodiment shown in FIG. 4 or one end of the cathode lead terminal 2 is formed as an inclined surface as in the third embodiment shown in FIG. 4, or as shown in the fourth embodiment shown in FIG. Of the cathode lead terminal 2 may be formed as a stepped surface.
May be configured so as to prevent the cathode lead terminal 2 from coming off from the mold portion 6 by bending it slightly, as in the fifth embodiment shown in FIG. Further, the anode rod 5 protruding from one end face 4 'of the chip piece 4 in the capacitor element 3 is welded to the lower surface of the anode lead terminal 1 as in the sixth embodiment shown in FIG. Alternatively, it may be configured to join. Next, FIG. 8 shows a method of manufacturing the solid electrolytic capacitor according to the present invention. That is,
In this manufacturing method, the anode lead terminal 1 projecting inward from one side frame A1 of the pair of left and right side frames A1 and A2 connected to each other by the section bar A3, and the anode lead terminal 1 facing inward from the other side frame A2. A lead frame A is prepared by shaping the cathode lead terminals 2 projecting from each other at appropriate intervals along the longitudinal direction, and the lead frame A is transferred in the longitudinal direction as shown by the arrow B. In the first stage on the way, a capacitor element 3 is inserted between each anode lead terminal 1 and each cathode lead terminal 2 from one end face 4 ′ of a chip piece 4 of the capacitor element 3. Is the anode lead terminal 1, and the other end surface 4 ″ of the chip piece 4 is the tip 2 of the cathode lead terminal 2 having a narrow width.
a. Next, in the second stage, the anode bar 5 is joined to the anode lead terminal 1 by welding or the like, and then, in the third stage, the cathode lead terminal 2 is joined.
In the portion between the tip 2a of the chip piece and the other end face 4 ″ of the chip piece 4,
The conductive paste 8 is applied. In this case, the conductive paste 8 may be applied only to the upper surface of the cathode lead terminal 2 or may be applied to both the front and back surfaces of the cathode lead terminal 2. In the fourth stage, the cathode lead terminal 2 is bonded to the cathode-side electrode film 7 of the chip piece 4 by irradiating the conductive paste 8 with a laser beam. In the stage 5, after packaging with the synthetic resin mold part 6, in the sixth stage, the lead frame A
Disconnect from it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional front view of a solid electrolytic capacitor according to a first embodiment of the present invention. FIG. 2 is a plan sectional view taken along line II-II of FIG. FIG. 3 is a plan sectional view of a solid electrolytic capacitor according to a second embodiment of the present invention. FIG. 4 is a plan sectional view of a solid electrolytic capacitor according to a third embodiment of the present invention. FIG. 5 is a plan sectional view of a solid electrolytic capacitor according to a fourth embodiment of the present invention. FIG. 6 is a vertical sectional front view of a solid electrolytic capacitor according to a fifth embodiment of the present invention. FIG. 7 is a vertical sectional front view of a solid electrolytic capacitor according to a sixth embodiment of the present invention. FIG. 8 is a perspective view illustrating a method of manufacturing a solid electrolytic capacitor according to the present invention. FIG. 9 is a vertical sectional front view of the solid electrolytic capacitor according to the invention of the prior application. 10 is a plan sectional view taken along line XX of FIG. 9; FIG. 11 is a vertical sectional front view of a capacitor element used for a solid electrolytic capacitor. [Explanation of Signs] 1 Anode lead terminal 2 Cathode lead terminal 2a Cathode lead terminal tip 3 Capacitor element 4 Chip piece 5 Anode bar 6 Mold part 7 Cathode side electrode film 8 Conductive paste

Claims (1)

(57) [Claims 1] An anode lead terminal made of a metal plate and a cathode lead terminal also made of a metal plate are disposed so as to face each other on substantially the same plane. Between the terminals, a capacitor element is disposed such that an anode rod protruding from one end surface of a chip piece of the capacitor element is joined to the anode lead terminal, and the entirety thereof is formed by a synthetic resin mold part. In the solid electrolytic capacitor formed by packaging, the width dimension of the cathode lead terminal is narrowed at the tip of the cathode lead terminal, and the tip is abutted on the other end surface of the chip piece of the capacitor element, and the surface of the chip piece is A structure of a packaged solid electrolytic capacitor which is bonded to a formed cathode electrode film.