1. Field of the Invention
The invention relates to a solid electrolytic capacitor in which portions of an anode terminal and a cathode terminal connected with a capacitor element are exposed out of a mold resin portion without entering in the mold resin portion.
2. Description of the Related Art
As a conventional solid electrolytic capacitor, for example, a solid electrolytic capacitor having a structure shown in FIG. 5 has been known. The solid electrolytic capacitor is provided with a capacitor element 101 obtained by successively forming a dielectric layer, a cathode layer, and a cathode lead-out layer on a circumferential surface of an anode body in which an anode lead 121 is implanted, a mold resin portion 106, an anode terminal 107, and a cathode terminal 108. Portions of the anode terminal 107 and the cathode terminal 108 are exposed out of the mold resin portion 106 and the exposed portions are bent along the circumferential surface of the mold resin portion 106.
To produce such a solid electrolytic capacitor having the above-mentioned structure, it is required to carry out a process according to which the capacitor element 101 is coated with the mold resin portion 106 and thereafter the anode terminal 107 and the cathode terminal 108 exposed out of the mold resin portion 106 are bent along the circumferential surface of the mold resin portion 106. However, in the bending process, it is practically difficult to perpendicularly bend the anode terminal 107 and the cathode terminal 108 and thus, strain to a certain extent is generated. Due to this strain, the produced solid electrolytic capacitor becomes larger than standardized sizes and it results in a problem of defective products. Further, to bend the anode terminal 107 and the cathode terminal 108, a margin for bending is required and therefore the size of the mold resin portion 106 has to be large to a certain degree and accordingly, it is difficult to make the solid electrolytic capacitor compact and low in height and improve the volume efficiency of the capacitor element 101. Further, there is a problem that a lead-out distance from the anode lead 121 to the exposed portion to be the terminal of the anode terminal 107 and a lead-out distance from the cathode lead-out layer to the exposed portion to be the terminal of the cathode terminal 108 become long and accordingly, an ESR of a solid electrolytic capacitor is increased.
In order to solve the above-mentioned problems, solid electrolytic capacitors having structures as described in a Prior Art 1 (Japanese Unexamined Patent Publication No. 2001-244145) and a Prior Art 2 (Japanese Unexamined Patent Publication No. 2001-167976) have been proposed.
That is, in the Prior Art 1, there is proposed a solid electrolytic capacitor in which a bottom surface of a mold resin portion and both lower surfaces of an anode terminal and a cathode terminal exposed out of the mold resin portion are in a same plane. However, in production process of a solid electrolytic capacitor with such a structure, it is required to protect lower surfaces of the anode terminal and the cathode terminal with an insulating tape or the like in order to prevent the mold resin from penetrating the respective lower surfaces of the anode terminal and the cathode terminal at the time of molding after the anode terminal and the cathode terminal are connected respectively to the capacitor element. Further, since it is impossible to completely prevent from the penetration of the mold resin even if the insulating tape or the like is adhered to the lower surfaces of the anode terminal and the cathode terminal, there occurs a problem of defective products. Furthermore, it is required to form a space in an interface between an upper mold and a lower mold at the time of molding in consideration of the thickness of the insulating tape; however, the pressure of the molds to the insulating tape is not so high and it also results in a problem that the mold resin leaks to the adhered surface of the insulating tape.
On the other hand, in the Prior Art 2, the volume efficiency of a capacitor element is improved by decreasing the volume of a mold resin portion by insulating an anode terminal made of a first conductive sheet and a cathode terminal made of a second conductive sheet with an insulating sheet. However, to produce a solid electrolytic capacitor with such a structure, a process of adhering an insulating sheet to both conductive sheets to be the anode terminal and the cathode terminal is required. Further, with such a structure, the contact surface area between the capacitor element and the cathode terminal is narrowed and at the same time, the lead-out distance between the cathode layer of the capacitor element and the exposed portion of the cathode terminal becomes not smaller than the thickness of the insulating sheet and accordingly, there occurs a problem that the ESR of the solid electrolytic capacitor cannot be decreased.