JPH0545050B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a solid electrolytic capacitor.

[Conventional technology]

Conventionally, this type of solid electrolytic capacitor has been generally used in various electronic circuits, and its advantage is that it has a low failure rate, but once a failure occurs, the failure mode is often short-circuit failure. As a result, a large short-circuit current flows and the capacitor generates heat, which may eventually lead to burnout. When a failure occurs due to this excessive short-circuit current, it is necessary to change the failure mode from short-circuit to open circuit in order to protect the circuit components, and fuses are generally used.

4 and 5 are a perspective view and a sectional view of a conventional solid electrolytic capacitor, in which an anode lead terminal 4 is connected to an anode lead 2 of a capacitor element 1 consisting of a cathode layer 3 and an anode lead 2, and a cathode layer 3 and the cathode lead terminal 5 are bonded via an insulating adhesive 21,
A chip-shaped solid electrolytic capacitor is constructed by bridge-connecting the fuse 6 with a solder 20, covering the fuse 6 with an elastic resin 7, and encasing the entire body with a resin 9.

[Problem that the invention seeks to solve]

In the conventional chip-shaped solid electrolytic capacitor with a fuse described above, the cathode layer and the cathode lead terminal are electrically connected by the fuse, so (1) the fuse and the capacitor element are close to each other;
When an overcurrent flows, the fuse generates heat, and this heat indirectly melts the solder on the cathode layer.
Thermal expansion may destroy the exterior resin, and solder may blow out from the broken surface, shorting other wiring circuits and causing secondary damage, or directly causing burnout of the capacitor element, and further damaging the entire circuit. (2) When connecting fuses, insulating resin is used to insulate between the cathode layer of the capacitor element and the cathode lead terminal, but this resin may harden. Since there is a risk of a short circuit between the cathode layer and the cathode lead terminal during the process, it is necessary to insulate the cathode layer or cathode lead terminal in advance.
In addition, since the surface of the cathode layer is not necessarily constant in size, shape, etc. of the capacitor element itself, it is difficult to set conditions for automatic soldering, and the process is complicated; (3) Chip-shaped solid electrolytic capacitors are required to have a particularly large capacity, so it is necessary to make the capacitor element to be accommodated large and the thickness of the outer resin as thin as possible, but it is necessary to connect a fuse to the cathode layer side. However, due to various factors such as securing space for the connections and the fuse itself, and increasing the thickness of the exterior resin to prevent solder from blowing out, the volumetric efficiency of the capacitance decreases contrary to the above requirements. Even if a solid electrolytic capacitor goes into open mode, it is not possible to check the fuse, so it is impossible to determine whether the fuse is disconnected or other parts are disconnected, making it difficult to analyze the cause. There are problems such as the fact that

[Means for solving problems]

In the chip-shaped solid electrolytic capacitor of the present invention, the connection part with the anode lead and the external electrode part are separated on the outside of the exterior surface, and the cut surface is connected to the anode lead terminal exposed on the exterior surface and the inside of the exterior resin. It is equipped with a fuse that bridges and connects the connection part with the anode lead and the external electrode part.

Therefore, even if a large short-circuit current flows, the fuse is separated from the cathode layer of the capacitor element, so no solder will blow out from the capacitor element or burnout will occur until the fuse heats up and breaks. Furthermore, since the connection part of the anode lead terminal and the external electrode part are manufactured by machining and have good flatness and uniformity of dimensions, the fuse can be connected by an automatic machine. The lead terminal side has more space for connecting the fuse than the cathode layer side, and there is no need to increase the size of the chip or reduce the size of the capacitor element, improving the volumetric efficiency of the capacitance.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially sectional perspective view showing the internal structure of an embodiment of the chip-shaped solid electrolytic capacitor of the present invention, and FIG. 2 is a sectional view of FIG. 1.

In the capacitor element 1 in which the anode lead 2 is planted on the cathode layer 3, a cathode lead terminal 5 is fixed to the surface of the cathode layer 3 opposite to the anode lead 2 and the top surface via a conductive adhesive 8. A connecting portion 4a of an anode lead terminal 4, in which a connecting portion 4a and an external connecting terminal 4b are connected to each other by a fuse 6 covered with silicone resin 7, is welded and fixed to the anode lead 2. External connection terminal 4
A chip-shaped solid electrolytic capacitor 10 is constructed by being insulated with an exterior resin 9 except for the exposed portions of the capacitor b and the cathode lead terminal 5.

Next, a procedure for assembling this chip-shaped solid electrolytic capacitor 10 will be explained. FIG. 3 shows the shape of the anode lead terminal 4 before assembly, in which the connection part 4a with the anode lead 2 and the external electrode part 4b are processed into a single plate via the bridging part 4c, and the bridging part 4c is formed into one plate. Part 4c
is formed so as to protrude outside the exterior resin 9. A conductive adhesive 8 is applied to one surface and the upper surface of the cathode layer 3, and the bent cathode lead terminal 5 is adhered to this, forming the connection portion 4a of the anode lead terminal 4.
is welded and fixed to the anode lead 2, and the connecting portion 4a and the external electrode portion 4b are bridge-connected by soldering a fuse 6, and the top thereof is covered with a silicone resin 7. The silicone resin 7 has elasticity and insulation properties. The assembly formed in this way is the external electrode portion 4b of the anode lead terminal 4.
After the bridging part 4c and the exposed parts of the cathode lead terminal 5 are insulated by transfer molding with the sheathing resin 9, the part outside the A-A line of the bridging part 4c is cut off. Then, the external electrode portion 4b of the anode lead terminal 4 and the cathode lead terminal 5 are bent along the outer wall of the exterior resin 9 to form a chip-shaped solid electrolytic capacitor 10. In this example, epoxy resin was used as the exterior resin 9.

Even if an overcurrent is applied to the chip-shaped solid electrolytic capacitor formed in this way, since the fuse 6 and the cathode layer 3 are not close to each other, the cathode layer 3 is removed from the fuse 6 after it generates heat until it blows out. No accidents such as solder blowing out from the capacitor element 3 or burnout of the capacitor element 1 occurred, and it was confirmed that the safety device functioned reliably and that no secondary disasters occurred.

Furthermore, since the anode lead terminal 4 is formed by machining into the shape shown in Fig. 3, it has good flatness and uniformity of dimensions, and it is possible to automatically connect the fuse by applying an automatic wire bonding machine or the like. Yes, the process has been simplified.

Furthermore, the anode lead terminal 4 side has more space for connecting the fuse 6 than the cathode lead terminal 5 side, and there is no need to enlarge the chip shape or reduce the shape of the capacitor element 1, making it compact and large in capacity. We have obtained a capacitor with volumetric efficiency equivalent to that of a chip-shaped solid electrolytic capacitor without a fuse, which can meet the demands of today's technology. Furthermore, by measuring between the connection part 4a of the anode lead terminal 4 and the external electrode part 4b with a tester, the connection resistance of the fuse 6 could be determined, and the connection state could be electrically confirmed. .

〔Effect of the invention〕

As explained above, the present invention provides an anode lead terminal in which the connection part with the anode lead and the external electrode part are separated outside the exterior resin, and the connection part with the anode lead and the external electrode part inside the exterior resin. By providing bridge-connected fuses, (1) there is no risk of solder blowing out from the cathode layer or burning out of the capacitor itself even in the event of a short circuit, and (2) there is no risk of solder blowing out from the cathode layer or burning out of the capacitor itself, and (2) the fuse between the connection part and the external electrode part The present invention has the effect of providing a chip-shaped solid electrolytic capacitor that can easily perform bridging connection using an automatic device, and (3) has high volumetric efficiency and can easily be made smaller and larger in capacity.

(4) The connection status of fuses can be checked even after packaging, making it easy to check during the manufacturing process and analyze the cause of failure.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the internal structure of one embodiment of the chip-shaped solid electrolytic capacitor of the present invention, Fig. 2 is a side sectional view of Fig. 1, and Fig. 3 is an example of the shape of the anode lead terminal before assembly. 4 is a perspective view showing the internal structure of an example of a conventional chip-shaped solid electrolytic capacitor, and FIG. 5 is a side sectional view of FIG. 4. 1...Capacitor element, 2...Anode lead, 3
... Cathode layer, 4 ... Anode lead terminal, 4a ... Connection section, 4b ... External electrode section, 4c ... Bridge section, 5
... cathode lead terminal, 6 ... fuse, 7 ... silicone resin, 8 ... conductive adhesive, 9 ... exterior resin, 10 ... chip-shaped solid electrolytic capacitor.

Claims (1)

[Scope of Claims] 1. A chip-shaped solid electrolytic capacitor in which an anode lead terminal and a cathode lead terminal are each connected to a capacitor element, and the capacitor is sheathed with resin, wherein the connection portion with the anode lead and the external electrode portion are located outside the exterior surface. It is characterized by comprising the anode lead terminal that is separated and whose cut surface is exposed on the exterior surface, and a fuse that bridges and connects the connection part with the anode lead and the external electrode part inside the exterior resin. Chip-shaped solid electrolytic capacitor.