JP3459277B2 - Solid electrolytic capacitors - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor or an aluminum solid electrolytic capacitor, which is provided with a function of a protection element against overcurrent in various electric circuits. It is about.

[0002]

2. Description of the Related Art Generally, a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor has a large capacity and a small size as compared with other types of capacitors, but when a defect occurs in the capacitor element, it generates heat at a high temperature. Also, when the solid electrolytic capacitor is installed in an electric circuit with its anode and cathode being mistaken, heat is generated at a high temperature.

Therefore, in a conventional solid electrolytic capacitor, as described in, for example, Japanese Patent Laid-Open No. 63-84010, there is, for example, between the chip piece and the cathode lead terminal in the capacitor element, The connection is made with a temperature fuse wire made of a low melting point metal such as solder, and the fusing of the temperature fuse wire prevents heat generation to a high temperature.

On the other hand, in an electric circuit device using the solid electrolytic capacitor, in order to prevent various semiconductor parts in the electric circuit from being damaged by an overcurrent generated by a short circuit or the like, for example, 59
As described in JP-A-141648 and JP-A-61-153262, an excess of a high melting point metal such as gold, copper or aluminum is provided so that a pair of left and right lead terminals is melted by an overcurrent. An overcurrent protection element, which is connected by a current fuse wire and these parts are packaged in a molded part of synthetic resin, is provided in the electric circuit.

In this case, conventionally, the solid electrolytic capacitor and the overcurrent protection element are separately mounted in an electric circuit on a printed circuit board or the like.

[0006]

[Problems to be Solved by the Invention] However, in this way,
It is necessary to mount the solid electrolytic capacitor and the overcurrent protection device separately to the electric circuit on the printed circuit board. In addition to having to secure a space for separately mounting the solid electrolytic capacitor and the overcurrent protection element in the electric circuit of the printed circuit board, etc., the electric circuit becomes complicated. The mounting density of various electric components (the number of electric components that can be mounted per unit area) is reduced, leading to an increase in size and weight of a printed circuit board or the like. ． Since the solid electrolytic capacitor and the overcurrent protection element are separately attached to the electric circuit, the number of steps required for attaching these to the electric circuit by soldering or the like increases, resulting in a significant cost reduction. To bring up the app. There was a problem to say.

The present invention focuses on the fact that a large number of solid electrolytic capacitors are generally used in an electric circuit on a printed circuit board or the like, and this solid electrolytic capacitor is used as the overcurrent protection element. It is a technical object to solve the above-mentioned problem by adding the function of and to prevent the reverse mounting in the solid electrolytic capacitor by utilizing this.

[0008]

In order to achieve this object, the present invention is to connect the anode side of a capacitor element to an anode lead terminal, while connecting between the cathode side and the cathode lead terminal of the capacitor element, A third lead terminal which is connected by a thermal fuse wire made of a low melting point metal , and is further separated from either of the anode side and the cathode side of the capacitor element and the lead terminals. Is connected with an overcurrent fuse wire made of a refractory metal , and the capacitor element and the fuse elements are molded by synthetic resin, and a part of each lead terminal is molded. The package is configured so that it is exposed outside.

[0009]

[Operation] By configuring as in the present invention, the third
The lead terminal of is electrically connected to the cathode lead terminal via the overcurrent fuse wire and the temperature fuse wire, or is electrically connected to the anode lead terminal via the overcurrent fuse wire. However, since the third lead terminal can be connected to the electric circuit independently of the anode lead terminal and the cathode lead terminal, the chip piece of the capacitor element and the first cathode lead terminal can be connected to each other. The capacitor fuse can prevent the capacitor element from generating heat at a high temperature by connecting the temperature fuse wire, while connecting either the anode side or the cathode side of the capacitor element to the third lead terminal. Since the overcurrent fuse wire can protect various semiconductor components in the electric circuit connected to the third lead terminal against the overcurrent. That.

[0010]

That is, according to the present invention, since the function as an overcurrent protection element can be integrally incorporated into one solid electrolytic capacitor with a temperature fuse, an electric circuit in a printed circuit board or the like can be conventionally provided. In contrast, it is not necessary to separately mount the solid electrolytic capacitor and the overcurrent protection element, and only one solid electrolytic capacitor needs to be mounted, so that the mounting density of electronic components on a printed circuit board or the like can be improved, This has the effect of making it possible to reduce the size and weight of the printed circuit board and the like and to achieve a significant reduction in the cost required for mounting the printed circuit board or the like by soldering or the like.

By the way, in the conventional solid electrolytic capacitor, as described in the above publication, the anode lead terminal and the cathode lead terminal are protruded from the left and right ends of the mold part for packaging the capacitor element part. Since the solid electrolytic capacitor has a substantially symmetrical shape, when mounting this solid electrolytic capacitor on a printed circuit board, etc.
There is a possibility that the anode lead terminal and the cathode lead terminal may be mounted in opposite directions.

On the other hand, in the solid electrolytic capacitor of the present invention, in addition to the protrusion of the anode lead terminal and the cathode lead terminal from the mold portion, the protrusion of the third lead terminal causes By the presence of the lead terminal, since it is possible to determine the direction of the anode lead terminal and the cathode lead terminal, it is possible to reliably avoid mistakenly mounting the anode and the cathode when mounting on a printed circuit board or the like. is there.

[0013]

Embodiments of the present invention will now be described with reference to the drawings along with the manufacturing method thereof. 1 to 4 show a solid electrolytic capacitor 1 according to the first embodiment. In this figure, reference numeral 1 indicates a capacitor element having a tip piece 6 and an anode rod 5 protruding from the tip piece 6, and the tip piece 6 is a solid electrolyte 7 such as manganese dioxide.
Graphite layer 8 formed on the surface of this solid electrolyte 7
And a connecting film 9 formed on the surface of the graphite layer 8.

Reference numeral 10 is an anode lead terminal, reference numeral 11 is a cathode lead terminal, and reference numeral 12 is a separate body from the anode lead terminal 10 and the cathode lead terminal 11, and the cathode is The 3rd lead terminal arrange | positioned in the site | part adjacent to the lead terminal 11 is each shown. The anode lead terminal 10 is integrally formed on one side frame 13a of the lead frame 13, and the cathode lead terminal 11 and the third lead terminal 12 are integrally formed on the other side frame 13b of the lead frame 13, respectively. ing.

Then, while the lead frame 13 is being transferred in the longitudinal direction, the anode lead terminal 10 and the cathode lead terminal 1 in the lead frame 13 are transferred.
The capacitor element 1 is provided between the first and third lead terminals 12 and the anode rod 5 in the capacitor element 1 is connected.
Is supplied so as to contact the anode lead terminal 10, and the anode rod 5 is fixed to the anode lead terminal 10 by welding or the like.

Next, the chip piece 6 on the cathode side of the capacitor element 1 and the cathode lead terminal 11 are provided.
Are connected to each other by a temperature fuse wire 2 made of solder and composed mainly of lead and tin and having a melting point of about 300 ° C. However, this melting point of about 300 ° C. does not melt the thermal fuse wire 2 due to heat when mounting the solid electrolytic capacitor on a printed circuit board or the like, and the synthetic resin mold portion 4 described below is used. Is a temperature that does not burn.

The solder thermal fuse wire 2 has a wire diameter of about 50 to 120 microns, which melts at a temperature of its melting point. When the wire diameter is 80 microns, the wire diameter is 1 to 2A. When the wire diameter is 120 μm, the fuse is melted by flowing a current of 5 A for 10 seconds, and the wire is melted by flowing a current of 5 A for 5 seconds.

The chip piece 6 on the cathode side of the capacitor element 1 and the third lead terminal 12 are also provided.
Is connected with an overcurrent fuse wire 3 made of a refractory metal such as gold, silver, copper or aluminum. When the overcurrent fuse wire 3 is made of gold, its wire diameter is 15 to 30.
When the wire diameter is set to 15 microns, it is blown by applying a current of 1 to 4 A for 5 seconds. When the wire diameter is set to 30 microns, 4 to 10
It is melted by passing the current of A for 5 seconds.

Then, the temperature fuse wire 2 and the overcurrent fuse wire 3 are covered with a protective resin 25 made of a soft synthetic resin such as a silicone resin, and then the whole of them is molded by a hard synthetic resin such as an epoxy resin. In the part 4, the lead terminals 10, 11, 12 are packaged so that a part of the lead terminals 10, 11, 12 protrude from the mold part 4, and then the lead frame 1
After separating from 3, each lead terminal 10, 11, 12
By appropriately bending, the solid electrolytic capacitor is completed as shown in FIGS.

By the way, the above-mentioned solder-made thermal fuse wire 2
5 is provided between the chip piece 6 and the cathode lead terminal 11, it is preferable to adopt a method as shown in FIGS. That is, the heater block 15 provided in the transfer path of the lead frame 13 is configured to heat the lead frame 13, and a tunnel space 17 is formed between the heater block 13 and the cover body 16 on the upper surface thereof. Approximately 4-5% of nitrogen gas in tunnel space 17
While supplying a redox gas or an inert gas in which hydrogen gas is mixed to some extent, the cover body 16 is provided with an opening 18 communicating with the tunnel space 17, and from this opening 18, the redox gas or It is configured so that an inert gas is blown out.

At this opening 18, a capillary tool 19 in which the temperature fuse wire 2 is inserted, a torch 20 for fusing the temperature fuse wire 2, a bending tool 21 which reciprocates sideways, and a vertical movement. And the bonding tool 22 to be arranged. Then, a redox gas or an inert gas blown upward from the tunnel space 17 through the opening 18 creates an oxygen-free atmosphere around the capillary tool 19, and the flame from the torch 20 is removed by the capillary tool. By approaching the thermal fuse wire 2 drawn out from the lower end of the thermal fuse wire 19, the thermal fuse wire 2 can be fused in an oxygen-free atmosphere, and at the same time, the ball portions 14a and 14b can be formed at both ends of the fused portion.

Then, the temperature fuse wire 2 joined to the cathode lead terminal 11 is connected to the bending tool 2
5, the ball portion 14b at the tip is bent toward the chip piece 6 in the capacitor element 1 as shown by the chain double-dashed line in FIG. 6, the lead frame 13 is fed one pitch, and the other ball portion 14 is pressed.
A is joined to the next cathode lead terminal 11 by pressing with the capillary tool 19.

In another method, the ball portion 14b is formed at a stage after the ball portion 14b is formed on the upper end of the temperature fuse wire 2 of the solder wire joined to the cathode lead terminal 11 at the ball portion 14a. As shown in FIG. 7, the thickness T is sandwiched by a pair of left and right punches 26a and 26b, and the flattened shape is crushed and deformed.
Forming a flat disk portion 14C having a diameter substantially equal to
Then, the thermal fuse wire 2 is bent by the bending tool 21 toward the chip piece 6 in the capacitor element 1 (FIG. 8) in the same manner as described above, and the disk portion 14C at the tip thereof is bonded by the bonding tool 22. That is, the chip piece 6 in the capacitor element 1 is pressed and joined.

By doing so, the disk portion 14C
Can be bonded to the chip piece 6 in a large area in a state in which the crushing deformation of the disk portion 14C is reduced, and therefore, the chip piece 6 can be reliably bonded without exerting a large stress. Since it is possible to reliably reduce the occurrence of chipping or cracking in the chip piece 6 which is a sintered body of metal particles, the thickness T of the disk portion 14c is substantially equal to the wire diameter of the thermal fuse wire 2. By
The cross-sectional area of the thermal fuse wire 2 is not reduced.

On the other hand, when the overcurrent fuse wire 3 made of gold, silver, copper or aluminum is provided between the chip piece 6 and the third lead terminal 12, the same method as in the case of the thermal fuse 2 is used. , Ball portions 14a 'and 14b' are formed at both ends of the overcurrent fuse wire 3, and the ball portions 14a 'and 14b' are formed.
a ', 14b' are respectively press-bonded to the third lead terminal 12 and the chip piece 6 of the capacitor element 1, or one ball portion 14b 'is crushed and deformed into a flat disk portion. The disc portion is press-bonded to the chip piece 6.

In this way, ball portions 14a, 14b, 14a ', 14b' are formed at both ends of the thermal fuse wire 2 and at both ends of the overcurrent fuse wire 3, respectively, and these respective 14a, 14b, By press-bonding with 14a 'and 14b', it is possible to surely bond without reducing the cross-sectional areas of the temperature fuse wire 2 and the overcurrent fuse wire 3, so that when molding the mold portion 4, etc. It is possible to prevent disconnection of the temperature fuse wire 2 and the overcurrent fuse wire 3 and reduce the occurrence rate of defective products. Moreover, the lead terminals of the temperature fuse wire 2 and the overcurrent fuse wire 3 are also reduced. Since the joint portion for 11, 12 can be brought close to the chip piece 6 in the capacitor element 1, the length of the mold portion 4 can be shortened and the solid electrolytic Than we can achieve the size and weight of the condensers.

In particular, one end of each of the thermal fuse wire 2 and the overcurrent fuse wire 3 has a thickness approximately equal to that of the thermal fuse wire 2.
And a flat disk portion having a diameter substantially equal to the wire diameter of the overcurrent fuse wire 3 is formed, and this disk portion is press-bonded to the chip piece 6 of the capacitor element 1, the temperature fuse wire is used. 2 and the overcurrent fuse wire 3, without reducing the cross-sectional area, it is possible to reliably reduce the occurrence of chipping or cracking in the chip piece 6 which is a sintered body of metal particles, and further reduce the defective product generation rate. You can do it.

FIG. 9 shows a case where the solid electrolytic capacitor is applied to an electric circuit. In this figure, reference numeral 23 indicates the power supply circuit side, reference numeral 24 indicates the load circuit side, and the anode lead terminal 10 is shown. While connecting both the power supply circuit side 23 and the load circuit side 24 to the cathode lead terminal 11
Then, the power supply circuit side 23 is connected to the third lead terminal 12, and the load circuit side 24 is connected.

As a result, when the capacitor element 1 generates heat due to a defect in the capacitor element 1 or the like,
The thermal fuse wire 2 is melted and the capacitor element 1 is opened from the power circuit side 23. Even if the temperature fuse wire 2 is not blown, if an overcurrent flows through the load circuit side 24 due to a short circuit or the like, the overcurrent fuse wire 3 is blown by the overcurrent, and the load circuit side 24 is connected to the power supply circuit. Since it is opened from the side 23, it is possible to prevent breakage of the semiconductor component on the load circuit side 24.

FIG. 10 shows a solid electrolytic capacitor according to the second embodiment. In this solid electrolytic capacitor, the anode rod 5 in the capacitor element 1 is fixed to the anode lead terminal 10, while the chip piece 6 in the capacitor element 1 and the cathode lead terminal 11 are provided with ball portions 14a at both ends. In the structure in which the thermal fuse wire 2 having the structure 14b is connected and the thermal fuse wire 2 is covered with the protective resin 25, the third lead terminal 12 is adjacent to the anode lead terminal 10. The third lead terminal 12 and the anode lead terminal 11 or the anode rod 5 are connected to each other by an overcurrent fuse wire 3 ', and the overcurrent fuse wire 3'is After covering with a protective resin (not shown), the entire lead terminals 1 are formed by a synthetic resin mold portion 4.
It is packaged so that a part of 0, 11, 12 is exposed to the outside of the mold part 4.

The solid electrolytic capacitor according to the second embodiment is similar to the use example shown in FIG.
0 and the cathode lead terminal 11 are connected to the power supply circuit side 23, and the cathode lead terminal 11 and the third lead terminal 12 are connected to the load circuit side 24 for use. As a result, when the capacitor element 1 generates heat due to a defect in the capacitor element 1 or the like, the thermal fuse wire 2 is melted and the capacitor element 1 is released from the power circuit side 23. Even if the temperature fuse wire 2 is not blown, if an overcurrent flows through the load circuit side 24 due to a short circuit or the like, the overcurrent fuse wire 3'is blown by the overcurrent and the load circuit side 24 is powered. Since it is opened from the circuit side 23, it is possible to prevent breakage of the semiconductor component on the load circuit side 24.

In particular, in the second embodiment, the cathode lead terminal 11 is electrically connected to the chip piece 6 without passing through the thermal fuse wire 2, while the anode lead terminal 10 or the like is connected to the anode side. By connecting a fuse wire made of solder between the third lead terminal 12 and the third lead terminal 12, the solder fuse wire functions as a temperature fuse wire,
By being configured to have both the function as the overcurrent fuse wire, it is possible to reduce the manufacturing cost and reduce the size and weight.

[Brief description of drawings]

FIG. 1 is a perspective view of a solid electrolytic capacitor according to a first embodiment of the present invention before a molding portion is molded.

FIG. 2 is a perspective view of a solid electrolytic capacitor according to a first embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG.

FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG.

FIG. 5 is a cross-sectional view of essential parts showing a joining operation of the thermal fuse wire in the first embodiment.

FIG. 6 is a perspective view of FIG. 5 when viewed from above.

FIG. 7 is a perspective view of a main portion showing another embodiment of the fuse wire joining operation.

8 is a perspective view showing the next state of FIG. 7. FIG.

FIG. 9 is a diagram showing a usage example of the solid electrolytic capacitor of the first embodiment.

FIG. 10 is a perspective view of a solid electrolytic capacitor according to a second embodiment of the present invention before a molding portion is molded.

FIG. 11 is a view showing a usage example of the solid electrolytic capacitor of the second embodiment.

[Explanation of symbols]

1 Capacitor element 5 Anode rod 6 chip pieces 2 Thermal fuse wire 3 Overcurrent fuse wire 4 Mold part 10 Anode lead terminal 11 Cathode lead terminal 12 Third lead terminal

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Claims (5)

(57) [Claims] Claim: What is claimed is: 1. An anode side of a capacitor element is connected to an anode lead terminal, and a cathode side of the capacitor element and a cathode lead terminal are connected by a low-melting-point metal temperature fuse wire. In addition, an overcurrent fuse wire made of a refractory metal is provided between one of the anode side and the cathode side of the capacitor element and the third lead terminal which is separate from the both lead terminals. Solid-state, wherein the capacitor element and the fuse wires are packaged in a synthetic resin mold part such that a part of each lead terminal is exposed to the outside of the mold part. Electrolytic capacitor. 2. The "claim 1" according to claim 1, wherein a ball portion is formed at an end portion on the cathode side of the temperature fuse wire and the overcurrent fuse wire, and the ball portion is connected to the cathode lead terminal and the third lead terminal. Solid electrolytic capacitor characterized by being pressed and connected to. 3. The ball device according to claim 1, wherein a ball portion is formed at the other end of the thermal fuse and the overcurrent fuse wire.
A solid electrolytic capacitor characterized in that the ball portion is press-bonded to a chip piece. 4. The disk according to claim 2, wherein the temperature fuse and the overcurrent fuse wire are formed at the other end with a flat disk portion having a thickness substantially equal to the wire diameter of each fuse wire. The solid electrolytic capacitor is characterized in that the portion is press-bonded to the chip piece. 5. The method according to claim 1, wherein the cathode lead terminal is electrically connected to the chip piece, while the anode side and the third lead terminal are connected by a solder fuse wire. Characteristic solid electrolytic capacitor.