JPH1064758A - Chip type solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic molded chip type solid electrolytic capacitor wherein generation of terminal crack at the time of molding a lead is less than the conventional case, and leak current is small. SOLUTION: A crank type bending work part 9A is bent in the reverse direction to the bending direction along an end surface in the outside of sheath resin, bent again at the bent tip part, parallel to an anode leading-out line 2, and stretched over the tip position of the anode leading-out line 2. The crank type bending work part 9A is arranged between a welding part to the anode leading-out line 2 and a leading-out position from a sheath resin 8 to an anode external lead terminal 4. It is also possible that a bending work part which is bent or recessed so as to limit the tip 3 of the anode leading-out line 2 is arranged in the same direction as the bending direction along the end surface in the outside of the sheath resin. Since the anode leading-out line 2 does not directly abutted against the anode external lead terminal 4, the force at the time of molding a lead is not applied on a molded part 5 of the anode external lead terminal 4 and a capacitor element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type solid electrolytic capacitor, and more particularly to a structure of an anode external lead terminal.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing an example of a conventional chip-type solid electrolytic capacitor, taking a tantalum capacitor as an example. Referring to FIG. 7, the capacitor shown in FIG. 7 is disclosed in Japanese Utility Model Laid-Open Publication No. 59-187131, and includes a capacitor element 1, an anode lead wire 2, an anode external lead terminal 4, and a cathode external lead. It consists of a lead terminal 6 and an exterior resin 8.

Generally, the above-mentioned capacitor is manufactured as follows. First, an anode lead wire 2 made of the same metal tantalum wire is planted in tantalum metal powder,
Then, it is pressed and sintered in a high vacuum to form an anode body. Next, anodization is performed electrochemically to form a tantalum oxide film as a dielectric on the surface of the anode body.

Subsequently, a step of immersing in a permanganate solution as a semiconductor mother liquor and performing thermal decomposition is repeated a plurality of times to form a manganese dioxide layer as a semiconductor layer. Further, a cathode conductor layer (not shown) composed of a graphite layer and a silver paste layer is formed, and the capacitor element 1 is prepared.

Thereafter, the anode lead wire 2 of the capacitor element 1 and the anode external lead terminal 4 are welded. at the same time,
The cathode conductor layer on the surface of the element 1 and the cathode external lead terminal 6 are fixedly connected by using a conductive adhesive 7. As the material of the external lead terminals 4 and 6, a 42 alloy or the like, which is usually softer than the anode lead wire 2 made of metal tantalum and easy to bend in a later lead forming step, is used.

Next, the whole is molded with the exterior resin 8, and finally, the anode external lead terminal 4 and the cathode external lead terminal 6 are lead-formed to complete a resin-sealed chip-type tantalum solid electrolytic capacitor.

Here, the capacitor shown in FIG. 7 is characterized by a position (lead molding portion 5) where the anode external lead terminal 4 comes out of the exterior resin 8 and is bent downward along the resin end face. A hole 12 is provided in the vicinity of the extension of the anode lead wire 2, and the tip 3 of the anode lead wire escapes into the hole 12 during lead molding. The holes 12 prevent the occurrence of terminal cracks (terminal cracks) in the molded portion 5 of the anode lead terminal in the above-described lead molding step, and prevent an increase in leakage current, thereby ensuring the reliability of the capacitor. It is for.

That is, in manufacturing this capacitor, the tip of the anode lead wire 2 may be displaced due to a positional deviation during welding between the anode lead wire 2 and the anode external lead 4 or a variation in the length of the anode lead wire 2. 3 is exterior resin 8
May jump out of In that case, if the hole 12
Is not provided, the anode lead wire 2 directly hits the anode external lead terminal 4. As a result, when the terminal is bent in the lead forming step, the tip 3 of the anode lead wire acts as a fulcrum, and stress is applied to the formed portion 5 of the anode external lead terminal, so that the anode external lead terminal made of a soft material is used. 4 has terminal cracks. In addition, the stress applied to the anode lead wire 2 damages the ultra-thin dielectric oxide film of the capacitor element 1 and deteriorates the leakage current characteristics as a capacitor.

[0009]

As described above, the through hole 12 is provided in the molded portion 5 of the anode external lead terminal, and the tip 3 of the anode lead wire is released into the hole 12.
Terminal cracking of the anode external lead terminal 4 can be prevented. Also, it is possible to prevent an increase in leakage current of the capacitor.

[0010] However, even in the capacitor in which such measures are taken, terminal cracking and deterioration of leakage current characteristics may still occur.

The reason is that if the anode lead wire 2 is displaced in a direction perpendicular to the lead-out direction (not in the extension direction),
This is because the tip 3 of the anode lead lead wire does not enter the hole 12 provided in the anode external lead terminal forming portion 5 but directly hits the anode external lead terminal 4. As a result, as in the past, the tip of the anode lead wire acts as a fulcrum, and the force at the time of forming the lead is concentrated on the anode external lead terminal forming portion 5, which causes terminal cracking and also causes dielectric breakdown of the capacitor element. The oxide film is damaged.

Accordingly, an object of the present invention is to provide a resin-sealed chip-type solid electrolytic capacitor having less terminal cracks at the time of lead molding and having a small leakage current.

[0013]

According to the present invention, there is provided a chip type solid electrolytic capacitor comprising: an anode body formed by extracting and sintering an anode lead wire from a columnar molded body of fine powder of a valve action metal; A capacitor element in which a semiconductor layer and a cathode conductor layer are sequentially provided; an anode external lead terminal welded to the anode lead wire; a cathode external lead terminal bonded to the cathode conductor layer; the capacitor element and the anode An exterior resin that covers the external lead terminal and the cathode external lead terminal except for predetermined portions of the anode external lead terminal and the cathode external lead terminal, wherein the anode external lead terminal is one end surface of the exterior resin. In, the cathode lead external terminal goes out of the exterior resin at the other end face, respectively,
In the solid electrolytic capacitor having a structure bent along the end surface of the exterior resin at each protruding position, the position of the anode external lead terminal between the welding position with the anode lead lead wire and the lead-out position from the exterior resin is determined. In the meantime, it bends in the direction opposite to the direction of the bend along the end surface outside the exterior resin, and then bends again at the bent point so as to be parallel to the anode lead lead line, and the tip position of the anode lead lead line And a crank-shaped bent portion extending beyond the bent portion is provided.

The same direction as the direction of the bend along the end surface outside the exterior resin is provided between the tip position of the anode lead lead wire and the lead-out position from the exterior resin with respect to the anode external lead terminal. A bent portion that bends or depresses so as to limit the tip of the anode lead wire.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the drawings using examples.

Embodiment 1 FIG. 1 is a sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to Embodiment 1 of the present invention. 1 and FIG. 7, the capacitor of this embodiment is the same as a conventional capacitor, except that the capacitor element 1, the anode external lead terminal 4 welded to the anode lead wire 2, and the cathode on the surface of the capacitor element It comprises a cathode external lead terminal 6 fixed to a conductor layer (not shown) with a conductive adhesive 7 and an exterior resin 8. However, the structure of the anode external lead terminal 4 is different. The anode external lead terminal 4 in the present embodiment has a bent portion 9A near a welded portion with the anode lead wire 2.

When viewed from the side of the capacitor, the bent portion 9A has a cross-sectional shape which is once bent upward from the welded portion, and extends horizontally in the extension direction of the anode lead wire 2 again at the bent portion. It has a bent, crank shape. The anode external lead terminal is thereafter separated from the anode lead wire 2 while the exterior resin 8
And bent downward along the end surface of the exterior resin.

The present inventor manufactured the capacitor of this embodiment as follows. First, a wire diameter of 0.
An anode lead wire 2 made of a 3 mm tantalum wire is planted, and then pressed and sintered to obtain an anode body of a square pillar having a length of 1.0 mm, a width of 1.0 mm and a height of 1.0 mm. Was. Next, a tantalum oxide film as a dielectric layer was formed on the surface of the anode body, and a manganese dioxide layer, a graphite layer, and a silver paste layer were sequentially provided on the oxide film to obtain a capacitor element 1.

After that, the capacitor element 1 has a thickness of 0.1 m.
The cathode external lead 6 made of a 42 m alloy was bonded with a conductive adhesive 7. At the same time, the anode external lead terminal 4 was resistance-welded to the anode lead wire 2. Anode external lead terminal 4
Is made of a 42 alloy having a thickness of 0.1 mm, and is bent in a crank shape on the opposite side to the anode lead wire 2 at a position 0.5 mm away from the tip on the capacitor element side. A portion 9A is provided.

Thereafter, the whole is molded with the exterior resin 8 and the lead of the anode external lead terminal 4 and the cathode external lead terminal 6 is formed to obtain the resin-sealed chip-type tantalum solid electrolytic capacitor of this embodiment. completed.

The anode lead wire 2 is separated from the exterior resin 8 for the capacitor according to the present embodiment described above and the conventional capacitor shown in FIG. 7 with and without the hole 12 in the anode external lead terminal 4. 0.1 mm protruded lead molded capacitors
00 pieces were produced. And the terminal crack of the molding part 5 of the anode external lead terminal was investigated. Table 1 shows the results.

[0022]

[Table 1]

Referring to Table 1, in the capacitor of this embodiment, the rate of occurrence of terminal cracks was zero. On the other hand, the capacitor according to the prior art has the hole 12,
Regardless of the presence or absence, the terminal cracks occurred, and particularly, those having no holes showed a high occurrence rate of 23%.

The above results show that, in this embodiment, the bent portion 9A is provided on the anode external lead terminal 4 so that the anode lead wire can be bent even if the tip end 3 protrudes from the exterior resin 8. Since the portions 9A are separated by a step of 0.2 mm, the protruding portions do not directly hit the anode external lead terminals 4 during lead molding. On the other hand, in the capacitor of the conventional structure,
If the anode lead wire 2 is laterally displaced, the protrusion from the exterior resin does not enter the hole 12 and directly hits the anode lead external terminal 4 during lead molding. As a result, the tip 3 of the anode lead lead wire functions as a fulcrum, and the molding force is concentrated on the molding portion 5 of the anode external lead terminal. In this case, since the anode external lead terminal 4 made of the 42 alloy is softer than the anode lead wire 2 made of the tantalum material, a terminal crack occurs in the molded portion 5 of the anode external lead terminal.

Further, 100 capacitors each of the capacitor according to the present embodiment and the conventional capacitor were manufactured, and the distribution of the change rate of the leakage current (LC) before and after the lead forming process was investigated. The results are shown in FIGS. 5 (a) and 5 (c). FIG.
Referring to this example, while the average value of the change rate is 3.35% and the standard deviation is 2.128 in FIG.
In the conventional capacitor, the average value is 5.60% and the standard deviation is 5.234. It can be seen that the average value and the standard deviation of this embodiment are both smaller and the leakage current characteristics are superior.

The above results show that, in the present embodiment, the bent portion 9A is provided on the anode external lead terminal, so that the stress at the time of forming the lead is absorbed by the bent portion 5 and the dielectric oxide film is damaged. It is considered that the probability was reduced.

(Embodiment 2) Next, a second embodiment of the present invention will be described. FIG. 2 is a sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to a second embodiment of the present invention. By comparing FIG. 2 with FIG. 1, the capacitor of the present embodiment is similar to the capacitor of the first embodiment in that the capacitor element 1
And an anode external lead terminal 4 to which the anode lead wire 2 is welded, and a cathode conductor layer (not shown) on the surface of the capacitor element.
A cathode external terminal 6 fixed by a conductive adhesive 7 to the
And an exterior resin 8. However, the structure of the anode external lead terminal 4 is different. The anode external lead terminal 4 in the present embodiment has a bent portion 9B near a welded portion with the anode lead wire 2.

When viewed from the side of the capacitor, the above-mentioned bent portion 9B has a sectional shape that is once below the welded portion (ie, at the position of the tip 3 of the anode lead lead wire).
It has a crank shape which is bent (to the side opposite to that in the first embodiment), and bent again at the point where it is bent so as to extend horizontally in the direction in which the anode lead wire 2 extends. The anode external lead terminal then comes out of the exterior resin 8 and is bent downward along the end surface of the exterior resin.
The portion of the crank-shaped bent portion 9B that first bends downward is hereinafter referred to as the abutting portion 10.

The present inventor manufactured this example as follows. First, a capacitor element having the same material and shape as in Example 1 was prepared.

Thereafter, the cathode external lead terminal 6 was bonded with the conductive adhesive 7 in the same manner as in Example 1. At the same time, the anode external lead terminal 4 was resistance-welded to the anode lead wire 2. The anode external lead terminal 4 has a thickness of 0.1 mm.
No. 42 alloy from the tip of the capacitor element side.
At a position separated by 5 mm, a bent portion 9B with a step difference of 0.2 mm, which is bent on the same side as the anode lead wire 2, that is, in a crank shape opposite to that in the first embodiment, is provided. In this embodiment, the abutting portion 1 of the bent portion 9B is used for welding.
0 (a part bent downward) anode lead wire 2
The tip 3 was abutted to perform positioning. In addition, since the step of the bent portion 9B is 0.2 mm, the wire diameter of the anode lead wire 2 is 0.3 mm, and there is a difference of 0.1 mm between the two, so that the welding electrode is securely At the anode lead wire 2. That is, the bent portion 9B does not interfere.

Thereafter, the whole was molded with the exterior resin 8 and the lead of the anode external lead terminal 4 and the cathode external lead terminal 6 was formed, thereby completing the chip type tantalum solid electrolytic capacitor of the present embodiment.

Next, 100 capacitors each of the capacitor of this embodiment and the conventional capacitor shown in FIG. 7 were manufactured, and the variation in the position of the anode lead wire 2 before the resin sheathing step was measured. The measurement of the position is based on the contact portion 10 of the anode external lead terminal in the present embodiment, and in the case of the conventional capacitor, the contact portion 10 of the present embodiment is used.
The position corresponding to. The result is shown in FIG.
(A) and (d) show. Referring to FIG. 6, the capacitor of this embodiment (FIG. 6A) has an average value of -0.03 mm and a standard deviation of 0.016, whereas the conventional capacitor (FIG. 6D) has an average value of -0.03 mm. Value 0.03, standard deviation 0.052
Thus, the direction of the displacement is opposite to that of the present embodiment, and the standard deviation is large. That is, it was confirmed that the present example was more excellent with less variation.

The above result is because, in the present embodiment, by providing the abutting portion 10 in the bent portion 9B of the anode external lead terminal, the anode lead wire 2 can be abutted and positioned on the abutting portion 10. is there. As a result, the bent portion 9B of the anode lead lead wire 2 serves as a stopper, does not protrude from the exterior resin 8, does not directly hit the anode external lead terminal forming portion 5, and the terminal crack does not occur. It is gone.

Next, 100 capacitors each of the present embodiment and the conventional capacitor were manufactured, and the distribution of the rate of change of LC before and after the lead forming process was evaluated. The result is shown in FIG. Referring to FIG. 5, it can be seen that the average value and the standard deviation of this embodiment are smaller than those of the conventional capacitor, and the leakage current characteristics are excellent, as in the first embodiment.

(Embodiment 3) Next, the anode external lead terminal 4
FIG. 3 shows a cross-sectional view of a third embodiment of the present invention as another example in which a stopper is provided in the third embodiment. By comparing FIG. 3 and FIG. 2,
The capacitor of this embodiment is manufactured by the same materials and manufacturing steps as in the second embodiment. However, the structure of the stopper provided on the anode external lead terminal 4 is different. In this embodiment, a protrusion 9C is provided as a stopper.

The protruding piece 9C is located at a position 0.5 mm from the tip 11 of the anode external lead terminal 11 on the capacitor element side, and a portion including the center of the center of the anode external lead terminal 4 in the width direction is 0.4 mm wide. Then, a protruding piece of 0.2 mm was cut and raised on the anode lead wire 2 side.

The tip 3 of the anode lead wire 2 is abutted against the abutting portion 10 of the projecting piece 9C to perform positioning. still,
Since the step of the projecting piece 9C is 0.2 mm, the wire diameter of the anode lead wire 2 is 0.3 mm, and there is a difference of 0.1 mm between the two, the welding electrode is securely connected to the anode lead during welding. This corresponds to Leader Line 2. That is, the projection 9C does not interfere.

(Embodiment 4) FIG. 4 is a cross-sectional view of a fourth embodiment of the present invention as still another example in which a stopper is provided on the anode external lead terminal 4. By comparing FIG. 4 with FIG. 2, the capacitor of this embodiment is manufactured by the same material and manufacturing process as in the second embodiment. However, the structure of the stopper provided on the anode external lead terminal 4 is different. In the present embodiment, a circular point 9D is provided as a stopper.

The circle point 9D protrudes 0.2 mm toward the anode lead wire 2 at a position 0.5 mm from the tip 11 of the anode external lead terminal 4 on the capacitor element side. The tip 3 of the anode lead wire 2 is abutted against the abutting portion 10 of the circular point 9D to perform positioning. The step of the round point 9D is 0.2 mm, and the diameter of the anode lead wire 2 is 0.3 m.
m and a difference of 0.1 mm between the two, the welding electrode surely hits the anode lead wire 2 during welding.
That is, the circle point 9D does not interfere.

Next, 100 capacitors were manufactured for each of the above Examples 3 and 4, and variations in the position of the tip 3 of the anode lead lead wire before entering the resin sheathing process were investigated. The position was measured with reference to the contact portion 10 of the anode external lead terminal. The results are shown in FIGS. 6 (c) and (d). Referring to FIG. 6, it can be seen that in each of Examples 3 and 4, the variation in position is significantly reduced as compared with the conventional capacitor, and it is understood that the same effect as that of Example 2 is obtained.

The above-mentioned effect is obtained by providing the protruding pieces 9C and the circular bosses 9D on the anode external lead terminals, using them as stoppers, and abutting the anode lead wires 2 for positioning. As a result, the anode lead wire 2 does not protrude from the exterior resin 8 and does not directly hit the molded portion 5 of the anode external lead, so that terminal cracking does not occur. In addition, an increase in leakage current is eliminated.

[0042]

The first effect is that it is possible to prevent the occurrence of terminal cracks in the anode external lead forming portion during lead forming of the anode external lead terminal.

The reason is that, by providing the anode lead terminal with the bent portion, the anode lead lead line does not directly hit the anode external lead terminal, and as a result, the anode lead lead line becomes a fulcrum at the time of forming the lead. The concentration of the molding force is applied to the molded part of the anode external lead terminal.
Because it is gone.

A second effect is that deterioration of leakage current characteristics during lead molding of the anode external lead terminal can be prevented.

The reason for this is that by providing the bent portion on the anode external lead terminal, the stress at the time of forming the lead is absorbed by the bent portion, and the effect on the capacitor element is reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to Embodiment 3 of the present invention.

FIG. 4 is a cross-sectional view of a resin-sealed chip-type tantalum solid electrolytic capacitor according to Embodiment 4 of the present invention.

FIG. 5 is a diagram showing distributions of a change rate of a leakage current before and after lead molding of a resin-sealed chip-type tantalum solid electrolytic capacitor in comparison with Examples 1, 2 and a conventional capacitor.

FIG. 6 shows the distribution of the positions of the anode lead wires during lead molding of a resin-sealed chip-type tantalum solid electrolytic capacitor.
FIG. 9 is a diagram showing a comparison between Example 2, Example 3, Example 4, and a conventional capacitor.

FIG. 7 is a cross-sectional view of an example of a resin-sealed chip-type tantalum solid electrolytic capacitor according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode lead wire 3 Anode lead wire tip 4 Anode external lead terminal 5 Anode external lead terminal forming part 6 Cathode external lead terminal 7 Conductive adhesive 8 Exterior resin 9A, 9B Bending part 9C Protrusion piece 9D circle Bottom 10 Anode outer lead terminal abutting portion 11 Anode lead terminal end 12 Hole

Claims (5)

[Claims] A capacitor element comprising: an anode body obtained by extracting and sintering an anode lead wire from a columnar molded body of fine powder of a valve action metal and sintering the anode element; An anode external lead terminal welded to the anode lead wire, a cathode external lead terminal adhered to the cathode conductor layer, the capacitor element, the anode external lead terminal and the cathode external lead terminal, An outer resin covering the external lead terminal and a predetermined portion of the cathode external lead terminal while leaving a predetermined portion of the outer resin. The anode external lead terminal is provided on one end surface of the outer resin, and the cathode lead external terminal is provided on the other end surface. In the chip-type solid electrolytic capacitor having a structure that is outside and bent along the end surface of the exterior resin at each of the protruding positions, the anode external lead end Hand, between the derived position from the packaging resin and the welding position between the anode lead lead line,
It bends in the opposite direction to the direction of the bend along the end surface outside the exterior resin, and at the point where it bends again, bends in parallel with the anode lead wire, beyond the tip position of the anode lead wire. A chip-type solid electrolytic capacitor provided with an extended crank-shaped bent portion. 2. A capacitor element comprising an anode body obtained by extracting and sintering an anode lead wire from a columnar molded body of fine powder of valve action metal, and sequentially providing an anodic oxide film, a semiconductor layer, and a cathode conductor layer on the anode body. An anode external lead terminal welded to the anode lead lead wire, a cathode external lead terminal adhered to the cathode conductor layer, the capacitor element, the anode external lead terminal and the cathode external lead terminal, A package resin covering a predetermined portion of the anode external lead terminal and the cathode external lead terminal, wherein the anode external lead terminal is provided on one end surface of the external resin, and the cathode lead external terminal is provided on the other end surface. As it goes out of the resin,
In a chip-type solid electrolytic capacitor having a structure bent along the end surface of the exterior resin at each protruding position, with respect to the anode external lead terminal, a tip position of the anode lead lead wire and a lead-out position from the exterior resin. A chip provided with a bent portion which is bent or depressed so as to limit the tip of the anode lead wire in the same direction as the direction of bending along the end surface outside the exterior resin. Type solid electrolytic capacitor. 3. The chip-type solid electrolytic capacitor according to claim 2, wherein the bent portion has the same direction as the direction of the bend along the end surface outside the exterior resin at the position of the tip of the anode lead wire. A chip-shaped solid electrolytic capacitor characterized in that it is a crank-shaped bent portion that is bent again in the direction in which the anode lead lead wire extends in the bent portion. 4. The chip-type solid electrolytic capacitor according to claim 2, wherein the bent portion has a portion including a center for center distribution of an anode external lead terminal at a position of a tip end of the anode lead wire, A chip-type solid electrolytic capacitor cut and raised in the same direction as the direction of bending along the end surface outside the resin. 5. The chip-type solid electrolytic capacitor according to claim 2, wherein the bent portion has the same direction as the direction of the bend along the end surface outside the exterior resin at the position of the tip of the anode lead wire. A chip-type solid electrolytic capacitor characterized by a circular bottom that sinks into the surface.