JPH10144575A - Chip type solid electrolytic capacitor and its packaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hinder permeation of water content, by spreading moisture-resistant coating material on the surface of sheath resin. SOLUTION: A lead frame 6 is connected with a capacitor element 5, which is sheath-molded by molding using sheath resin composed of epoxy resin, in such a manner that a part of the lead frame 6 is led out to the outside. By the terminal working and the aging process of the lead frame 6, a chip type solid electrolytic capacitor is constituted. By dipping the capacitor in solution of silicon oil or isobutylene rubber, moisture-proof coating material 8 is spread on the surface of the sheath resin 7. By drying the coating material, a chip type solid electrolytic capacitor 9 is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chip-type solid electrolytic capacitor using a conductive polymer as a solid electrolyte and a method for packaging the same.

[0002]

2. Description of the Related Art In recent years, the miniaturization and high frequency of electronic devices have been advanced, and solid electrolytic capacitors using conductive polymers as solid electrolytes capable of realizing low impedance at high frequency have been commercialized. ing. Since this solid electrolytic capacitor uses a conductive polymer with high conductivity as a solid electrolyte, its equivalent series resistance component is lower than that of a dry electrolytic capacitor using a conventional electrolytic solution or a solid electrolytic capacitor using manganese dioxide. , A large-capacity and small-sized solid electrolytic capacitor close to the ideal can be realized, so that various improvements have been made, and the capacitor has been gradually accepted in the market.

In addition, in order to cope with high-density mounting of electronic equipment, these solid electrolytic capacitors are continuously taped on an embossed continuous hoop-shaped embossed carrier tape for automatic surface mounting of electronic components. After packaging, the embossed carrier tape was wound up on a reel and packed as it is in a packaging box before shipment. The mounting efficiency of the chip-type solid electrolytic capacitor packaged in this manner has been improved by mounting the reel on an automatic mounting machine and then automatically mounting the reel on a circuit board by the automatic mounting machine. In addition, surface mount components must have solder heat resistance that can withstand reflow and flow soldering under severe temperature conditions.Therefore, chip solid electrolytic capacitors with various improvements made to ensure these solder heat resistances Is being developed.

[0004]

However, in a conventional chip-type solid electrolytic capacitor in which a capacitor element using the above-described conductive polymer as a solid electrolyte layer is molded with an exterior resin, the capacitor element is mounted on a circuit board, and When exposed to high temperatures of reflow or flow conditions for soldering, it is rarely found that a change in capacitor characteristics or a change in characteristics over long-term reliability is caused.

[0005] As a result of studying the cause, the following has been found. In other words, when a chip-type solid electrolytic capacitor in which a capacitor element using a conductive polymer as a solid electrolyte is molded with an exterior resin is manufactured in a manufacturing process, even after the capacitor element is molded with an exterior resin,
Since the product is shipped after going through many heat processes such as the process of curing the exterior resin, it is almost dry at the time of shipment. Therefore, in this state, it is exposed to a high temperature condition under soldering conditions. It has been confirmed that no change in capacitor characteristics or change in long-term reliability characteristics will occur at all.

[0006] However, after shipment, it is subject to seasonal changes and environmental changes in the distribution process. Particularly, in the case of transportation in containers during the rainy season or when using a ship, the room temperature may be up to about 60 ° C. And the relative humidity may rise to about 90%, and under such an environment, the exterior resin in which the capacitor element is molded absorbs the moisture in the atmosphere and becomes a state of absorbing a considerable amount of moisture. .

The chip-type solid electrolytic capacitor that has passed through such an environment is exposed to the above-mentioned high temperature conditions of soldering while absorbing moisture, and the temperature of the elements of the solid electrolytic capacitor rapidly rises to a high temperature. In addition, due to the explosive expansion of the volume due to the boiling of the absorbed moisture, cracks may occur in the exterior resin or peeling may occur at the interface between the lead frame and the exterior resin, thereby increasing the leakage current value of the capacitor. It was found that the exterior airtightness was sometimes exposed. When the exterior airtightness is exposed in this way, oxygen in the atmosphere penetrates to the capacitor element, reacts with the conductive polymer which is a solid electrolyte, and deteriorates the conductivity of the conductive polymer, This proved that the mechanism was such that the capacitor characteristics gradually changed.

The present invention solves such a conventional problem. After a chip type solid electrolytic capacitor is left for a long time in an environment of high temperature and high humidity, it is mounted on a circuit board and soldered. It is an object of the present invention to provide a chip-type solid electrolytic capacitor which does not cause a problem in the characteristics and reliability of the capacitor even when heated at a high temperature.

[0009]

In order to achieve the above object, a chip-type solid electrolytic capacitor of the present invention is provided with an anodic oxide film on the surface of an electrode body made of a metal having a valve action.
A capacitor element comprising a solid electrolyte layer containing at least a conductive polymer provided on the anodic oxide film and a cathode conductor layer provided on the solid electrolyte layer; a lead frame connected to the capacitor element; and a lead frame connected to the capacitor element. Is provided with an exterior resin for molding the capacitor element so that a part of the exterior is led out, and a moisture-proof coating material is applied to the surface of the exterior resin. According to this configuration, the chip-type solid electrolytic capacitor Even if the capacitor is left in a high-temperature and high-humidity environment for a long time and then mounted on a circuit board and subjected to high-temperature heating for soldering, it does not cause a problem in the characteristics and reliability of the capacitor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an anodic oxide film is provided on the surface of an electrode body made of a metal having a valve action, and the anodic oxide film contains at least a conductive polymer. A capacitor element having a solid electrolyte layer, a cathode conductor layer provided on the solid electrolyte layer, a lead frame connected to the capacitor element, and the capacitor so that a part of the lead frame is led out. An exterior resin for molding the element is provided, and a moisture-proof coating material is applied to the surface of the exterior resin. According to this configuration, the capacitor element is molded so that a part of the lead frame is led out. Because the moisture-proof coating material is applied to the surface of the exterior resin, even if left for a long time in a high-temperature and high-humidity environment,
The moisture-proof coating prevents moisture from penetrating, thereby delaying the water from reaching the inside of the capacitor element, so that the capacitor element is molded even in the same environment. The moisture absorbed by the exterior resin is reduced. By reducing the moisture absorption, even if the capacitor is mounted on a circuit board and subjected to high-temperature heating for soldering after distribution, no problem occurs in the characteristics and reliability of the capacitor.

According to a second aspect of the present invention, a fluorine-based coating material dissolved in an organic solvent is used as a moisture-proof coating material, and the fluorine-based moisture-proof coating material dissolved in a volatile organic solvent is used. By using, the capacitor element is molded with the exterior resin, the exterior molding is performed, and then when the moisture-proof coating material is applied to the surface of the exterior resin, the lead frame can be dipped and applied to this coating material. In addition, since a volatile organic solvent is used, the drying process can be performed in a short time, and the coating process can be simplified.

According to a third aspect of the present invention, an anodic oxide film is provided on a surface of an electrode body made of a metal having a valve action, and a solid electrolyte layer containing at least a conductive polymer is provided on the anodic oxide film. A capacitor element having a cathode conductor layer provided on a solid electrolyte layer, a lead frame connected to the capacitor element, and an exterior resin for molding the capacitor element so that a part of the lead frame is led out. The chip type solid electrolytic capacitor provided is stored in the embossed pocket provided on the embossed carrier tape,
And take up this embossed carrier tape on a reel,
Furthermore, when the reel is packed and sealed with a packaging material, a desiccant is enclosed and sealed. According to this packing method, the effects of seasonal changes and environmental changes in the distribution process after shipping are achieved. In particular, when transporting in a condenser during the rainy season or when using a ship, the room temperature may be 60 ° C in some cases.
And the relative humidity may also rise to about 90%. However, even if the chip-type solid electrolytic capacitor is left in such a high-temperature and high-humidity environment, the chip-type solid electrolytic capacitor is placed in the embossed pocket provided on the embossed carrier tape. When storing and winding this embossed carrier tape on a reel, and then wrapping this reel with a packaging material and sealing it, a desiccant is enclosed and sealed. It is possible to realize a state that does not absorb moisture. As a result, even if the capacitor is mounted on a circuit board and subjected to high-temperature heating for soldering, it does not cause a problem in the characteristics and reliability of the capacitor.

According to a fourth aspect of the present invention, an anodic oxide film is provided on the surface of an electrode body made of a metal having a valve action, and a solid electrolyte layer containing at least a conductive polymer is provided on the anodic oxide film. A capacitor element having a cathode conductor layer provided on a solid electrolyte layer, a lead frame connected to the capacitor element, and an exterior resin for molding the capacitor element so that a part of the lead frame is led out. The chip type solid electrolytic capacitor provided is stored in the embossed pocket provided on the embossed carrier tape,
And take up this embossed carrier tape on a reel,
Furthermore, the reel is wrapped with a moisture-resistant packaging material and sealed, and in this packaging method,
Similarly to the invention according to claim 3, since the chip-type solid electrolytic capacitor is sealed with the moisture-proof packaging material even if it is left in a high-temperature and high-humidity environment in the distribution process after shipping, The solid electrolytic capacitor itself can realize a state that hardly absorbs moisture. As a result, even if the capacitor is mounted on a circuit board and subjected to high-temperature heating for soldering, it does not cause a problem in the characteristics and reliability of the capacitor.

Next, specific embodiments of the present invention will be described with reference to the accompanying drawings. (Embodiment 1) FIG. 1 shows a configuration of a capacitor element of a chip-type solid electrolytic capacitor according to Embodiment 1 of the present invention.
The surface of the electrode body 1 made of 9.99% aluminum is electrolytically etched by a known method to roughen the surface, and then a voltage of 59 V is applied with a 3% aqueous solution of ammonium adipate to form a surface for 30 minutes. Thus, the anodic oxide film 2 of aluminum oxide, which is a dielectric, is formed on the surface of the electrode body 1.
Was formed. Next, the punched cross section of the electrode body 1 was again placed in a 3% aqueous solution of ammonium adipate for 59%.
After applying a voltage of 30 V to form a cross-section for 30 minutes, 0.1 mol of pyrrole and 0.1 mol of alkyl naphthalene sulfonate were added.
The polymer was immersed in an aqueous solution containing 15 mol and subjected to electrolytic polymerization, whereby a conductive polymer of polypyrrole was uniformly deposited to form a solid electrolyte layer 3.

On the solid electrolyte layer 3, a cathode conductor layer 4 composed of a carbon paint layer and a silver paint layer
Was formed to form the capacitor element 5.

As shown in FIG. 2, a lead frame 6 is connected to the capacitor element 5 constructed as described above, and the capacitor element 5 is made of epoxy resin so that a part of the lead frame 6 is led out. Exterior resin 7
After performing exterior molding by molding with a lead frame 6
A chip-type solid electrolytic capacitor was formed by performing terminal processing and aging treatment of the above.

Then, the chip type solid electrolytic capacitor is immersed in a solution of silicon oil or isobutylene rubber to apply a moisture-proof coating material 8 on the surface of the exterior resin 7, and is vacuum impregnated at 5 torr for 5 minutes. A resin having a moisture-proof coating material 8 applied to the surface of the resin 7 was dried at 125 ° C. for 1 hour to form a chip-type solid electrolytic capacitor. Each chip-type solid electrolytic capacitor constructed as described above was left for 500 hours in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90%, and the result of measuring the moisture absorption from the change in weight is shown in Table 1.

[0018]

[Table 1]

(Embodiment 2) As the moisture-proof coating material 8, Florad FC- manufactured by Sumitomo 3M Limited is used.
722 (diluted with a perfluorocarbon solvent containing 2% of a fluorine-based polymer solid content), and immersed in this solution to apply a moisture-proof coating material 8 on the surface of the exterior resin 7; Impregnated and coated with a coating material 8 on the surface of the exterior resin 7 at room temperature
The mixture was left for 0 minutes to evaporate the solvent to form a chip-type solid electrolytic capacitor. Then, these chip-type solid electrolytic capacitors are placed in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90%.
The results obtained by measuring the moisture absorption from the change in weight after leaving for 00 hours are shown in Table 1 above.

Comparative Example 1 A chip-type solid electrolytic capacitor constructed in the same manner as in Embodiment 1 without applying the moisture-proof coating material 8 was left in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90% for 500 hours. The results obtained by measuring the moisture absorption from the change in weight are also shown in Table 1 above.

The first and second embodiments of the present invention described above
Changes in leakage current when the test capacitor left for 2 seconds at 250 ° C. in an atmosphere at 250 ° C. and the test for 500 hours at 125 ° C. and high temperature after solder heat resistance Change and tan δ
The occurrence rate of the abnormal value of the change is shown in Table 2 for each condition as the abnormal rate. The anomaly rate represents the occurrence rate of the data that changes away from the group of measured data. At this time, the data of the test of the test capacitor (Comparative Example 1) which is not left under high temperature and high humidity are shown in Table 2 together.

[0022]

[Table 2]

From the measurement results (Table 1) and (Table 2) comparing Embodiments 1 and 2 of the present invention and Comparative Example 1, the moisture-proof coating material 8 was applied to the surface of the exterior resin 7. It can be seen that the cured product has a lower moisture absorption rate to the exterior resin 7 than the non-coated one. It was also found that the vacuum impregnation of the coating material 8 had a slightly lower moisture absorption than that of the coating material 8 alone. Furthermore, when a fluorine-based material is used as the coating material 8, the moisture absorption rate tends to be lower than that of the other coating materials 8, which indicates that the effect as a moisture-proof coating material is large.

In Table 1, those having a low moisture absorption rate show in Table 2 that the change in leakage current during solder heat resistance is small. Further, it can be seen that the probability of causing a characteristic change (capacitance change, tan δ change) in a standing test at a high temperature of 125 ° C. after solder heat resistance is low. On the other hand, it is apparent that the higher the moisture absorption rate, the more the tendency is reversed. Therefore, it is effective to apply the moisture-proof coating material 8 for suppressing moisture absorption to the surface of the exterior resin 7. Was confirmed.

(Embodiment 3) A chip-type solid electrolytic capacitor 9 in which the moisture-proof coating material 8 shown in Embodiment 1 of the present invention is not applied to the surface of the exterior resin 7 is shown in FIG.
As shown in FIG. 2, the tape is housed in an embossed pocket 11 provided in an embossed carrier tape 10 and a sealing tape 12
Then, the embossed carrier tape 10 is wound on a reel 13, and the reel 13 finished with the winding has a thickness of 7 as shown in FIG.
In a 0 μm polyethylene packaging bag 14, and when the opening of the packaging bag 14 is heat-sealed for hermetic packaging,
A desiccant 15 of silica gel was enclosed and hermetically sealed, and then placed in a packaging box 16 shown in FIG.

The packaged as above is left for 500 hours in a high-temperature and high-humidity atmosphere at a temperature of 60 ° C. and a relative humidity of 90% as an accelerated evaluation, and then the package is opened. Change in leakage current value when a solder heat resistance test is performed by leaving the chip-type solid electrolytic capacitors 9 individually taken out in an atmosphere of 250 ° C. for 210 seconds and leaving them at a high temperature of 125 ° C. after solder heat resistance for 500 hours The change in the capacity and the change in the tan δ value in the test were measured, and the results were shown in Table 3 with the occurrence rate of those that changed apart from the group of measured data as the abnormal rate. The moisture absorption was measured from the change in weight before and after being left under high temperature and high humidity, and the value was also shown in Table 3 below.

[0027]

[Table 3]

(Embodiment 4) As in Embodiment 3 of the present invention, a chip-shaped solid in which the moisture-proof coating material 8 shown in Embodiment 1 of the present invention is not applied to the surface of the exterior resin 7 The electrolytic capacitor 9 is housed in an embossed pocket 11 provided on an embossed carrier tape 10 as shown in FIG. 3, and is covered with a sealing tape 12 to package the product.
Reel 3 and reel 1 after this winding
3 has a thickness of 12 in which an aluminum foil is laminated with a polyethylene film and a polyester film, as shown in FIG.
It was placed in a moisture-proof packaging bag 14 having a thickness of 0 μm, and the opening of the packaging bag 14 was heat-sealed and hermetically sealed, and then placed in a packaging box 16 shown in FIG.

The packaged as above was left for 500 hours in a high-temperature, high-humidity atmosphere at a temperature of 60 ° C. and a relative humidity of 90% as an accelerated evaluation, and then the package was opened. Change in leakage current value when a solder heat resistance test is performed by leaving the chip-type solid electrolytic capacitors 9 individually taken out in an atmosphere of 250 ° C. for 210 seconds and leaving them at a high temperature of 125 ° C. after solder heat resistance for 500 hours The change in the capacity and the change in the tan δ value in the test were measured, and the results were shown in Table 3 with the occurrence rate of those that changed apart from the group of measured data as the abnormal rate. The moisture absorption was measured from the change in weight before and after being left under high temperature and high humidity, and the value was also shown in Table 3 below.

(Comparative Examples 2-3) As a comparative example of the third and fourth embodiments of the present invention, embossed carrier tape 1
After the reel wound with 0 is packed in the packaging box 16 without being packed in the packaging bag 14 as in the present invention, the reel is left under high temperature and high humidity as in the third and fourth embodiments of the present invention. The same solder heat resistance test was performed on the sample that had absorbed moisture (Comparative Example 2) and the sample that was not left under high temperature and high humidity (Comparative Example 3), and then the capacity after being left at 125 ° C. for 500 hours. The change and the change in tan δ value were measured, and the results are shown in Table 3 together with the occurrence rate of those that changed apart from the group of measured data as the abnormal rate.

As is clear from the results shown in Table 3, the moisture absorption of the products according to Embodiments 3 and 4 of the present invention is significantly lower than that of Comparative Example 2. In addition, the degree is the same as that of Comparative Example 3 in which the semiconductor device was not left under high temperature and high humidity in the fourth embodiment of the present invention. Even if left unattended, it is possible to hardly absorb moisture.

It can also be seen that the smaller the amount of moisture absorption, the smaller the change in leakage current during solder heat resistance. Further, it can be seen that the probability of causing a characteristic change in a standing test at a high temperature of 125 ° C. after solder heat resistance is similarly reduced. From these results, it was confirmed that implementing the packaging method according to the third or fourth embodiment of the present invention was an effective means.

The coating material 8 used in the construction of the chip-type solid electrolytic capacitor 9 was evaluated with a material such as silicone oil, isobutylene rubber, or a fluorine-based polymer. However, the material is not limited to the above. Further, the method of application has been described with respect to immersion and vacuum impregnation, but the method of formation is not limited to these. Also, as the packaging material, the example of enclosing a desiccant of silica gel in a polyethylene bag having a thickness of 70 μm and the example of a polyfilm laminated with aluminum foil have been described, but are not limited to these materials. It goes without saying that any material that can achieve the same effect can be used similarly.

[0034]

As described above, in the chip-type solid electrolytic capacitor of the present invention, an anodic oxide film is provided on the surface of an electrode body made of a metal having a valve action, and the anodic oxide film contains at least a conductive polymer. A capacitor element provided with a solid electrolyte layer, and a cathode conductor layer provided on the solid electrolyte layer,
A lead frame connected to the capacitor element and an exterior resin for molding the capacitor element so that a part of the lead frame is led out to the outside are provided, and a moisture-proof coating material is applied to the surface of the exterior resin. According to this configuration, a moisture-proof coating material is applied to the surface of the exterior resin for molding the capacitor element so that a part of the lead frame is led out to the outside. Even if left for a long time in a humid environment, the moisture-proof coating material will prevent moisture from penetrating, thereby delaying the moisture from reaching the inside of the capacitor element. Even when placed in an environment, the exterior resin for molding the capacitor element absorbs less moisture. By reducing the moisture absorption, even after being mounted on a circuit board and subjected to high-temperature heating for soldering after distribution, no problem occurs in the characteristics and reliability of the capacitor.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view showing a configuration of a capacitor element of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an external shape of a chip-type solid electrolytic capacitor according to Embodiments 1 and 2 of the present invention.

FIG. 3 is a plan view showing a state in which a chip-type solid electrolytic capacitor according to Embodiments 3 and 4 of the present invention is housed in an embossed carrier tape.

FIG. 4 is a perspective view showing a state in which the reel on which the embossed carrier tape is wound is placed in a packaging bag.

FIG. 5 is a perspective view showing a state in which the packaging bag is put in a packaging box and packed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode body 2 Anodized film 3 Solid electrolyte layer 4 Cathode conductor layer 5 Capacitor element 6 Lead frame 7 Outer resin 8 Coating material 9 Chip type solid electrolytic capacitor 10 Emboss carrier tape 11 Emboss pocket 13 Reel 14 Packaging bag 15 Drying agent

Claims (4)

[Claims] An anodic oxide film is provided on a surface of an electrode body made of a metal having a valve action, a solid electrolyte layer containing at least a conductive polymer is provided on the anodic oxide film, and a cathode conductive film is provided on the solid electrolyte layer. A capacitor element provided with a body layer,
A lead frame connected to the capacitor element, and an exterior resin for molding the capacitor element so that a part of the lead frame is led out, is provided with a moisture-proof coating material on the surface of the exterior resin. Chip type solid electrolytic capacitor. 2. A fluorine-based coating material dissolved in an organic solvent as a moisture-proof coating material.
2. The chip-type solid electrolytic capacitor according to item 1. 3. An anodic oxide film is provided on the surface of an electrode body made of a metal having a valve action, a solid electrolyte layer containing at least a conductive polymer is provided on the anodic oxide film, and a cathode conductive film is provided on the solid electrolyte layer. A capacitor element provided with a body layer,
An embossed pocket provided on a embossed carrier tape with a lead frame connected to the capacitor element and a chip-type solid electrolytic capacitor provided with an exterior resin for molding the capacitor element so that a part of the lead frame is led out. And packaging the embossed carrier tape on a reel, and further sealing and sealing the reel with a wrapping material, wherein a desiccant is enclosed and sealed. 4. An anodic oxide film is provided on the surface of an electrode body made of a metal having a valve action, a solid electrolyte layer containing at least a conductive polymer is provided on the anodic oxide film, and a cathode conductive layer is provided on the solid electrolyte layer. A capacitor element provided with a body layer,
An embossed pocket provided on a embossed carrier tape with a lead frame connected to the capacitor element and a chip-type solid electrolytic capacitor provided with an exterior resin for molding the capacitor element so that a part of the lead frame is led out. The embossed carrier tape is wound around a reel, and the reel is further packaged with a moisture-resistant packaging material and hermetically sealed.