JPH01287919A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent the deterioration of TCNQ salt as an oxide film and an organic semiconductor formed on the anode of a capacitor element by a method wherein the capacitor element is coated with a specific resin which practically does not react with the TCNQ salt. CONSTITUTION:After TCNQ salt 2 has been impregnated into a capacitor element 1, it is cooled down and solidified, and the capacitor element 1 is coated with denatured acrylate resin 8, cyanoacrylate resin, or nylon resin. As the above-mentioned denatured acrylate resin 8, cyano acrylate resin or nylon resin has the mechanical strength and the heat-resisting property in the same degree as epoxy resin, said resins are suitable for coating on the capacitor element 1, and at the same time, they practically do not react with the TCNQ salt 2. As a result, the deterioration of the organic semiconductor 2, as the oxide film and a solid electrolyte formed on the positive electrode of the capacitor element 1, caused by the reaction of epoxy resin with an organic semiconductor 2 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a solid electrolytic capacitor using TCNQ salt as an organic semiconductor.

(b) Conventional technology Conventionally, organic semiconductors, especially TCNQ salt (herein, TCNQ is 7.7.8.
8 (meaning tetracyanoquinodimethane)) (Japanese Patent Publication No. 62-52939 (H
(See OIG 9102).

In the above conventional technology, an appropriate amount of organic semiconductor powder made of TCNQ salt is stored under moderate pressure in a thermally conductive case (aluminum case), and the powder is heated to 250 to 300°C.
The capacitor element, which has been preheated, is immersed in the capacitor element. Furthermore, after rapidly cooling the capacitor element together with the case, the opening of the case is filled with a thermosetting resin, such as an epoxy resin, and the epoxy resin is cured by heating at a temperature of 85 to 105° C. for a long period of time. FIG. 9 is a sectional view showing the structure of the conventional solid electrolytic capacitor described above.
) is a capacitor element, (2) is TCNQ salt (organic semiconductor), (3) is a case, (4) is an epoxy resin, (5)
is a lead boss, (6) is an anode lead wire, and (7) is a cathode lead wire. In addition, in the case of the so-called resin dip type, in which the capacitor element is not housed in a case, as shown in Figure 9,
Cover the entire capacitor element with epoxy resin (full resin sealing).

In such a conventional solid electrolytic capacitor, the oxide film completely formed on the anode of the capacitor element (1) and the organic semiconductor as the solid electrolyte deteriorate due to the reaction between the thermosetting resin and the organic semiconductor. As a result, the oxide film has weak parts due to the above factors, leading to increased leakage current and short circuit when high voltage is applied. Furthermore, during soldering, the weak parts of the oxide film are sometimes destroyed due to thermal stress during heating, leading to an increase in leakage current.

(c) Problems to be Solved by the Invention The present invention solves the above problems, that is, the oxide film formed on the anode of a capacitor element and the organic semiconductor as a solid electrolyte,
This solves the problem of deterioration due to the reaction between epoxy resin and organic semiconductor, which increases leakage current when high voltage is applied or during soldering.

(d) Means for Solving the Problems In the present invention, a capacitor element is impregnated with TCNQ salt, cooled and solidified, and the capacitor element is coated with a modified acrylate resin, a cyanoacrylate resin, or a nylon resin. Furthermore, after being coated with the modified acrylate resin, cyanoacrylate resin, or nylon resin, it is further coated with an epoxy resin having particularly excellent moisture resistance.

In addition, if the capacitor element is to be housed in a case rather than a so-called resin dip type in which the entire surface is sealed with resin, the capacitor element is covered with a modified acrylate resin, cyanoacrylate resin, or nylon resin that covers the opening of the case. This is to seal the area. Furthermore, the opening of the case is coated with an epoxy resin having particularly excellent moisture resistance.

(e) Action-modified acrylate resin, cyanoacrylate resin,
Nylon resin has the same mechanical strength and heat resistance as epoxy resin, so it is suitable for covering capacitor elements, and it hardly reacts with TCNQ salt, so it can be used to coat oxide films and TCNQ salt (organic semiconductors). ) will not deteriorate.

Furthermore, if the modified acrylate resin, cyanoacrylate resin, or nylon resin is coated with an epoxy resin, moisture can be doubly prevented from entering the capacitor element. In addition, at this time, a resin layer that hardly reacts with the TCNQ salt is formed between the epoxy resin and the TCNQ salt, so the oxide film and TCNQ salt (organic semiconductor) deteriorate due to the reaction between the epoxy resin and the TCNQ salt. There's nothing to do.

In addition, if the capacitor element is coated with a nylon resin having a thickness of 1 mm or less, and then further coated with an epoxy resin, a sufficient thickness of the epoxy resin, which has particularly excellent moisture resistance, can be obtained, and it is possible to obtain a sufficient thickness of the epoxy resin, which has particularly excellent moisture resistance. It has the same level of moisture resistance as conventional solid electrolytic capacitors.

(f) Examples The present invention will be explained below with reference to FIGS. 1 to 8. Incidentally, the same parts as in the prior art are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention. First, an aluminum foil that has been subjected to etching treatment and chemical conversion treatment is used as an anode foil, separated between it and an opposing cathode foil, and then rolled up into a cylindrical shape to form a capacitor element (1).

Next, powder of TCNQ salt (2), for example, TCNQ salt of N-n-butylisoquinolinium ((N-n-butylisoquinolinium)” (TCNQ)-(TCNQ)), is placed in case (3). TCNQ salt (2
) is melted and liquefied. Furthermore, 29 pieces of melted and liquefied TCNQ salt
Maintain the temperature between 0℃ and 300℃, capacitor element (1)
to impregnate with TCNQ salt (2). After the impregnation, the case (3) is cooled, and the TC impregnated into the capacitor element (1) is
The NQ salt (2) is cooled and solidified, and the capacitor element (1) is fixed in the case (3). Note that the time from melting and liquefying the TCNQ salt (2) to cooling and solidifying it must be within about 4 minutes; after this time, the organic semiconductor becomes almost an electrical insulator.

Next, in case (3), the modified acrylate system m5 (8〉(
For example, the product name 'Vegalock, 1 manufactured by Kosatsu Gas Kogyo Co., Ltd.
Part number 9073) is injected to form a capacitor element 'f-(1)
At the same time, the opening (3a) of the case (3) is sealed. The modified acrylate resin (8) is cured by being left at room temperature (20°C to 30°C) for about 2 hours.

FIG. 2 is a sectional view showing a solid electrolytic capacitor according to another embodiment of the present invention. As mentioned above, the capacitor element (1)
is fixed in the case (3) by cooling and solidifying after impregnation with TCNQ salt (2), and then the capacitor element (1) is coated with modified acrylate resin (8). At this time, the amount of modified acrylate resin (8) is much smaller than in the case of FIG. 1 described above, and is not sufficient to seal the opening (3a) of the case (3). 1
) is coated with the modified acrylate resin (8), and then left to stand at room temperature (20° C. to 30° C.) for about 2 hours as described above to harden the wood Ji11 (8).

Next, epoxy resin (4) (for example, trade name "Epifutonyo" manufactured by Tanabe Chemical Industry Co., Ltd.) is injected into the case (3), and the capacitor element (1) is doubled over the modified acrylate resin (8). The epoxy resin (4) is then cured through primary curing at 85° C. for 2 hours and secondary curing at 105° C. for 15 hours.

Table 1 shows a comparison of the initial characteristics of the thus completed solid electrolytic capacitor of the present invention and a conventional solid electrolytic capacitor at 20°C.

(Hereafter, blank space) Table 1 In Table 1, (A >, (B), (C) are rated voltage 25V, capacity 3.311F, (D), (E), (F
) Rated voltage 35V, 4.7up (7) Ko? /
In the capacitor, (A) and (D> have the structure shown in FIG. 1 of the present invention described above, (B) and (E) have the structure shown in FIG. 2 of the present invention described above, and (C) and (F') have the structure shown in FIG. This is the structure of the conventional example described above as shown in Fig. 9.Car is the capacitance at 120Hz, t
and.delta. is the dielectric loss tangent at 120 Hz, LC is the leakage current data and indicates the value (μ^) and yield rate (%) after 15 seconds of application of the rated voltage, and ESR is the equal series resistance at 100 kHz. In addition, all numerical values are average values of 10 samples except for LC. Regarding LC, the average value of 10 good products within the standard is shown, and the yield is the yield of 50 samples, but the LC standard for each model is 25V, 3.3
For J, 1, 6 (IJA/15sec, ) or less, 3
5V, 4.7LP (7) case Ha 3.3 (u^/15se
(,) is below. From Table 1, it can be seen that the product of the present invention has significantly improved yield of leakage t flow compared to the conventional product.

Table 2 shows a comparison of the characteristics of the products of the present invention and the conventional products before and after soldering using glue flow soldering equipment.

Table 2 In Table 2, (G), (H), and (I) are capacitors with a rated voltage of 25 V and a capacity of gk1iiF+, (G) is the structure of the present invention shown in FIG. The structure shown in FIG. 2 of the present invention is shown in FIG. 2, and (I) is the structure shown in FIG. 9 of the conventional example described above. The description of each characteristic value is the same as that in Table 1 above, but the LC value is different from that in Table 1.
This is the average value of 10 items including defective items. From Table 2, it can be seen that the products of the present invention are extremely resistant to soldering compared to the conventional products in terms of leakage current value (LC), and are also excellent in tan8.

FIG. 3 is a sectional view showing a solid electrolytic capacitor according to another embodiment of the present invention. As mentioned above, the capacitor element (1)
is fixed in the case (3) by cooling and solidifying after impregnation with the TCNQ salt (2), and the capacitor element (1) is coated with a cyanoacrylate resin (9) (for example, 2-cyanoacrylate monomer, Toagosei Chemical Industry Co., Ltd.). 0.03cc~0.
Drop 2 cc to completely cover the surface of the capacitor element (1). The amount of the cyanoacrylate resin (9) dropped is approximately proportional to the outer diameter of the capacitor element (1). The curing of the 2-cyanoacrylate monomer (formation of a 2-cyanoacrylate polymer by polymerization of the 2-cyanoacrylate monomer) is completed by leaving it at room temperature (20 to 30"C) for about 12 hours.

After curing, apply the above-mentioned epoxy resin (4) to the case (3).
is injected to seal the opening (3a). This epoxy resin (4) is cured through primary curing at 85° C. for 2 hours and secondary curing at 105° C. for 15 hours. Table 3 shows a comparison of the initial characteristics of the thus completed solid electrolytic capacitor (Fig. 3) and a conventional solid electrolytic capacitor at 20°C.

(Left below) Table 3 In Table 3, (J) and (K) are rated voltage 25v and capacity ILF, (L) and (M> are rated voltage 25v and capacity 10
IJI-1 (N), (0) has a rated voltage of 25V and a capacity of 10
y, (P), (Q) are rated voltage EE35V, capacity 4.71
JF, (R), (S) are rated at 1 pressure 35V, capacity! 2.2L
This is an IF capacitor. Also, (J), (L),
(N), (P), and (R) are the structures shown in FIG. 3 of the present invention, and (K), (M), (0), (Q), and (S) are the structures shown in FIG. 9 of the conventional example. It is a structure. Furthermore, (J) is the above-mentioned “Aron Alpha J,” manufactured by Toagosei Kagaku Kogyo Co., Ltd. (
L) is the same company's "Aron Alpha [F] 201", (N)
1 Cemedine 3000 Gold J manufactured by Cemedine Co., Ltd. (P)
R) uses 1 Cemedine woodworking grade 3000 J manufactured by the same company as the cyanoacrylate resin (9).

The description of each characteristic value is omitted because it is the same as that in Table 1 above, but unlike in Table 1, for LC, the value (U^) and yield (%) after 30 seconds of applying the rated voltage are It shows. In addition, except for LC, all numerical values are average values of 20 samples. Regarding LC, the average value of 20 non-defective products within the specifications is shown, and the yield is the yield of each 100 samples, but the LC standard for each model is 25V, and in the case of ILIF, it is 0.
25 (IJA/30sec, ) or less, 25V, 1
In the case of OW, 2.5 (u^/30sec, ) or less, 3
5v.

In the case of 4.7W, it is 1.6 (IJA/30sec, ) or less, and in the case of 35L 2.21JF, it is 0.77 (μ^/3
0sec, ) or less. It can be seen from Table 3 that the products of the present invention are significantly improved in yield (%) of leakage current <LC> compared to conventional products.

FIG. 4 is a sectional view showing a solid electrolytic capacitor according to an embodiment of the present invention. That is, in the structure of the present invention described above (FIGS. 2 and 3t5), the epoxy resin layer, which has particularly excellent moisture resistance, is made of a modified acrylate resin or cyanoacrylate resin that covers the capacitor element, and is made as thin as the epoxy resin layer that is particularly excellent in moisture resistance. Since its moisture resistance is worse than conventional products, the capacitor element is coated with modified acrylate resin or nylon resin, which can be formed thinner than cyanoacrylate resin. As mentioned above, the capacitor element (1) is fixed in the case (3) by cooling and solidifying after impregnating with TCNQ salt (2), and the capacitor element (1) is coated with nylon resin (for example, General Tsusho Co., Ltd. product name: Nycoat MT25J) and inject it up to the opening (3a) of the case (3).The above nylon resin is a liquid nylon resin with lower alcohol as the main solvent, and is heated at room temperature (20°C to 30°C). ) from 1 to
Leave it for about 8 hours (approximately proportional to the outer diameter of the element) to evaporate the solvent in the liquid nylon resin, and then remove the capacitor element (1).
A film of nylon resin (10) with a thickness of 1 m or less is formed on top. Case (3) after formation of the nine film (after solvent evaporation)
) as mentioned above. Epoxy resin (4) is injected to double cover the capacitor element (1) from above the nylon resin (10) and seal the opening (3a) of the case (3).

This epoxy resin (4) is then cured through primary curing at 85° C. for 2 hours and secondary curing at 105° C. for 15 hours.

Table 4 shows a comparison of the characteristics of the thus completed solid electrolytic capacitor of the present invention and a conventional solid electrolytic capacitor soldered by flow soldering before and after soldering using the device.

(Hereinafter, blank spaces) Table 4 In Table 4, (T), (U), and (V) are capacitors with a rated voltage of 25 cm and a capacity ILJP, and (T) is the capacitor shown in Fig. 4 of the present invention described above. The structure, (U) is the structure shown in FIG. 9 of the conventional example described above, and (V) is the structure shown in FIG. 2 of the invention described above. In addition, CaP is the capacitance at 120Hz,
tan δ is the dielectric loss tangent at 120 Hz, LC is the leakage current data and indicates the value (+1^) 15 seconds after application of the rated voltage, and ESR is the equal series resistance at 100 kHz. All numerical values are average values of 10 values. Table 4 shows that the product of the present invention (Figure 4) has a leakage current (LC) of
It can be seen that this product is extremely resistant to soldering compared to the conventional product using only epoxy resin (Fig. 9).

Table 5 shows a comparison of the moisture resistance properties of the products of the present invention and the conventional products in a pressure courier test (conditions = 120° C., 2 atm, 32 hours).

Table 5 In Table 5, (W), (X), and (Y) are the rated voltage 2
5V, capacity 11y capacitor, (W> is the structure shown in FIG. 4 of the present invention described above, (X) is the structure shown in FIG. 9 of the conventional example described above, (Y) is the structure shown in FIG. It has the structure shown in the figure.The explanation of each characteristic value is the same as that in Table 4 above.Table 5 shows that the product of the present invention (No. 4130) has the same moisture resistance as the product using modified acrylate resin. It can be seen that the moisture resistance properties are extremely good compared to the invented product (Fig. 2) and are on the same level as the conventional product (Fig. 9) using only epoxy resin.

In this embodiment, the case of the type in which the capacitor element is housed in the case has been described, but it may also be of the so-called resin de-1 knob type in which the capacitor element is entirely sealed with resin without using a case, for example, as shown in Fig. 5. 6 shows a case where a modified acrylate resin is used, FIG. 7 shows a case where a cyanoacrylate resin is used, and FIG. 8 shows a case where a nylon resin is used.

(G) Effects of the Invention As described above, according to the present invention, the capacitor element is TCN
Since the coating is made with a modified acrylate resin, cyanoacrylate resin, or nylon resin that hardly reacts with Q salt, the oxide film formed on the anode of the capacitor element and the TCNQ salt as an organic semiconductor will interact with the epoxy resin. Deterioration due to reaction with TCNQ salt is prevented, leakage current does not increase when applying high voltage or during soldering, and yields are significantly improved compared to conventional products. In addition, if the capacitor element is coated with a nylon resin with a thickness of 1 a or less and then further coated with an epoxy resin, the epoxy resin layer will be approximately the same thickness as the conventional product in which the capacitor element is coated with only epoxy resin. can be formed, so the moisture resistance can be improved compared to when modified acrylate resin or cyanoacrylate resin is used, and it can be made to the same level as conventional products.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a solid electrolytic capacitor according to an embodiment of the present invention, FIGS. 2, 3, and 4 are sectional views showing an embodiment of a pond, respectively, and FIGS. 8 and 8 are sectional views showing an embodiment of the resin dip type, respectively, and FIG. 9 is a sectional view showing a conventional example. (1) Capacitor element, (2) TCNQ salt (organic semiconductor), (3) Case, (4) Epoxy resin, (8) Modified acrylate resin ,
(9)...Cyanoacrylate resin, (10)...
・Nylon resin.

Claims (4)

[Claims] (1) A capacitor element in which an anode foil and a cathode foil are wound with a separator in between, TCNQ salt that is impregnated into the capacitor element and solidified by cooling, and a modified acrylate resin and a cyanoacrylate resin that cover the capacitor element. A solid electrolytic capacitor characterized in that it is made of , or nylon resin. (2) The solid electrolytic capacitor according to claim 1, wherein the capacitor element is coated with the modified acrylate resin, cyanoacrylate resin, or nylon resin and then further coated with an epoxy resin. (3) The solid electrolyte according to claim (1), wherein the capacitor element is housed in a case, and an opening of the case is sealed with the modified acrylate resin, cyanoacrylate resin, or nylon resin. capacitor. (4) The solid electrolytic capacitor according to claim (3), wherein the opening of the case is further sealed with an epoxy resin.