JPH056829U - Solid electrolytic capacitor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a fixed electrolytic capacitor in which leakage current and equivalent series resistance do not increase even if a resin coating is applied to the capacitor element. A dielectric oxide film is formed on the surface of a substrate capable of forming a dielectric oxide film, an insulating resin thin film layer is formed on the dielectric oxide film layer, and a heterocyclic ring is formed on the insulating resin thin film layer. In a solid electrolytic capacitor comprising a conductive polymer layer of a formula compound and a conductive layer, the conductive layer serving as one electrode and the metal substrate serving as the other electrode, one of the capacitor elements A metal terminal is attached to the electrode and the other electrode, and a wax layer as a first undercoat is formed on the outer surface of the capacitor element.
A low thermal expansion coefficient resin layer as an undercoat for
Is characterized in that a wax layer is sequentially formed as an undercoat and a resin layer is further formed as an exterior.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention charges an organic semiconductor of a heterocyclic compound such as pyrrole, furan and thiophene. The present invention relates to a solid electrolytic capacitor to be degraded.

[0002]

[Prior art]

  Conventionally, as a solid electrolytic capacitor, for example, JP-A-60-244017, There is one disclosed in JP-A-61-2315. This solid electrolytic capacitor On the surface of a metal substrate on which a dielectric oxide film such as aluminum is formed, Coating layer, conductive polymer layer of heterocyclic compound, graphite layer, silver paste layer One by one, the metal substrate was used as one electrode and the silver paste layer was used as the other electrode. It is provided with a capacitor element.

[0003]

[Problems to be solved by the device]

  The capacitor element having the above-mentioned structure is subjected to a thermal shock test, for example, at a temperature of −55 ° C. There is no increase in leakage current in the thermal shock of + 105 ° C, but the exterior is made of resin. By applying the stress, the resin exterior receives stress, which results in leakage current and equivalent series resistance. There is a problem that (ESR) increases.

[0004]   The present invention has been made in view of the above points, and the capacitor element is provided with a resin exterior. However, a solid electrolytic capacitor that does not increase leakage current and equivalent series resistance is proposed. The purpose is to serve.

[0005]

[Means for Solving the Problems]

  In order to solve the above problems, the present invention is directed to the surface of a substrate on which a dielectric oxide film can be formed. After forming the dielectric oxide film, the surface of the dielectric oxide film is divided on the dielectric oxide film layer. An insulating resin thin film layer is formed, and the dielectric oxide is divided by the insulating resin thin film layer. A conductive polymer layer of a heterocyclic compound and a conductive layer are sequentially formed on the coating, and the conductive layer A capacitor element having a body layer as one electrode and the metal substrate as the other electrode In the solid electrolytic capacitor, the one electrode and the other electrode of the capacitor element Attach a metal terminal and attach a first undercoat on the outer surface of the capacitor element. The wax layer as a layer, the linear expansion coefficient as the second undercoat layer is 2.5 ×     -Five A resin layer of 10 / ° C or less and a wax layer as a third undercoat layer are sequentially formed. And a resin layer is formed as an exterior.

[0006]

[Action]

  By configuring the solid electrolytic capacitor as described above, the first undercoat layer and The wax layer used as the second undercoat layer is, for example, an epoxy resin layer. Equivalent series (ESR) of the capacitor increases due to the organic solvent when using a resin material It has the effect of preventing In addition, low thermal expansion as the second undercoat layer The resin layer having a tensile coefficient has a function of improving the thermal shock performance of the capacitor. Furthermore, The wax layer as the third undercoat layer improves the weather resistance, that is, the equivalent series resistance. It has the effect of preventing an increase in resistance. Thus, in the present invention, the first, second and And the action of the third undercoat layer reduce the leakage current and the equivalent series resistance of solids. An electrolytic capacitor can be provided.

[0007]

【Example】

  FIG. 1 is a diagram showing the structure of the solid electrolytic capacitor of the present invention, and FIG. An external view, FIG. 1B is a sectional view of the capacitor portion. In the figure, 1 is conden The capacitor element 1 forms a dielectric oxide film such as aluminum oxide. After forming a dielectric oxide film on the surface of a metal substrate such as An insulating resin thin film layer for partitioning the surface of the dielectric oxide film is formed on the dielectric oxide film layer. , Pyrrole, thiophene, on one oxide film divided by the insulating resin thin film layer, A conductive polymer layer of a heterocyclic compound such as furan is formed, and a grapha And a conductor layer such as a silver paste layer, and the conductor layer is used as one electrode, The metal substrate is the other electrode

[0008]   The manufacturing method of this capacitor element is described in the above-mentioned conventional example, Japanese Patent Laid-Open No. 60-244. The details are disclosed in Japanese Patent Application Laid-Open No. 017 and Japanese Patent Application Laid-Open No. 61-2315, so here Then, the explanation is omitted. In addition, the one electrode of the capacitor element 1 and the other electrode Metal terminals 2 and 3 are attached to the poles, respectively.

[0009]   The outer surface of the capacitor element 1 has a first undercoat layer 4 and a second undercoat layer. The coat layer 5 and the third undercoat layer 6 are sequentially formed. In addition, the third An exterior 7 is formed on the outer side of the undercoat layer 6.

The first undercoat layer 4 prevents the entry of H ₂ O, O ₂ , organic solvents, etc. into the capacitor element 1 when the second undercoat layer 5 is formed of a resin material. The wax layer formed for the purpose is formed by immersing and impregnating the capacitor element 1 in polyethylene wax or fluorine wax. The thickness of this wax layer is several μm.

[0011]                                                      -Five   The second undercoat layer 5 is a resin material having a linear expansion coefficient of 2.5 × 10 5 / ° C. or less. Formed by. For example, 40 times silica or silica is added to a phenolic epoxy resin. % Or more is used. The layer thickness is 10 μm to 20 μm.

[0012]   The third undercoat layer 6 has improved weather resistance, that is, a capacitor element in weather resistance. 1 for preventing an increase in the equivalent series resistance of the first undercoat layer 4 and Similarly, dip it in polyethylene wax or fluorine wax to impregnate it. It is formed by and. The layer thickness is several μm.

[0013]   The exterior 7 is heated at a high temperature in, for example, epoxy powder for the purpose of improving strength and airtightness. So-called fluid immersion powder coating, in which a capacitor element is inserted and the surrounding powder is melted to form It is formed by clothing. The thickness of the layer is several 0.2 mm to 1.5 mm. The metal terminal 2 , 3 extend to the outside of the exterior 7 to form a lead type capacitor.

[0014]   By configuring the solid electrolytic capacitor as described above, as described above, As the wax layer as the overcoat layer 4, the second undercoat layer 5 is formed by, for example, epoxy. Prevention of increase in equivalent series resistance of capacitors due to organic solvent etc. when forming with resin material Is formed of a resin layer having a low coefficient of thermal expansion, the second undercoat layer 5 is The wax layer as the third undercoat layer 6 is weatherproofed to improve the thermal shock performance. This prevents the increase of the equivalent series resistance. Therefore, the solid electrolytic capacitor The capacitor becomes a solid electrolytic capacitor with little leakage current and equivalent series resistance.

[0015]   FIG. 2 is a partially cut external view showing another structure of the solid electrolytic capacitor of the present invention. Figure In FIG. 2, the parts denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In Figure 2 8 is a case, and inside the case 8, the outer surface of the capacitor element 1 is 1 undercoat layer 4, 2nd undercoat layer 5 and 3rd undercoat A capacitor element in which layer 6 is sequentially formed is inserted, and a third undercoat layer 6 and a case are formed. Epoxy resin is injected into 8 to form a resin layer 9.

[0016]   FIG. 3 shows a wack which is the first undercoat layer 4 and the third undercoat layer 6. It is a figure which shows the effect of operation when there is a spatter layer, and when it does not. Wack as shown If a layer is provided, the series equivalent resistance (ESR) increases by 0 to 5%, and the capacitance change during moisture absorption. The ratio is about 5%, while the series equivalent resistance increases without the wax layer. 10 to 30%, the capacity change when absorbing moisture is around 5% to 15%, and the equivalent series resistance increases. Addition is greatly improved, and capacity change is small.

[0017]   FIG. 4 shows the function and effect of the low thermal expansion coefficient resin layer which is the second undercoat layer 5. It is a figure. As shown in the figure, 100 cycles were performed at an impact temperature of -55 ° C to + 105 ° C. As a result, the leakage current defect rate was 0% when the low thermal expansion coefficient resin layer was provided. On the other hand, when the low thermal expansion coefficient resin layer is not provided, it is 50 to 80%. By providing several resin layers, the rate of occurrence of leakage current (LC) defects due to thermal shock is high Improved in width.

[0018]   FIG. 10 shows the linear expansion coefficient of the resin used for the undercoat layer 5 and the thermal shock of the capacitor. It is an experimental result which shows correlation with data. The solid used as a sample in this experiment The body electrolytic capacitor is rated at a voltage of 16 VG, a capacity of 3.3 μF, and a test temperature range of −55. C. to + 125.degree. C., thermal shock 50 cycles, leakage current of 1 .mu.A or more were regarded as defects. Illustration                                 -Five As described above, when the linear expansion coefficient is 2.5 × 10 ° C. or less, the defective rate is 0%.

[0019]   FIG. 5 is a diagram showing the capacity change during the pressure cooker test. In the case of solid electrolytic capacitor, the capacitance change rate ΔC / C [%] exceeds 25%. On the other hand, the solid electrolytic capacitor of the present invention has a capacity of 5% or less, which is a significant improvement in capacitance change. I can do good.

[0020]   FIG. 6 is a diagram showing a leakage current (LC) defect occurrence rate in a thermal shock test. I will show you As in the case of conventional solid electrolytic capacitors, defects occur as the number of test cycles increases. However, the solid electrolytic capacitor of the present invention has no defects and the The occurrence rate of leakage current defects against strikes is greatly improved.

[0021]   FIG. 7 is a sectional view showing another structure of the solid electrolytic capacitor of the present invention. I will show you As described above, the present solid electrolytic capacitor has the first underlayer on the outer surface of the capacitor element 1. -Coat layer 4, second undercoat layer 5 and third undercoat layer 6 in that order After the formation, the molding resin exterior 10 is formed on the outside of the undercoat layer 6. It Metal terminals 2 and 3 attached to both electrodes of the capacitor element are molded resin exterior Bend both sides of 10 to the bottom and expose the terminals on the bottom of the exterior 10. It is a so-called chip type capacitor.

[0022]   The second undercoat layer 5 is formed by forming the second undercoat layer 5 as shown in FIG. A mold-forming silicon rubber base 11 having a recess 11a having the same shape is prepared. A silicon rubber stand 11 having a first undercoat layer 4 formed in a concave portion 11a thereof. After accommodating the capacitor element 1, the same low thermal expansion as the second undercoat layer 5 in FIG. Pour the coefficient of tension resin. Then, the wack that is the third undercoat layer 6 Then, the outer layer is formed, and finally, the mold resin exterior is formed.

[0023]   The chip-type capacitor with the above configuration is similar to other electronic components in reflow soldering. Since it is mounted by mounting, it is required that the thermal shock characteristics are particularly good. Figure 9 above The leakage current (LC) failure occurred in the thermal shock test of the chip type solid electrolytic capacitor. It shows the raw rate. As shown in the figure, the rated voltage is 16V and the capacity is 3.3μF. Conducted a 50-cycle thermal shock test on solid electrolytic capacitors at a temperature of -55 ° C to + 125 ° C. As a result, 50/50 of the conventional one had a defective leakage current, but The defector rate was 0/50, that is, the defect rate was zero.

[0024]

[Effect of device]

  According to the present invention as described above, the first, second and third undercoat layers are provided. Can provide a solid electrolytic capacitor with low leakage current and equivalent series resistance. The excellent effect of

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a solid electrolytic capacitor of the present invention, in which FIG. 1A is a partially cut external view and FIG.

FIG. 2 is a partially cut external view showing another configuration of the solid electrolytic capacitor of the present invention.

FIG. 3 is a diagram showing a function and effect with and without a wax layer which is a first undercoat layer and a third undercoat layer.

FIG. 4 is a diagram showing a function and effect of a low thermal expansion coefficient resin layer which is a second undercoat layer.

FIG. 5 is a diagram showing a change in capacity during a pressure cooker test.

FIG. 6 is a diagram showing a leakage current defect occurrence rate in a thermal shock test.

FIG. 7 is a cross-sectional view showing another configuration of the solid electrolytic capacitor of the present invention.

8 is a diagram for explaining a method 0 of forming a second undercord of the solid electrolytic capacitor shown in FIG. 7. FIG.

FIG. 9 is a graph showing a leakage current defect occurrence rate in a thermal shock test of the chip type solid electrolytic capacitor of the present invention.

FIG. 10 is a diagram showing an experimental result of a correlation between a linear expansion coefficient of a resin used as a second undercoat layer and thermal shock data of a capacitor.

[Explanation of symbols]

1 Capacitor element 2,3 metal terminals 4 First undercoat layer 5 Second undercoat layer 6 Third undercoat layer 7 Exterior 8 cases 9 resin layer 10 Mold resin exterior

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Creator Koji Izawa             260 Kitakatakata, Takatsu-ku, Kawasaki City, Kanagawa Prefecture             At Tsuko Co., Ltd. (72) Inventor Keizo Ikari             260 Kitakatakata, Takatsu-ku, Kawasaki City, Kanagawa Prefecture             At Tsuko Co., Ltd.

Claims (6)

[Scope of utility model registration request] 1. A dielectric oxide film is formed on the surface of a substrate capable of forming a dielectric oxide film, and then an insulating resin thin film layer for partitioning the dielectric oxide film surface is formed on the dielectric oxide film layer. , A conductive polymer layer of a heterocyclic compound and a conductor layer are sequentially formed on one oxide film divided by the insulating resin thin film layer, the conductor layer is one electrode, and the metal substrate is the other. In a solid electrolytic capacitor including a capacitor element as an electrode of, a metal terminal is attached to one electrode and the other electrode of the capacitor element, and
Wax layer as the undercoat layer of the second 3. A solid electrolytic capacitor according to 3, wherein a wax layer as an undercoat layer is sequentially formed, and a resin layer is further formed as an exterior. 2. A solid electrolytic capacitor characterized in that the capacitor element having the first to third undercoat layers formed therein is inserted into a case, and an epoxy resin injection layer is formed between the capacitor element and the case. 3. The solid electrolytic capacitor according to claim 1 or 2, wherein the metal terminal attached to the electrode is extended to the outside of the package to form a lead type capacitor. 4. The solid electrolytic capacitor element according to claim 1, wherein the resin layer as the exterior is formed by inserting a capacitor element heated at high temperature into a resin powder layer and melting the resin powder on the surface of the capacitor element. Solid electrolytic capacitor characterized by being a thing. 5. The solid electrolytic capacitor according to claim 1, wherein the resin layer as the outer package is formed by resin molding. 6. The solid electrolytic capacitor according to claim 5, wherein the metal terminals attached to the electrodes are exposed on the outer surface of the package to form a chip type.