KR19990033263A - Manufacturing Method of Chip Aluminum Solid Electrolytic Capacitor - Google Patents

Abstract

The present invention relates to a method of manufacturing a chip-type aluminum solid electrolytic capacitor, and more particularly, to a device manufactured by sequentially forming a conductive polymer, a carbon layer, and a silver layer on a surface of an aluminum foil having a single-plate dielectric oxide film formed thereon. A method of manufacturing a chip-shaped aluminum solid electrolytic capacitor by transfer molding using an external resin for shaping chips after electrically connecting to a frame, wherein the lead frame is electrically connected to protect internal elements from the pressure of transfer molding. After forming a protective layer or a protective film using a material having excellent hardness, elasticity and insulation resistance on the whole or a part of the device, and fabricated a chip-shaped aluminum solid electrolytic capacitor by transfer molding method using the EMC as an external resin material as described above. To protect internal components from transfer molding The electrolytic capacitor and the leakage current characteristic of the chip-type aluminum solid capable of improving the yield to provide a method of manufacturing a capacitor.

Description

Manufacturing Method of Chip Aluminum Solid Electrolytic Capacitor

The present invention relates to a method for producing a chip-shaped aluminum solid electrolytic capacitor, and more particularly, to a method for manufacturing the capacitor, which improves leakage current characteristics and yield by protecting the aluminum foil from transfer molding.

A structure of a general aluminum solid electrolytic capacitor is formed by forming a dielectric oxide film on an electrolytically etched aluminum foil as shown in FIG. 1 and applying a wound aluminum foil 14 formed by applying a conductive solid electrolyte layer thereon. After enclosing (13) in a circular aluminum case (11) in which it is internalized, it has a structure which wrapped the exterior of the aluminum case (11) with the external resin (12). At this time, the electrical characteristics of the solid electrolytic capacitor manufactured according to the type and the formation method of the conductive solid electrolyte is also changed.

The solid electrolyte used in the above-mentioned aluminum solid electrolytic capacitor can be largely divided into an inorganic solid electrolyte and an organic solid electrolyte, and the organic solid electrolyte is divided into an organic semiconductor type and a polymer electrolyte type. Typical inorganic solid electrolytes include manganese dioxide and lead dioxide. In the case of the solid electrolytic capacitor, after the impregnation of manganese nitrate solution into the tantalum sintered body, a tantalum electrolytic capacitor using manganese dioxide produced by pyrolysis as a solid electrolyte layer was developed and put into practical use.

In addition, the organic semiconductor is tetracyanoquinone dimethane (TCNQ) complex salt. The aluminum solid electrolytic capacitor using this TCNQ complex salt has been developed and commercialized, but TCNQ also has low conductivity and poor thermal stability and is formed by hot melt impregnation. have.

In addition, other organic solid electrolytes include conductive polymer materials such as polyaniline and polypyrrole. Polypyrrole produced by electrolytic oxidation polymerization is known as a conductive polymer with a high conductivity of 10 ² S / cm or more and excellent thermal stability. It has the advantage of being able to chip the product with excellent thermal stability.

Therefore, a chip-type aluminum solid electrolytic capacitor is manufactured and put into practical use by overcoming the problems of the conventional aluminum electrolytic capacitor and using an organic solid electrolyte capable of chipping.

2 shows a conventional chip-type aluminum solid electrolytic capacitor, and a method of manufacturing the aluminum foil 21 having the dielectric oxide film 22 formed on the anode layer aluminum foil 21 and the dielectric oxide film 22 formed thereon is shown. ), The conductive polymer layer 23, the carbon layer 24, and the silver layer 25 are sequentially formed to cover the aluminum solid electrolyte capacitor. Next, the capacitor device is electrically connected to the anode lead frame 27 and the cathode lead frame 28 using a conductive adhesive 26 on the cathode of the cathode, and the lead frames 27 and 28. ) Was formed in the form of a chip by forming the external resin 30 by the transfer molding method.

In the above-described conventional method of transfer molding a capacitor, a device for shaping into a chip is formed by preheating an EMC (Epoxy Molding Compound) having a disk shape (diameter x height) in a solid state with a preheater and converting it into a fluid form. It is usually injected into a mold at a pressure of 100 psi or less and cured at a temperature of 150 to 175 캜 for about 3 to 5 minutes. At this time, about 80% of hardening is carried out by EMC, and 4 to 6 hours of post hardening is performed at 175 ° C for the remaining 20% of hardening.

Like the chip-type solid electrolytic capacitor described above, the encapsulation method plays a very important role because components shaped as chips such as diodes, transistors, integrated circuits, tantalum capacitors, and the like are sensitively affected by changes in minute environments. In general, encapsulation materials are currently using a thermosetting epoxy resin to maintain the airtightness of the chip, to protect the components from ambient conditions such as temperature and humidity, and to prevent breakage and change of properties due to mechanical shock and vibration. In particular, parts manufactured by low pressure transfer molding using EMC, a packaging material, have various advantages such as accurate size of the part, surface mounting, mass production, high reliability, and excellent environmental resistance.

The above-mentioned transfer molding needs to protect internal elements from the working environment of various components in the form of chips. The transfer molding is a fluid EMC injected into the mold where the device is located by pressure is a cavity in which the device is formed at a very high pressure (Cavity: space for shaping the chip, where the fluid EMC is injected and cured). You come into me. In this process, the main parts of the device are broken or the parts adhered to the lead frame fall, which may cause a problem.

Aluminum foil, which is the main material of the conventional chip-type aluminum solid electrolytic capacitor, is very thin, having a thickness of 60 to 100 μm, and thus, may be easily bent or deformed even by slight external pressure during manufacturing or assembly. In particular, under high pressure, such as transfer molding, the surface of the aluminum foil is damaged by pressure and does not reach the voltage to be used, or causes a large problem in leakage current and yield, so a protective film that can protect it is necessary.

Therefore, in the present invention, an oxide film is formed on the anode layer of aluminum foil, and then a conductive polymer layer, a carbon layer, and a silver layer are sequentially formed on the cathode layer to manufacture an aluminum solid electrolytic capacitor device, and the finished device is welded and a conductive adhesive. After the electrical contact with the positive electrode and the negative lead frame by using, in order to protect the device by pressure and thermal expansion during the transfer molding operation, all or part of the aluminum foil on which the negative electrode layer is formed, such as epoxy or silicone rubber in the form of liquid or gel When left in the air after coating or hardened by applying a little heat, it becomes a solid state and has a hardness or elastic force on the material itself. It has excellent electrical resistance and can act as a protective layer or protective film that does not interfere with the operation of the capacitor. Transfer mall by providing a manufacturing method using a material It can be protected inside the device according to the aims to improve the leakage current characteristics and the yield.

1 is a cross-sectional view showing a conventional aluminum electrolytic capacitor.

2 is a cross-sectional view showing a conventional chip-type aluminum solid electrolytic capacitor.

3 is a cross-sectional view showing another chip-type aluminum solid electrolytic capacitor according to the present invention.

<Explanation of symbols for main parts of the drawings>

11: aluminum case 12: resin

13: terminal 14: pierced aluminum foil

21, 31: aluminum foil 22, 32: dielectric oxide film

23, 33: conductive polymer layer 24, 34: carbon layer

25,35: silver layer 26,36: conductive adhesive

27,37: anode lead frame 28,38: cathode lead frame

29, 39: weld 30, 40: external resin

41: protective layer

As shown in FIG. 3, the present invention uses the aluminum foil 31 having the dielectric oxide film 32 formed thereon as an anode layer and has a conductive polymer layer 33, a carbon layer 34, and a silver layer as a cathode layer on the surface thereof. By sequentially forming 35), an aluminum solid electrolytic capacitor element is completed. Welding 29 and conductive adhesive 26 are also used to bring the finished device into contact with the positive and negative lead frames 27 and 28. In addition, the protective layer 41 is formed on all or a part of the capacitor device to which the anode and the cathode lead frames 27 and 28 are electrically connected. As described above, a capacitor-type aluminum solid electrolytic capacitor is manufactured by a transfer molding method using the EMC external resin 40 using a capacitor device in which the anode and the cathode lead frames 27 and 28 are electrically connected and the protective layer 41 is formed.

In the present invention, the protective layer or protective film 41 formed on the aluminum foil is completed as a protective layer in order to protect from the pressure of the transfer during the molding operation, thermal stress due to the difference in thermal expansion coefficient with EMC, moisture, moisture, etc. By buffering with the hardness and elasticity of the protective material itself, it protects the aluminum foil from the pressure shrinking as the high-pressure flowable EMC and epoxy resin are pushed in and out by the pressure of transfer molding.

In the aluminum solid electrolytic capacitor, the material to be used as the protective layer 41 on the aluminum foil 31 on which the negative electrode layer is formed may be a viscosity suitable for the process of the present invention in the form of a liquid or gel having an initial shape of viscosity. Dipping, dropping, or syringes are used to coat all or a portion of the aluminum foil. Thereafter, to harden the protective layer, it is processed by exposing it to the air as it is or applying a little heat to make the protective layer solid. The protective layer formed by the above-described method has hardness, heat resistance, elasticity, and the like on its own to protect the aluminum foil on which the cathode layer is formed from the transfer molding.

Table 1 shows the aging of 150 ° C and 10V for a large number of devices (primary devices) that do not use a protective layer for the internal device of an aluminum solid electrolytic capacitor and a plurality of devices (the device of the present invention) assembled after forming the protective layer. ) Shows a comparison of the leakage current characteristics and the yield after discharge for a certain time (about 120 seconds) under the condition of). As shown in Table 1, since the device of the present invention has no device whose short or leakage current exceeds a reference value (3 mA or less), the formation of the protective layer is very effective.

Leakage current characteristics with or without protective layer (film). division Leakage Current No protective layer With protective layer One short 0.23 2 187 0.68 3 0.1 0.47 4 short 0.16 5 128 0.18 6 0.61 0.34 7 1.81 0.51 8 0.46 0.28 9 short 0.99 10 short 0.34 11 164 0.77 12 0.97 0.13 13 2.12 0.18 14 short 0.42 15 35.4 0.12 Yield 40% 100%

The aluminum solid electrolytic capacitor which electrolytically polymerizes a conductive polymer on the top of a single plate-shaped aluminum film as described above is very thin with a thickness of 60 to 100 μm and can be easily deformed during each manufacturing process and assembly process. During the transfer molding process, the deformation caused by the press pressure and the damage inside the cavity where the internal device is located have a great influence on the leakage current characteristics and the final yield of the product.

However, the aluminum solid electrolytic capacitor of the present invention becomes a solid state when it is cured by leaving it in the air or applying a little heat after coating a material such as a two-component epoxy, Teflon, silicone rubber, etc. in liquid or gel form as described above. Alternatively, a material capable of acting as a protective layer or a protective film using a material having elastic force is used. These materials improve the surface protection and moisture resistance of aluminum foil from thermal stress due to transfer pressure or thermal expansion differences that can occur during temperature changes at high / low temperatures during molding operations, and materials such as silicon are present in the molding compound. There is an effect to block α-rays emitted from radioactive impurities such as ppb uranium.

In addition, the protective material coated on the whole or a certain part of the aluminum foil is an electrical resistor having a very high volume resistivity (10 ¹³ to 10 ¹⁶ Pa · cm) and a low dielectric constant (4 or less). It does not affect the electrical properties.

Claims (3)

Forming an oxide film on the anode layer aluminum foil; Manufacturing an aluminum solid electrolytic capacitor device sequentially forming a conductive polymer layer and a carbon layer silver layer so as to surround the aluminum foil having the oxide film formed thereon; Electrically contacting the condenser element with a lead frame using welding and a conductive adhesive; In the method of manufacturing a chip-type aluminum solid electrolytic capacitor in which the device in which the lead frame is in electrical contact is made into a chip shape by a transfer molding method using an EMC material, And forming a protective layer having hardness, elasticity, and electrical resistance in all or a part of the device in which the lead frame is electrically contacted in the previous step of performing the transfer molding. Method of manufacturing the denser. The method of claim 1, The material used as the protective layer is a method of manufacturing a chip-type aluminum solid electrolytic capacitor, characterized in that using a two-component epoxy, Teflon or silicone rubber in the form of a liquid or gel. The method according to claim 1 or 2, The protective layer is a method of manufacturing a chip-type aluminum solid electrolytic capacitor, characterized in that formed using dipping, dropping or syringe.