JP2784124B2 - Liquid insulation coating method for lead wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a lead wire with a liquid insulating material. More particularly, it relates to a coating method and a solid electrolytic capacitor manufacturing method using the same liquid insulation to the lead wire for providing a uniform insulating portion in a narrow range of fine lead.

[0002]

2. Description of the Related Art With the miniaturization of electronic equipment, the lead wires of electronic parts have become shorter and thinner, and the use of insulating parts for preventing leakage in a narrow range has been increasing.

For example, in the production of a tantalum electrolytic capacitor, as shown in FIG. 4, for example, tantalum powder is sintered into a cube of about 1 mm cube, and
Capacitor element 11 with embedded lead wire 12 of about μmφ
When a manganese dioxide layer is formed by impregnating a manganese nitrate aqueous solution into the manganese dioxide layer, the manganese nitrate aqueous solution travels along the lead wire 12 so as to scatter during the pyrolysis.
When the manganese dioxide layer is formed on the tip of the lead wire 12, that is, the surface of the lead wire 12 which spreads upward in FIG. 4 and has no oxide film,
A short circuit occurs between the lead wire 12 and the surface of the capacitor element 11 body, that is, between both electrodes of the capacitor. In order to solve the above-mentioned problem, a water-repellent insulating portion for stopping an electrolytic solution is provided at a root portion of a lead wire embedded in a capacitor element. As a method of forming the insulating portion, for example, as shown in FIG. 4, a method of applying and solidifying a liquid insulating material 14 with a dispenser 15 on a base portion of a lead wire 12 embedded in a capacitor element 11 or an insulating ring such as a Teflon ring Is inserted.

[0004]

However, the above-mentioned insulating portion 14
The method of forming a thin lead wire is a method in which a liquid insulating material is discharged from the dispenser 15 and applied onto the lead wire 12.
It is not possible to form the insulating portion 14 accurately and in a short time in a narrow range on 12.

When the insulating portion 14 is formed on the lead wire of the solid electrolytic capacitor, the insulating material is applied to the root portion of the lead wire 12 in the above-described forming method. Insulating material penetrates into the gaps of the sintered body, and when forming a metal oxide film by anodic oxidation, no metal oxide film is formed on the portion of the gap where the insulating material adheres. become. As a result, there is a problem that the quality of the capacitor deteriorates, for example, the capacitance of the capacitor element becomes lower than the design value, the dielectric loss tangent (ε tan δ) increases, the power loss increases, and the yield in the production stage decreases. .

Further, since the root portion of the lead wire 12 is covered with an insulating material and cannot form a manganese dioxide layer, it is molded with a resin and then subjected to thermal shock due to a difference in thermal expansion between the molding resin and tantalum metal. However, there is a problem that the heat resistance of the capacitor decreases, and the leakage current increases.

Further, the method of inserting an insulating ring such as a Teflon ring has a problem that components are expensive and the number of work steps is increased to increase the cost.

[0008] The present invention provides such a problem to eliminate, thin liquid insulating material can be formed precisely insulating portion in a narrow range of lead coating or a solid electrolytic capacitor using the same method The purpose is to:

[0009]

The method of coating a lead wire with a liquid insulating material according to the present invention is a method of coating a liquid insulating material on a narrow area of a thin lead wire, the method comprising:
A plurality of lead wires are arranged and fixed, and the arranged
A liquid insulating material is attached around the wire in a range longer than the entire width of the lead wire, and the wire is connected to the plurality of lead wires.
The liquid insulating material is coated in a liquid state on the plurality of lead wires by pressing the entirety of the lead wire.

Further, according to the method of manufacturing a solid electrolytic capacitor of the present invention, a capacitor element formed by burying a lead wire in a center portion and sintering a metal powder is provided on a mounting plate at the tip of the lead wire.
By fixing the parts, a plurality of
Providing a metal oxide film by anodization on the internal voids and the outer wall surfaces of the individual capacitor elements , and before or after providing the metal oxide film, providing an insulating portion at the root of the lead wire; A method for producing a solid electrolytic capacitor in which a manganese dioxide layer is provided on a film using a manganese nitrate aqueous solution, wherein the plurality of capacitor elements arranged in a line are provided.
Liquid insulation around the wire over a length longer than the entire width of the child
And the wire is connected to all of the plurality of capacitor elements.
The insulating part is formed by pressing against the base of the body lead wire and coating the liquid insulating material in a liquid state.
And it is characterized in Rukoto forming.

[0011]

According to the present invention, the liquid insulating material is applied to the periphery of the wire, and then the wire is pressed against the lead wire to coat the liquid insulating material on the lead wire. An insulating portion can be accurately provided in the area.

[0012] According to the solid electrolytic capacitor of the process of the present invention, by pressing the wire with attached liquid insulating material at a fixed interval from the base of the lead wire, since an insulating portion, It is possible to accurately coat only the root portion of the lead wire without invading the insulating material into the gap between the capacitor elements, thereby forming the insulating portion. As a result, it is possible to prevent the electrolyte solution from spreading along the lead wire, thereby preventing a short circuit and a leak, and also prevent a decrease in capacitance and an increase in power loss due to a dielectric loss tangent.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for coating a lead wire with a liquid insulating material according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a method of coating a lead wire of a solid electrolytic capacitor with a liquid insulating material, which is one embodiment of a method of coating a lead wire with an insulating material according to the present invention, and FIG. FIG. 3 is a cross-sectional explanatory view showing a method of attaching a material, and FIG. 3 is a perspective view of a capacitor element provided with an insulating portion at regular intervals from the root of a lead wire.

When a solid electrolytic capacitor, for example, a tantalum electrolytic capacitor is manufactured, the procedure is as follows.

[0016] First, a metal powder such as tantalum is weighed 1 m on each side.
The capacitor element 1 is formed by molding into a cube of about m and burying a lead wire 2 made of a tantalum wire or the like on the upper surface thereof, followed by sintering. The stainless steel bar 3 is connected to, for example, 70 lead wires 2 of the capacitor element 1.
Are welded to perform the subsequent manufacturing processes at once.

Next, by providing a water-repellent insulating portion 4 (see FIG. 3) at a fixed distance from the capacitor element body at the root of the lead wire, the immersion in a manganese nitrate aqueous solution to be immersed in a later step and During the subsequent pyrolysis,
A manganese dioxide layer is formed on the surface of the lead wire along the lead wire to prevent short-circuit and leak failure between the lead wire and the outer peripheral surface of the capacitor element body, that is, between both electrodes of the capacitor. The formation of the insulating portion 4 can be performed after the following chemical conversion treatment. Then, an oxide film (for example, Ta ₂ O ₅ ) to become a dielectric by anodic oxidation (chemical conversion treatment) in a phosphoric acid aqueous solution is provided on the surface of the gap inside the sintered body and around the capacitor element.

Next, the capacitor element is immersed in an aqueous solution of manganese nitrate, pulled up, and thermally decomposed at 200 to 250 ° C. to form a metal oxide layer serving as an electrolyte, that is, a manganese dioxide layer.

The step of forming the oxide film and the step of forming a manganese dioxide layer by immersion in an aqueous solution of manganese nitrate and then thermally decomposing the same are usually repeated three times or more. Formed.

Next, a graphite layer and a silver layer serving as electrode layers are provided around the capacitor element 1, and both electrodes are connected to a lead frame or the like and sealed with an epoxy resin or the like, whereby a solid electrolytic capacitor of a resin package is formed. available.

Next, a method for providing an insulating portion to the lead wire of the solid electrolytic capacitor will be described with reference to FIGS.

The lead wire 2 of the capacitor element 1 welded to the above-mentioned stainless steel bar 3 usually has a length (A in FIG. 1) from the main body of the capacitor element 1 to the stainless steel bar 3 of about 5 m.
m (Length of about 400 μm when assembled in a package
And a wire made of tantalum or the like having a diameter of about 100 to 200 μm is used. The insulating part 4 is placed at a position 50 to 150 μm from the main body of the capacitor element 1 (B in FIG. 3) and has a width of 200 to 250 μm (C in FIG. 3).
m.

In order to provide the water-repellent insulating portion 4 on the lead wire 2, in the present invention, a wire 5 having a liquid insulating material 4 a adhered to the periphery thereof is pressed against a predetermined position of the lead wire 2. Is to be coated. As described above, in order to form an insulating portion having a width of 200 to 250 μm, an insulating material 4a having a thickness (E in FIG. 2) of about 50 μm is attached to a wire 5 having a diameter of about 50 μm φ (D in FIG. 2). As shown in FIG. 1, by pushing the capacitor element 1 in a direction three-dimensionally intersecting with the lead wire 2, the outer diameter of the liquid insulating material attached to the wire (about 150 μm) is increased.
Coated with a width of about 200 μm. At this time, by rubbing the wire in the axial direction of the wire (the left and right direction in FIG. 1), the liquid insulating material is sufficiently coated up to the back side of the lead wire. After that, depending on the type of insulating material, solidification treatment is performed by drying, heat curing, ultraviolet curing, or the like.

Examples of the insulating material include fluorine resins such as polytetrafluoroethylene, silicone resins such as polyorganosiloxane, rubbers such as silicone rubber and butadiene rubber, and the like.
It is used in a liquid form such as a melt. In this case, the liquid insulating material is coated in the form of transfer by attaching it to a thickness of about 50 μm around the wire, so if the viscosity of the liquid insulating material is too small, a sufficient thickness of the insulating material will be attached to the wire. If the viscosity is too large, the insulating portion having a uniform thickness cannot be formed because the resin does not sufficiently reach the back side of the lead when transferring and coating the lead. Insulating material with thickness of 100 to 500 μm is attached to the wire, and the viscosity of the insulating material for providing a uniform thickness of insulating part on the lead wire with thickness of 100 to 200 μm is 5,000 to 50,000 cP.
Within the range, a good insulating portion was obtained. In addition, 10
A range of 000 to 30,000 cP is preferable because workability is improved and a more uniform insulating portion is obtained. Specific examples of preferable insulating materials include polyfluorocarbon paste P-9001 (Daikin Industries, Ltd., trade name) and KJR 9050 (Shin-Etsu Chemical Co., Ltd., trade name).

As a method of adhering an insulating material around the wire 5, for example, as shown in FIG.
Insert the wire 5 into the tank 6 filled with the insulating material 4a,
An opening 6 having an inner diameter of about 150 μm provided in the tank 6.
By drawing the wire 5 at a speed of, for example, 1 cm / sec through the wire a, the wire 5 having the liquid insulating material 4a adhered to a thickness of about 50 μm is obtained. As shown in FIG. 1, the drawn wire 5 is pressed against a predetermined position of the lead wire 2 of the capacitor element 1 to coat the liquid insulating material. Note that the thickness of the wire 5 is appropriately selected according to the width of the insulating portion to be formed.

In the above embodiment, the example of the spread of the liquid along the lead wire 2 of the solid electrolytic capacitor, that is, the prevention of swelling was described. However, the present invention is not limited to the prevention of swelling but also for maintaining insulation between both ends. The present invention can be applied to a case where an insulating material is coated on a thin and narrow lead wire portion.

[0027]

According to the present invention, it is possible to accurately provide an insulating portion with a narrow width even in a narrow place on a thin lead wire, thereby improving the insulation characteristics of the element and welding the tip of the lead wire. When soldering, the yield is improved without any trouble.

Further, according to the present invention, a narrow width insulating portion having a constant thickness can be formed in a narrow place of a lead wire of a solid electrolytic capacitor. It can be completely prevented from spreading along the wire, and insulation failure can be eliminated.In addition, the excess liquid insulating material penetrates into the capacitor element, reducing the capacitance of the capacitor and increasing the power loss due to dielectric loss tangent Nothing to do. Further, since a manganese dioxide layer can be formed also at the root of the lead wire, a capacitor having excellent heat resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating one embodiment of a method for coating a liquid insulating material of the present invention.

FIG. 2 is an explanatory sectional view showing a method for attaching a liquid insulating material to a wire.

FIG. 3 is a perspective view showing a state in which an insulating section is provided on the capacitor element.

FIG. 4 is an explanatory view showing a state in which an insulating portion of a conventional solid electrolytic capacitor is provided.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Lead wire 4 Insulating part 4a Liquid insulating material 5 Wire

Claims (2)

(57) [Claims] 1. A method of coating a liquid insulating material over a narrow area of a thin lead wire, the method comprising:
Fix several side-by-side lead wires
Body width depositing a liquid insulating material around the wire longer range, the said liquid insulation material remains liquid plurality by pressing the wire to the whole of the plurality of lead wires
A method for coating a lead wire with a liquid insulating material, characterized by coating the lead wire. 2. A capacitor element formed by sintering a metal powder with a lead wire buried in a central portion thereof is mounted on a mounting plate by the lead.
Attaching multiple wires by fixing the tip of the wire
A metal oxide film is provided by anodization on the internal voids and outer wall surfaces of the plurality of capacitor elements , and an insulating portion is provided at the root of the lead wire before or after providing the metal oxide film, A method for producing a solid electrolytic capacitor in which a manganese dioxide layer is provided on the metal oxide film using an aqueous solution of manganese nitrate, the method comprising:
Around the wire over the entire width of the capacitor element.
A liquid insulating material is attached, and the wire is connected to the plurality of capacitors.
The absolute by coating a liquid state to the liquid insulating material pressed against the root portion of the capacitors elements overall lead
Preparation of a solid electrolytic capacitor characterized that you form an edge.