JPS5940759Y2 - High voltage feedthrough capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-voltage feed-through capacitor used as a noise filter for high-frequency, high-power equipment, such as microwave ovens, magnetron casings for broadcasting equipment, or X-ray tubes.

Recently, UHF has been used not only in industrial equipment such as broadcasting equipment, X-ray medical equipment, but also in consumer equipment such as microwave ovens.

High-power electromagnetic waves in the VHF band have come to be used, and as this usage increases, noise pollution caused by electromagnetic waves leaking from these devices has come into focus.

In order to prevent such noise pollution, various noise films have been proposed.

Figure 1 shows a conventional example of a high-voltage feed-through capacitor used as this type of noise filter.
A cylindrical dielectric ceramic 1 having a cylindrical shape 3 formed thereon is fixed on the floating part 5 of the grounding fitting 4 so that the electrode 3 is in contact with it, and
Electrode fitting6. The through terminal 8 with the insulating tube T inserted,
Through hole 1 provided in dielectric ceramic 1 and floating part 5 of grounding fitting 4
a. After penetrating the interior of Sa, the electrode fitting 6 is fixed onto the electrode 2 of the dielectric ceramic 1 by means such as soldering, and the penetrating portion of the dielectric ceramic 1, the electrode fitting 6, the through terminal 8, etc. The outer periphery of the insulating resin 9 is covered with an insulating case 10 and an insulating cover 11.

The insulating resin 9I/'i is provided to ensure the insulation and moisture-proof properties of the dielectric ceramic 1 constituting the capacitor, and is formed by injecting epoxy resin into the inside of the insulating case 10 and the insulating cover 11. It was done.

The insulating case 10 is made of a synthetic resin such as ABS, nylon, or polyethylene resin, which is compatible with the insulating resin 9 such as epoxy and has strong adhesion.

However, with the above structure, when the insulating resin 9 hardens and shrinks, residual stress or adhesive force generated due to differences in thermal expansion coefficients of each part may cause the epoxy resin 9 to shrink.
Gaps and cracks may occur due to peeling between the insulating case 10, the dielectric ceramic 1, and the like.

Region where the difference in thermal expansion coefficient between the epoxy resin 9 and the dielectric ceramic 1 was large. Cracks sometimes occurred in the dielectric ceramic 1 due to heat shock during the heat cycle test.

When such gaps and cracks occur, moisture proofing properties are impaired and water and moisture enter, resulting in a significant drop in dielectric withstand voltage characteristics and impairing reliability.

Especially recently, microwave ovens with steam openers have been commercialized, and feed-through capacitors are used in high-temperature and humid environments.
Therefore, it is necessary to minimize the occurrence of the above-mentioned gaps and cracks, and to improve the temperature resistance, moisture resistance, and dielectric withstand voltage characteristics several times more than in the past.

Generally, in the case of a feedthrough capacitor as described above, since the feedthrough terminal 8 made of a metal material is passed through the through hole 1a of the dielectric ceramic 1, when the insulating resin 9 hardens and shrinks,
Residual stress during heat cycle testing tends to increase, and consideration must be given to internal residual stress, such as selection of through terminals 8 and insulating resin 9 to reduce residual stress, which also has the drawback of increasing costs.

Furthermore, since the insulating resin 9 is made of electrically resistant epoxy, the material cost is high, a casting process, an indigo drying process, etc. are required, resulting in high manufacturing costs, and work using ordinary epoxy resin. Problems such as pollution caused to people also arose.

This invention eliminates the above-mentioned drawbacks, does not generate gaps or cracks due to residual stress, has excellent insulator voltage characteristics and temperature resistance characteristics, is low cost, and does not cause pollution problems. The purpose is to provide a high voltage feedthrough capacitor.

In order to achieve the above object, the high-voltage feedthrough capacitor according to the present invention uses dielectric ceramics each having an electrode formed thereon as a housing for a through hole opened on both sides, with one of the electrodes facing the grounding metal fitting. At the same time, an electrode connecting body is fixed to the other of the electrodes of the dielectric ceramic, and a through terminal penetrated through the through hole of the dielectric ceramic is electrically connected to the electrode connecting body. An insulating tube is inserted around the outer periphery of the portion penetrating the through hole, and silica is applied to substantially all of the inner and outer surfaces of the dielectric ceramic and the electrode connector, and to the outer circumferential surfaces of the insulating tube and the through terminal. A high voltage feed-through capacitor in which an insulating film is formed by adhering an inorganic coating material mainly composed of The thickness of the insulating tube and the through terminal is such that an annular space is created between the insulating film formed on the inner surface of the insulating tube and the insulating film formed on the outer peripheral surface of the insulating tube and the outer peripheral surface of the through terminal. The insulating tube and the through terminal are attached to the electrode connecting body on the outer circumferential surface so as to be integrated with the insulating film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings, which are examples.

FIG. 2 is an exploded view of a high voltage feedthrough capacitor according to the present invention, and FIG. 3 is a sectional view thereof.

In the figure, the same reference numerals as in FIG. 1 indicate the same components.

As shown in the figure, in this embodiment, silica gold is applied to the inner and outer peripheral surfaces of the dielectric ceramic 1, the electrode connector 6 fixed to the electrode 2 of the dielectric ceramic 1, and the surface of the penetration part 8a of the penetration terminal 8. The insulating film 12 is formed by depositing an inorganic coating material as a main component.

In the through hole 1a of the dielectric ceramic 1, the insulating film 12 includes an insulating film 12 formed on the inner peripheral surface of the through hole 1a and the inner peripheral side of the electrode connector 6, and the outer peripheral surface of the insulating tube γ or the through hole. The insulation film 12 formed on the outer peripheral surface of the terminal 8 is thick enough to create an annular space due to the through hole 1a. The through terminals 8 are attached so as to be integrated with the electrode connecting body 6 through the insulating film 12.

The inorganic coating material forming the insulating film 12 is, for example, the following chemical formula: % where M is an alkali metal n is expressed as the molar ratio of SiO3 to M2O.

One example is so-called water glass.

This water glass hardens at room temperature. In addition, the insulation case 10
The insulating cover 11 is desirably made of an insulating resin that has excellent flame retardancy, insulation properties, and good workability, such as polybutylene terephthalate.

In addition, the insulating tube 7 is made of silicone rubber.

With the above structure, the following effects can be obtained.

(a) Since the thermal expansion coefficient of the inorganic coating material constituting the insulating film 12 approximates the thermal expansion coefficient of the dielectric ceramic 1, the electrode connector 6, and the through terminal 8, which are also modal materials, the interface due to residual stress Accidents such as peeling and cracking are almost completely prevented, and the temperature resistance characteristics and insulation voltage resistance characteristics are significantly improved.

(b) Instead of filling the dielectric ceramic 1, the electrode connector 6, and the through terminal 8 with an inorganic coating material, the inner circumferential surface of the through hole 1a and the electrode connector 6 and the outer circumferential surface of the insulating tube T or the outer circumferential surface of the through terminal 8.
Since the insulating film 12 was formed in such a way that an annular space formed by the through hole 1a was formed between the insulating film 12 and the insulating film 12 formed by the through hole 1a, the annular space was formed so that the thermal expansion of each part 1, 6.8, etc. It acts as a buffer space against the residual stress caused by the difference in coefficients, prevents the generation of gaps and cracks in the through hole 1a of the dielectric ceramic 1, and improves the temperature resistance characteristics and the voltage resistance characteristics.

(c) Since the insulating film 12 is attached to the outer peripheral surfaces of the insulating tube 7 and the through terminal 8 so that the insulating tube γ and the through terminal 8 are integrated with the electrode connector 6 by the insulating film 12, Misalignment of the insulating tube 7 with respect to the electrode connector 6 is prevented.

Even in the case where an exposed portion of the through terminal 8 occurs between the lower surface of the electrode connector 6 and the upper end surface of the insulating tube T, it is covered with the insulating film 12.

Therefore, the insulation withstand voltage between the one-through terminal 8 and the dielectric ceramic 1 is increased, and reliability is improved.

) Unlike organic synthetic resins such as epoxy resins, inorganic coating materials generally have excellent flame retardancy, heat resistance, and moisture resistance. A high-voltage feedthrough capacitor suitable for use as a filter that is exposed to such environments and requires high flame retardancy can be realized.

(e) Since it is a structure in which an inorganic coating material is attached as a film, the material cost is lower than that of the conventional Molt Mave insulation method, and it is less susceptible to residual stress, adhesive strength, etc.

Gaps and cracks caused by interfacial delamination are prevented.

Improves temperature resistance and voltage resistance.

(f) When forming the insulating film 12, methods such as dipping, spraying, or brush coating can be employed, and drying, which was necessary in the case of filling with epoxy resin, can be adopted.

By omitting the casting process, manufacturing costs can be significantly reduced.

(g) Inorganic coating materials are safe because they do not cause the pollution problems that epoxy resins do.

Specific examples of the above-mentioned inorganic coating materials include the product name rCerarra and Coat TM512 Jr.
CERA MA-PREG550 J (manufactured by Alemco Products, Inc.) is effective.

This inorganic coating material is mainly composed of silica, and its thermal expansion coefficient is about (11,2 The coefficient of thermal expansion is close to (12-15X10), and therefore residual stress arises from the difference in coefficient of thermal expansion and interfacial peeling due to this residual stress.

It is possible to prevent the occurrence of cracks, etc.

Moreover, in order to form the insulating film 12 using the above-mentioned inorganic coating material, a premix of the above-mentioned inorganic coating material and paste is applied to the surface of the capacitor block before the insulating case 10 and the insulating cover 11 are attached. On the other hand, with jab pickling and spraying, it is only necessary to apply it by means such as coating with a box or brush, and by leaving it in the air for about an hour, it hardens, becomes hard, dense, heat resistant, and electrically resistant. An insulating film 12 with excellent scratch resistance can be formed.

The above-mentioned curing time can be shortened by, for example, performing the curing in an atmosphere of 100°C.

In general, it is also possible to add miga, glass filler, etc. to the inorganic coating material.

FIG. 4A is a sectional view of another embodiment of the high voltage feedthrough capacitor according to the present invention, and FIG. 4B is an enlarged perspective view of the capacitor portion.

The feature of this embodiment is that two through holes 1a are provided in the dielectric ceramic 1.
1 and 1a2 are provided, and the through holes 1a1 and 1a2! Instead, the electrodes 2, 2 are provided independently from each other, and the electrodes 2,
2, through-hole terminals 8, 8 penetrated through the through-holes 1a1, 1a2 are conductively connected via electrode connectors 6, 6, and a common electrode provided on the lower surface of the dielectric ceramic 1 3 are fixed in contact with each other on the grounding fitting 4, and on the surfaces of the dielectric ceramic 1, the electrode connectors 6, 6 and the through terminals 8, 8,
An insulating film 12 made of an inorganic coating material is deposited.

Even in this embodiment, the same effects as described above can be obtained.

As described above, the high-voltage feedthrough capacitor according to the present invention is constructed by using dielectric ceramic with electrodes formed around the through-holes that are open on both sides, so that one of the electrodes is in contact with the grounding fitting. At the same time, an electrode connecting body is fixed to the other of the electrodes of the dielectric ceramic, and a through terminal penetrated through the through hole of the dielectric ceramic is electrically connected to the electrode connecting body. An insulating tube is inserted around the outer periphery of the portion penetrating the through hole, and silica is applied to the outer periphery of the dielectric porcelain and the electrode connecting body, and to the outer periphery of the insulating tube and the through terminal. A high voltage feed-through capacitor in which an insulating film is formed by adhering an inorganic coating material mainly composed of The thickness of the insulating tube and the through terminal is such that an annular space is created between the insulating film formed on the inner surface of the insulating tube and the insulating film formed on the outer peripheral surface of the insulating tube and the outer peripheral surface of the through terminal. On the outer circumferential surface, the insulating tube and the through terminal are attached to the electrode connecting body so as to be integrated with the insulating film, so that there are no gaps or cracks caused by residual stress. To provide a high-voltage feed-through capacitor that has excellent insulation voltage resistance characteristics, temperature resistance characteristics, and flame retardancy, has low material costs and low manufacturing costs, can achieve a significant total cost reduction, and does not cause problems such as pollution. be able to.

Therefore, according to the present invention, a highly reliable high-voltage feed-through type that exhibits sufficient temperature resistance and insulation voltage resistance even when exposed to high temperature and humidity environments, such as a magnetron filter for a microwave oven with a steam opening. Capacitors can be provided.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional high-voltage feedthrough capacitor;
The figure is an exploded view of a high voltage feed-through capacitor according to the present invention, FIG. 3 is a sectional view of the assembled state, FIG. 4A is a sectional view of another embodiment, and FIG. 4B is an enlarged view of the capacitor. FIG. 1...Dielectric porcelain, la, 1a1, 1a2...
...Through hole, 2,3... Electrode, 4...
・Grounding fitting, 6... Electrode connection body, T...
Insulation tube, 8... Through terminal, 12...
・Insulating film.

Claims (1)

[Scope of claim for utility model registration] A through hole that opens on both sides! Instead, dielectric ceramics each having an electrode formed thereon are fixed on a grounding fitting so that one of the electrodes is in contact with the other, and an electrode connecting body is fixed to the other of the electrodes of the dielectric ceramic. A through terminal passed through the through hole of the dielectric ceramic is electrically connected to the through hole, an insulating tube is inserted around the outer periphery of the portion of the through terminal that penetrates the through hole, and the dielectric ceramic and the electrode are connected. A high-voltage feed-through capacitor in which an inorganic coating material containing silica as a main component is adhered to substantially the entire circumferential surface of the inner and outer surfaces of the body and the outer circumferential surfaces of the insulating tube and the feed-through terminal to form an insulating film. , the insulating film is. In the through-hole of the dielectric ceramic, an annular layer is formed between the fcIeJR coating formed on the inner peripheral surface of the through-hole and the inner surface of the electrode connection body, and the annular coating formed on the outer peripheral surface of the insulating tube and the outer peripheral surface of the through-hole terminal. The insulating tube and the through terminal are attached to the electrode connecting body so that the insulating tube and the through terminal are integrated with the insulating film on the outer circumferential surface of the insulating tube and the through terminal so as to have a film thickness that creates a space. A high voltage feed-through capacitor featuring: