Title of Invention

"A METHOD FOR MAKING A ZINC METALLIZED FILM FOR A FILM CAPACITOR EXHIBITING AN IMPROVED ANTI-OXIDATION CHARACTERISTIC"

Abstract ABSTRACT: A method for making a inc metallized film for a film capacitor, being capable of protecting he zinc film from moisture and thereby preventing it from oxidizng, comprising: treating a srface of a polymer film with a metal having a high bonding energy by use of a spluttering process or an evaporation process a seed layer, of aluminum, tin or silver, having a sngle or multi layer structure over the polymer film surface by use of a thermal evaporation process; and depositing . zinc or zinc-aluminum alloy over the resulting structure ocained at the step (a), to obtain a total surface resistance c from 2 to 10 ohms/m2.
Full Text This invention relates to a method for making a zinc metallized film for a film capacitor exhibiting an improved anti-oxidation characteristic.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a method for making a zinc metallized film for film capacitors exhibiting an improved adhesion of zinc to a polymer film and thereby having excellent anti-oxidation characteristics.
Description of the Prior Art
Recently, use of wrapped film capacitors using metallized films have greatly increased as most electric and electronic appliances have a compact and thin structure. In particular, such wrapped film capacitors exhibit a high reliability because they have excellent high frequency characteristics and self healing capabilities for curing film damage on the electrode surface or defects caused by a possible contamination by themselves. They are also advantageous in terms of manufacturing and cost, as compared to conventional electrolytic capacitors. For these reasons, use of film capacitors using metal-deposited (metallized) films has been increasing.
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Metallized films for capacitors are classified into a pure aluminum (Ai) deposited type, an aluminum-zinc (Al-Zn) deposited type and a zinc (Zn) deposited type in terms of the kind of the deposited metal.
Metallized film capacitors using the zinc metallized film (hereinafter, referred to as MF-Zn capacitors) have a superior electrical characteristic, as compared to those using the aluminum deposited film (hereinafter, referred to as MF-A1 capacitors). However, such MF-Zn capacitors have a limitation on their utility because their anti-humidity and self healing characteristics are more or less low.
On the other hand, the aluminum-deposited film exhibits a superior self healing characteristic because it can have a reduced thickness by virtue of the fact that aluminum has a higher electrical conductivity than zinc metallized film. In particular, the aluminum-metallized film is advantageous in terms of storage because it is formed at its surface with an aluminum oxide which serves to chemically stabilize the film, thereby providing an excellent anti-oxidation property. However, such an aluminum-metallized film has the disadvantage that a reduction in capacitance appears by the lapse of time. Furthermore, it is disadvantageous in terms of the cost because it involves a high evaporation temperature from 1,500
to 1,800°C at a vacuum from l0-4 to 10-5 torrs as its deposition condition. The deposited film is too thin (100 to 250 A) to
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be in contact with the lead wires. Due to such a small thickness, the deposited film is difficult to have a heavy edge. As a result, an aluminum oxide, which is a nonconducting substance, is formed on a surface portion of the film coming into contact with a metallicon. The aluminum oxide on the Al-metallized film serves to increase the contact resistance between the electrode and the lead wires.
On the contrary, the zinc-metallized film involves little or no increase in capacitance by the lapse of time. The
deposition is achieved at a low temperature of about 600°C at
a vacuum of 10-2 to 10-3 torrs. Since the zinc-metallized film
has a larger thickness than the aluminum-metallized film, a zinc oxide is formed on a surface portion of the film being in contact with the leads, thereby reducing the contact resistance between the lead and electrode. This film is also advantageous in terms of cost, as compared to the aluminum-metallized film. By virtue of such advantages, the zinc-metallized film has been widely used.
However, zinc exhibits a high oxidation property and a weak adhesion to the polymer film made of a dielectric material such as polyethylene terephthaiate (PET), oriented polyprophylene (OPP), polyethylene (PE) or polycarbonate (PC). For this reason, the zinc layer exhibits a low surface adhesion strength. As a result, the zinc-metallized film has a disadvantage in that scratches may easily form on the zinc

layer.
Typically, the oxidation of the zinc-metallized film is carried out in a continued method through two steps as moisture and oxygen penetrate into the film. The oxidation is continued, in so far as moisture exists in the film.
The oxidation at the primary step is carried out in such a form that Zn + 2H2O - Zn(OH)2 + H2 whereas the oxidation at the secondary step is carried out in such a form that 2Zn(0H)i + 2O2 - 2ZnO + 2H2O + O2. The penetration of moisture is carried out through three paths A, B and C as shown in FIG. 2. Through path A, moisture existing in the atmosphere is coupled to the zinc-metallized film. Through path B, the zinc-metallized film is coupled with moisture contained in the capacitor polymer film. The zinc-metallized film is also coupled, through path C, with moisture permeating through the polymer film. The coupling degree of moisture to the zinc-metallized film is highest in the case of path A and lowest in the case of path C.
Since the zinc thin film has the property that it is rapidly oxidized in the atmosphere as well as the property that its oxidation is continued during the fabrication of the capacitor after the deposition of the film until a dipping step is initiated, it involves a limited utility in spite of its excellent electrical characteristic. There is also a problem when stord for a long period of time. In order to

improve the adhesion characteristic of the deposited film while still maintaining the advantages obtained in the zinc metallized film, accordingly, the U.K. Patent No. 1,754,064 proposes a method involving depositing a metal oxide such as Al2O3 over a polymer film and metallizing zinc over the metal oxide layer, thereby improving the anti-oxidation characteristic of the zinc-metallized film. In Germany Patent No. 0,083,137, another method is disclosed, wherein in place of a multi-layer film, a zinc-based alloy such as Zn-Al alloy is deposited as a single layer over a plastic film, thereby achieving an improvement in the anti-oxidation characteristic. Actually, the anti-oxidation characteristic is improved when a metal such as Cr is deposited over a Zn layer. In this case, however, a high temperature and high vacuum are required to deposit Cr. For this reason, this method is not yet practical to use.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to provide a method for making a zinc metallized film for film capacitors exhibiting an excellent anti-oxidation characteristic, being capable of protecting the zinc metallized film from moisture
by surface - treating a polymer film, over which the zinc metallized film is deposited, to increase the surface

tension of the polymer film, or by depositing a metal exhibiting a high bonding energy over the zinc film.
In accordance with one aspect, the present invention provides a method for making a zinc metallized film for a film capacitor exhibiting an improved anti-oxidation characteristic, comprising the steps of:
(a) treating a surface of a polymer film with a metal having a high bonding energy by use of a sputtering process or an evaporation process a seed layer, of aluminum, tin or silver, having a single or multi-layer structure over the polymer film surface by use of a thermal evaporation process, and
(b) depositing a zinc or zinc-aluminum alloy over the resulting structure obtained at the step (a), to obtain a total surface resistance of from 2 to 10 Ω/m2
In accordance with another aspect, the method further comprises the steps of depositing a seed layer made of a metal, comprised of aluminum, silver or titanium, having a higher oxidation property than zinc over the resulting structure obtained at the step (a) before depositing the zinc or zinc-aluminum alloy to obtain a surface resistance of 3.5 to 10 Ω/m2 and depositing aluminum over the seed layer in a continued method.
In accordance with another aspect, the present invention provides a method for making zinc metallized film for a film capacitor exhibiting an excellent anti-oxidation
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characteristic, comprising the steps of: generating O2 groups at a surface of a polymer film in an atmosphere of O2, mixed gas such as O2 + Ar or O2 + N2 + Ar by use of a glow discharge process; depositing zinc as an electrode metal over the polymer film surface having no metal seed layer, to obtain a total surface resistance of 2 to 10 Ω/m2; and forming a zinc protecting oxide film over the zinc film by use of a glow discharge or sputtering process.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and aspects of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings in which:
FIG. 1 is a schematic view illustrating the condition of zinc deposited in accordance with the present invention;
FIG. 2 is a schematic view illustrating various penetration paths of moisture through a metallized polymer film;
FIG. 3 is a sectional view illustrating a zinc metallized film made in accordance with the present invention;
FIG. 4 is a schematic view illustrating a vacuum furnace used to make the zinc metallized film in accordance with the present invention; and
FIG. 5 is a graph illustrating an anti-oxidation

characteristic of the zinc metallized film according to the present invention as compared to the conventional film.
DETAILED DESCRIPTION OF THE INVENTION
Where a metallized film is formed over a polymer film using a heat resistance evaporation method, it tends to have a porous structure. When the film is exposed to the atmosphere, moisture existing in the atmosphere can easily permeate into the film. In this case, the film has a degraded adhesion, so that it may be abruptly oxidized. For improving the anti-oxidation characteristic of the metallized film to prevent such an oxidation, a seed layer comprised of a metal or oxide exhibiting a high adhesion to the polymer film may be used which is metallized over the polymer film before zinc is deposited over the polymer film. The adhesion and oxidation property of the metallized film may be dependent of the kind of the seed layer. When the bonding force between the seed layer and polymer film is low, the seed layer is non-uniformly deposited such that lumps are formed due to the surface tension energy of the seed. In this case, the zinc metallized film over the seed layer exhibits a degraded adhesion. This tendency is remarkably generated when a polyprophylene or polycarbonate film is used. The anti-oxidation characteristic and oxidation mechanism of the deposited layer is greatly
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affected by the adhesion of the deposited layer to the polymer film. In particular, biaxially-elongated polyprophylene films (OPP films), which are typically used as polymer films for capacitors, exhibit a degraded adhesion to the zinc layer because they have considerably low adhesion tension of, for example, 32 dyne/cm2 as polyester (PET) films which have adhesion tension of 48 dyne/cm2 respectively. To this end, such polyprophylene films are subjected to a specific treatment such as corona treatment to raise the adhesion tension thereof to a level of not less than 38 - 42 dyne/cm2. In accordance with the present invention, the zinc-metallized film is made by metallizing aluminum having an excellent anti-oxidation property, as a seed layer, over a capacitor polymer film having a thickness of from 1.5 to 20 µm such that the aluminum layer has a surface resistance of from 100 to 300 Ω/m2 or treating the surface of the polymer film in accordance with a glow discharge or sputtering method, and then metallizing zinc over the resulting film structure such that the film structure has a total surface resistance of 3 to 4.0 Ω/m2. The formation of the zinc metallized film is conducted in a continued method in a vacuum furnace which includes an upper chamber 9 maintained at a vacuum of 2 x 10-2 torrs and a lower chamber 10 maintained at a vacuum of 2 x 10-4 torrs, as shown in FIG. 4. In particular, the metallizing of aluminum is carried out in an aluminum metallizing section 5
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of the vacuum furnace whereas the metallizing of zinc is carried out in a zinc metallizing section 6 of the vacuum furnace. On the other hand, the treatment of the polymer film is carried out in a plasma applying section 4 included in the vacuum chamber.
In the vacuum chamber shown in FIG. 4, the capacitor polymer film is continuously fed from a base film roll 2 to a cooling drum 1 at a speed of not less than 6 m/sec. Thereafter, the polymer film is fed along the cooling drum 1 while being in contact with the cooling drum 1 and then wound around a film winding roll 3. While the polymer film is fed along the cooling drum 1, it passes through the zinc metallizing section 6 where hot zinc vapor of 600 to 800°C adheres the polymer film. The zinc metallized film is then rapidly cooled by the cooling drum 1 maintained at a temperature of from -25 to -10°C. A metal seed layer is formed over the polymer film or metal electrode of the polymer film, which is fed at a high speed. The formation of the metal seed layer is achieved by generating plasma of a metal exhibiting a high oxidation rate in the plasma section 4, which is a batch type vacuum vessel, in accordance with the glow discharge or sputtering method using a DC or RF power supply while supplying inert gas and either oxygen or nitrogen in a certain ratio to the plasma section 4. Alternatively, the metal seed layer may be formed in the aluminum metallizing
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section 5 in accordance with a thermal evaporation method. By virtue of the metal seed layer, an anti-oxidation film having high bonding energy can be formed over the polymer film or metal electrode.
Since the metallized zinc film has a micro-polycrystal structure, it has an atomic bonding force to the polymer film. However, this bonding force is insufficient because of an energy consumption resulting from the transformation of the thermal energy into the absorption energy. Polyethylene terephthalate (PET) and oriented polyprophylene (OPP), which are used to form an insulating polymer thin film, have the following molecular structures, respectively.

Where a metal exhibiting a high oxidation property is deposited as a seed layer over the PET, a high adhesion is exhibited between the PET and seed metal because the PET has oxygen in its molecular structure. That is, a bonding force is generated between the oxygen and the atoms of the seed layer. When Zn is deposited over the seed layer, a uniform and tight zinc film can be obtained because the bonding between the seed metal and zinc is a strong metallic bonding.

The method of the present invention is adapted to treat one or both surfaces of the metal electrode or polymer film at a vacuum of 10-2 to 10-6 torr/cm3 to increase the bonding force between the film and electrode, thereby achieving an improvement in adhesion which results in an improvement in the anti-oxidation property.
In accordance with the method of the present invention, an oxide or nitride film is coated over the thin film metal electrode which is formed to a thickness of 100 to 1,500 A over one or both surface of the polymer film in a continued deposition method. The formation of the oxide or nitride film is carried out in a plasma atmosphere formed by an electric field established at a DC or RF voltage of 400 to 1,000 V. The plasma atmosphere is supplied with a mixture of inert gas and either oxygen or nitrogen through a gas control valve (MFC: mass flow controller). In the plasma atmosphere, the oxygen or nitrogen reacts with a target material, namely, a material to be deposited as the oxide or nitride, thereby forming an oxide or nitride coating of 50 to 200 A over the metal electrode.
In order to prevent the zinc film from being oxidized by moisture or oxygen, a layer made of a material, such as chromium, titanium, niobium or aluminum, exhibiting a high oxidation property is formed over the zinc film to form a tight oxide film. By virtue of this oxide film, the zinc film
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In this case, accordingly, an improvement in the anti-oxidation characteristic is obtained.
However, such a characteristic can not be expected in the case of polymers having no oxygen group such as polyprophylene. For such polymers, accordingly, it is required to conduct a surface treatment in a plasma atmosphere containing oxygen in a small amount in accordance with the sputtering or glow discharge method. When a polymer film is subjected to this surface treatment, it can have molecules with oxygen groups at its surface. Subsequently, a metal exhibiting a high oxidation property is formed over the surface-treated polymer film using the sputtering or ion plating method. In this case, a uniform and tight zinc layer can be deposited over the polymer film by virtue of the above treatment, as in the case of the PET film. Accordingly, it is possible to obtain capacitors exhibiting a high bonding force and an excellent anti-oxidation characteristic. The surface treatment and coating of the metal film exhibiting a high oxidation property are carried out in a continuous method. The present invention, therefore, intends to prevent an oxidation of the metal electrode by forming an oxide or nitride layer by use of a plasma oxidation or nitrification treatment using a DC power supply or by depositing a metal exhibiting a high oxidation property by use of the sputtering process.

exhibits a superior anti-oxidation property.
In accordance with a first embodiment of the present invention applied to capacitors using an OPP film, the surface tension of the polymer film is increased to increase the bonding force between the polymer film and the metal deposited film. By the increased bonding force, the metallized metal film and polymer film are firmly bonded together. In order to increase the surface tension energy, the polymer film is treated by plasma generated in a vacuum depositing device in accordance with the glow discharge process. By the plasma treatment, a seed layer is formed to a thickness of from 20 to several ten thousand angstroms over the polymer film, thereby activating the polymer film (Zn-O-C, Zn-N-C, Al-O-C or Al-N-C) as follows:

Thereafter, a metal such as Cr, Ti, Al or Ag or an aluminum alloy both exhibiting a high oxidation property is uniformly deposited to a thickness of from 5 to over several hundred angstroms over the seed layer. Over the resulting structure, Zn or Al-Zn alloy is deposited. Thus, a multi-

layer film structure is obtained.
In accordance with a second embodiment of the present invention, a seed layer is formed over the polymer film using a target of Cr, Ti, Al, Ag or Zr in an atmosphere of Ar, Ar + O2 or Ar + N2 made by a DC or RF power supply in accordance with the sputtering method. At this time, oxygen or nitrogen groups are provided at the surface of the polymer film. Thereafter, Zn or Al-Zn alloy is deposited over the resulting structure in the same method as in the first embodiment. In accordance with this embodiment, an improvement in anti-oxidation and bonding characteristic is obtained. The metallized film has an improved anti-oxidation characteristic by virtue of the tight oxide or nitride layer serving to protect the metal film from moisture contained in the polymer film or penetrated from the outside into the polymer film. Also, the oxide or nitride film, which is formed to a thickness of from 50 to 100 A over the metal electrode, serves to provide a film protecting the metallized electrode from moisture existing in the atmosphere.
In accordance with a third embodiment of the present invention, a metal exhibiting a higher oxidation than zinc is deposited, as an intermediate layer, to a thickness of from 20 to 50 A over the polymer film using a thermal evaporation method. Thereafter, a zinc film is deposited over the resulting structure. Since the zinc film is at a reducing

potential state, the intermediate layer is oxidized prior to an oxidation of the zinc film, thereby forming an oxide film having a tight structure. Where the intermediate layer is made of aluminum, it is an oxidizing potential state while the zinc film is at a reducing potential state because aluminum exhibits a potential of -1.662 V while zinc exhibits a potential of -0.763 V. Accordingly, the aluminum film is oxidized prior to an oxidation of the zinc film. Moreover, no galvanic cell is formed because an aluminum oxide is formed as the aluminum is oxidized. Accordingly, a rapid oxidation of the zinc film is prevented. This oxide film serves to protect the zinc film from moisture contained in the polymer film or penetrated through the polymer film. Accordingly, the zinc film exhibits an improved anti-oxidation property.
The intermediate layer metal (Al+3) migrates to the surface of the polymer film through the electrode metal, namely, zinc (Zn+2), so that it is coupled to oxygen in advance of the zinc film, thereby forming a tight oxide film with a thickness of from 20 to 50 A. This oxide film serves to protect the zinc film from moisture penetrated from the atmosphere into the polymer film.
In accordance with the present invention, another method may also be implemented which is applicable to high voltage capacitors. This method involves coating an anti-oxidation film over the polymer film, depositing zinc as the electrode
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metal over the zinc film, and then depositing, over the zinc film, a protecting metal layer adapted to prevent the zinc film from being oxidized. In accordance with this method, zinc is deposited over the polymer film to obtain a surface resistance of from 4 to 100 Ω/m2. Over the zinc film, the protecting metal is deposited in a continued method to obtain a surface resistance of 2 to 10 Ω/m2 . Thus, a multi-layer structure is obtained in the continued deposition method.
In accordance with the above-mentioned method, it is possible to obtain a superior anti-oxidation characteristic as well as various advantages of the zinc film.
The present invention will be understood more readily with reference to the following examples; however these examples are intended to illustrate the invention and are not to be construed to limit the scope of the present invention.
Example 1
In a vacuum chamber with an upper chamber vacuum of 2 x 10-2 torrs and a lower chamber vacuum of 2 x 10-4 torrs, aluminum was deposited, as a seed layer, over a corona-treated polyprophylene film having a thickness of from 4 to 6 urn. The deposition was carried out to obtain a surface resistance of from 100 to 300 Q/m . Over the aluminum film, zinc was then deposited to obtain a surface resistance of from 3 to 4 Ω/m2 .
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Thus, a metallized capacitor film structure was obtained.
The capacitor film structure was then maintained in a thermostatic and humidistatic vessel kept at a temperature of 60°C and a relative humidity of 80% for different periods of 2, 8, 12, and 20 hours to measure a variation in surface resistance. Based on the measured variation in surface resistance, an oxidized degree of the film was measured. The results are depicted in FIG. 5.
Example 2
A capacitor film structure was made in the same manner as in Example 1. Over the zinc film of the capacitor film structure, aluminum was then deposited to have a surface resistance of 3 Ω/m2 . For the resulting capacitor film structure, the same measurement as in Example 1 was carried out to measure the oxidized degree. The results are depicted in FIG. 5.
Example 3
A polyprophylene film of 6um subjected to no corona treatment was prepared. In a vacuum furnace with an upper chamber vacuum of 2 x 10 ' torrs and a lower chamber vacuum of 2 x 10 torrs, the polyprophylene film was then subjected to a glow discharge treatment in an atmosphere of Ar(60%) + O2(40%) formed in the upper chamber. Aluminum was then
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deposited as a seed layer over the polyprophylene film. Over the aluminum layer, zinc was deposited in a continued method to obtain a total surface resistance of 3 Ω/m2. Thus, a metallized capacitor film structure was obtained. For the capacitor film structure, the same measurement as in Example 1 was carried out to measure the oxidized degree. The results are depicted in FIG. 5.
Example 4
A metallized capacitor film structure was obtained in the same method as in Example 3, except that no seed layer was formed over the polyprophylene film. For the capacitor film structure, the same measurement as in Example 1 was carried out to measure the oxidized degree. The results are depicted in FIG. 5.
Example 5
Over the same polyprophylene film as that in Example 3, aluminum and zinc were deposited in a continued method using the same method as in Example 3. Over the zinc film, aluminum was deposited again in a continued manner to have a surface resistance of 10 Ω/m2 , thereby obtaining a total surface resistance of about 2.5 Ω/m2. Thus, a metallized capacitor film structure was obtained. For the capacitor film structure, the same measurement as in Example 1 was carried

out to measure the oxidized degree. The results are depicted in FIG. 5.
Example 6
Over the same polyprophylene film as that in Example 3, aluminum and zinc were deposited in a continued method using the same method as in Example 3. The zinc film was then subjected to a glow discharge treatment in the lower chamber, thereby obtaining a total surface resistance of from 4 to 5.5 Ω/m2 . Thus, a metallized capacitor film structure was obtained. For the capacitor film structure, the same measurement as in Example 1 was carried out to measure the oxidized degree. The results are depicted in FIG. 5.
Comparative Example
Zinc was deposited over a polyprophylene or polyethylene terephthalate film to obtain a total surface resistance of 3 . 5 Ω/m2 . Thus, a deposited capacitor film structure was obtained. For the capacitor film structure, the same measurement as in Example 1 was carried out to measure the oxidized degree. The results are depicted in FIG. 5.
Referring to FIG. 5, it can be found that those of Examples 1 to 6 exhibit superior anti-oxidation characteristic than that of Comparative Example. It can also be found that those of Examples 1 to 6 exhibit an improvement in electrical

properties (improved reliability for long time and small capacitance reduction).
Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.








We Claim:
1. A method for making a zinc metallized film for a film capacitor exhibiting
an improved anti-oxidation characteristic, comprising the steps of:
(a) treating a surface of a polymer film with a metal having a high
bonding energy by use of a sputtering process or an evaporation
process a seed layer of aluminum, tin or silver, having a single or
multi-layer structure over the polymer film surface by use of a
thermal evaporation process, and
(b) depositing a zinc or zinc-aluminum alloy over the resulting structure
obtained at the step (a), to obtain a total surface resistance of from 2
to 10 Ω/m2
2. The method as claimed in claim 1 wherein a seed layer made of metal
comprised of aluminum, silver or titanium, having a higher oxidation
property than zinc over the resulting structure obtained at the step (a) is
deposited before depositing the zinc or zinc-aluminum alloy to obtain a
surface resistance of 3.5 to 10 Ω/m2 and depositing aluminum over the seed
layer I in a continued manner.
3. A method for making a zinc metallized film substantially as herein
described with reference to and as illustrated by the accompanying
drawings & foregoing examples.


Documents:

2179-del-1995-abstract.pdf

2179-del-1995-claims.pdf

2179-del-1995-correspondence-others.pdf

2179-del-1995-correspondence-po.pdf

2179-del-1995-description (complete).pdf

2179-del-1995-drawings.pdf

2179-del-1995-form-1.pdf

2179-del-1995-form-2.pdf

2179-del-1995-form-3.pdf

2179-del-1995-gpa.pdf

2179-del-1995-petition 138.pdf

2179-del-1995-petition others.pdf


Patent Number 247980
Indian Patent Application Number 2179/DEL/1995
PG Journal Number 23/2011
Publication Date 10-Jun-2011
Grant Date 07-Jun-2011
Date of Filing 27-Nov-1995
Name of Patentee SUNG MOON ELECTRONICS CO., LTD
Applicant Address 441-6, SANGDAEWON-DONG, JUNGWON-KU, SUNGANAM-CITY, KYUNGKI-DO, THE REPUBLIC OF KOREA.
Inventors:
# Inventor's Name Inventor's Address
1 YONG-HAN KIM 339-409, JAMSIL JUKONG APT., SONGPA-KU, SEOUL, KOREA.
PCT International Classification Number H01G 4/33
PCT International Application Number NA
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA