KR100841142B1 - Ptc-device with improved safety and manufacturing method thereof - Google Patents

Abstract

A PTC(Positive Temperature Coefficient) device with improved safety and a method for manufacturing the same are provided to implement a stable current flow in a small size by improving the non-resistivity of a PTC material layer. A PTC device(100) includes a PCT material layer(110), and first and second electrodes(121,122). The PTC material layer is made of conductive polymer resin composition including crystalline polymer of 10~30wt% and metallic conductive material of 70~90wt%. The first and second electrodes are arranged on an upper part and a lower part of the PTC material layer to face each other. The metallic conductive material existing on PTC exposed surfaces(111) is removed at a predetermined depth by removing edges of the first and second electrodes through a wet etching process.

Description

PTC device with improved safety and manufacturing method

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a cross-sectional view schematically showing the structure of a PTC element introduced to a conventional overcurrent breaker.

2A through 2E are a series of cross-sectional views illustrating a process of manufacturing a PTC device according to a preferred embodiment of the present invention.

3 is a cross-sectional view showing the configuration of a PTC device according to a preferred embodiment of the present invention.

4 is an enlarged cross-sectional view illustrating an enlarged portion A of FIG. 3.

FIG. 5 is a view showing a PTC device in which an electrode edge is removed by etching according to Embodiment 1 of the present invention.

6 is a view illustrating a PTC device in which the electrode edges according to Comparative Example 1 are not removed.

7 is a view illustrating a PTC device in which an electrode edge is removed by machining according to Comparative Example 2. FIG.

<Description of main reference numerals in the drawings>

100 PTC element 110 PTC layer

111: PTC exposed surface 121: First electrode

122: second electrode

The present invention relates to a PTC (Positive Temperature Coefficient) device, and more particularly, to a PTC device and a method for manufacturing the same, using a material capable of improving the specific resistance of the PTC device and improving the electrode structure to improve safety. will be.

In general, PTC characteristics are relatively low resistance at room temperature to pass a current, but when the temperature rises, the electrical resistance increases rapidly in a relatively narrow temperature range. PTC elements having such characteristics are applied to circuit protection elements and the like that change depending on ambient temperature and current conditions.

1 is a cross-sectional view schematically showing the structure of a PTC element introduced to a conventional overcurrent breaker.

Referring to FIG. 1, the structure of the conventional PTC device 10 includes the PTC material layer 11 and the first and second electrodes 21, which are welded and disposed on upper and lower surfaces of the PTC material layer 11. 22).

When the conventional PTC element 10 is introduced to an overcurrent breaker and used for the purpose of limiting short circuit current of 100 V or more and 10 KA or more, the PTC material layer 11 and the first and second electrodes 21 and 22 in contact therewith are used. The electron repulsion force is generated at the gap between the PTC material layer 11 and the first and second electrodes 21 and 22. As a result, an arc is generated at the interface between the PTC material layer 11 and the first and second electrodes 21 and 22, and this arc decomposes and carbonizes the PTC material layer 11, resulting in insulation breakdown. The lifetime of the device 10 is reduced. In addition, due to the heat generated by the arc and the PTC material layer 11 itself, the PTC material is vaporized and released to the outside of the PTC material layer 11. The material (gas) emitted to the outside destroys the air insulation layer between the first and second electrodes 21 and 22 and generates an arc between the first and second electrodes 21 and 22. As a result, an arc generated between the PTC material layer 11 and the first and second electrodes 21 and 22 or an arc generated between the first and second electrodes 21 and 22 is provided inside the overcurrent breaker. By exposure to electrical and mechanical components, the problem arises that the life of the overcurrent breaker is shortened.

In addition, when the PTC element 10 is used in a device having a limited size and requiring a high capacitance operating current, the size of the PTC element 10 inserted into the circuit is limited. In general, the maximum current value, ie, the hold current value, at which the PTC element 10 can be kept in a normal operating state without switching, depends on the power consumption. Power consumption is related to the initial resistance of the device. That is, the lower the initial resistance, the smaller the power consumption, and thus may have a higher hold current value. Therefore, in the PTC device 10, the gap between the pair of first and second electrodes 21 and 22 may be reduced or the first and second electrodes 21 and 22 may be reduced in order to lower the initial resistance of the device. Increase the area. However, when the gap between the first and second electrodes 21 and 22 is small, the resistance value decreases. However, when the gap is too small, the PTC material layer 11 interposed therebetween is easily broken by a weak impact. There is a limit in processing as well. Therefore, generally, the areas of the first and second electrodes 21 and 22 are enlarged while maintaining a constant thickness. However, when the resistance value of the PTC material layer 11 inserted between the first and second electrodes 21 and 22 is not low enough to satisfy, in order for the molded device to have a high capacitance hold current value, the device is limited in circuit. There is no choice but to grow beyond the size of the inside. Therefore, there is an urgent need for a method in which the PTC device 10, which is to be inserted into a circuit of limited size, has a sufficiently small size and a high hold current.

The present invention was devised to solve the problems of the prior art as described above, and when the current flows normally, the current can stably flow even in small dimensions, and effectively suppress the arc generated when the overcurrent or short-circuit current is limited, and the electrode It is an object of the present invention to provide a PTC device and a method of manufacturing the same having improved safety capable of preventing liver flashover.

In order to achieve the above object, the PTC device according to the present invention comprises 10 to 30% by weight of the crystalline polymer with respect to the total material layer content and 70 to 90% by weight with respect to the total material layer content. A PTC material layer made of a conductive polymer resin composition; And first and second electrodes disposed to face the upper and lower portions with the PTC material layer interposed therebetween, wherein the edges of the first and second electrodes are removed by a wet etching process to be exposed to the PTC exposed surface. The metallic conductive material present is removed to a certain depth.

In the present invention, the crystalline polymer is composed of any one selected from polyethylene, silicone and polyvinyl difluoride or mixtures thereof.

In the present invention, the metal-based conductive material is made of any one selected from nickel metal, nickel metal alloy, nickel carbonate and nickel nitride having a filament shape or a mixture thereof.

Preferably, the specific resistance of the PTC material layer is 0.005 to 0.1 Ωcm.

In the present invention, the first and second electrodes are made of any one material selected from copper foil, nickel plated copper foil, and nickel foil.

Preferably, the metallic conductive material is removed to a depth of at least 0.1 mm.

Method for manufacturing a PTC device according to the present invention for achieving the above technical problem, (a) melting 10 to 30% by weight of the crystalline polymer with respect to the total material layer content; (b) preparing a conductive polymer resin composition by processing the metal-based conductive material having a filament shape of 70 to 90% by weight based on the total material layer content and adding the molten crystalline polymer to the molten crystalline polymer; (c) molding the conductive polymer resin composition into a sheet to form a PTC material layer; (d) placing and laminating respective first and second electrodes on top and bottom of the PTC material layer; (e) forming an etching protection film on surfaces of the first and second electrodes except for edge portions of the first and second electrodes; (f) exposing the first and second electrodes to an etching solution simultaneously to remove edge portions of the first and second electrodes; And (g) removing the etching protection film.

In the present invention, the etching solution is any one selected from acetic acid, nitric acid, iron chloride and hydrochloric acid.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

2A through 2E are a series of cross-sectional views illustrating a process of manufacturing a PTC device according to a preferred embodiment of the present invention.

First, 10 to 30% by weight of the crystalline polymer relative to the total material layer content is put into a mixer and heated to about 180 ° C. to be melted. Here, the crystalline polymer may be composed of a polymer such as polyethylene, silicon, polyvinyl difluoride.

Subsequently, a metal-based conductive material of 70 to 90% by weight based on the total material layer content is processed into a powder form and added to the molten crystalline polymer to prepare a conductive polymer resin composition. Here, the metal-based conductive material may be composed of a conductive material such as nickel metal, nickel metal alloy, nickel carbonate, nickel nitride and the like having a filament shape.

Then, as shown in FIG. 2A, the prepared conductive polymer resin composition is molded into a sheet to form the PTC material layer 110.

Subsequently, as illustrated in FIG. 2B, the first and second electrodes 121 and 122 are disposed on the upper and lower portions of the PTC material layer 110, and the roll pressing process or press is performed at a temperature above the melting point of the crystalline polymer. The first and second electrodes 121 and 122 are laminated on the PTC material layer 110 through the pressing process. The first and second electrodes 121 and 122 may be copper foil, nickel plated copper foil, nickel foil, or the like.

Then, as shown in FIG. 2C, the etching protection layer 130 is formed at the center of the first and second electrodes 121 and 122 so as to expose edge portions of a predetermined length on the surfaces of the first and second electrodes 121 and 122. ).

Then, as illustrated in FIG. 2D, edge portions of the first and second electrodes 121 and 122 are removed by using a wet etching process. At this time, the etching solution used may be used acetic acid, nitric acid, iron chloride, hydrochloric acid and the like. In the second half of the wet etching process, the first and second electrodes 121 and 122 are removed to form a PTC exposed surface 111 through which the PTC material layer 110 is exposed to the outside, and the etching solution is applied to the PTC exposed surface 111. The metal-based conductive material penetrated and exposed to the PTC exposed surface 111 is removed. Preferably, the etching process time is adjusted such that the removal depth of the metal-based conductive material is at least 0.1 mm.

Finally, as shown in FIG. 2E, the etching protection layer 130 that protects the first and second electrodes 121 and 122 is removed.

3 is a cross-sectional view showing the configuration of a PTC device according to a preferred embodiment of the present invention, Figure 4 is an enlarged cross-sectional view showing an enlarged portion A of FIG.

3 and 4, the PTC device 100 according to the present invention includes a PTC material layer 110 having PTC characteristics, and first and second electrodes disposed above and below the PTC material layer 110. And the edges of the first and second electrodes are removed by an etching process to expose the PTC material layer 110. The exposed PTC material layer is referred to as PTC exposed surface 11 for convenience of explanation below.

The PTC material layer 110 is formed by mixing a crystalline polymer and a metal-based conductive material. When the temperature rises, the crystal region becomes amorphous and the resistance is separated by separating the contact between the conductive particles with volume expansion. Provide rising PTC characteristics. Preferably, the specific resistance of the PTC material layer 110 is 0.005 to 0.1 Ωcm.

The first and second electrodes 121 and 122 are fusion-spliced so as to face the top and the bottom with the PTC material layer 110 therebetween. As the material of the first and second electrodes 121 and 122, copper foil, nickel plated copper foil, nickel film, or the like is preferably used.

The PTC exposed surface 111 is in a state in which the metal-based conductive material inside the PTC material layer 110 exposed to the surface is removed by the action of the etching solution used in the etching process. The depth at which the metal-based conductive material is removed varies depending on the size and use of the PTC element 100, but preferably 0.1 mm or more.

<Examples and Comparative Examples>

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the embodiments are only illustrative of the present invention, and the scope of the present invention is not limited thereto.

Example 1

After 100 phr of high density polyethylene (HDPE, Tm = 125 ° C.) was melted at 180 ° C. with a Haake mixer, a conductive polymer resin composition was prepared by adding 750 phr of nickel powder having a filament shape to the molten polymer. The prepared conductive polymer resin composition was then molded into sheet formation to form a PTC material layer. Then, a pair of nickel plated copper foils were placed on the upper and lower portions of the formed PTC material layer and molded for 10 minutes at 180 ° C. so as to have a thickness of 2 mm. The processed sheet was irradiated with an electron beam with a particle beam accelerator to crosslink the resin composition.

The sheet was then processed into a coin shape with a diameter of 30 mm as shown in FIG. Then, an etching protection film was coated on the center of the electrode to remove the metal material constituting the electrode from the edge of the nickel-plated copper foil electrode disposed on the top and bottom 5 mm. Subsequently, the electrode having the etching protective film coated thereon was exposed to an iron chloride solution to remove the edge portion of the electrode, thereby manufacturing a PTC device according to the present invention.

Comparative Example 1

As illustrated in FIG. 6, the processed sheet manufactured in Example 1 was processed into a coin shape having a diameter of 30 mm to prepare a PTC device.

Comparative Example 2

The processed sheet prepared in Example 1 is processed into a coin shape having a diameter of 30 mm, as shown in FIG. Then, the surface of the electrode was cut to remove the metallic material constituting the electrode from the edges of the nickel plated copper foil electrodes disposed at the upper and lower portions to 5 mm, thereby manufacturing a PTC device having the same shape as in Example 1.

Table 1 below shows the results of the short-circuit simulation test, which shows the initial resistance of the PTC device and the presence or absence of arcing at two short-circuit currents.

Initial resistance (mΩ) 300VAC 1kA 300VAC 10kA Example 1 0.34 No arc generation No arc generation Comparative Example 1 0.14 Arc generating oil Arc generating oil Comparative Example 2 0.35 No arc generation Arc generating oil

As shown in Table 1 above, in Comparative Example 1, although the initial resistance characteristics were better than those of Example 1 and Comparative Example 2 in which the edges of the electrodes were removed, an arc occurred when a short circuit current of 1 kA was applied. On the other hand, in Example 1 and Comparative Example 2, an arc did not occur at a short circuit current of 1 kA. It can be seen from this that removing the edge of the electrode has an effect of suppressing the generation of arc.

On the other hand, when a short circuit current of 10 kA was applied, an arc occurred in Comparative Example 2, but an arc did not occur in Example 1. In the case of the PTC device of Example 1, the metal-based conductive material present on the PTC exposed surface is removed to a constant depth in the process of removing the edge electrode by the etching process, thereby increasing the actual conduction distance of the arc through the air. This is because the dielectric breakdown resistance of air is improved. Therefore, it can be seen that the stability of the PTC device can be improved by removing the edge portion of the electrode according to the present invention by an etching process.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

As described above, the PTC device according to the present invention is introduced into an overcurrent breaker to effectively suppress the flashover of the arc due to insulation breakdown of the air when the overcurrent or the short-circuit current is limited, thereby improving the stability of the PTC device. The degradation of the PTC material layer can be prevented. In addition, by improving the specific resistance of the PTC material layer, it is possible to implement a more stable current flow even in a small dimension it can be usefully applied to the protection of portable electronic devices, batteries, and the like.

Claims (13)

In a PTC device, A PTC material layer comprising a conductive polymer resin composition comprising 10 to 30% by weight of the crystalline polymer with respect to the total material layer content and 70 to 90% by weight with respect to the total material layer content; And And first and second electrodes disposed to face the upper and lower portions with the PTC material layer interposed therebetween. A PTC device having improved safety, characterized in that the vicinity of the edges of the first and second electrodes are removed by a wet etching process so that the metallic conductive material present on the PTC exposed surface is removed to a constant depth. The method of claim 1, The crystalline polymer is improved PTC device, characterized in that consisting of any one selected from polyethylene, silicone, and polyvinyl difluoride or mixtures thereof. The method of claim 1, The metal-based conductive material is improved PTC device, characterized in that made of any one or a mixture of nickel metal, nickel metal alloy, nickel carbonate and nickel nitride having a filament shape. The method of claim 1, The PTC device of claim 1, wherein the PTC material layer has a specific resistance of 0.005 to 0.1 Ωcm. The method of claim 1, The first and second electrodes are improved PTC device, characterized in that made of any one material selected from copper foil, nickel plated copper foil and nickel foil. The method of claim 1, The metal conductive material is improved PTC device, characterized in that removed to a depth of 0.1 mm or more. In the method of manufacturing a PTC device, (a) melting 10-30% by weight of the crystalline polymer relative to the total material layer content; (b) preparing a conductive polymer resin composition by processing the metal-based conductive material having a filament shape of 70 to 90% by weight based on the total material layer content and adding the molten crystalline polymer to the molten crystalline polymer; (c) molding the conductive polymer resin composition into a sheet to form a PTC material layer; (d) placing and laminating respective first and second electrodes on top and bottom of the PTC material layer; (e) forming an etching protection film on surfaces of the first and second electrodes except for edge portions of the first and second electrodes; (f) exposing the first and second electrodes to an etching solution simultaneously to remove edge portions of the first and second electrodes; And (g) removing the etching protection film; and improved PTC device manufacturing method comprising a. The method of claim 7, wherein The crystalline polymer is a PTC device manufacturing method with improved safety, characterized in that consisting of any one selected from polyethylene, silicone and polyvinyl difluoride or mixtures thereof. The method of claim 7, wherein The metal-based conductive material is a PTC device manufacturing method with improved safety, characterized in that made of any one or a mixture of nickel metal, nickel metal alloy, nickel carbonate and nickel nitride having a filament shape. The method of claim 7, wherein The specific resistance of the PTC material layer is 0.005 to 0.1 Ωcm characterized in that the improved safety of the PTC device manufacturing method. The method of claim 7, wherein The method of claim 1, wherein the first and second electrodes are made of any one material selected from copper foil, nickel plated copper foil, and nickel foil. The method of claim 7, wherein The method of claim 1, wherein the metal-based conductive material is removed to a depth of 0.1 mm or more. The method of claim 7, wherein The etching solution is improved PTC device manufacturing method characterized in that any one selected from acetic acid, nitric acid, iron chloride and hydrochloric acid.

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