KR100985978B1 - polymer PTC thermistor and thereof. - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer PTC thermistor element and a method of manufacturing the same, and more particularly, to a polymer PTC thermistor element and a method of manufacturing the same, using an electrically conductive filler of a metal and constituting an insulating layer for preventing a short circuit of the metal. It is about.

The polymer PTC thermistor element of the present invention,

An external terminal for connecting to the outside when mounting parts;

Two electrodes formed to be in contact with the external terminal to allow a current to flow through the conductive polymer;

A conductive polymer disposed between the two electrodes and composed of a crystalline polymer material and a conductive filler;

An insulating layer is formed to surround the electrode and the conductive polymer, wherein a portion of the external terminal protrudes out of the insulating layer.

The present invention solves the problem of inherent oxidation, which is a problem when using a conductive filler of a metal material to realize low resistance, thereby providing an effect of preventing the deterioration of properties.

PTC, thermistor, polymer.

Description

Polymer PTC thermistor and its manufacturing method

The present invention relates to a polymer PTC thermistor device and a manufacturing method thereof.

More specifically, the present invention relates to a polymer PTC thermistor element using a conductive filler of a metal and at the same time constituting an insulating layer for preventing short of the metal and a method of manufacturing the same.

Typical static temperature coefficient (PTC) resistance of conductive materials is sensitive to temperature changes.

Using these properties, PTC conductive materials are used as current sensing materials and are widely used in overcurrent protection devices and circuits.

The PTC conductive material is kept at a low value at room temperature so that the overcurrent protection device or circuit operates normally.

However, when overcurrent and overheat conditions occur, the resistance of the PTC conductive material immediately increases to at least ten thousand times (> 10,000 ohms), which is a high resistance state.

Generally, the PTC conductive material comprises at least one crystalline polymer and a conductive filler, the conductive filler is uniformly dispersed in the crystalline polymer, and the crystalline polymer is mainly a polyolefin polymer, such as polyethylene (POLYETHYLENE). .

Conductive fillers are mainly carbon black (CARBON BLACK), metal particles and non-oxidized ceramic powders, for example titanium carbide (CARBIDE) or tungsten carbide.

The conductivity of the PTC conductive material depends on the type and type of conductive filler.

Generally speaking, the rough surface carbon black has better adhesion with the polyolefin polymer and thus has better resistance resilience. However, carbon black conductivity is lower than that of metal particles. If metal particles are used as the conductive filler, larger particle sizes become non-uniformly dispersed and the metal particles tend to oxidize to produce high resistance.

In order to effectively reduce the resistance of the overcurrent protection device and prevent oxidation, the ceramic powder is used as the conductive filler in the PTC conductive material.

Since the ceramic powder lacks a rough surface such as carbon black, the ceramic powder has poor adhesion with polyolefin and consequently, the resistance return force of the PTC conductive material is not well controlled.

Recently, low resistance (about 20 mΩ) PTC conductive materials using nickel as the conductive filler have been used in the market, but they withstand up to 6V voltage.

If nickel is not well isolated from air, it oxidizes after a period of time and consequently the resistance increases.

More specifically, PTC thermistors that are commonly used as overcurrent and overheat protection devices and can be used repeatedly include polymer PTC thermistors and ceramic PTC thermisors.

Ceramic PTC thermistor has high initial resistance and high power consumption, which makes it unsuitable for protecting secondary batteries.

Therefore, polymer PTC thermistor has been used to protect the secondary battery. In recent years, the internal resistance of the secondary battery has to be lowered in accordance with the demand of increasing the capacity of the secondary battery and increasing the use time with a single charge. There is a growing need for lowering the need for resistance at the same time.

In the case of conventional polymer PTC thermistors, carbon black is mostly used as a conductive material. In the case of carbon black, there is a limit of resistance that can be realized. Therefore, in order to meet the requirements of miniaturization and low resistance, metal materials having lower resistivity than carbon black are used. Only possible.

When using a conductive filler of a metal material, the product can be made small and low resistance, but due to the inherent oxidation problem of the metal may cause degradation of properties when oxidation occurs in the process.

Therefore, the present invention has been proposed in view of the problems of the prior art as described above, and an object of the present invention is to solve the problem of inherent oxidation, which is a problem when using a conductive filler of a metal material to realize low resistance, thereby deteriorating characteristics. To prevent.

It is another object of the present invention to provide a manufacturing method which does not cause a deterioration of properties due to oxidation in a process or use without using a special oxygen barrier material.

Still another object of the present invention is to provide an insulating layer so as to prevent shorting with adjacent parts when mounting parts.

In order to achieve the problem to be solved by the present invention,

The polymer PTC thermistor element according to the embodiment of the present invention,

An external terminal for connecting to the outside when mounting parts;

Two electrodes formed to be in contact with the external terminal to allow a current to flow through the conductive polymer;

A conductive polymer disposed between the two electrodes and composed of a crystalline polymer material and a conductive filler;

An insulating layer is formed to surround the electrode and the conductive polymer, wherein a portion of the external terminal protrudes out of the insulating layer.

The polymer PTC thermistor device and the method of manufacturing the same according to the present invention having the above-described configuration and function solve the problem of oxidation inherent in the metal, which is a problem when using a conductive filler of a metal material to realize low resistance, thereby preventing the deterioration of properties. It will provide an effect.

In addition, the present invention provides a manufacturing method that does not cause a deterioration in characteristics due to oxidation in a process or use without using a special oxygen barrier material.

In addition, by providing an insulating layer to provide an effect that can prevent a short with the adjacent parts when mounting the component.

The polymer PTC thermistor device according to an embodiment of the present invention for achieving the above object,

An external terminal for connecting to the outside when mounting parts;

Two electrodes formed to be in contact with the external terminal to allow a current to flow through the conductive polymer;

A conductive polymer disposed between the two electrodes and composed of a crystalline polymer material and a conductive filler;

An insulating layer is formed to surround the electrode and the conductive polymer, wherein a portion of the external terminal protrudes out of the insulating layer.

At this time, the conductive filler,

It is characterized in that the powder material having conductivity to impart conductivity.

At this time, the crystalline polymer,

It is characterized in that the polyolefin-based crystalline polymer.

In addition, the conductive filler,

In the case of kneading with the crystalline polymer material to prevent oxidation during the molding process, it is characterized in that the use of a nitrogen atmosphere in the case of sheet formation, pressing, soldering and coating.

At this time, when using a nitrogen atmosphere for soldering,

The oxygen concentration in the atmosphere is characterized in that less than 500ppm.

In addition, when using a nitrogen atmosphere,

Atmospheric oxygen concentration is characterized in that less than 10,000ppm.

At this time, the insulating layer,

When measured at 50% humidity of 23 ℃ characterized in that the liquid epoxy insulating material having a volume resistance of 10 ¹² ~ 10 ¹⁷ 절연 insulation properties.

In addition, when the metal conductive material constituting the conductive filler is used in more than 500phr, the specific resistance of the conductive polymer is characterized in that less than 0.02Ωcm.

On the other hand, the polymer PTC thermistor element manufacturing method of the present invention,

A kneading milling step of grinding a conductive polymer obtained by kneading a polyolefin-based crystalline polymer, a conductive filler, and an additive;

Extruding the pulverized conductive polymer to form a sheet having a desired thickness and thermoforming the electrode;

A punching step of punching the crimped sheet to a size exhibiting PTC characteristics;

A PTC characteristic forming step of crosslinking the punched device using an electron beam to form a device exhibiting PTC characteristics;

And an insulating layer coating step of attaching the external electrode by soldering and coating the insulating layer to form a final finished product.

At this time, in the kneading grinding step,

The metal conductive material for forming the conductive filler is used more than 500phr, the specific resistance of the conductive polymer (ρ = R * S / t, R = resistance, S = area, t = thickness) is characterized in that it has a 0.02 0.0cm or less .

At this time, in the sheet forming step,

The thickness of the sheet to be formed is characterized by being 0.6 mm or less.

At this time, in the PTC characteristic forming step,

Crosslinking dose is characterized in that more than 150Mrad.

At this time, in the insulating layer coating step,

The coating thickness of the insulating layer is characterized in that the max. 300㎛.

Hereinafter, the polymer PCT thermistor device and the method of manufacturing the same according to the present invention will be described in detail.

1 is a cross-sectional view of a polymer PTC thermistor device according to an embodiment of the present invention.

As shown in FIG. 1, the polymer PTC thermistor element 100 of the present invention is

An external terminal 110 for connecting to the outside when mounting components;

Two electrodes (130) formed in contact with the external terminals to allow a current to flow through the conductive polymer;

A conductive polymer 120 positioned between the two electrodes and composed of a crystalline polymer material and a conductive filler;

The insulating layer 140 is formed so as to surround the electrode and the conductive polymer, wherein a portion of the external terminal protrudes out of the insulating layer.

Conductive polymer 120 formed of a crystalline polymer material and a conductive filler is formed between the two electrodes 130 to be in contact with the external terminal 110 for connecting to the outside when mounting components, respectively. ).

In addition, an insulating layer 140 is formed to surround the electrode and the conductive polymer, and a part of the two external terminals protrudes to the outside of the insulating layer to be connected to the outside.

At this time, the conductive filler,

In order to impart conductivity, it is composed of a conductive powder material (metal, carbon black, etc.).

The conductive polymer is composed of a crystalline polymer material and a conductive filler to form a material layer having PTC properties.

In addition, the electrode is an electrode material for forming a current flow through the conductive polymer is preferably configured by plating a max. 8㎛ nickel on an electrolytic copper foil of max. 35㎛.

The crystalline polymer is a polymer material having a high degree of crystallinity, and is preferably a polyolefin-based crystalline polymer to impart PTC characteristics due to the volume expansion ratio during phase change.

The present invention uses a nitrogen atmosphere in the process to prevent oxidation, it is possible to prevent the short by forming an insulating layer.

The external terminal is preferably made of a rolled nickel of 0.1mm ~ 0.15mm.

The most important of the insulating layer in the present invention are adjacent when the component mounting part (particularly a secondary battery can and PCM) and short-circuit the isolation of the volume resistivity is 10 ¹² ~ 10 ¹⁷ Ω when measured at 23 ℃ humidity of 50% as to prevent A liquid epoxy insulating material having properties is used.

In particular, when a metal material is used as a conductive filler, oxidation occurs during the forming process by applying heat, thereby deteriorating product characteristics. Thus, a process of kneading with a crystalline polymer material, a sheet forming process, and a soldering process are performed. Processes and coating processes should be protected from oxidation using a nitrogen atmosphere (typically about 20% oxygen in the air, blowing nitrogen to create a low oxygen atmosphere).

At this time, the oxygen concentration in the air should be less than 10,000ppm, especially in the soldering process, which is the process of applying the most heat to the PTC device, the oxygen concentration should be less than 500ppm.

In this case, when the metal conductive material constituting the conductive filler is used in more than 500phr, the specific resistance of the conductive polymer is characterized in that less than 0.02Ωcm.

2 is a process chart showing a method for manufacturing a polymer PTC thermistor device according to an embodiment of the present invention.

As shown in Figure 2, the kneading milling step (S110) for grinding the conductive polymer kneaded polyolefin-based crystalline polymer, conductive filler and additives;

A sheet forming step (S120) of extruding the pulverized conductive polymer to form a sheet having a desired thickness and thermocompressing an electrode;

A punching step (S130) of punching the crimped sheet to a size indicating PTC characteristics;

A PTC characteristic forming step (S140) of crosslinking the punched device using an electron beam to form a device exhibiting PTC characteristics;

It characterized in that it comprises a; insulating layer coating step (S150) of attaching the external electrode by soldering and coating the insulating layer to form a final product.

The additives are flame retardants [Mg (OH) ₂ ] and crosslinking aids [TAIC] and processing aids [stearic acid] in Examples, and the contents are 20 phr, 5 phr, and 10 phr as max contents, respectively.

That is, the kneading grinding step is a step of melting the polymer material and mixing with the conductive material, the metal conductive material for forming the conductive filler is used more than 500phr, in this case the specific resistance of the conductive polymer (ρ = R * S / t, R = resistance , S = area, t = thickness) should be less than 0.02Ωcm.

The kneading is kneader and the temperature is 200 ℃ ℃ crystalline polymer HDPE (density 0.958g / cm3, Tm = 131 ℃) and flame retardant [Mg (OH) ₂ ] first melting the conductive filler (amorphous nickel powder) And stearic acid are divided into 4 times and kneaded.

At this time, the total kneading time is less than 30 minutes, and after the conductive filler is sufficiently kneaded, additionally kneaded within 5 minutes by adding TAIC, a crosslinking aid, and then taken out.

At this time, the raw materials taken out are put into the grinder, and then subjected to the first coarse grinding (particle size of 10 mm or less), followed by the second fine grinding to grind the particle size to 3 mm or less, and the raw material is put into an extruder to form the sheet into sheets.

The sheet formed in the sheet forming step has a thickness of 0.6 mm or less, and the crosslinking dose of the PTC characteristic forming step should be 150 Mrad or more.

In addition, the coating thickness of the insulating layer in the insulating layer coating step is preferably max. 300㎛.

Electrical properties and test results shown through three examples of the polymer PTC thermistor device of the present invention are shown as follows.

(1) Composition (Unit: g)

No Kinds Contents Polymer HDPE conductivity
additive Flame retardant
Mg (OH) ₂ Crosslinking aid
TAIC Processing aid
Stearic acid One  Example 1  Waiting 10 70 2 0.5 One 2  Example 2  50,000 ppm oxygen 10 70 2 0.5 One 3  Example 3 Oxygen 10,000 ppm /
500 ppm soldering 10 70 2 0.5 One

(2) electrical characteristics

No Kinds Contents Element diameter
(mm) thickness
(mm) Ri
(mΩ) ρ
(Ωcm) One Example 1 Waiting 3.0 0.6 14.9 0.0175 2 Example 2 50,000 ppm oxygen 3.0 0.6 14.2 0.0167 3 Example 3 Oxygen 10,000 ppm /
500 ppm soldering 3.0 0.6 14.1 0.0167

(3) Trip Cycle Test

No Kinds Contents DC6V, 50A Trip cycle test (unit: mΩ) initial One
cycle 10
cycle 50
cycle 100
cycle 500
cycle 1000
cycle 3000
cycle 6000
cycle One Example 1 Waiting 14.9 16.6 20.6 32.0 57.8 259.1 364.7 5761 771.0 2 Example 2 50,000 ppm oxygen 14.2 17.0 19.3 36.5 44.9 99.2 114.3 194.3 293.7 3 Example 3 Oxygen 10,000 ppm /
500 ppm soldering 14.1 16.3 17.3 20.6 23.0 30.0 34.4 43.0 58.0

(4) Trip Endurance Test

No Kinds Contents DC6V, 50A Trip endurance test (unit: mΩ) initial 100hr 250hr 500hr 750 hr 1000hr One Example 1 Waiting 14.5 245.5 769.0 5745.0 6685.0 31625.0 2 Example 2 50,000 ppm oxygen 14.7 145.5 615.0 2207.2 3605.0 4505.0 3 Example 3 Oxygen 10,000 ppm /
500 ppm soldering 14.3 17.0 16.9 19.1 19.9 33.6

3 is a table showing experimental results according to an embodiment of a polymer PTC thermistor device according to an embodiment of the present invention.

For the experiment, the device thickness was 0.6mm and the device size was 3mm in diameter. The crosslinking conditions were electron beam accelerators, and the maximum irradiation was investigated 24 times with a voltage of 0.95MeV, a current of 23mA and a feed rate of 2.5m / min.

At this time, the measurement was carried out Trip trip test and Trip endurance test, Trip cycle test was 6 seconds on, 54 seconds off at DC6V, 50A, 6,000 cycles repeated test and the resistance was measured.

In addition, the trip endurance test was applied to DC 6V, 50A for 1,000 hours and the resistance was measured.

The result measured under the above conditions has the above resistance value, and the trip cycle test is a test for repeatedly applying the overcurrent to the product, and the trip endurance test is a test for maintaining the tripped state for a long time with the overcurrent applied to the product. .

At this time, the resistance change rate is small, so the closer to the initial resistance value means that the function of the product is maintained without being degraded.

Therefore, in the case of Trip cycle test, Example 1 increased the initial resistance of 14.9mΩ, the resistance after the test increased to 571 times to 771mΩ, and Example 2 increased the initial resistance of 14.2mΩ and the resistance after the test to 293.7mΩ by 20.7 times. Initial resistance 14.1mΩ, after the test resistance was increased by 4.1 times to 58mΩ, it can be seen that the resistance increase rate is significantly reduced, thereby indicating that the performance of the product is maintained in a relatively initial state.

Trip endurance test also compares the increase rate of resistance it can be seen that Example 1 is 2181 times, Example 2 is 306 times, Example 3 is 2.3 times.

The above result was found to change the resistance according to the repeat test as shown in FIG.

In other words, the high rate of resistance increase after the test can be regarded as the degradation of the performance of the product due to the oxidation of the conductive material.

Those skilled in the art to which the present invention pertains as described above may understand that the present invention may be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

The polymer PTC thermistor device of the present invention and a method for manufacturing the same provide an effect of preventing the deterioration of properties by solving the oxidation problem inherent in a metal, which is a problem when using a conductive filler of a metal material for realizing low resistance, thereby preventing overcurrent protection. It will be widely used in the field.

1 is a cross-sectional view of a polymer PTC thermistor device according to an embodiment of the present invention.

2 is a process chart showing a method for manufacturing a polymer PTC thermistor device according to an embodiment of the present invention.

3 is a table showing experimental results according to an embodiment of a polymer PTC thermistor device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: device of the present invention

110: external device

120: conductive polymer

130 electrode

140: insulation layer

Claims (13)

An external terminal for connecting to the outside when mounting parts; Two electrodes formed to be in contact with the external terminal to allow a current to flow through the conductive polymer; A conductive polymer disposed between the two electrodes and composed of a crystalline polymer material and a conductive filler; An insulating layer is formed to surround the electrode and the conductive polymer, and a portion of the external terminal protrudes out of the insulating layer, The conductive filler, Powder material having conductivity to impart conductivity, The conductive filler, A polymer PTC thermistor element characterized by using a nitrogen atmosphere when kneading with a crystalline polymer material to prevent oxidation during a molding process, when forming a sheet, pressing, and soldering and coating. delete delete delete The method of claim 1, When using a nitrogen atmosphere for soldering, Polymeric PTC thermistor element, characterized in that the oxygen concentration in the atmosphere is 500ppm or less. delete The method of claim 1, The insulating layer, Polymeric PTM thermistor element, characterized in that the liquid epoxy insulating material having a volume resistance of 10 ¹² ~ 10 ¹⁷ kPa when measured at 23 ℃ humidity 50%. The method of claim 1, When the metal conductive material constituting the conductive filler is used in 500 phr or more, the polymer PTC thermistor device, characterized in that the resistivity of the conductive polymer is less than 0.02Ωcm. delete delete delete delete delete

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