KR101782382B1 - Ceramic composition for ntc thermistor temperature sensor, method of forming sintered material using the same and ntc thermistor device having the same - Google Patents

Abstract

Disclosed are a ceramic composition for NTC thermistor temperature sensors, a manufacturing method of a ceramic sintered body for NTC thermistor temperature sensors using the same, and an NTC thermistor element comprising the same. The ceramic composition for NTC thermistor temperature sensors according to one embodiment of the present invention comprises (a) La_2O_3, (b) Al_2O_3, (c) ZrO_2, and (d) Mn_3O_4, and is mixed by mole ratios of (a) 0.6 to 0.9, (b) 0.1 to 0.4, (c) 0.7 to 0.8 and (d) 0.2 to 0.3. Accordingly, the NTC thermistor element manufactured thereby meets an integer B which is relatively low compared with a high resistance value, and can stably measure the temperature in a high temperature range. In addition, the element can stably measure the temperature in a low temperature range, thereby improving the utilization of a temperature sensor in various temperature ranges.

Description

TECHNICAL FIELD [0001] The present invention relates to a ceramic composition for an NTC thermistor temperature sensor, a method of manufacturing a ceramic sintered body for the NTC thermistor temperature sensor using the same, and an NTC thermistor element including the same. BACKGROUND OF THE INVENTION SAME}

The present invention relates to a ceramic composition for an NTC thermistor temperature sensor, a method of manufacturing a ceramic sintered body for an NTC thermistor temperature sensor using the same, and an NTC thermistor element including the same. More particularly, A method of manufacturing a ceramic sintered body for an NTC thermistor-on sensor using the same, and an NTC thermistor element including the same.

Generally, a sensor is a device that responds appropriately to external stimuli or changes in the environment and can take appropriate measures as required. There are various kinds of sensors, for example, an on-sensor, a pressure sensor, a gas sensor, and an infrared sensor. These sensors are widely used in various industries, and their principles, types, requirements, and the like are gradually diversified and become more important.

A thermistor is an on-sensor that has a characteristic that the resistance changes with the change of the ON. The types of the thermistor include a negative temperature coefficient (NTC) thermistor and a positive temperature coefficient (PTC) thermistor. These are representative examples of electrical ceramics.

The thermocouple (NTC) thermistor is a thermistor that uses a phenomenon in which the resistance decreases as the temperature increases. The resistance of the thermistor is exponentially declining in a wide temperature range, and most of the thermistors are equivalent thereto.

The thermocouple (PTC) thermistor is a special thermistor using a phenomenon in which the resistance increases abruptly when the temperature exceeds a certain value when the temperature is increased. This affects the electrical property causing a large resistance change in a very small temperature range in the intergranular region It can be said that the cause is the change of dielectric property.

In general, the NTC thermistor is widely used as a sensor for on-detection of a fire detector, a home appliance, an industrial device, an aviation device, an OA device, a medical device, and an on-compensation device of various electronic devices. In addition, it has a wide range of applications such as liquid level sensors for automobiles using current and voltage characteristics, wet and anemometer sensors, and inrush current limiting for electronic circuit devices using current and time specification.

The thermistor material and its composition have been studied in the United Kingdom and the United States from the late 1930s to the early 1940s, and transition metals such as Mn, Ni, Co, Fe, and Cu Oxides as raw materials, and a composite oxide product of two or more of these oxides. In 1946, the Bell Institute of the United States developed a composite sintered body of Mn and Ni oxides. The thermistor was named as a thermistor and began to be put into practical use. Then, in the 1950s, the thermistor was composed of three components of Mn, Since then, the development of materials containing Fe, Cu oxide, and the like has been attracting attention as an on-sensor due to a remarkable improvement in manufacturing technology.

The types of thermistors can be classified into a disk type, a diode type, a chip (in epoxy, a glass) type using a classical ceramic manufacturing technology, and the like; Surface-mounted type using thick film or thick film laminating process; Thin film type, and the like. Since the price of the thermistor is low and the change rate of the resistance according to the change of temperature is large, it is easy to manufacture a sensor capable of precise temperature measurement and management. In addition, a relatively high room temperature resistance value can be realized.

The sensing range of the on-sensor applied to the exhaust system is usually 300 to 800, but the DPF must meet the on-range of -40 to 900 in accordance with the OBD II application in overseas.

As a direct injection method is adopted for an automobile engine, an automobile engine requires a filter for filtering the exhaust gas discharged at the initial start of cold weather. In the case of an automobile engine, it is difficult to measure up to 1,000 ranges, In order to satisfy such a temperature range, a composition having a low B constant relative to a high resistance value is required.

Japanese Laid-Open Patent Publication No. 10-2012-043910

The present invention seeks to provide a ceramic composition for an NTC thermistor-on-sensor which can stably measure temperature in a wide range of temperature range of high temperature and low temperature.

The present invention also provides a method of manufacturing a ceramic sintered body for an NTC thermistor-on sensor using the ceramic composition for an NTC thermistor-on-sensor.

Further, it is intended to provide an NTC thermistor device including the above-mentioned ceramic composition for an NTC thermistor-on-sensor.

Ceramic composition for NTC thermistor temperature sensor according to one embodiment of the present invention for solving the aforementioned problems _{is, (a) La 2 O 3} , (b) Al 2 O 3, (c) ZrO 2 , and (d) Mn ₃ O ₄ and are mixed in a molar ratio of (a) 0.6 to 0.9, (b) 0.1 to 0.4, (c) 0.7 to 0.8, and (d) 0.2 to 0.3.

(A) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO _2, and (d) at least one rare earth element selected from the group consisting of ) Mn ₃ O ₄ and is mixed in a molar ratio of (a) 0.6 to 0.9, (b) 0.1 to 0.4, (c) 0.7 to 0.8, and (d) 0.2 to 0.3. Calcining for 1 to 5 hours at a temperature of 1,200 to 1,300 占 폚 and sintering for 1 to 5 hours at 1,500 to 1,600 占 폚 of temperature.

Also, according to an embodiment of the present invention, the powder obtained by pulverizing the calcined composition may be put into a press mold having a plurality of lead wires, followed by press molding and sintering.

The NTC thermistor element according to an embodiment of the present invention includes (a) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO _2, and (d) Mn ₃ O ₄ . And a ceramic composition which is mixed at a molar ratio of (a) 0.6 to 0.9, (b) 0.1 to 0.4, (c) 0.7 to 0.8, and (d) 0.2 to 0.3; and a plurality of ceramic sintered bodies Of lead wires.

Also, according to an embodiment of the present invention, the NTC thermistor element may have a resistance value of 0.1 to 900 k? In a temperature range of -50 to 1,000 占 폚.

According to an embodiment of the present invention, the NTC thermistor element may have a B constant according to the following formula (1) in a temperature range of -50 to 1,000 ° C: 1,800 to 2,400.

(1) where R1 is the time required to reach the target position,

In addition, according to an embodiment of the present invention, the lead wires are two lead wires and can be disposed parallel to each other.

According to the ceramic composition for the NTC thermistor-on-sensor according to the embodiments of the present invention, the method for manufacturing the ceramic sintered body for the NTC thermistor-on sensor, and the NTC thermistor element including the same, It is possible to stably measure the temperature in the low temperature region and to improve the utilization of the sensor.

FIG. 2 is a graph showing resistance values of temperature of an NTC thermistor device according to an embodiment of the present invention.
FIGS. 3 and 4 are graphs showing resistance values of the NTC thermistor devices according to the comparative examples.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing resistance values of an NTC thermistor element according to embodiments and comparative examples of the present invention. FIG.
5 is a cross-sectional view of an NTC thermistor device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms.

FIG. 2 is a graph showing resistance values of temperature of an NTC thermistor device according to an embodiment of the present invention. FIGS. 3 and 4 are graphs showing resistance values of the NTC thermistor devices according to the comparative examples. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing resistance values of an NTC thermistor element according to embodiments and comparative examples of the present invention. FIG. 5 is a cross-sectional view of an NTC thermistor device according to an embodiment of the present invention.

1 to 5, a ceramic composition for an NTC thermistor temperature sensor according to an embodiment of the present invention, a method for manufacturing a ceramic sintered body for an NTC thermistor temperature sensor using the same, and an NTC thermistor element including the same will be described in detail .

An NTC thermistor element according to an embodiment of the present invention includes a ceramic sintered body 10 and two lead wires 20.

Wherein the NTC thermistor element comprises (a) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO _2, and (d) Mn ₃ O ₄ , 0.4, (c) 0.7 to 0.8, and (d) 0.2 to 0.3 in terms of molar ratio.

The ceramic sintered body 10 is manufactured by calcining and sintering the ceramic composition for an NTC thermistor temperature sensor.

The ceramic composition for an NTC thermistor temperature sensor according to an embodiment of the present invention includes (a) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO _2, and (d) Mn ₃ O ₄ , (a) 0.6 to 0.9, (b) 0.1 to 0.4, (c) 0.7 to 0.8, and (d) 0.2 to 0.3.

When the mixture of (a) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO ₂ and (d) Mn ₃ O ₄ is out of the molar ratio described above, It is difficult to measure the resistance value, or the resistance value is hardly changed, so that the noise is processed and the temperature is difficult to measure.

The ceramic composition for the NTC thermistor temperature sensor is wet-mixed and calcined at a temperature of 1,200 to 1,300 DEG C for 1 to 5 hours. Preferably, the composition is calcined in air at a temperature of 1,230 to 1280 DEG C for 2 to 4 hours.

The reliability of the thermistor element can be further improved through the calcination process.

The calcined composition is pulverized to prepare a powder. Thereafter, after the binder is added to the powder, it can be put into a press mold having the two lead wires 20 and press-molded.

For example, the lead wire 20 may be platinum (Pt).

For example, the two lead wires 20 may be arranged parallel to each other.

The sintered ceramic body 10 for the NTC thermistor temperature sensor can be manufactured by sintering the press-formed formed body at a temperature of 1,500 to 1,600 ° C for 1 to 5 hours. Preferably, the shaped body is sintered in air at a temperature of 1,520 to 1,580 캜 for 2 to 4 hours.

The metal oxide may be physically and chemically reacted through the sintering process and closely contacted with the lead wires 20.

The NTC thermistor element may have a resistance value of 0.1 to 900 k? In a temperature range of -50 to 1,000 占 폚.

When the resistance value is less than 0.1 k OMEGA, the resistance value is very small and it is difficult to distinguish it from noise, so that it is difficult to measure the temperature. When the resistance value is more than 900 k OMEGA, the resistance value increases toward the low temperature range, There is a problem that this becomes difficult.

The NTC thermistor element may have a B constant in the range of -50 to 1,000 ° C according to the following formula (1): 1,800 to 2,400.

(1) where T1 and T2 are the temperatures at which T1 and T2 are converted to absolute temperatures, respectively, and B (R1 / R2) = ln [R1 / R2] / [1 / T1-1 / T2] And R1 and R2 are the resistance values at T1 and T2.)

Generally, for accurate temperature measurement or easy management, it is advantageous that the rate of change of resistance with temperature change is large.

And the B constant has a large value when the change rate of the resistance according to the temperature change is large. However, the resistance of the NTC thermistor decreases as the temperature increases. When the B constant has a large value, the resistance value increases sharply toward the low temperature, which makes it difficult to measure the temperature at a low temperature.

Therefore, it may be preferable that the thermistor element has a B constant according to the formula (1) within a temperature range of -50 to 1,000 占 폚 of 1,800 to 2,400.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example  One

A composition of La ₂ O ₃ , Al ₂ O ₃ , ZrO ₂ and Mn ₃ O ₄ is mixed so that the composition ratio of La _a Al _b Zr _c Mn _d in the composition for exhaust temperature sensor is 0.9 mol, b is 0.1 mol, c is 0.8 mol, and d was determined to be 0.2 mol. The quantified metal oxides were wet-mixed and calcined in air at 1,250 ° C for 3 hours. Then, the calcined powder was pulverized. The pulverized powder was mixed with polyvinyl acetate (PVA), put into a press mold, and press-formed into a metal oxide by a cylindrical structure. Here, two Pt lead wires were inserted into the molding specimen in parallel with the interval at the time of the press molding. Thereafter, the metal oxide formed body having undergone the above press forming and lead wire insertion was sintered through air heat treatment at 1,550 ° C for 3 hours to prepare a thermistor element.

Thereafter, the resistance value of the thermistor element was measured by temperature, and the B constant according to the above formula (1) was calculated and shown in Table 1 below.

Temperature (℃) Resistance (kΩ) B integer formula B integer value (K) -50 415.0 B (-50 / -40) 1,850 -40 290.8 B (-40 / -20) 1,847 -20 155.5 B (-20 / 0) 1,864 0 90.71 B (0/100) 1,881 100 14.33 B (100/200) 1,910 200 4.858 B (200/300) 1,962 300 2.356 B (300/400) 1,838 400 1.463 B (400/500) 1,831 500 1.029 B (500/600) 1,967 600 0.7689 B (600/700) 2,164 700 0.5960 B (700/800) 2,191 800 0.4832 B (800/900) 2,354 900 0.4008 B (900/1000) 2,365 1,000 0.3421 - -

FIG. 2 is a graph showing resistance values of temperature of an NTC thermistor device according to an embodiment of the present invention.

Referring to Table 1 and FIG. 2, in order to graph, the resistance value is converted into a log value and set as a y-axis of the graph, and the temperature value is set as an x-axis by converting 10 ³ / T (K). As a result, the change of the resistance value according to the temperature change of the thermistor element manufactured according to the first embodiment of the present invention can be seen.

Comparative Example  One

A composition of Ba ₂ O ₃ , Al ₂ O ₃ , ZrO _2, and Mn ₃ O ₄ in the La _a Al _b Zr _c Mn _d composition is 0.5 mol, b is 0.5 mol, c is 0.9 mol, and d was determined to be 0.3 mol, a thermistor element was prepared in the same manner as in Example 1 above.

Thereafter, the resistance value of each thermistor element was measured by temperature, and the B constant according to the above formula (1) was calculated and shown in Table 2 below.

Temperature (℃) Resistance (kΩ) B integer formula B integer value (K) -50 - B (-50 / -40) - -40 - B (-40 / -20) - -20 - B (-20 / 0) - 0 1,299,048,002 B (0/100) 6,005 100 35,904,820 B (100/200) 6,314 200 1,004,482 B (200/300) 6,016 300 109,287 B (300/400) 6,763 400 18,937 B (400/500) 8,252 500 3,879 B (500/600) 12,344 600 623.2 B (600/700) 10,959 700 171.6 B (700/800) 10,341 800 63.75 B (800/900) 9,604 900 29.73 B (900/1000) 10,807 1,000 14.4200 - -

FIG. 3 is a graph showing resistance values of temperature of NTC thermistor devices according to comparative examples.

Referring to Table 2 and FIG. 3, in order to make a graph, the resistance value is converted into a log value and set as a y-axis of the graph, and the temperature value is set as an x-axis by converting 10 ³ / T (K). As a result, it can be seen that the B integer value of the thermistor element manufactured according to Comparative Example 1 of the present invention is too large to measure the resistance value in a temperature range of less than 0 ° C.

Comparative Example  2

A composition of Ba ₂ O ₃ , Al ₂ O ₃ , ZrO _2, and Mn ₃ O ₄ in the La _a Al _b Zr _c Mn _d composition is 0.5 mol, b is 0.5 mol, c is 0.6 mol, and d was determined to be 0.4 mol, the thermistor element was prepared in the same manner as in Example 1 above.

Thereafter, the resistance value of the thermistor element was measured by temperature, and the B constant according to the above formula (1) was calculated and shown in Table 3 below.

Temperature (℃) Resistance (kΩ) B integer formula B integer value (K) -50 0.0198 B (-50 / -40) 554 -40 0.0178 B (-40 / -20) 816 -20 0.0135 B (-20 / 0) 436 0 0.0119 B (0/100) 805 100 0.0054 B (100/200) 67 200 0.0052 B (200/300) 1,152 300 0.0034 B (300/400) 749 400 0.0028 B (400/500) 590 500 0.0025 B (500/600) 276 600 0.0024 B (600/700) 362 700 0.0023 B (700/800) 464 800 0.0022 B (800/900) 0 900 0.0022 B (900/1000) 695 1,000 0.0021 - -

4 is a graph showing resistance values of the NTC thermistor devices according to the comparative examples.

Referring to Table 3 and FIG. 4, in order to make a graph, the resistance value is converted into a log value to be set as a y-axis of the graph, and the temperature value is set as an x-axis by converting 10 ³ / T (K). As a result, the thermistor device manufactured according to Comparative Example 2 of the present invention has a temperature range of less than 1,200 and a B integer of 0 because the rate of change of resistance with temperature is very small, This difficulty can be seen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing resistance values of an NTC thermistor element according to embodiments and comparative examples of the present invention. FIG.

Referring to FIG. 1, the resistance value is converted into a log value to be set as the y-axis of the graph, and in the graph where the temperature value is converted into 10 ³ / T (K) The slope (logR / ㅿ (10 ³ / T)) at 400 캜 is as large as 0.799 in Example 1, 2.942 in Comparative Example 1 and 0.324 in Comparative Example 2, which is very small.

That is, when the slope in the graph of FIG. 1 is much larger than that in Embodiment 1, it is difficult to measure the resistance at low temperature. If the slope is much smaller than that in Embodiment 1, . That is, the slope (logR / ㅿ (10 ³ / T)) of the thermistor element according to an embodiment of the present invention may be 0.7 to 1.1.

The slope (logR / ㅿ (10 ³ / T)) on the graph of Comparative Example 1 is 2.608 to 4.693, and the slope (ㅿ logR / ㅿ (10 ³ / T) ) Is 0 to 0.356.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited thereto. Those skilled in the art will readily obviate modifications and variations within the spirit and scope of the appended claims. It will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

10: Thermistor 20: Lead wire

Claims (7)

delete delete delete (a) La ₂ O ₃ , (b) Al ₂ O ₃ , (c) ZrO ₂ and (d) Mn ₃ O ₄ , 0.7 to 0.8 and (d) 0.2 to 0.3 in a molar ratio of the ceramic composition; And
And a plurality of lead wires in contact with the ceramic sintered body,
An NTC thermistor element having a resistance value of 0.1 to 900 kΩ in a temperature range of -50 to 1000 ° C. and capable of stably measuring the temperature in a wide temperature range. delete 5. The method of claim 4,
Wherein the NTC thermistor element has a B constant in the range of -50 to 1,000 DEG C according to the following formula (1): 1,800 to 2,400. (Where T1 and T2 are values obtained by converting T1 ° C and T2 ° C to absolute temperatures, and R1 and R2 are resistance values at T1 and T2, respectively).
(1) where R1 is the time required to reach the target position, 5. The method of claim 4,
Wherein the lead wires are two lead wires and are arranged parallel to each other.

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