KR20230090901A - Composition for manufacturing NTC thermistor Thick films having low resistance and the manufacturing method of the same - Google Patents

Abstract

The present invention relates to a composition for preparing a thick NTC thermistor film having low resistance and a small B constant (temperature coefficient) and a method for preparing the same, and more particularly, to a spinel compound of the formula (100-x) (Cu _1+a Zn _b Mn _{2- a} O ₄ ) + x ruthenium oxide (RuO ₂ ) + y lead-free glass (Pb free Glass), in which x is 0 to 60% by weight, y is 0 to 30% by weight, and a is 0 to 0.5 mol, and b is also 0 to 0.5 mol.

Description

Composition for manufacturing NTC thermistor Thick films having low resistance and the manufacturing method of the same}

The present invention relates to a composition for preparing a thick NTC thermistor film having low resistance and a small B constant (temperature coefficient), and a method for manufacturing the same, and more particularly, to a copper-manganese spinel having a low sintering temperature in manufacturing a thick NTC thermistor film. A composition for preparing a thick NTC thermistor film having low resistance and B constant (temperature coefficient) by mixing an appropriate amount of ruthenium oxide with a compound and further adding lead-free glass for densification at about 850 ° C. and a method for manufacturing the same are provided. In particular, the present invention is characterized in that an NTC thermistor thick film having various characteristics of resistance and B constant (temperature coefficient) is easily implemented.

A thermistor is a heat-sensitive resistor with a large temperature coefficient of resistance. There are two types of these thermistors. One shows a positive change in resistance with increasing temperature (Positive Temperature Coefficient, PTC), and the other shows a negative change in resistance with increasing temperature (Negative Temperature Coefficient, NTC) . NTC thermistors are usually made of sintered semiconductor material and can be used to manufacture devices with resistance values of 10 to 1,000,000 Ω at room temperature, and these thermistors are widely used as thermal sensors or temperature compensation devices.

In addition, thermistors are miniaturized by manufacturing thick or thin films according to high density and high integration of electronic devices, and their applications to hybrid microcircuits are expanding.

On the other hand, as a negative temperature coefficient ₍ NTC) thermistor, a NiMn ₂ O ₄ -based material in _the form of a spinel crystal is generally used. A spinel-based negative temperature coefficient (NTC) thermistor thick film having high density and nanocrystalline grains made of was manufactured by a vacuum powder spraying method, and in Korean Patent No. 1260048 (April 25, 2013), NiMn A method for manufacturing a negative temperature coefficient (NTC) thermistor thick film by dispersing conductive LaNiO ₃ perovskite powder particles in _an O ₄ spinel material is disclosed, but the manufacturing method is difficult and it is difficult to manufacture a low resistance thick film. there is

As is already known, a thick film with a wide range of resistance changes by adjusting the ratio of ruthenium compounds such as ruthenium oxide (RuO ₂ ), calcium ruthenate (CaRuO ₄ ), or bismuth ruthenate (Bi ₂ Ru ₂ O ₇ ) and glass components. We are manufacturing thick film resistors. In addition, in Korean Patent Publication No. 1994-702640 (August 20, 1994), (1) one or more platinum group metal oxides and (2) Co ₂ RuO ₄ The negative temperature coefficient of mixing a glassy binder on a conductor (NTC) Although a low-resistance thick film was realized by disclosing a method for manufacturing a thermistor thick film, there is a problem in that the change in B constant (temperature coefficient) is limited.

Therefore, there is a need for a composition and method for preparing a thick NTC thermistor film that has low resistance, can change B constant (temperature coefficient), and is easy to manufacture.

Republic of Korea Patent Publication No. 10-2010-0113321 (2009.04.13.) Korean Patent Registration No. 10-1260048 (2013.04.25.) Korean Patent Publication No. 10-1994-702640 (1994.08.20.)

The present invention has been made to solve the above-mentioned problems of the prior art, and the present invention relates to a composition for preparing an NTC thermistor thick film having a low resistance and a small B constant (temperature coefficient) and a method for manufacturing the same, and more particularly, to NTC In manufacturing the thermistor thick film, by mixing an appropriate amount of ruthenium oxide for low resistance with a copper-manganese spinel compound having a low sintering temperature, and further adding lead-free glass for densification at about 850 ° C, low resistance and B constant (temperature coefficient It is an object of the present invention to provide a composition for preparing a thick film of an NTC thermistor having a ) and a method for manufacturing the same.

In particular, the present invention is characterized in that an NTC thermistor thick film having various characteristics of resistance and B constant (temperature coefficient) is easily implemented.

In order to solve the above problems, the present invention provides the following means.

Provided is a composition for preparing a low-resistance NTC thermistor thick film comprising a copper-manganese spinel compound and a ruthenium compound.

The ruthenium compound is preferably ruthenium oxide having low resistance.

The copper-manganese spinel compound is Cu _1+a Zn _b Mn _2-a O ₄ , the ruthenium compound is ruthenium oxide, and the chemical formula (100-x) spinel compound (Cu _1+a Zn _b Mn _{2- a} O ₄ ) + x ruthenium oxide (RuO ₂ ) + y in the formula represented by lead-free glass (Pb free Glass), x is 0 to 60% by weight, y is 0 to 30% by weight, a and b are 0 to It is preferably 0.5 mol.

The lead-free glass is preferably a glass powder that does not contain lead and has a glass transition temperature of 700° C. or less.

In addition, the present invention is a chemical formula (100-x) spinel compound (Cu _1+a Zn _b Mn _2-a O ₄ ) + x ruthenium oxide (RuO ₂ ) + y lead-free glass (Pb free Glass), x is 0 to 60% by weight, y is 0 to 30% by weight, and a and b are mixed to prepare a mixed powder so that they are 0 to 0.5 mol; mixing the mixed powder with an organic binder prepared using ethylcellulose resin and dehydro terpineol as a solvent; And for uniform mixing of the mixed powder, the resin, and the solvent and uniform dispersion of the mixed powder, thick-film NTC paste is prepared using a 3-roll mill, screen-printed, dried, and heat-treated to form a low-resistance NTC thermistor thick film. Provides a method for manufacturing.

Mixing the mixed powder with an organic binder prepared using ethylcellulose resin and dehydro terpineol as a solvent; Mixing an organic binder prepared by using dehydro terpineol at a weight ratio of 10:90 to 20:80 at a ratio of 60:40 to 50:50 wt%; preferably.

The drying and heat treatment is preferably performed at 100 to 200 ° C and heat treated at 750 ° C to 950 for 20 to 40 minutes.

In manufacturing an NTC thermistor thick film with low resistance and a small B constant (temperature coefficient), the present invention provides a composition capable of forming a thick film by a general printing method and then heat-treating at about 850 ° C to achieve densification and a method for manufacturing the same. As a result, miniaturization, hybridization, and high density of electronic components are possible, so the market expansion of related electronic components is expected.

1 is a change in sheet resistance and B constant of an NTC thermistor thick film with respect to ruthenium oxide (RuO ₂ ) content according to the present invention.

NTC thermistor thick film is manufactured by using specific equipment such as vacuum powder spraying or plasma spraying, or by mixing ruthenium compound with glass, and the change in resistance and B constant (temperature coefficient) is limited.

On the other hand, by mixing an appropriate amount of a ruthenium compound for low resistance, preferably ruthenium oxide having a low resistance value, with a copper-manganese spinel compound having a low sintering temperature, low resistance and B constant (temperature coefficient) are realized, and densification is achieved. Development was carried out to confirm the suitability by preparing an NTC thermistor thick film composition for printing by adding lead-free glass for printing. Lead-free glass was adopted as lead-free in consideration of the environment.

The present invention relates to a composition for preparing a thick NTC thermistor film having a low resistance and a small B constant (temperature coefficient) and a method for preparing the same, and more particularly, to a composition having the chemical formula (100-x) spinel compound (Cu _1+a Zn _b Mn _{2- a} O ₄ ) + x ruthenium oxide (RuO ₂ ) + y in the formula represented by lead-free glass (Pb free Glass), x is 0 to 60% by weight, y is 0 to 30% by weight, and a is 0 to 0.5 mol, and b is also 0 to 0.5 mol.

Here, if the ruthenium oxide exceeds 60% by weight, it is undesirably converted to PTC characteristics, and there is also a problem that the conversion rate of the constant B value by the spinel compound is limited due to the small number of spinel compounds. Therefore, it is recommended not to exceed this value.

In addition, if the Zn value is too large, the resistance rises very high, and thus the performance of the thermistor is deteriorated. Therefore, it is preferable to add only up to 0.5 mol. In particular, the unique function of the copper-manganese spinel compound is significantly diluted.

Such a composition of the present invention can be easily prepared by a general ceramic manufacturing method as follows.

To prepare the spinel compound (Cu _1+a Zn _b Mn _2-a O ₄ ) powder, reagent grade MnCO ₃ (99%, Daejung Chem. Co., Korea), CuO (99%, Yakuri, Chem. Co., Japan) and ZnO (99.9%, Kojundo Chem. Co., Japan) were used. The powders of MnCO ₃ , CuO and NiO weighed according to the composition of [Table 1] were placed in a polyethylene container, and mixed by ball milling using 10 mm diameter zirconia balls and ethanol for 12 hours. After drying the pulverized and mixed powder, it was calcined at 750° C. for 5 hours to synthesize a copper-manganese spinel-like powder.

The synthesized powder was molded at a pressure of 100 MPa using a hydraulic press in a circular metal mold having a diameter of 10 mm, and then sintered at 1000 ° C. for 1 hour using an electric furnace. The basic physical properties of the sintered body were evaluated by heat treatment at 650° C. for 30 minutes after printing silver (Ag) paste on both sides.

As described above, the thick-film NTC paste according to the present invention is obtained by dispersing NTC-characteristic spinel synthetic powder and lead-free glass powder that serves to bond and insulate conductive particles such as ruthenium oxide in an organic binder at a certain ratio.

Therefore, the synthesized powder was weighed together with ruthenium oxide and lead-free glass powder according to the composition shown in Table 2, put into a polyethylene container, and ball milled for 12 hours using a 10 mm diameter zirconia ball and ethanol and mixed. . The pulverized and mixed powder was dried, then pulverized using a mortar, and then sieved using a 325 mesh sieve to be used as a powder for preparing a thick film. Here, the lead-free glass powder (PSG Co., Korea) is a BaO - ZnO - Al ₂ O ₃ - B ₂ O ₃ - SiO ₂ -based glass with a Tg of 690 °C, a density of 3.3 g/cm ² , and an average particle diameter of 2 μm.

In addition, the mixed powder was dispersed with the organic binder to be 60:40 wt%, where the mixed powder and the organic binder are preferably in the range of 60:40 to 50:50 wt%. The organic binder was prepared by using ethylcellulose resin and dehydro terpineol as a solvent in a weight ratio of 10:90, and for uniform dispersion with inorganic materials (synthetic powder, RuO ₂ powder and glass powder), 3 - Thick film NTC paste was prepared using a roll mill. Here, the weight ratio is preferably in the range of 10:90 to 20:80.

Before forming a thick film using the prepared thick film NTC paste, a commercially available Ag-Pd paste was first printed on an alumina substrate by screen printing, and then heated at 50 °C/min and sintered at 850 °C for 30 minutes to form an electrode. On the electrode pattern obtained in this way, the pattern was printed by screen printing so that the width and length were 1 in × 1 in, that is, the width and height ratio was 1. At this time, the material of the screen used was 325 mesh stainless steel, and the thickness of the fluid film was 10 μm. After printing, the NTC thick film was dried by holding at 150 ° C for 10 minutes, and then sintered at 850 ° C for 30 minutes at a heating rate of 50 ° C / min using a horizontal rapid heating furnace, and then furnace cooled to form the final thick film NTC.

The resistivity of the sintered thick film NTC thermistor was measured for resistivity and sheet resistance using a multimeter (3457A, Hewlett Packard, USA). In addition, the B constant of the NTC thick film is calculated by the following formula using a thermostat.

In the above formula, R ₂₅ and R ₈₅ are electrical resistances measured at 25°C and 85°C, respectively, and T ₂₅ and T ₈₅ are absolute temperatures of 25°C and 85°C.

Hereinafter, the configuration and effects of the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, but the scope of the present invention is not limited by these examples.

<Example>

To prepare spinel compound (Cu _1+a Zn _b Mn _2-a O ₄ ) powder, reagent grade MnCO ₃ (99%, Daejung Chem. Co., Korea), CuO (99%, Yakuri, Chem. Co. ., Japan) and ZnO (99.9%, Kojundo Chem. Co., Japan) were used. The powders of MnCO ₃ , CuO and NiO weighed according to the composition of [Table 1] were placed in a polyethylene container, and mixed by ball milling using 10 mm diameter zirconia balls and ethanol for 12 hours. After drying the pulverized and mixed powder, it was calcined at 750° C. for 5 hours to synthesize a copper-manganese spinel-like powder.

The synthesized powder was molded at a pressure of 100 MPa using a hydraulic press in a circular metal mold having a diameter of 10 mm, and then sintered at 1000 ° C. for 1 hour using an electric furnace. The basic physical properties of the sintered body were evaluated by heat treatment at 650° C. for 30 minutes after printing silver (Ag) paste on both sides.

Electrical properties of the sintered copper-manganese spinel compound are shown in Table 1 below.

Electrical properties of sintered copper-manganese spinel compounds Mark Composition (wt%) Sintering temperature (℃) Resistivity (ohm.mm) BInteger (K) CEM Cu _1.5 Mn _1.5 O ₄ 1000 37.1 1350 CCM CuMn ₂ O ₄ 1000 178.8 2187 CZM Cu _0.5 Zn _0.5 Mn ₂ O ₄ 1000 1376.8 2462

In general, a nickel-manganese spinel compound is used as an NTC thermistor material. It has a high sintering temperature and high resistivity, so it was judged that a copper-manganese spinel compound would be suitable for the present invention, and as a result of basic experiments, the results shown in Table 1 As shown, sufficient sintering with a shrinkage rate of about 20% was achieved at 1000 ° C, and it was found that the specific resistance value was also very low. In addition, when the amount of copper increases, the resistivity and B constant decrease, and when substituted with manganese or zinc, the resistivity and B constant increase. These results are very useful for controlling the characteristics of the NTC thermistor thick film. That is, by adjusting the relative amounts of copper and zinc, it is possible to increase the change in B constant, which is a key differentiator compared to the prior art.

As described above, the thick-film NTC paste according to the present invention is obtained by dispersing NTC-characteristic spinel synthetic powder and lead-free glass powder that serves to bond and insulate conductive particles such as ruthenium oxide in an organic binder at a certain ratio.

Therefore, the synthesized powder was weighed together with ruthenium oxide and lead-free glass powder according to the composition shown in Table 2, put into a polyethylene container, and ball milled for 12 hours using a 10 mm diameter zirconia ball and ethanol and mixed. . The pulverized and mixed powder was dried, then pulverized using a mortar, and then sieved using a 325 mesh sieve to be used as a powder for preparing a thick film. Here, the lead-free glass powder (PSG Co., Korea) is a BaO - ZnO - Al ₂ O ₃ - B ₂ O ₃ - SiO ₂ -based glass with a Tg of 690 °C, a density of 3.3 g/cm ² , and an average particle diameter of 2 μm.

In addition, the mixed powder was dispersed with an organic binder in a weight ratio of 60:40, and the organic binder was prepared by using ethylcellulose resin and dehydro terpineol as a solvent in a weight ratio of 10:90. powder, RuO ₂ powder and glass powder) and thick film NTC paste were prepared using a 3-roll mill for uniform dispersion.

Before forming a thick film using the prepared thick-film NTC paste, a commercially available Ag-Pd paste was first screen-printed on an alumina substrate and then heated at 50 °C/min and sintered at 850 °C for 30 minutes to form an electrode. On the electrode pattern obtained in this way, the pattern was printed by screen printing so that the width and length were 1 in × 1 in, that is, the width and height ratio was 1. At this time, the material of the screen used was 325 mesh stainless steel, and the thickness of the fluid film was 10 μm. After printing, the NTC thick film was dried by holding at 150 ° C for 10 minutes, and then sintered at 850 ° C for 30 minutes at a heating rate of 50 ° C / min using a horizontal rapid heating furnace, and then furnace cooled to form the final thick film NTC. Here, the drying temperature may be in the range of 100 to 200°C.

The sheet resistance of the sintered thick film NTC thermistor was measured using a multimeter (3457A, Hewlett Packard, USA). In addition, the B constant of the NTC thick film was calculated from the electrical resistance measured at 25 ° C and 85 ° C using a thermostat.

<Comparative example>

In order to examine the effect of the change of ruthenium oxide in the present invention, as shown in Table 2 below, a specimen was prepared by sintering at 900 ° C. for 30 minutes in the same manner as described above for the composition without the addition of ruthenium oxide, and the characteristics were evaluated. evaluated.

Changes in sheet resistance and B constant according to composition number Composition (wt%) Lead-free glass (wt%) Sheet resistance (ohm/in ² ) BInteger (K) CEM CCM CZM RuO ₂ comparative example 0 100 0 0 5 1,380,000 2695 Example 1 0 90 0 10 10 245,400 2417 Example 2 0 82 0 18 20 17,400 1574 Example 3 0 75 0 25 20 1750 1376 Example 4 0 70 0 30 20 485 1225 Example 5 0 65 0 35 20 88 345 Example 6 0 65 0 35 25 427 1103 Example 7 0 65 0 35 30 2416 1462 Example 8 0 60 0 40 20 52 97 Example 9 0 50 0 50 20 25 9 Example 10 0 40 0 60 20 15 6 Example 11 75 0 0 25 20 598 1429 Example 12 70 0 0 30 20 233 904 Example 13 0 0 77.5 22.5 20 113,700 1948 Example 14 0 0 70 30 20 8606 1858 Example 15 0 0 70 30 15 982 1324 Example 16 0 0 70 30 10 244 259 Example 17 35 35 0 30 20 302 1036 Example 18 35 0 35 30 20 478 1158 Example 19 0 35 35 30 20 866 1427

Table 2 shows the changes in sheet resistance and B constant of thick-film NTC thermistors prepared by varying the composition of a copper-manganese spinel compound together with ruthenium oxide and lead-free glass powder. Table 2 shows that the amount of copper-manganese spinel compound and ruthenium oxide is 100wt%, and the sheet resistance and B constant decrease as the content of ruthenium oxide increases, as in the basic experiment results. can As shown in FIG. 1, the lead-free glass powder is fixed at 20wt% and the sheet resistance of the NTC thermistor thick film and the B constant change with respect to the ruthenium oxide (RuO ₂ ) content can be seen more clearly. On the other hand, the B constant can be seen that the ruthenium oxide (RuO ₂ ) content rapidly changes between 30wt% and 40wt%.

From these results, it is clear that conductive ruthenium oxide (RuO ₂ ) is a very important component for changing the sheet resistance and B constant in the thick-film NTC thermistor composition, and the spinel compound plays a major role in the characteristics until the ruthenium oxide (RuO ₂ ) content is about 30 wt%. And, at 40wt% or more, it can be determined that ruthenium oxide (RuO ₂ ) contributed to the main role. In addition, when the ruthenium oxide (RuO ₂ ) content exceeds 60wt%, there may be a possibility of conversion to PTC characteristics in which resistance increases with temperature.

On the other hand, in the case of lead-free glass serving as a binder, sheet resistance and B constant increase slightly as the content increases, but an appropriate amount is preferably added for densification and stabilization of the thick film, and in the case of the present invention, between 10wt% and 30wt% is suitable can know

In manufacturing the NTC thermistor thick film with low resistance and low B constant through the present invention, the NTC-characteristic spinel synthetic powder and lead-free glass powder, which plays a bonding and insulating role with conductive particles such as ruthenium oxide, are added to an organic binder at a certain ratio. It is believed that miniaturization, hybridization, and high density of electronic components are possible by providing a composition and a manufacturing method capable of achieving densification by preparing a dispersed paste, forming it by a general printing method, and heat-treating at about 850 ° C. Here, it is possible to heat treatment in the range of 750 ~ 950 ℃, therefore, it is not limited to the above 850 ℃. In addition, the heat treatment time may be performed in the range of 20 to 40 minutes.

As described above, the present invention has been described in detail based on the accompanying drawings and preferred embodiments, but it will be apparent that the claims of the present invention should not be construed as being limited by the present embodiments.

Claims (7)

A composition for preparing a low resistance NTC thermistor thick film comprising a copper-manganese spinel compound and a ruthenium compound. According to claim 1,
The composition for preparing a low resistance NTC thermistor thick film, characterized in that the ruthenium compound is ruthenium oxide having a low resistance. According to claim 2,
The copper-manganese spinel compound is Cu _1+a Zn _b Mn _2-a O ₄ ,
The ruthenium compound is ruthenium oxide,
Formula (100-x) spinel compound (Cu _1+a Zn _b Mn _2-a O ₄ ) + x ruthenium oxide (RuO ₂ ) + y In the formula represented by lead-free glass (Pb free Glass), x is 0 to 60% by weight, y is 0 to 30% by weight, and a and b are 0 to 0.5 mol. According to claim 1,
The lead-free glass is a composition for preparing a low resistance NTC thermistor thick film, characterized in that the glass powder does not contain lead and has a glass transition temperature of 700 ℃ or less. Formula (100-x) spinel compound (Cu _1+a Zn _b Mn _2-a O ₄ ) + x ruthenium oxide (RuO ₂ ) + y lead-free glass (Pb free Glass), x is 0 to 60% by weight, preparing a mixed powder by mixing y to be 0 to 30% by weight and a and b to be 0 to 0.5 mol;
mixing the mixed powder with an organic binder prepared using ethylcellulose resin and dehydro terpineol as a solvent; and
To uniformly mix the mixed powder, the resin, and the solvent, and to uniformly disperse the mixed powder, a thick film NTC paste is prepared using a 3-roll mill, then screen printed, dried, and heat treated to form a low resistance NTC thermistor thick film. manufacturing method. According to claim 5,
Mixing the mixed powder with an organic binder prepared using ethylcellulose resin and dehydro terpineol as a solvent;
An organic binder prepared by using the mixed powder, ethylcellulose resin, and dehydro terpineol as a solvent in a weight ratio of 10: 90 to 20: 80, 60: 40 to 50: 50 wt% A method for manufacturing a low-resistance NTC thermistor thick film, characterized in that the step of mixing so as to be. According to claim 5,
The drying and heat treatment is a method for manufacturing a low resistance NTC thermistor thick film, characterized in that drying at 100 ~ 200 ℃ and heat treatment at 750 ℃ ~ 950 for 20 to 40 minutes.

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