TW202116934A - Aluminum electrode slurry and manufacturing method thereof and ceramic positive temperature coefficient thermistor - Google Patents

Abstract

The present invention provides an aluminum electrode slurry, which contains 40 wt% to 65 wt% of aluminum powder, 13 wt% to 27 wt% of inorganic binder, and 20 wt% to 35 wt% of organic binder, wherein the inorganic binder includes zinc oxide and diantimony trioxide. The aluminum electrode made from the aluminum electrode slurry of this invention can form a good ohmic contact with the ceramic sheet, and has an excellent anti-aging performance and a room temperature anti-breaking performance. Therefore, it can be applied to fabricate ceramic positive temperature coefficient thermistors.

Description

Aluminum electrode slurry and its preparation method and ceramic positive temperature coefficient thermistor

This creation is about an aluminum electrode paste, especially about an aluminum electrode paste and its preparation method and a ceramic positive temperature coefficient thermistor.

Thermistor is a kind of resistor sensitive to heat, and its resistance value changes with the change of the ambient temperature. Because the thermistor can detect subtle temperature changes, it has high sensitivity and high accuracy. As the temperature changes, the resistance value decreases or increases. Thermistors can be divided into negative temperature coefficient (NTC) thermistors and positive temperature coefficient (PTC) thermistors.

Positive temperature coefficient thermistors are widely used in overcurrent protection components. Before the temperature of the positive temperature coefficient thermistor reaches a certain temperature, its resistance value is kept at a low level, so that the circuit can operate normally; and once a failure occurs, the current of the circuit increases abnormally, and the overcurrent makes the positive temperature coefficient thermistor present high temperature When the Curie temperature is exceeded, the resistance value of the PTC thermistor increases sharply as the temperature rises, thereby limiting the overcurrent to protect the circuit. When the cause of the fault is eliminated, the current returns to normal, and the resistance value of the positive temperature coefficient thermistor returns to a low level after cooling, so that the circuit can continue to operate normally.

Ceramic positive temperature coefficient (CPTC) thermistor is a kind of positive temperature coefficient thermistor, which is a semiconductor ceramic element made of polycrystalline ceramic material doped with metal oxide. Since the ceramic positive temperature coefficient thermistor is a kind of semiconductor component, it is necessary to attach a layer of electrodes to the surface of the ceramic positive temperature coefficient thermistor to exhibit various electrical properties during the manufacturing process, before it can be used in the circuit normally.

Nowadays, there are two main methods for making electrodes for ceramic positive temperature coefficient thermistors: (1) Printing method, printing precious metal (such as silver) conductive paste on the surface of the ceramic sheet, and then sintering at high temperature to form electrodes. However, The high price of precious metals has led to an increase in the manufacturing cost of ceramic positive temperature coefficient thermistors; (2) Sputtering method, spraying base metal materials (mainly aluminum, copper, nickel, etc.) on the surface of the ceramic sheet to form electrodes, Although the manufacturing cost of aluminum is relatively low, there are safety concerns due to the explosion of aluminum dust during the process of spraying metal aluminum. Therefore, the prior art is trying to develop a method for preparing the electrode of the ceramic positive temperature coefficient thermistor using aluminum electrode slurry.

In order to make the electrode and the ceramic sheet have good adhesion and electrical properties, the aluminum electrode paste developed in the prior art usually has a high content of lead, but lead is a harmful substance and pollutes the environment. Lead-containing products are regulated by EU legislation. Electronic and electrical products restricted to be used in the "Directive on Restriction of the Use of Certain Hazardous Components in Electrical and Electronic Equipment" (Restriction of Hazardous Substances, RoHS).

Therefore, the industry is still trying to develop an aluminum electrode paste that can selectively omit lead as an essential component according to different needs, so as to prepare the electrode of the ceramic positive temperature coefficient thermistor. However, aluminum electrodes prepared from lead-free aluminum electrode pastes in the prior art have the following problems: (1) poor ohmic contact, (2) poor aging resistance, and (3) poor resistance to on-off at room temperature, resulting in The ceramic positive temperature coefficient thermistor made from lead-free aluminum electrode paste cannot meet market specifications and is difficult to commercialize.

In view of the above technical shortcomings, the purpose of this creation is to develop an aluminum electrode paste that does not require the use of precious metals, in order to reduce manufacturing costs.

Another purpose of this creation is to develop a safe aluminum electrode paste, so as not to cause any casualties due to aluminum dust explosion in the process of manufacturing aluminum electrodes.

In order to achieve the foregoing purpose, the present invention provides an aluminum electrode slurry, which includes: 40 wt% (wt%) to 65 wt% of aluminum powder, 13 wt% to 27 wt% of inorganic binder, and 20 wt% to 35 wt% % Of organic binders, where inorganic binders include zinc oxide (ZnO) and antimony trioxide (Sb ₂ O ₃ ).

By adopting the above technical features, the aluminum electrode made from the aluminum electrode paste of this invention has good adhesion between the aluminum electrode and the ceramic sheet and has good ohmic contact performance. In addition, the aluminum electrode prepared by using this aluminum electrode slurry can have both excellent anti-aging performance and room temperature resistance on-off performance.

Preferably, based on the total weight of the entire inorganic binder, the inorganic binder contains 8 wt% to 45 wt% of zinc oxide and 18 wt% to 45 wt% of antimony trioxide. More preferably, based on the total weight of the overall inorganic binder, the inorganic binder contains 8 wt% to 30 wt% zinc oxide and 18 wt% to 40 wt% antimony trioxide.

Preferably, in addition to the aforementioned zinc oxide and antimony trioxide, the inorganic binder also contains boric acid (H ₃ BO ₃ ), _{silicon dioxide (SiO 2} ), and aluminum oxide (Al ₂ O ₃ ). , Sodium carbonate (Na ₂ CO ₃ ), barium oxide (BaO) or a combination thereof.

More specifically, the inorganic binder is sintered from boric acid, silicon dioxide, aluminum oxide, zinc oxide, antimony trioxide, sodium carbonate, and barium oxide. Accordingly, when special considerations such as environmental issues are concerned, this creation can omit the use of lead oxide (PbO) as an inorganic binder component and develop an aluminum electrode paste that is more environmentally friendly, in order to reduce environmental pollution.

Preferably, based on the total weight of the overall inorganic binder, the inorganic binder contains 15 wt% to 25 wt% boric acid, 4 wt% to 10 wt% silica, 2 wt% to 5 wt% three Aluminum oxide, 8 wt% to 45 wt% zinc oxide, 18 wt% to 45 wt% antimony trioxide, 1 wt% to 4 wt% sodium carbonate, and 0.1 wt% to 3 wt% barium oxide.

Preferably, in addition to the aforementioned zinc oxide and antimony trioxide, the inorganic binder contains boric acid, silicon dioxide, aluminum trioxide, sodium carbonate, barium oxide, lead oxide or a combination thereof.

Preferably, the inorganic binder is sintered from boric acid, silicon dioxide, aluminum oxide, zinc oxide, antimony oxide, sodium carbonate, barium oxide, and lead oxide. Accordingly, when there is no need for special considerations such as environmental protection issues, this creation can also use lead oxide as one of the components of the inorganic binder to improve ohmic contact performance, anti-aging performance and room temperature resistance to on-off.

Preferably, based on the total weight of the overall inorganic binder, the inorganic binder contains 15 wt% to 25 wt% boric acid, 4 wt% to 10 wt% silica, 2 wt% to 5 wt% three Aluminum oxide, 8 wt% to 45 wt% zinc oxide, 18 wt% to 45 wt% antimony trioxide, 1 wt% to 4 wt% sodium carbonate, 0.1 wt% to 3 wt% barium oxide, and 14 wt% to 40 wt% lead oxide. More preferably, based on the total weight of the overall inorganic binder, the inorganic binder contains 15 wt% to 20 wt% boric acid, 4 wt% to 9 wt% silica, and 2 wt% to 5 wt% Aluminum oxide, 8 wt% to 45 wt% zinc oxide, 18 wt% to 45 wt% antimony trioxide, 1 wt% to 4 wt% sodium carbonate, 0.1 wt% to 3 wt% barium oxide, and 14 wt% to 40 wt% lead oxide.

Preferably, the fineness of the inorganic binder is less than 25 microns (μm); more preferably, the fineness of the inorganic binder is less than or equal to 22.5 microns.

Preferably, the purity of the aluminum powder is greater than or equal to 99.5%. Preferably, the average particle size of the aluminum powder is 2 μm to 10 μm; more preferably, the average particle size of the aluminum powder is 6 μm to 8 μm.

According to the invention, the organic binder includes ethyl cellulose, rosin, and organic solvents. The rosin has the function of protecting the surface of the electrode from oxidation, so it can reduce the surface resistance of the electrode.

Preferably, based on the total weight of the overall organic binder, the organic binder contains 2 wt% to 5 wt% ethyl cellulose, 20 wt% to 45 wt% rosin, and 50 wt% to 75 wt% Organic solvents.

Preferably, the organic solvent includes terpineol, diethylene glycol butyl ether, dibasic acid ester, or a combination thereof.

According to this creation, the aluminum electrode made of the aluminum electrode slurry has good adhesion between the aluminum electrode and the ceramic sheet and has good ohmic contact performance. Compared with the indium-gallium electrode, the aluminum electrode prepared by this creation has a resistance value change rate of less than 3%, preferably, the resistance value change rate is less than 2.5%, and even better, the resistance value change rate is less than 2% .

According to this creation, the aluminum electrode made of aluminum electrode paste has excellent anti-aging performance. The aluminum electrode of this creation has a resistance value change rate of less than 9.1% after applying 500 volts direct current at a temperature of 60°C and energizing for 1,000 hours. Preferably, the resistance value change rate is less than 8.6%, more preferably , The change rate of resistance value is less than 8.2%.

According to this creation, the aluminum electrode made of aluminum electrode paste has excellent room temperature resistance to on-off. After 10,000 on-off cycles of the aluminum electrode made in this creation at room temperature, the resistance value change rate is less than 9.4%, preferably, the resistance value change rate is less than 8.7%, and even better, the resistance value is low The rate of change is less than 8%, and even better, the rate of change of the resistance value is less than 7.5%.

According to this creation, the preparation method of the aforementioned aluminum electrode slurry includes the following steps: (1) mixing zinc oxide and antimony trioxide and smelting to obtain an inorganic binder; and (2) mixing 40 wt% to 65 wt% aluminum Mix powder, 13 wt% to 27 wt% inorganic binder and 20 wt% to 35 wt% organic binder, and grind to a fineness of less than 25 microns and a viscosity of 55 Pa·S (Pa·S) to 75 Pa ·S aluminum electrode paste.

Preferably, the fineness of the aforementioned aluminum electrode paste is greater than or equal to 10 microns and less than or equal to 22.5 microns; more preferably, the fineness of the aforementioned aluminum electrode paste is greater than or equal to 15 microns and less than or equal to 22.5 microns.

Preferably, the step (2) in the preparation method of the aluminum electrode slurry is smelted at a temperature of 1200°C to 1250°C to obtain an inorganic binder.

Preferably, the viscosity of the aluminum electrode paste is 60 Pa·S to 75 Pa·S.

In addition to the aforementioned aluminum electrode paste, this creation also provides a ceramic positive temperature coefficient thermistor, which includes an aluminum electrode sintered from the aforementioned aluminum electrode paste.

In the following, several examples will be used to illustrate the specific implementation of the aluminum electrode paste of this creation. Those who are familiar with this technique can easily understand the advantages and effects of this creation through the content of this manual, and will not be contrary to Various modifications and changes are carried out under the spirit of this creation to implement or apply the content of this creation.

Reagent description:

Aluminum powder (Al): A spherical aluminum powder with a purity greater than or equal to 99.5%, an average particle size of 6.2 microns, and a specific surface area of 0.8567 square meters per gram (m ^{2 /g).}

Preparation of organic binder:

The mixture obtained by mixing 3.5 weight percent ethyl cellulose, 31.5 weight percent rosin, 39 weight percent terpineol, and 26 weight percent diethylene glycol butyl ether, at 80°C to 100°C Heat and stir in a water bath until the mixture becomes a transparent organic binder.

Preparation of inorganic binder:

According to the formula in Table 1, the raw materials of inorganic binders A to D were mixed to obtain a mixture, and each mixture was preheated at a temperature of 200°C to 250°C for 30 minutes, and then immediately sent to 1200°C to 1250°C Smelt in a high-temperature furnace for 20 minutes, then cold-roll the molten liquid into glass slag with a roller, and then break the glass slag into glass coarse powder, mix the glass coarse powder with terpineol to form a slurry, and then use zirconia The grinding ball is wet-milled to make it into fine glass powder with a fineness of 22.5 microns. The fine glass powder is filtered and dried to obtain inorganic binders A to D (glass powder).

Table 1: The weight percentage of the composition of inorganic binder A to D (wt%) Inorganic Binder A Inorganic Binder B Inorganic Binder C Inorganic Binder D H ₃ BO ₃ 19.7% 35.8% 19.7% 22.5% SiO ₂ 8.9% 26.1% 4.6% 8.5% Al ₂ O ₃ 4.5% 20.5% 2.7% 3.9% ZnO 23.5% 0 9.6% 0 Sb ₂ O ₃ 39.4% 0 19.5% 0 Na ₂ CO ₃ 2.2% 6.6% 2.6% 2.6% BaO 1.8% 11.0% 1.8% 5.8% PbO 0 0 39.5% 56.7%

Preparation examples 1 to 6 And comparative example 1 to 6 The aluminum electrode paste:

According to the mixing ratios of Examples 1 to 6 and Comparative Examples 1 to 6 in Table 2 and Table 3, the aluminum powder, inorganic binder and organic binder were mixed and stirred for 30 minutes according to the listed weight percentages, and then ground until fine With a degree of 22.5 microns, aluminum electrode pastes (viscosity of about 55 Pa·S to 75 Pa·S) used in Examples 1 to 6 and Comparative Examples 1 to 6 were obtained.

Preparation examples 1 to 6 And comparative example 1 to 6 The ceramic positive temperature coefficient thermistor:

The aluminum electrode pastes of Examples 1 to 6 and Comparative Examples 1 to 6 prepared above were passed through a 200-mesh screen printing screen and printed on a ceramic positive temperature coefficient thermistor with barium titanate as the main body On the ceramic chip, a green body is obtained. After the green body is dried at 200°C, it is put into a tunnel furnace at a temperature greater than 610°C and sintered at a peak temperature of 645°C for 5 minutes to obtain the implementation The ceramic positive temperature coefficient thermistors with aluminum electrodes of Examples 1 to 6 and Comparative Examples 1 to 6.

Test example 1 : Ohmic contact performance

In this test example, the ceramic positive temperature coefficient thermistors of Examples 1 to 6 and Comparative Examples 1 to 6 are used as the samples to be tested, and each sample to be tested is placed at a room temperature of 25°C to measure the resistance value of the aluminum electrode. , Expressed as "R(Al)" in Table 2 and Table 3 below. In order to evaluate the ohmic contact performance between the aluminum electrode and the ceramic sheet, the aluminum electrode of each sample to be tested was additionally ground off, and then coated with an indium-gallium (In:Ga=1:3) electrode, and the resistance of the indium-gallium electrode was measured The value is expressed as "R (In-Ga)" in Table 2 and Table 3 below. Calculate by subtracting the resistance value of the indium-gallium electrode from the resistance value of the aluminum electrode and then dividing by the resistance value of the indium-gallium electrode and multiplying by 100% [(R _Al -R _In-Ga )/R _In-Ga *100%] The rate of change of resistance value. The test results of each sample to be tested are listed in Table 2 and Table 3 below. If the resistance value change rate is low, it means that the aluminum electrode and the ceramic sheet form a better ohmic contact.

Test example 2 ：Anti-aging performance

In this test example, the ceramic positive temperature coefficient thermistors of Examples 1 to 6 and Comparative Examples 1 to 6 are used as the samples to be tested, and the initial resistance value of each sample to be tested is measured at a temperature of 60°C, as shown in Table 2 and It is represented by "R _{0 hr} "in Table 3. Next, apply 500 volts direct current and energize each sample at 60°C for 1,000 hours, and then measure the resistance value of each sample under test after 1,000 hours of energization at 60°C, as shown in the table below 2 and Table 3 are _{expressed as "R 1,000 hr} ". Calculate by subtracting the initial resistance value of the aluminum electrode from the resistance value of the aluminum electrode after 1,000 hours of electrification, then dividing by the initial resistance value of the aluminum electrode and multiplying by 100% [(R _{1,000 hr} -R _{0 hr} )/R _{0 hr} *100%] Obtain the resistance value change rate. The test results of each sample to be tested are listed in Table 2 and Table 3 below. The lower the resistance value change rate, the better the anti-aging performance of the aluminum electrode.

Test example 3 : Room temperature resistance to on-off performance

In this test example, the ceramic positive temperature coefficient thermistors of Examples 1 to 6 and Comparative Examples 1 to 6 are used as the samples to be tested, and the initial resistance values of the samples to be tested are measured at a temperature of 25°C, as shown in Table 2 and In Table 3, it is represented by "R _{initial value} ". Apply 500 volt direct current to each test sample at a temperature of 25°C, turn off the power immediately after 1 minute and wait for 5 minutes, which is 1 cycle; measure the resistance value after repeating the continuity test of 10,000 cycles , Expressed _{as "R 10,000} " in Table 2 and Table 3 below. The resistance value of the aluminum electrode after 10,000 cycles minus the initial resistance value of the aluminum electrode is divided by the initial resistance value of the aluminum electrode and then multiplied by 100% [(R _10,000 -R _{initial value} )/R _{initial value} *100%] Obtain the resistance value change rate. The test results of each sample to be tested are listed in Table 2 and Table 3 below. If the resistance value change rate is lower, it means that the room temperature resistance of the aluminum electrode is better.

Table 2: The composition and characteristics of the aluminum electrode pastes of Examples 1 to 3 and Comparative Examples 1 to 3, and the analysis results of the characteristics of the ceramic positive temperature coefficient thermistors made therefrom. Example 1 Comparative example 1 Example 2 Comparative example 2 Example 3 Comparative example 3 Aluminum electrode paste The content of aluminum powder (wt%) 40 40 55 55 65 65 Types of inorganic binders A B A B A B The content of inorganic binder (wt%) 25 25 20 20 15 15 Content of organic binder (wt%) 35 35 25 25 20 20 Slurry fineness (μm) 22.5 22.5 22.5 22.5 22.5 22.5 Slurry viscosity (Pa·S) 61 62 67 68 73 74 Ohmic contact performance R (Al) 3601 3891 3620 3991 3490 3845 R (In-Ga) 3498 3356 3533 3486 3412 3402 Resistance value change rate 2.94% 15.94% 2.46% 14.49% 2.29% 13.02% Anti-aging performance R _{0 hr} 3,193.6 3372.1 3432.9 3258.2 3,349.8 3285.8 R _{1,000 hr} 3,465.4 3,895.4 3738.2 3756.2 3652.0 3798.0 Resistance value change rate 8.51% 15.52% 8.89% 15.28% 9.02% 15.59% Room temperature resistance to on-off performance R _{initial value} 3353.4 3403.0 3624.8 3263.5 3532.4 3,346.8 R _10,000 3629.4 3898.5 3938.2 3758.5 3862.8 3892.8 Resistance value change rate 8.23% 14.56% 8.65% 15.17% 9.35% 16.31%

Table 3: The composition and characteristics of the aluminum electrode pastes of Examples 4 to 6 and Comparative Examples 4 to 6 and the characteristic analysis results of the ceramic positive temperature coefficient thermistors made therefrom. Example 4 Comparative example 4 Example 5 Comparative example 5 Example 6 Comparative example 6 Aluminum electrode paste The content of aluminum powder (wt%) 40 40 55 55 65 65 Types of inorganic binders C D C D C D The content of inorganic binder (wt%) 25 25 20 20 15 15 Content of organic binder (wt%) 35 35 25 25 20 20 Slurry fineness (μm) 22.5 22.5 22.5 22.5 22.5 22.5 Slurry viscosity (Pa·S) 62 62 68 68 73 73 Ohmic contact performance R (Al) 3513 3744 3706 3642 3781 3757 R (In-Ga) 3428 3642 3628 3561 3709 3680 Resistance value change rate 2.48% 2.80% 2.15% 2.27% 1.94% 2.09% Anti-aging performance R _{0 hr} 3,567.9 3403.8 3531.4 3,629.9 3630.5 3,468.2 R _{1,000 hr} 3859.0 3,691.2 3825.8 3938.4 3940.3 3775.6 Resistance value change rate 8.16% 8.44% 8.34% 8.50% 8.53% 8.86% Room temperature resistance to on-off performance R _{initial value} 3728.0 3423.9 3,694.3 3526.8 3,446.6 3,577.5 R _10,000 4006.2 3688.4 3,982.2 3815.6 3754.7 3903.7 Resistance value change rate 7.46% 7.73% 7.79% 8.19% 8.94% 9.12%

Discussion of experimental results

Referring to Table 1 above, it can be seen that both inorganic binder A and inorganic binder B are lead-free inorganic binders, and the difference in composition between the two is that inorganic binder A contains ZnO and Sb ₂ O ₃ , while inorganic binder B does not Contains ZnO and Sb ₂ O ₃ . When the aluminum electrode paste with inorganic binder A is used, the resistance value R (Al) of the aluminum electrodes prepared in Examples 1 to 3 are all controlled below 3% compared to R (In-Ga) ; On the contrary, when the aluminum electrode paste with inorganic binder B is used, the resistance value R (Al) of the aluminum electrode prepared in Comparative Examples 1 to 3 has a high rate of change compared to R (In-Ga) 13% or more; the experimental results show that compared with Comparative Examples 1 to 3, the aluminum electrodes of Examples 1 to 3 have good adhesion and good ohmic contact performance between the aluminum electrode and the ceramic sheet. In addition, in terms of anti-aging performance, the resistance value change rate of the samples to be tested in Examples 1 to 3 can be controlled below 10%, but the resistance value change rate of the samples to be tested in Comparative Examples 1 to 3 obviously exceeds 14%. , Even more than 15%; the experimental results show that compared with Comparative Examples 1 to 3, the samples to be tested in Examples 1 to 3 have excellent anti-aging performance. In terms of room temperature resistance to on-off performance, the resistance change rate of the samples to be tested in Examples 1 to 3 can all be controlled below 10%, while the resistance change rate of the samples to be tested in Comparative Examples 1 to 3 are all over 14 %, even more than 16%; the experimental results show that compared with Comparative Examples 1 to 3, the samples to be tested in Examples 1 to 3 have excellent room temperature resistance to on-off.

From the experimental results of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 2, it can be seen that the aluminum electrode prepared by the aluminum electrode paste _{containing ZnO and Sb 2} O _{3 without lead-free inorganic binder A, its} It has good ohmic contact performance, excellent anti-aging performance and room temperature resistance on-off performance.

Referring to Table 1 above, it can be seen that both inorganic binder C and inorganic binder D are lead-containing inorganic binders, and the difference in composition between the two is that inorganic binder C contains ZnO and Sb ₂ O ₃ , while inorganic binder D does not ZnO and Sb ₂ O ₃ . When the content of aluminum powder, inorganic binder and organic binder in the aluminum electrode paste is the same, when the aluminum electrode paste with inorganic binder C (such as Examples 4 to 6) is used, the prepared The resistance value of the aluminum electrode R (Al) and R (In-Ga) are less than the resistance of the aluminum electrode prepared by using the aluminum electrode paste with inorganic binder D (such as Comparative Examples 4 to 6) In particular, the resistance value change rate of the aluminum electrode prepared in Example 6 can be as low as 2% or less, while the resistance value change rate of the aluminum electrode prepared in Comparative Examples 4 to 6 is all higher than 2%; The experimental results show that compared with Comparative Examples 4 to 6, the aluminum electrodes of Examples 4 to 6 have better adhesion to the ceramic sheet and have better ohmic contact performance. In addition, in terms of anti-aging performance, when the content of aluminum powder, inorganic binder and organic binder in the aluminum electrode paste is the same, use the test sample with inorganic binder C (as in Examples 4 to 6 The resistance value change rate of) is less than the resistance value change rate of the test sample with inorganic binder D (such as Comparative Examples 4 to 6). In particular, the resistance value change rate of the test sample in Example 4 can be as low as 8.2 % Or less, but the resistance change rates of the samples to be tested in Comparative Examples 4 to 6 are all higher than 8.4%; the experimental results show that compared to Comparative Examples 4 to 6, the samples to be tested in Examples 4 to 6 have better results The anti-aging performance. In terms of room temperature resistance to on-off performance, when the contents of aluminum powder, inorganic binder and organic binder in the aluminum electrode paste are the same, use the sample to be tested with inorganic binder C (as in Examples 4 to 6) The resistance value change rate of the test samples with inorganic binder D (such as Comparative Examples 4 to 6) is less than the resistance value change rate. Especially, the resistance value change rate of the test sample of Example 4 can be as low as The resistance value change rate of the samples to be tested in Comparative Examples 4 to 6 are all higher than 7.7%; the experimental results show that compared with Comparative Examples 4 to 6, the samples to be tested in Examples 4 to 6 have higher Good room temperature resistance to on-off performance.

From the experimental results of Examples 4 to 6 and Comparative Examples 4 to 6 in Table 3, it can be seen that the aluminum electrode prepared by the aluminum electrode paste _{containing ZnO and Sb 2} O _{3 containing lead-containing inorganic binder C further improves} The performance of the aluminum electrode prepared by the aluminum electrode paste containing the lead-containing inorganic binder D without ZnO and Sb ₂ O ₃ , that is, the use of the lead-containing inorganic binder C _{containing ZnO and Sb 2} O ₃ The aluminum electrode made of the aluminum electrode paste has better ohmic contact performance, anti-aging performance and room temperature resistance on-off performance.

In addition, the experimental results of Example 1 and Example 4 were further compared. Example 1 uses inorganic binder A containing ZnO and Sb ₂ O ₃ but no PbO, and Example 4 uses inorganic binder C _{containing ZnO, Sb 2} O _{3 and PbO.} In the ohmic contact performance test, the resistance value change rate of the sample to be tested in Example 1 was 2.94%, and the resistance value change rate of the sample to be tested in Example 4 was 2.48%, although the resistance of the sample to be tested in Example 1 The value change rate is slightly higher than the resistance value change rate of the sample to be tested in Example 4, but the increase is still within an acceptable range, indicating that the sample to be tested in Example 1 has the same value as the sample to be tested in Example 4. The ohmic contact performance. In the anti-aging performance test, the resistance value change rate of the sample to be tested in Example 1 was 8.51%, and the resistance value change rate of the sample to be tested in Example 4 was 8.16%. The resistance value change rate is slightly higher than the resistance value change rate of the sample to be tested in Example 4, but the increase is still within an acceptable range, indicating that the sample to be tested in Example 1 has the same value as the sample to be tested in Example 4. Equivalent anti-aging performance. In the room temperature continuity resistance test, the resistance value change rate of the sample to be tested in Example 1 was 8.23%, and the resistance value change rate of the sample to be tested in Example 4 was 7.46%. The resistance value change rate of the test sample is slightly higher than the resistance value change rate of the sample to be tested in Example 4, but the increase is still within an acceptable range, indicating that the sample to be tested in Example 1 has the same value as that in Example 4. The test sample has comparable room temperature resistance to on-off performance.

Further compare the experimental results of Example 2 and Example 3 with Example 5 and Example 6, respectively. The samples to be tested in Example 2 and Example 3 selected _{inorganic binder A containing ZnO and Sb 2} O ₃ but no PbO, while the samples to be tested in Example 5 and Example 6 were selected to include ZnO, Sb ₂ O ₃ and PbO inorganic binder C. Like the comparison result of Example 1 and Example 4, in the ohmic contact performance test, the anti-aging performance test and the room temperature resistance continuity performance test, it can be found that although the resistance value change rate of the embodiment 2 and the embodiment 3 are slightly higher respectively In Example 5 and Example 6, the resistance value change rate, but the increase is still within an acceptable range, which means that the samples to be tested in Example 2 and Example 3 have the same values as in Example 5 and Example 6. The test sample has equivalent ohmic contact performance, anti-aging performance and room temperature resistance on-off performance, but can omit the use of lead oxide to make aluminum electrode paste. From the above experimental results, it can be seen that if the lead oxide-containing inorganic binder C cannot be used due to special considerations of environmental protection, the lead oxide-free inorganic binder A is a good substitute. The aluminum electrode prepared by using the aluminum electrode paste of the inorganic binder A without lead oxide has the same ohmic contact performance, anti-aging performance and room temperature resistance to on-off performance and the aluminum electrode using the inorganic binder C containing lead oxide The aluminum electrode made by the slurry is comparable.

Based on the above experimental results, whether it is ohmic contact performance test, anti-aging performance test or room temperature resistance continuity test, it is made by using this creative aluminum electrode slurry containing zinc oxide and antimony trioxide inorganic binder The obtained aluminum electrode can form a good ohmic contact with the ceramic sheet, and at the same time has excellent anti-aging performance and room temperature resistance on-off performance.

The above-mentioned embodiments are only examples to illustrate this creation, and do not limit the scope of rights claimed by this creation in any respect. The scope of rights claimed in this creation should be subject to the scope of the patent application, rather than limited to the specific embodiments described above.

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Claims (12)

An aluminum electrode slurry comprising: 40 wt% to 65 wt% aluminum powder, 13 wt% to 27 wt% inorganic binder, and 20 wt% to 35 wt% organic binder, wherein the inorganic binder includes Zinc oxide and antimony trioxide. The aluminum electrode slurry according to claim 1, wherein based on the total weight of the entire inorganic binder, the inorganic binder comprises 8 to 45 weight percent of zinc oxide and 18 to 45 weight percent of trioxide Antimony. The aluminum electrode slurry according to claim 1, wherein the inorganic binder comprises boric acid, silicon dioxide, aluminum oxide, zinc oxide, antimony oxide, sodium carbonate, barium oxide, or a combination thereof. The aluminum electrode slurry according to claim 1, wherein the inorganic binder is composed of boric acid, silicon dioxide, aluminum oxide, zinc oxide, antimony trioxide, sodium carbonate, and barium oxide. The aluminum electrode paste according to claim 1, wherein based on the total weight of the whole inorganic binder, the inorganic binder contains 15 to 25 weight percent of boric acid and 4 to 10 weight percent of silicon dioxide , 2 weight percent to 5 weight percent aluminum oxide, 8 weight percent to 45 weight percent zinc oxide, 18 weight percent to 45 weight percent antimony trioxide, 1 weight percent to 4 weight percent sodium carbonate and 0.1 Weight percent to 3 weight percent of barium oxide. The aluminum electrode slurry according to claim 3, wherein the inorganic binder comprises boric acid, silicon dioxide, aluminum trioxide, zinc oxide, antimony trioxide, sodium carbonate, barium oxide, lead oxide, or a combination thereof. The aluminum electrode slurry according to claim 6, wherein based on the total weight of the whole inorganic binder, the inorganic binder contains 15 to 25 weight percent of boric acid and 4 to 10 weight percent of silicon dioxide , 2 weight percent to 5 weight percent of aluminum oxide, 8 weight percent to 45 weight percent of zinc oxide, 18 weight percent to 45 weight percent of antimony trioxide, 1 weight percent to 4 weight percent of sodium carbonate, 0.1 The weight percent to 3 weight percent of barium oxide and 14 weight percent to 40 weight percent of lead oxide. The aluminum electrode slurry according to any one of claims 1 to 7, wherein the average particle size of the aluminum powder is 6 to 8 microns. The aluminum electrode slurry according to claim 8, wherein based on the total weight of the overall organic binder, the organic binder comprises 2 wt% to 5 wt% ethyl cellulose, 20 wt% to 45 wt% Rosin and 50% to 75% by weight of organic solvents. A method for preparing the aluminum electrode slurry according to any one of claims 1 to 9, which comprises the following steps: (1) Mix antimony trioxide and zinc oxide and smelt to obtain an inorganic binder; and (2) Mix 40 wt% to 65 wt% aluminum powder, 13 wt% to 27 wt% of the inorganic binder, and 20 wt% to 35 wt% of organic binder, and grind to a fineness of less than 25 microns. Aluminum electrode paste with a viscosity of 55 Pascal·sec to 75 Pascal·sec. The method for preparing aluminum electrode slurry according to claim 10, wherein the method is smelted at a temperature of 1200°C to 1250°C to obtain the inorganic binder. A ceramic positive temperature coefficient thermistor, which comprises an aluminum electrode sintered from the aluminum electrode paste described in any one of claims 1 to 9.