Nickel electrode slurry for thick film type resistor

Abstract

The invention discloses a nickel electrode slurry for a thick film type resistor, the nickel electrode slurry comprises 20-60% of mixed nickel powder, 20-50% of coated nickel powder, 5-10% of inorganic powder, 2-5% of an organic carrier, and 5-15% of an additive, the mixed nickel powder comprises first nickel powder, second nickel powder, and third nickel powder, the coated nickel powder comprises the first nickel powder, the second nickel powder and the third nickel powder, and the inorganic powder comprises the first nickel powder, the second nickel powder, the inorganic powder, the organic carrier and the third nickel powder. The coated nickel powder is nickel powder coated with glass powder. The nickel electrode slurry provided by the invention still has relatively good conductivity after being sintered in an air atmosphere, can be suitable for a production process line of an existing thick film type resistor, and can reduce the production cost of the resistor and improve the anti-vulcanization performance of the resistor.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic components, and particularly to a nickel electrode paste for thick film chip resistors with low cost, high reliability and anti-sulfuration performance. Background Art

[0002] With the development of electronic devices towards high performance and high density, resistors, as important basic components, are widely used in fields such as communication devices, automotive electronics and industrial control systems. However, with the rapid development of industries such as petrochemical, coal chemical and metallurgy, a large amount of sulfur-containing gases (such as sulfur dioxide SO 2 , hydrogen sulfide H 2 S) are emitted, resulting in a gradual increase in the concentration of sulfur elements in the environment, posing a serious threat to the long-term stability of electronic components. In recent years, the feedback problem of thick film chip resistors failing due to sulfuration has become increasingly prominent. Sulfuration failure can cause abnormal drift of the resistance value and even lead to the fracture of the conduction path, thus affecting the performance stability of electronic devices and even directly causing system failures. Especially for resistors with a silver conductive layer at the lead-out end, after long-term exposure (3 - 5 years) in the air, silver ions are extremely easy to react with sulfur elements in the environment to form silver sulfide (Ag 2 S), thereby significantly reducing the reliability of the resistor and ultimately causing performance degradation or failure.

[0003] Currently, to achieve good anti-sulfuration performance of thick film chip resistors, common technical approaches include introducing precious metals (such as gold) into the electrode or using precious metal protective layers (such as palladium, platinum) to inhibit the sulfuration reaction. However, precious metals are expensive, and their requirements for high-temperature sintering are not conducive to the existing production processes of large-scale thick film chip resistors. In contrast, base metals have the advantage of low cost and have become one of the preferred electrode materials for current thick film resistors.

[0004] Base metal electrodes are usually prepared by screen printing with base metal electrode pastes followed by sintering. Among them, nickel and copper electrode pastes are typical representatives. However, copper is prone to sulfuration reaction in a sulfur-containing environment and is difficult to effectively replace silver electrodes. Nickel has good chemical stability in a sulfur-containing environment, but since the sintering process of thick film chip resistors is usually carried out in an air atmosphere, when using nickel electrode paste to replace silver electrode paste, the nickel electrode is easily oxidized under this condition to form nickel oxide with poor conductivity, significantly reducing the conductivity of the electrode. Therefore, to maintain the good conductivity of the nickel electrode, sintering needs to be carried out under a reducing atmosphere or inert gas protection. However, this process method is quite different from the silver electrode air sintering process, resulting in the complication of the process route and being not conducive to the direct application of the existing thick film resistor production line. Therefore, there is an urgent need to develop a new type of nickel electrode to make it match the existing manufacturing process line of thick film chip resistors. Summary of the Invention

[0005] The object of the present invention is to provide a nickel electrode paste for thick film chip resistors, which still has good conductivity after sintering in an air atmosphere, is applicable to the existing production process line of chip thick film resistors, and can replace the traditional silver (palladium) electrode paste by using it, so as to optimize the production process flow of thick film chip resistors, reduce the production cost of resistors, and improve the anti-sulfuration performance of resistors.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A nickel electrode paste for thick film chip resistors, in terms of weight percentage, is composed of the following components; 20-60% of mixed nickel powder, 20-50% of coated nickel powder, 5-10% of inorganic powder, 2-5% of organic carrier, 5-15% of additive, and the sum of the weight percentages of each component is 100%.

[0007] Further, the mixed nickel powder includes a first nickel powder, a second nickel powder, and a third nickel powder.

[0008] Furthermore, the particle size of the first nickel powder is 50-100nm. The particle size of the second nickel powder is 300-400nm. The particle size of the third nickel powder is 0.8-1μm.

[0009] Furthermore, the weight percentage ratio of the first nickel powder, the second nickel powder, and the third nickel powder is (10%-15%):(25%-30%):(50%-60%).

[0010] Further, the coated nickel powder is nickel powder coated with glass powder, and its preparation method includes the following steps: 1) Dissolve barium source, boron source, and silicon source in a solvent to obtain a BaO-B 2 O 3 -SiO 2 glass precursor; 2) Mix and stir the obtained BaO-B 2 O 3 -SiO 2 glass precursor with nickel powder, and evaporate the solvent used to obtain the coated nickel powder.

[0011] Furthermore, in step 1), the amounts of barium source, boron source, and silicon source are converted according to the weight percentages of BaO, B 2 O 3 , SiO 2 being 38:52:10. Preferably, the boron source is boric acid. Preferably, the barium source is barium acetate. Preferably, the silicon source is tetraethyl orthosilicate.

[0012] Furthermore, in step 2), the BaO-B 2 O3 -SiO 2 The weight ratio of the glass precursor to the nickel powder is 1:10.

[0013] Preferably, the temperature for evaporating the solvent in step 2) is 80 ± 5 °C.

[0014] Furthermore, the particle size of the coated nickel powder is 300 - 500 nm.

[0015] Furthermore, the inorganic powder is selected from one or more of borosilicate glass (SiO 2 -B 2 O 3 -Na 2 O), bismuth borate glass (Bi 2 O 3 -B 2 O 3 ), aluminum borate glass (SiO 2 -B 2 O 3 -Al 2 O 3 ), MgO, Li 2 CO 3 , CaO.

[0016] Furthermore, the organic carrier is prepared by adding 35% - 65% by mass of a polymer resin to an organic solvent and mixing uniformly, and then heating until the polymer resin dissolves. Furthermore, the organic solvent is prepared by mixing terpineol and terpinyl acetate in a volume ratio of 1:(1.5 - 3). Furthermore, the polymer resin is ethyl cellulose.

[0017] Furthermore, the additive is formed by mixing boron powder and ceramic powder in a mass ratio of 2:1. Furthermore, the ceramic powder is Al 2 O 3 . Preferably, the particle size of the boron powder is 1 - 3 μm. Preferably, the ceramic powder is Al 2 O 3 , and its particle size is 1 - 3 μm.

[0018] The above nickel electrode paste can be used to prepare a low-cost, highly reliable, and sulfur-resistant thick film chip resistor. The preparation method is specifically to print a back electrode paste and a resistor body paste on one side of a ceramic substrate in sequence, and then perform a first sintering to form a back electrode and a resistor body. Then, print the above nickel electrode paste on the other side of the ceramic substrate, print a glass coating once after drying, and then perform a second sintering to form a front electrode and a protective layer. Then, perform subsequent processing to obtain the thick film chip resistor.

[0019] Furthermore, the back electrode paste is a silver electrode paste.

[0020] Further, the resistor paste is ruthenium oxide paste.

[0021] Further, the first sintering is carried out in an air atmosphere, the sintering temperature is 800 - 830 °C, and the sintering time is 20 - 30 min.

[0022] Further, the second sintering is carried out in an air atmosphere, the sintering temperature is 750 - 800 °C, and the sintering time is 20 - 30 min.

[0023] Further, the subsequent treatment includes but is not limited to laser trimming, printing a secondary glass protective layer and a mark, electroplating end electrodes, and performing a sulfurization acceleration test.

[0024] Compared with the existing solution, the present invention has the following beneficial effects: (1) The present invention uses nickel powders with different particle size distributions and nickel powders coated with glass powder as the conductive phase of the electrode paste. On the one hand, adding nickel powders coated with glass powder is beneficial to reducing the oxidation of nickel powder during the sintering process in an air atmosphere. On the other hand, by adding nickel powders with different particle size distributions, it is beneficial to form a dense nickel conductive layer. Even if a part of nickel is oxidized, continuous nickel oxide will not be formed, which can minimize the adverse impact of the formation of nickel oxide on the conductivity of the electrode layer.

[0025] (2) The nickel electrode paste prepared by the present invention can replace the ordinary commercially available nickel electrode paste for preparing anti-sulfurization resistors. It can be sintered in air and has good conductivity, is suitable for the existing resistor process production line, and avoids problems such as high production line transformation costs caused by using a reducing atmosphere, reducing the production cost of resistors.

[0026] (3) Using the nickel electrode paste of the present invention to prepare an anti-sulfurization resistor can realize co-firing with the subsequent glass protective layer, which can further reduce the production cost of the resistor, make the nickel oxidation reaction during the sintering process of the prepared resistor small, and the resistor has excellent anti-sulfurization performance.

[0027] (4) The resistor prepared by using the nickel electrode paste of the present invention has excellent anti-sulfurization performance, can be used normally for a long time in a high-sulfur environment, meets the applications in harsh environments, and has good electrical properties. Specific Embodiments

[0028] Silver electrode paste is not easily oxidized during sintering in air and can be directly sintered to form a silver electrode. Due to the excellent electrical conductivity of silver and the mature process, silver electrode paste is the most widely used electrode paste in the current market and is widely used in electronic products such as thick film chip resistors and capacitors. However, although silver electrode paste is not easily oxidized during sintering in an air atmosphere, due to the characteristics of silver itself, the silver electrode exposed to the ambient air is prone to react with sulfides in the ambient air, resulting in the sulfidation of the silver in the resistor electrode, generating silver sulfide with a high resistivity, thereby increasing the resistance value of the resistor and reducing the reliability of the resistor.

[0029] Nickel is prone to react with oxygen in the air at high temperatures to form nickel oxide, resulting in a decrease in the electrical conductivity of the electrode. Therefore, when using nickel electrode paste instead of silver electrode paste as the raw material for the resistor electrode, sintering is usually required in a reducing atmosphere or an inert atmosphere, which requires a significant change in the process of producing resistors with silver electrode paste, adding special links for the sintering of nickel electrode paste, which will significantly increase the production cycle and production cost.

[0030] To address this problem, the present invention provides a nickel electrode paste that can be sintered in an air atmosphere and has good electrical conductivity, is suitable for the existing production process line of resistors, can replace the traditional technical route using silver electrode paste, and significantly reduces the production cost of resistors and improves their reliability in use.

[0031] In terms of weight percentage, the nickel electrode paste is composed of the following components: 20-60% of mixed nickel powder, 20-50% of coated nickel powder, 5-10% of inorganic powder, 2-5% of organic carrier, and 5-15% of additive, and the sum of the weight percentages of each component is 100%.

[0032] Among them, the mixed nickel powder includes a first nickel powder, a second nickel powder, and a third nickel powder, and the weight percentage ratio of the three is (10%-15%):(25%-30%):(50%-60%). The particle size of the first nickel powder is 50-100nm. The particle size of the second nickel powder is 300-400nm. The particle size of the third nickel powder is 0.8-1μm.

[0033] The coated nickel powder is nickel powder coated with glass powder, and its preparation method includes the following steps: 1) Dissolve barium source, boron source, and silicon source in a solvent according to the weight percentage of BaO, B 2 O 3 , SiO 2 being 38:52:10 to obtain a 38% BaO-52% B 2 O 3 -10% SiO 2 glass precursor; 2) Mix and stir the obtained 38% BaO - 52% B 2 O 3 -10% SiO 2 glass precursor and nickel powder in a weight ratio of 1:10, and evaporate the solvent used at 80 ± 5 °C to obtain the coated nickel powder with a particle size of 300 - 500 nm.

[0034] Among them, the boron source is boric acid. The barium source is barium acetate. The silicon source is tetraethyl orthosilicate. The solvent includes any one or more of anhydrous ethanol, deionized water, methanol, isopropanol, etc.

[0035] The inorganic powder is selected from borosilicate glass (SiO 2 -B 2 O 3 -Na 2 O), bismuth borate glass (Bi 2 O 3 -B 2 O 3 ), aluminum borate glass (SiO 2 -B 2 O 3 -Al 2 O 3 ), MgO, Li 2 CO 3 , CaO, one or several of them.

[0036] The organic carrier is prepared by adding 35% - 65% by mass of a polymer resin to an organic solvent and mixing evenly, and then heating until the polymer resin dissolves. Among them, the organic solvent is prepared by mixing terpineol and terpinyl acetate in a volume ratio of 1:(1.5 - 3). Further, the polymer resin is ethyl cellulose.

[0037] The additive is composed of boron powder and ceramic powder mixed in a mass ratio of 2:1.

[0038] The following is further described in combination with specific examples and comparative examples. The raw materials involved in the following examples, unless otherwise specified, can all be obtained commercially. The instruments used, unless otherwise specified, can all be obtained commercially. Example

[0039] This example provides a method for preparing a nickel electrode paste and a method for preparing a resistor using the same. The specific steps are as follows: 1) By weight percentage, respectively take 15% of the first nickel powder with a particle size of 50 - 100 nm, 30% of the second nickel powder with a particle size of 300 - 400 nm, and 55% of the third nickel powder with a particle size of 0.8 - 1 μm and mix them to obtain a mixed nickel powder; 2) Add 1000 g of barium acetate to 2 L of water to obtain a barium acetate solution, add 50 g of boric acid to 1 L of ethanol to obtain a boric acid solution, and add 70 g of tetraethyl orthosilicate to 1 L of 20% ethanol aqueous solution to obtain a tetraethyl orthosilicate solution. Then mix the prepared barium acetate solution, boric acid solution and tetraethyl orthosilicate solution according to the composition ratio of 38% BaO - 52%B 2 O 3 -10% SiO 2 and mix them, and stir at 40 °C for 1 hour to form a transparent gel to obtain a glass precursor; 3) Ultrasonically disperse 50 g of nickel powder in ethanol, then add 5 g of the transparent gel of the glass precursor, and heat to 85 °C to evaporate and dry to remove ethanol and water, obtaining nickel powder coated with glass powder with a particle size of 300 - 500 nm.

[0040] 4) Mix 1 L of terpineol, 1.5 L of terpinyl acetate and 1.5 Kg of ethyl cellulose, then heat to 60 °C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0041] 5) By weight percentage, take 35% of mixed nickel powder, 20% of coated nickel powder, B 2 O 3 2%, Bi 2 O 3 3%, 5% of Al 2 O 3 powder, 10% of B powder, and 25% of organic carrier and mix them evenly to obtain nickel electrode paste.

[0042] 6) Print 0.05 g of silver electrode paste and 0.25 g of ruthenium oxide paste in sequence on one side of an Al 2 O 3 ceramic substrate (3.2 × 1.6 mm 2 ), then sinter at 830 °C for 20 min, then print 0.05 g of the prepared nickel electrode paste on the other side of the substrate, dry at 125 °C, then print a glass protection layer once again, co-fire at 800 °C for 15 min, laser trim the resistance, print the glass protection layer and mark twice, perform primary die cutting, silver coating, sinter at 600 °C for 30 min, perform secondary die cutting, electroplate to obtain a resistor.

[0043] Comparative Example 1 This comparative example provides a method for preparing nickel electrode paste and a method for preparing a resistor using the same. The main difference from the example is that coated nickel powder is not added. The specific steps are as follows: 1) According to the weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Mix 1L of pine alcohol, 1.5L of pine acetate and 1.5Kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0044] 3) Take 55% mixed nickel powder, B 2 O 3 2%,Bi 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0045] 4) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6 mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0046] Comparative Example 2 This comparative example provides a method for preparing a nickel electrode slurry and a method for preparing a resistor using the same. The main difference between the comparative example and the embodiment is that the amount of glass precursor used to prepare the coated nickel powder is different. The specific steps are as follows: 1) According to weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Add 1000 g of barium acetate to 2 L of water to obtain a barium acetate solution, add 50 g of boric acid to 1 L of ethanol to obtain a boric acid solution, and add 70 g of tetraethyl orthosilicate to 1 L of 20% ethanol aqueous solution to obtain a tetraethyl orthosilicate solution.

[0047] Then the prepared barium acetate solution, boric acid solution and tetraethyl orthosilicate solution were mixed in a composition ratio of 38% BaO-52% B 2 O 3 -10%SiO 2The mixture was mixed and stirred at 40° C. for 1 hour to form a transparent gel, thereby obtaining a glass precursor; 3) 50 g of nickel powder was ultrasonically dispersed in ethanol, and then 2.5 g of transparent gel of glass precursor was added, and the mixture was heated to 85°C to evaporate and dry to remove ethanol and water, thereby obtaining nickel powder with a particle size of 300-500 nm covered by glass powder; 4) Mix 1 L of pine alcohol, 1.5 L of pine acetate and 1.5 kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0048] 5) According to the weight percentage, take 35% of mixed nickel powder, 20% of coated nickel powder, and B 2 O 3 2%,Bi 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0049] 6) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6 mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0050] Comparative Example 3 This comparative example provides a method for preparing a nickel electrode slurry and a method for preparing a resistor using the same. The main difference between the comparative example and the embodiment is that the amount of glass precursor used to prepare the coated nickel powder is different. The specific steps are as follows: 1) According to the weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Add 1000g of barium acetate to 2L of water to obtain a barium acetate solution, add 50g of boric acid to 1L of ethanol to obtain a boric acid solution, and add 70g of tetraethyl orthosilicate to 1L of 20% ethanol aqueous solution to obtain a tetraethyl orthosilicate solution. Then, the prepared barium acetate solution, boric acid solution and tetraethyl orthosilicate solution were mixed in a composition ratio of 38% BaO-52% B 2 O3 -10%SiO 2 The mixture was mixed and stirred at 40° C. for 1 hour to form a transparent gel, thereby obtaining a glass precursor; 3) 50 g of nickel powder was ultrasonically dispersed in ethanol, and then 7.5 g of transparent gel of glass precursor was added, and the mixture was heated to 85°C to evaporate and dry to remove ethanol and water, thereby obtaining nickel powder with a particle size of 300-500 nm covered by glass powder; 4) Mix 1 L of pine alcohol, 1.5 L of pine acetate and 1.5 kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0051] 5) According to the weight percentage, take 35% of mixed nickel powder, 20% of coated nickel powder, and B 2 O 3 2%,Bi 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0052] 6) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6 mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0053] Comparative Example 4 This comparative example provides a method for preparing a nickel electrode slurry and a method for preparing a resistor using the same. The main difference between the comparative example and the embodiment is that the content of the glass precursor component used to prepare the coated nickel powder is different. The specific steps are as follows: 1) According to weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Add 1000g of barium acetate to 2L of water to obtain a barium acetate solution, add 50g of boric acid to 1L of ethanol to obtain a boric acid solution, and add 70g of tetraethyl orthosilicate to 1L of 20% ethanol aqueous solution to obtain a tetraethyl orthosilicate solution. Then, the prepared barium acetate solution, boric acid solution and tetraethyl orthosilicate solution were mixed in a composition ratio of 30% BaO-60% B 2 O 3 -10%SiO 2 The mixture was mixed and stirred at 40° C. for 1 hour to form a transparent gel, thereby obtaining a glass precursor; 3) 50 g of nickel powder was ultrasonically dispersed in ethanol, and then 5 g of transparent gel of glass precursor was added, and the mixture was heated to 85°C to evaporate and dry to remove ethanol and water, thereby obtaining nickel powder with a particle size of 300-500 nm covered by glass powder; 4) Mix 1 L of pine alcohol, 1.5 L of pine acetate and 1.5 kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0054] 5) According to the weight percentage, take 35% of mixed nickel powder, 20% of coated nickel powder, and B 2 O 3 2%,Bi 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0055] 6) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6 mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0056] Comparative Example 5 This comparative example provides a method for preparing a nickel electrode slurry and a method for preparing a resistor using the same. The main difference between the comparative example and the embodiment is that the content of the glass precursor component used to prepare the coated nickel powder is different. The specific steps are as follows: 1) According to weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Add 1000g of barium acetate to 2L of water to obtain a barium acetate solution, add 50g of boric acid to 1L of ethanol to obtain a boric acid solution, and add 70g of tetraethyl orthosilicate to 1L of 20% ethanol aqueous solution to obtain a tetraethyl orthosilicate solution. Then, the prepared barium acetate solution, boric acid solution and tetraethyl orthosilicate solution were mixed in a composition ratio of 40% BaO-50% B 2 O 3 -10%SiO 2 The mixture was mixed and stirred at 40° C. for 1 hour to form a transparent gel, thereby obtaining a glass precursor; 3) 50 g of nickel powder was ultrasonically dispersed in ethanol, and then 5 g of transparent gel of glass precursor was added, and the mixture was heated to 85°C to evaporate and dry to remove ethanol and water, thereby obtaining nickel powder with a particle size of 300-500 nm covered by glass powder; 4) Mix 1 L of pine alcohol, 1.5 L of pine acetate and 1.5 kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0057] 5) According to the weight percentage, take 35% of mixed nickel powder, 20% of coated nickel powder, and B 2 O 3 2%,Bi 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0058] 6) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6 mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0059] Comparative Example 6 This comparative example provides a method for preparing a nickel electrode slurry, a method for preparing a resistor using the same, and a method for preparing a resistor. The main difference between the comparative example and the embodiment is that the coated nickel powder used is coated with organic matter. The specific steps are as follows: 1) According to weight percentage, 15% of a first nickel powder with a particle size of 50-100 nm, 30% of a second nickel powder with a particle size of 300-400 nm, and 55% of a third nickel powder with a particle size of 0.8-1 μm are taken and mixed to obtain a mixed nickel powder; 2) Add 1L Ni(CO) to 0.8L acetone 4 and 200g of boric acid, and then add 1L of polyvinyl alcohol, mix thoroughly to obtain a nickel boride slurry precursor; then add 400g of nickel powder, heat to 80°C to evaporate and remove acetone, and then grind the product to obtain an organic-coated nickel powder with a particle size of 0.5μm~2μm.

[0060] 3) Mix 1 L of pine alcohol, 1.5 L of pine acetate and 1.5 kg of ethyl cellulose, then heat to 60°C and stir for 2 hours to dissolve the ethyl cellulose to obtain an organic carrier.

[0061] 5) According to the weight percentage, take 35% of mixed nickel powder, 20% of organic-coated nickel powder, and 20% of Bi 2 O 3 2%, B 2 O 3 3%, Al 2 O 3 5% of Ni powder, 10% of B powder and 25% of organic carrier are evenly mixed to obtain nickel electrode slurry.

[0062] 6) Print 0.05g of silver electrode paste and 0.25g of ruthenium oxide paste on the Al 2 O 3 Ceramic substrate (3.2×1.6mm 2 ) on one side, and then sintered at 830℃ for 20min, and then printed 0.05g of the prepared nickel electrode slurry on the other side of the substrate, dried at 125℃, printed a glass protection layer again, co-fired at 800℃ for 15min, laser trimmed, printed a second glass protection layer and logo, split once, coated with silver, sintered at 600℃ for 30min, split twice, and electroplated to obtain the resistor.

[0063] The conductivity and anti-sulfurization performance of the resistors prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0064] Table 1 Performance characteristics

[0065] As can be seen from Table 1, the embodiment uses 38%BaO-52%B2 O 3 -10% SiO 2 The resistor prepared from the nickel electrode paste made of glass powder-coated nickel powder has good conductivity.

[0066] In addition, the resistors prepared in the examples and Comparative Examples 1 and 6 were subjected to long-term anti-sulfuration testing. The testing scheme referred to the ANSI / EIA-977 standard. That is, first, take the resistor sample to be tested and record the initial resistance value; then, evenly lay an appropriate amount of sulfur powder at the bottom of the test container, and fix the resistor sample in the container to ensure that it is not in direct contact with sulfur. Subsequently, close the container and ensure good sealing; then heat the container to 105 °C and expose it for 1000 hours under constant temperature conditions. After that, turn off the heating device. After the container cools to room temperature, take out the sample and measure the resistance value of the sample. The results are shown in Table 2.

[0067] Table 2 Results of Long-Term Anti-Sulfuration Performance Testing

[0068] As shown in the results of Table 2, the resistance values of the resistors prepared in Comparative Example 1 and Comparative Example 6 basically did not change after being exposed to a sulfur-containing environment for 500 hours, but after being exposed to a sulfur-containing environment for 1000 hours, the resistance values of the resistors increased to varying degrees. In contrast, the resistance values of the resistors prepared in the examples basically did not change before and after being exposed to a sulfur-containing environment for 500 hours and 1000 hours, proving that they have excellent long-term anti-sulfuration performance and can meet the long-term use requirements in a high-sulfuration environment.

[0069] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A nickel electrode slurry for thick film chip resistors, characterized in that: The nickel electrode slurry is composed of the following components in weight percentage: 20-60% of mixed nickel powder, 20-50% of coated nickel powder, 5-10% of inorganic powder, 2-5% of organic carrier, and 5-15% of additives, and the sum of the weight percentages of each component is 100%; The coated nickel powder is nickel powder coated with glass powder.

2. The nickel electrode paste for thick film chip resistor according to claim 1, characterized in that: The mixed nickel powder comprises a first nickel powder, a second nickel powder and a third nickel powder, and the weight percentage ratio of the three is (10%-15%): (25%-30%): (50%-60%); The particle size of the first nickel powder is 50-100 nm, the particle size of the second nickel powder is 300-400 nm, and the particle size of the third nickel powder is 0.8-1 μm.

3. The nickel electrode paste for thick film chip resistor according to claim 1, characterized in that: The particle size of the coated nickel powder is 300-500 nm.

4. The low-cost nickel electrode paste for thick film chip resistors according to claim 1, characterized in that: The method for preparing the coated nickel powder comprises the following steps: 1) Dissolve a barium source, a boron source and a silicon source in a solvent to obtain a BaO-B2O3-SiO2 glass precursor; 2) The obtained BaO-B2O3-SiO2 glass precursor is mixed with nickel powder and stirred, and the solvent is evaporated to dryness to obtain the coated nickel powder.

5. The nickel electrode paste for thick film chip resistor according to claim 4, characterized in that: In step 1), the amount of the barium source, the boron source and the silicon source is converted according to the weight percentage of BaO, B2O3 and SiO2 being 38:52:10; Wherein, the boron source is boric acid, the barium source is barium acetate, and the silicon source is tetraethyl orthosilicate.

6. The nickel electrode paste for thick film chip resistor according to claim 4, characterized in that: The weight ratio of the BaO-B2O3-SiO2 glass precursor to the nickel powder used in step 2) is 1:

10.

7. The nickel electrode paste for thick film chip resistor according to claim 1, characterized in that: The inorganic powder is selected from one or more of borosilicate glass, bismuth borate glass, aluminoborate glass, MgO, Li2CO3, and CaO.

8. The nickel electrode paste for thick film chip resistor according to claim 1, characterized in that: The organic carrier is prepared by adding 35% to 65% of the mass of a polymer resin into an organic solvent and mixing them evenly, and then heating until the polymer resin is dissolved.

9. The nickel electrode paste for thick film chip resistor according to claim 8, characterized in that: The organic solvent is prepared by mixing pine alcohol and pine acetate in a volume ratio of 1:(1.5-3); and the polymer resin is ethyl cellulose.

10. The nickel electrode paste for thick film chip resistor according to claim 1, characterized in that: The additive is prepared by mixing boron powder and ceramic powder in a mass ratio of 2:1.

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