Method for producing oxidation-resistant base metal or base metal alloy conductive material by sintering under air

Abstract

A method for producing oxidation-resistant base metals and alloys using high temperature sintering under air is provided. [Solution] The electrode material of the existing thick film printing is completely changed from precious metal to base metal, and when using base metal instead of precious metal to avoid oxidation of metal, high temperature sintering is not required under reducing atmosphere, but the method of the present invention uses a very cheap base metal or alloy, uses a cheap process, does not oxidize, can be sintered at high temperature under air, and maintains excellent electrical properties. That is, since base metal material can be used instead of precious metal material, there is no need to purchase new equipment, and material costs are greatly reduced.

Description

[Technical Field]

[0001] The present invention relates to a method for producing oxidation-resistant base metals and alloys by high-temperature sintering under air, and in particular to a base metal thick-film printed conductor or alloy technology that uses high-temperature sintering under air. Furthermore, the present invention relates to a method for producing oxidation-resistant base metals and alloys by high-temperature sintering under air, which not only prevents oxidation but also maintains excellent electrical properties when sintered under air. [Background technology]

[0002] Existing thick film printed conductor paste technology has the following problems.

[0003] 1. Thick film printing The precious metals silver and silver-palladium alloys can be subjected to high-temperature heat treatment in air, but precious metals and alloy materials that can be sintered at high temperatures in air and are resistant to oxidation are extremely expensive.

[0004] 2. When using nickel or copper-nickel alloys instead of the base metal copper or the precious metal silver or silver-palladium alloys in thick film printing, unless heat treatment is carried out by high-temperature sintering in a reducing atmosphere (nitrogen or nitrogen-hydrogen mixture), the base metal copper or nickel or copper-nickel alloy will oxidize and lose its properties. Therefore, although it is possible to change the material from a precious metal to a base metal and reduce costs, the heat treatment process requires changing from air sintering to a reducing atmosphere for sintering, which increases the cost of the sintering process.

[0005] 3. There are base metal materials that cannot be subjected to high-temperature heat treatment even in a reducing atmosphere. For example, when resistance alloy materials are used as chip resistors, or when they are used as electrodes in ceramic thermistors or induction magnetometers, manganese copper alloys or nickel-chromium alloys are used. If the original ceramic elements are sintered in a reducing atmosphere, their properties will change, so when manufacturing these parts, they must be sintered by heat treatment in air.

[0006] In order to overcome the above drawbacks, the inventors have conducted careful research and utilized scientific principles to propose the present invention, which can effectively overcome the above drawbacks and has a rational design. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] The existing prior art has the following drawbacks:

[0008] 1. In existing technologies, conductive thick-film printed copper, nickel, and copper-nickel alloy paste films must be heat-treated and sintered in a reducing atmosphere, such as nitrogen or a nitrogen-hydrogen mixture, which causes the base metals copper and nickel or copper-nickel alloys to lose their effectiveness due to oxidation. Although base metals and alloys are inexpensive, sintering them in a reducing atmosphere by heat treatment significantly increases the process cost.

[0009] 2. Existing multilayer ceramic devices have a shrinkage mismatch problem when the ceramic matrix and electrodes are co-fired. Existing technologies reduce the shrinkage mismatch problem when the ceramic matrix and electrodes are co-fired by covering the ceramic matrix with a non-shrinkage ceramic matrix that has a higher temperature than the co-fired ceramic matrix or by inserting another ceramic matrix that has a lower temperature than the co-fired ceramic matrix, using a sintering technique that can suppress shrinkage in both the X and Y axes during co-firing. However, this extra step increases the manufacturing cost.

[0010] 3. When making external electrodes on existing ceramic elements, sintering the sintered ceramic body in a reducing atmosphere changes the properties of the sintered ceramic body, such as chip resistors, negative temperature coefficient (NTC) thermistors, positive temperature coefficient (PTC) thermistors, voltage dependent resistors (VDR), and piezoelectrics (PZT). Therefore, nitrogen sintering of copper electrodes is not possible.

[0011] 4. Existing chip alloy resistors have a very low temperature coefficient of resistance and are typically fabricated by first printing a positive electrode paste on both ends of a substrate 61, then printing a resistive alloy paste, and then air-sintering (e.g., 850°C) the precious metal silver electrodes 62 and 63 and the silver-palladium resistive alloy layer 64, as shown in Figure 18. Alternatively, they can be fabricated by sintering the base metal copper electrodes and the copper-nickel resistive alloy layer in a reducing atmosphere using nitrogen (or nitrogen and hydrogen). However, the precious metal silver-palladium is expensive, and the base metal copper-nickel alloy is inexpensive, but the sintering heat treatment in a reducing atmosphere significantly increases the process cost to avoid oxidation.

[0012] As the cost of precious metal raw materials increases, it is possible to use base metal raw materials, which are abundant in ore reserves, instead. However, the existing method of producing thick-film printed conductive paste films by sintering base metals and alloys in a reducing atmosphere does not meet the technical and market needs. Therefore, an invention is needed that can improve the shortcomings of the existing technology and avoid the problem of high precious metal material prices. [Means for solving the problem]

[0013] The main object of the present invention is to provide a method that can solve the above-mentioned problems of the conventional art, that can change the existing thick-film printed electrode material from a noble metal to a base metal, and that can utilize base metals and alloys, which are very inexpensive materials, and that can sinter base metal electrodes and alloys at high temperatures under air using a low-cost process that not only does not oxidize but also maintains excellent electrical properties, thereby significantly reducing material costs, and that does not require any additional equipment.

[0014] In order to achieve the above-mentioned object, the present invention provides a method for high-temperature sintering of base metal electrodes or alloys in air, in which 10 to 90 wt% of metallic aluminum powder is added to a thick-film printed base metal conductor paste or base metal alloy paste, and the mixture is heated in air at 500 to 1400°C, utilizing the highly aerobic properties of the metallic aluminum powder to avoid oxidation of the base metal conductor paste or base metal alloy paste due to sintering in high-temperature air, or after the base metal conductor paste or base metal alloy paste is sintered in high-temperature air and oxidized, the strong reducing properties of the metallic aluminum powder are used to reduce the oxidized base metal conductor paste or base metal alloy paste to metal or alloy, thereby obtaining a thick-film base metal electrode film or alloy film.

[0015] According to an embodiment of the present invention, the base metal conductive paste is one of metallic copper powder and nickel powder.

[0016] According to an embodiment of the present invention, the base metal alloy paste is one of copper-nickel alloy powder, manganese-copper powder, or nickel-chromium powder.

[0017] According to an embodiment of the present invention, the thick base metal electrode film or alloy film is applied to external electrodes of bulk ceramic elements, internal electrodes of multilayer ceramic elements, chip resistor electrodes, and alloy chip resistors.

[0018] According to an embodiment of the present invention, the bulk ceramic element is a GPS ceramic antenna, a Negative Temperature Coefficient (NTC) thermistor, a Positive Temperature Coefficient (PTC) thermistor, a Voltage Dependent Resistor (VDR), or a safety capacitor.

[0019] According to an embodiment of the present invention, the multilayer ceramic element is a low temperature co-fired ceramic (LTCC), a multilayer ceramic capacitor (MLCC), a multilayer NTC component, a multilayer VDR component, or a multilayer piezoelectric component.

[0020] The present invention also provides another method, in which a single layer of thick-film aluminum conductor paste film is printed on top of a thick-film printed base metal conductor paste film or base metal alloy paste film, and then heat-treated in air at 500 to 1400°C. The highly aerobic nature of the aluminum conductor paste film is utilized to protect the base metal conductor paste film or base metal alloy paste film from oxidation when sintered in high-temperature air, or the base metal conductor paste film or base metal alloy paste film is sintered and oxidized in high-temperature air, and then the strong reducing properties of the aluminum conductor paste film are utilized to reduce the oxidized base metal conductor paste film or base metal alloy paste film to a metal or alloy, thereby obtaining a thick-film base metal electrode film or alloy film.

[0021] According to an embodiment of the present invention, the base metal conductor paste film is one of a metallic copper film and a nickel film.

[0022] According to an embodiment of the present invention, the base metal alloy paste film is one of an alloy copper-nickel film, a manganese-copper film, or a nickel-chromium film.

[0023] According to an embodiment of the present invention, the thick base metal electrode film or alloy film is applied to external electrodes of bulk ceramic elements, internal electrodes of multilayer ceramic elements, chip resistor electrodes, and alloy chip resistors.

[0024] According to an embodiment of the present invention, the thick base metal electrode film or alloy film can be applied to a new alloy chip resistor process, in which the protective aluminum layer located in the middle is removed by laser engraving to expose the resistive alloy layer, and the aluminum layer at both ends that is not removed by laser engraving is used as the terminal electrodes of the alloy chip resistor.

[0025] According to an embodiment of the present invention, the bulk ceramic element is a GPS ceramic antenna, an NTC thermistor, a PTC thermistor, a VDR, or a safety capacitor.

[0026] According to an embodiment of the present invention, the multilayer ceramic element is an LTCC, an MLCC, a multilayer NTC component, a multilayer VDR component, or a multilayer piezoelectric component.

[0027] Hereinafter, the features and technical contents of the present invention will be described in detail with reference to the drawings. However, these drawings are for reference and explanation purposes only, and the present invention is not limited thereto. BEST MODE FOR CARRYING OUT THE INVENTION

[0028] 1 to 14 are respectively a graph showing the change in weight with increasing temperature in a thermal analysis when copper is added to the aluminum of the present invention, a graph showing the change in weight with increasing temperature in a thermal analysis when nickel is added to the aluminum of the present invention, a sintered microstructure diagram when copper is added to the aluminum of the present invention, a sintered microstructure diagram when nickel is added to the aluminum of the present invention, a sintered aluminum alloy microstructure diagram when nickel is added to the aluminum of the present invention, a sintered microstructure diagram when a copper film is coated on the aluminum film of the present invention, a sintered microstructure diagram when a nickel film is coated on the aluminum film of the present invention, and an aluminum alloy of the present invention. a microstructure diagram of sintering when a copper-nickel film is coated on an aluminum film of the present invention; a microstructure diagram of sintering when a manganese-copper film is coated on an aluminum film of the present invention; a structural conceptual diagram of an external electrode of a bulk ceramic element produced by a new process according to the present invention; a structural conceptual diagram of an internal electrode that does not shrink of a multilayer ceramic element produced by a new process according to the present invention; a structural conceptual diagram of a multilayer internal electrode that does not shrink of a multilayer ceramic element produced by a new process according to the present invention; a structural conceptual diagram of a chip resistor electrode produced by a new process according to the present invention; and a structural conceptual diagram of a chip resistor alloy produced by a new process according to the present invention.As shown in the figure, the method of the present invention for producing oxidation-resistant base metals and alloys by using high-temperature sintering under air is to add 10 to 90 wt% of metallic aluminum powder to a thick-film printing base metal conductor paste or base metal alloy paste, or to print a layer of thick-film aluminum conductor paste film on the top surface of a thick-film printing base metal conductor paste film or base metal alloy paste film, and then heat-treat at 500 to 1400°C under air, utilizing the highly aerobic and strongly reducing properties of the aluminum used, and the highly aerobic and strongly reducing properties of the metallic aluminum powder to produce oxidation-resistant base metal conductors and alloys. By avoiding oxidation of base metal alloys by sintering them under high-temperature air, or by sintering and oxidizing the base metal conductors or base metal alloys under high-temperature air, the strong reducing properties of the metallic aluminum powder are utilized to reduce the oxidized base metal conductors or base metal alloys to metal or alloy, thereby obtaining thick base metal electrode films or alloy films, which allow base metal conductors (e.g., copper and nickel) or base metal alloys (e.g., copper-nickel alloys), which are easily oxidized by high-temperature sintering under the original air, to maintain their metal conductivity and alloy properties.

[0029] The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0030] Tables 1, 2, and 3 below show that aluminum metal powder is added to copper metal powder, nickel metal powder, or copper-nickel alloy powder to prepare a thick film paste, and a thick film is formed by screen printing. This results in the resistance value and resistance characteristics when sintered by heat treatment at 500 to 900°C under air.

[0031] [Table 1]

[0032] As can be seen from Table 1, the antioxidant ability of metallic copper powder during heat treatment increases as the amount of metallic aluminum powder added increases. Among these, when 40 wt% metallic aluminum powder is added to 60 wt% metallic copper powder, the copper-aluminum mixed conductor paste can maintain high conductivity even when sintered at 900°C in air.

[0033] [Table 2]

[0034] As can be seen from Table 2, the oxidation resistance of metallic nickel powder during heat treatment increases with the amount of metallic aluminum powder added. Among these, the nickel-aluminum mixed conductor paste obtained by adding 50 wt% metallic aluminum powder to 50 wt% metallic nickel powder can maintain high conductivity even when sintered at 900°C in air.

[0035] [Table 3]

[0036] As can be seen from Table 3, the copper-nickel alloy powder exhibits stronger oxidation resistance during heat treatment as the amount of metallic aluminum powder added increases. When 40 wt% metallic aluminum powder is added to 60 wt% copper-nickel alloy powder, or when 30 wt% metallic aluminum powder is added to 70 wt% copper-nickel alloy powder, the copper-nickel alloy aluminum mixed resistor paste maintains excellent resistance properties even when sintered in air at 500-900°C, and also exhibits a low temperature coefficient of resistance (TCR), i.e., TCR<±100 ppm.

[0037] [Table 4]

[0038] As can be seen from Table 4, when a thick-film printed aluminum metal film is coated onto a thick-film printed copper metal film, nickel metal film, copper-nickel alloy, manganese copper, or nickel-chromium film, and then sintered under air at 700-900°C, the electrical properties are obtained. The copper metal film or nickel metal film coated with the aluminum metal film maintains an extremely low resistance value, and the copper-nickel alloy film coated with the aluminum metal film exhibits an extremely low temperature coefficient of resistance (TCR<±100 ppm), providing excellent resistance properties. These properties are comparable to the resistance values ​​of existing, general thick-film printed copper metal films, nickel metal films, or copper-nickel alloy films sintered under a reducing atmosphere (nitrogen or nitrogen-hydrogen mixture), and also correspond to resistance properties including a low temperature coefficient of resistance.

[0039] As can be seen from the thermogravimetric analysis (TGA) of the 50 wt% copper and 50 wt% aluminum mixed paste shown in Figure 1, which shows that the weight of the sample changes very little up to 1000°C, copper can be sintered under air, protected by the highly aerobic aluminum powder.

[0040] As can be seen from the thermogravimetric analysis of the 50 wt% nickel plus 50 wt% aluminum mixed paste as a function of temperature in Figure 2, the weight of the sample hardly changes up to 1000°C, which means that the nickel can be sintered under air, protected by the highly aerobic aluminum powder.

[0041] Figure 3 shows the microstructure of the copper powder sintered at 850°C / min under air after adding aluminum powder. Due to the presence of highly aerobic aluminum powder, the copper can maintain its high conductivity even when sintered at high temperatures under air.

[0042] Figure 4 shows the microstructures of nickel powder sintered at 850°C / min in air after adding aluminum powder in different ratios. Due to the presence of highly aerobic aluminum powder, the nickel aluminum alloy or nickel metal formed can maintain its high electrical conductivity even after high-temperature sintering in air.

[0043] Figure 5 shows the microstructure of copper-nickel alloy powder after adding aluminum metal powder and sintering it under air at a temperature of 850°C / min. Due to the presence of highly aerobic aluminum metal powder, the copper-nickel alloy can maintain its high conductivity even when sintered under air at high temperatures.

[0044] Figure 6 shows the microstructure of a printed copper metal film coated with an aluminum film and sintered at 850°C in air. Because the aluminum metal film has high aerobic and highly reducing properties, the underlying copper metal film can maintain its high electrical conductivity even when sintered at high temperatures in air.

[0045] Figure 7 shows the microstructure of an aluminum film printed on top of a printed metallic nickel film, which is then sintered at 850°C in air. Due to the presence of the highly aerobic and strongly reducing aluminum metal film, the metallic nickel film can maintain its high electrical conductivity even when sintered at high temperatures in air.

[0046] Figure 8 shows the microstructure of a printed copper-nickel alloy film after an aluminum film is printed on top of it and sintered at 850°C in air. Due to the presence of the aluminum metal film with high aerobic and strongly reducing properties, the copper-nickel alloy film can maintain the excellent resistance properties of the alloy even after high-temperature sintering in air.

[0047] Figure 9 shows the microstructure of a printed manganese copper alloy film coated with an aluminum film and then sintered at 850°C in air. Due to the presence of the highly aerobic and strongly reducing aluminum film, the manganese copper alloy film can maintain the excellent resistance properties of the alloy even when sintered at high temperatures in air.

[0048] [Example 1] According to the present invention, the novel process can be applied to the external electrodes of bulk ceramic elements, such as GPS ceramic antennas, negative temperature coefficient (NTC) thermistors, positive temperature coefficient (PTC) thermistors, voltage dependent resistors (VDRs), or safety capacitors, as shown in FIG. 10.

[0049] In the present invention, copper aluminum (or nickel aluminum) is mixed to prepare a conductive paste, which is then printed on both sides of the bulk ceramic element 11 to form copper aluminum (or nickel aluminum) electrodes 12 as external electrodes, which can then be subjected to a heat treatment at 500 to 1000°C under air, as shown in Figure 10(a).

[0050] Furthermore, according to the present invention, copper (or nickel) electrodes 13 are printed on both sides of the bulk ceramic element 11, and aluminum electrodes 14 are printed on the copper (or nickel) electrodes 13. Then, a heat treatment is performed at 500 to 1000°C under air, and the aluminum electrode 14 on the upper surface protects the copper (or nickel) electrode 13 on the lower surface, thereby preventing oxidation, as shown in Figure 10(b).

[0051] [Example 2] According to the present invention, the novel process can be applied to the internal electrodes of multilayer ceramic elements, such as low temperature co-fired ceramics (LTCC), multilayer ceramic capacitors (MLCC), multilayer NTC components, multilayer VDR components, or multilayer piezoelectric components, as shown in FIGS. 11 and 12.

[0052] 1. In the case of multilayer ceramic co-fired components, if the sintering temperature is less than 1050°C, a copper thick film conductor paste mixed with 10 to 90 wt% aluminum powder can be used to print a copper-aluminum electrode 22 as an internal electrode, and then co-fired with the ceramic embryo 21 under air, resulting in an LTCC like that shown in Figure 11(a).If the sintering temperature is between 1050°C and 1450°C, a nickel or nickel-copper thick film conductor paste mixed with 10 to 90 wt% aluminum powder can be used to print a nickel-aluminum electrode 23 as an internal electrode, and then co-fired with the ceramic embryo 21 under air, resulting in an MLCCD like that shown in Figure 11(b).

[0053] 2. For multilayer ceramic co-fired components, at a sintering temperature of less than 1050°C, first print a layer of copper thick-film conductor paste film, then print a layer of thick-film aluminum conductor paste film, and then co-fire with ceramic embryo 21 under air, using both copper electrode 24 and aluminum electrode 25 as internal electrodes, to produce an LTCC as shown in Figure 12(a).If the sintering temperature is between 1050 and 1450°C, first print a layer of nickel (or copper-nickel) thick-film conductor paste film, then print a layer of thick-film aluminum conductor paste film, and then use both nickel (or copper-nickel) electrode 26 and aluminum electrode 27 as internal electrodes, to produce an MLCC as shown in Figure 12(b).

[0054] 3. Multilayer ceramic co-fired parts are produced at sintering temperatures below 1050°C by first printing a layer of copper thick film conductor paste, and then co-firing the three layers of copper electrode 24, aluminum electrode 25, and copper electrode 24 as internal electrodes with ceramic embryo 21 under air, resulting in an LTCC as shown in Figure 12(c). If the sintering temperature is between 1050 and 1450°C, first forming a layer of nickel (or copper-nickel) thick film conductor paste, then printing a layer of thick film aluminum conductor paste, and finally printing a layer of nickel (or copper-nickel) thick film conductor paste, and finally co-firing the three layers of nickel (or copper-nickel) electrode 26, aluminum electrode 27, and nickel (or copper-nickel) electrode 26 as internal electrodes with ceramic embryo 21 under air, resulting in an MLCC as shown in Figure 12(d).

[0055] 4. When the internal electrodes are co-fired as described above, since they contain aluminum electrodes, they do not shrink in the X or Y axes when co-fired with the ceramic embryo, and the effects of sintering are limited to the Z axis. As a result, there is almost no change in the electrode shape after printing and after sintering. Furthermore, since the shrinkage after sintering is concentrated in the thickness direction of the Z axis, it is twice as effective in reducing the thickness of the dielectric layer and improving the capacitance value, as in multilayer ceramic capacitors.

[0056] [Example 3] Chip resistor

[0057] 1. This invention applies a new process to the electrodes of chip resistors, as shown in Figure 13, where (a) and (b) show the lower electrode structure, and (c) and (d) show the upper electrode structure.

[0058] When a chip resistor is to produce a positive electrode connected to the resistive layer 31, a positive electrode conductor paste made of copper (or copper-nickel) with 10 to 90 wt % aluminum powder added is printed on the upper surface of the substrate 35 (for example, an alumina substrate) and connected to the resistive film, followed by a heat treatment at 500 to 1000°C. Alternatively, a single layer of copper or copper-aluminum conductor paste film is printed and connected to the resistive film, and then a single layer of aluminum conductor paste film is printed on the upper surface to protect the copper or copper-aluminum conductor paste film, followed by a heat treatment at 500 to 1000°C. This results in a highly conductive aluminum-copper electrode 32 (e.g., as shown in Figures 13(b) and (d)) that can be sintered under air. Alternatively, a copper (or copper-aluminum) electrode 34 (e.g., as shown in Figures 13(a) and (c)) coated on an aluminum electrode 33 can be used to connect the resistive layer 31. Alternatively, a resistive layer 31 can be printed on the copper-aluminum electrode 34, and then an aluminum electrode 33 can be printed as a protective layer. The resulting product, as shown in Figure 14, ensures stable resistor characteristics and is comparable in conductivity to existing positive silver electrodes that are sintered under air.

[0059] 2. The present invention applies the new process to alloy chip resistors, as shown in Figure 15.

[0060] Method 1: Alloy powder + aluminum powder

[0061] For example, a suitable amount of aluminum powder is added to copper-nickel alloy, manganese-copper alloy, or nickel-chromium alloy powder to obtain a resistive paste, which is then printed with a resistive film and sintered at 500-1400°C. The addition of aluminum powder prevents oxidation of the alloy powder and maintains the high-efficiency resistive properties of the alloy film.

[0062] Method 2: Copper, nickel, manganese and chromium mixed film coated with aluminum film

[0063] A resistive alloy paste is printed on the upper surface of an (alumina) substrate 43 having an aluminum-copper electrode 44, such as a copper-nickel film, a manganese-copper film, or a nickel-chromium (silicon) film. Then, a thick aluminum film is printed on the alloy film, and a heat treatment at 500 to 1400°C is performed to form a copper-nickel (or manganese-copper or nickel-chromium) resistive alloy layer 41 covered with an aluminum (or aluminum-nickel) layer 42. The printed aluminum conductive paste film protects the alloy film and prevents oxidation during the heat treatment, thereby maintaining the high-performance resistive properties of the alloy film, as shown in Figure 15(a).

[0064] Wherein, the copper-nickel film can be obtained by mixing metallic copper powder 411 and metallic nickel powder 412 in a specific ratio as required, or can be made from copper-nickel alloy powder 413, as shown in Figure 15(b).

[0065] Wherein, the manganese copper film can be obtained by mixing metallic copper powder 411 with metallic manganese powder 414 or copper-coated manganese powder 415 in a specific ratio as required, or can be made with manganese copper alloy powder 416, as shown in Figure 15(c).

[0066] The nickel-chromium film can be obtained by mixing metallic nickel powder 412 with metallic chromium powder 417 or nickel-coated chromium powder 418 in a specific ratio as required, or can be made from nickel-chromium alloy powder 419, as shown in FIG. 15(d).

[0067] The present invention also proposes a novel process for manufacturing base metal alloy chip resistors, as shown in FIG. 16. A base metal resistive alloy paste, such as a copper-nickel film, a manganese-copper film, or a nickel-chromium (silicon) film, is printed on a substrate 51, followed by printing an anti-oxidation aluminum film. High-temperature sintering (e.g., 850°C) is carried out under air to form aluminum layers 52 and 53 and a copper-nickel (or manganese-copper or nickel-chromium) resistive alloy layer 54 covered with the aluminum layer 52. After that, the aluminum layer located above the middle of the copper-nickel (or manganese-copper or nickel-chromium) resistive alloy layer 54 is removed by laser engraving. The electronic image of this structure is shown in FIG. 17(a) and (b). In this way, the aluminum layers 52 located at both ends that are not removed by laser engraving can be used as terminal electrodes of the alloy chip resistor.

[0068] Therefore, the method according to the present invention has the following technical features:

[0069] 1. Thick-film printing base metal powder (e.g., nickel or copper) or base metal alloy powder (e.g., copper-nickel, manganese-copper, and nickel-chromium) is mixed with 10-90 wt% metallic aluminum powder, and then heated at 500-1400°C in air, thereby preventing oxidation of the base metal or alloy and producing a thick, highly efficient base metal electrode film or alloy film.

[0070] 2. For example, a layer of base metal nickel or copper conductor paste film, or a copper-nickel, manganese-copper, or nickel-chromium (silicon) base metal alloy paste film is thick-film printed on the upper surface of a substrate, and then a layer of thick-film printed aluminum conductor paste film is printed on the top surface of the base metal conductor paste film or base metal alloy paste film. After heat treatment at 500-1400°C in air, the aluminum layer can protect the base metal or alloy from oxidation, resulting in a thick-film base metal electrode film or alloy film with high performance properties. The intermediate protective aluminum layer is then removed by laser engraving, and the aluminum layers remaining at both ends without being removed by laser engraving can be used as terminal electrodes of an alloy chip resistor.

[0071] 3. For multilayer ceramic co-fired parts, if the sintering temperature is less than 1050°C, copper thick film conductor paste mixed with 10-90wt% aluminum powder can be used as the internal electrode, and the ceramic embryo can be co-fired under air, similar to LTCC. If the sintering temperature is between 1050°C and 1450°C, nickel or nickel-copper thick film conductor paste mixed with 10-90wt% aluminum powder can be printed as the internal electrode, and the ceramic embryo can be co-fired under air, similar to MLCC.

[0072] 4. Multilayer ceramic co-firing parts can be made at sintering temperatures below 1050°C by first printing a layer of copper thick film conductor paste, then printing a layer of thick film aluminum conductor paste on top of it, and then co-firing the two layers of the laminated electrode concept under air to form a ceramic embryo, similar to LTCC. If the sintering temperature is between 1050 and 1450°C, first printing a layer of nickel or nickel-copper thick film conductor paste, then printing a layer of thick film aluminum conductor paste, and then co-firing the two layers of the laminated electrode concept under air to form a ceramic embryo, similar to MLCC.

[0073] 5. Multilayer ceramic co-firing parts can be produced at sintering temperatures below 1050°C by first printing a layer of copper thick film conductor paste, then printing a layer of thick film aluminum conductor paste, and finally printing another layer of copper thick film conductor paste, with the three layers of the laminated electrode concept as the internal electrode, and then co-firing to form a ceramic embryo under air, similar to LTCC. If the sintering temperature is between 1050 and 1450°C, first printing a layer of nickel or copper-nickel thick film conductor paste, then printing a layer of thick film aluminum conductor paste, and finally printing another layer of nickel or nickel-copper thick film conductor paste, with the three layers of the laminated electrode concept as the internal electrode, and then co-firing to form a ceramic embryo under air, similar to MLCC.

[0074] 6. When manufacturing a positive electrode connecting a chip resistor and a resistive layer, first print a positive electrode conductive paste made of copper or copper-nickel with 10-90 wt% aluminum powder added to connect the resistive film, and then heat treat at 500-1000°C; alternatively, print a layer of copper or copper-nickel conductive film to connect the resistive film, and then print a layer of aluminum conductive paste film on the top surface to protect the copper or copper-nickel conductive film and prevent high-temperature oxidation, and then heat treat at 500-1000°C.

[0075] 7. Semiconductor ceramic PTC thermistor electrodes not only require high conductivity but also the ability to form ohmic contact with the semiconductive ceramic. Therefore, by adjusting the ratio of aluminum (10-90 wt%) to copper or nickel, ohmic contact can be formed with thick film electrodes of different work functions.

[0076] 8. Printing the resistance alloy paste to form an alloy film, such as a copper-nickel film, a manganese-copper film, or a nickel-chromium (silicon) film, and then printing a thick aluminum film on the alloy film to protect the alloy film from oxidation during heat treatment (500-1400°C) and maintain the high-efficiency resistance properties of the alloy film.

[0077] The present invention differs from existing techniques in the following respects.

[0078] 1. According to existing technology, when base metals are heat-treated to thick-print conductive copper, nickel, and copper-nickel alloy paste films, the base metals are sintered by heat treatment in a reducing atmosphere, such as nitrogen or a nitrogen-hydrogen mixture, to prevent the base metals copper, nickel, or alloys from oxidizing and losing their effectiveness.

[0079] The novel technology of the present invention protects base metals such as copper, nickel, and alloys by adding or coating them with aluminum powder or aluminum film that has highly aerobic and strongly reducing properties, and prevents oxidation and loss of efficacy even when sintered by high-temperature heat treatment in air.

[0080] 2. Existing multilayer ceramic elements have a shrinkage mismatch problem when ceramic embryos and electrodes are co-fired. Existing technologies use a non-shrink ceramic embryo that has a higher temperature than the co-fired ceramic embryo, or insert another ceramic embryo that has a lower temperature than the co-fired ceramic embryo, to use a sintering technique that does not shrink in both the X and Y axes when co-fired, thereby reducing the co-fired mismatch problem between ceramic embryos and electrodes.

[0081] The novel technology of the present invention utilizes the property that metal electrodes do not shrink when co-fired with ceramic matrix, and uses a sintering technique that does not shrink in both the X and Y axes when co-fired, thereby reducing the problem of mismatch between ceramic matrix and electrodes when co-fired.

[0082] 3. Many existing ceramic elements, such as chip resistors, NTC, PTC, VDR, and piezoelectric PZT, cannot have their copper electrodes sintered in nitrogen because the ceramic body is sintered in a reducing atmosphere during the production of external electrodes, which changes the properties of the sintered ceramic body.

[0083] The new technology of the present invention protects a thick copper electrode film with a thick aluminum film and performs heat treatment under air, thereby enabling the fabrication of copper electrodes for ceramic elements such as chip resistors, NTC, PTC, VDR, and piezoelectric PZT.

[0084] 4. Existing alloy resistors have a very low temperature coefficient of resistance, and are mainly manufactured by using a precious metal silver-palladium alloy sintered in air, or by sintering a base metal copper-nickel alloy in a reducing atmosphere of nitrogen (or nitrogen and hydrogen).

[0085] The novel technology of the present invention allows base metal alloy (e.g., copper-nickel, manganese-copper, nickel-chromium) resistors to be sintered in an air atmosphere, which is comparable to the characteristics of sintering in a reducing atmosphere (e.g., copper-nickel, manganese-copper, nickel-chromium). Furthermore, the novel air-sintered chip-type base metal resistance alloy manufacturing method differs from existing chip alloy resistor manufacturing methods. For example, as in the background art, the conventional process involves first printing a positive electrode paste on both ends, then printing a resistance alloy paste, and then sintering precious metal silver electrodes 62, 63 and a silver-palladium resistance alloy layer 64 in air, as shown in Figure 18. Alternatively, base metal copper electrodes and a copper-nickel resistance alloy layer sintered in a nitrogen-reducing atmosphere can be used.

[0086] The novel process of the present invention involves printing a base metal resistance alloy paste, then printing an oxidation-resistant aluminum film, and then sintering it at high temperature under air. The intermediate protective aluminum layer is then removed by laser engraving, and the aluminum at both ends that is not removed by laser engraving becomes the two terminal electrodes of the chip resistor.

[0087] Therefore, the method of the present invention for producing oxidation-resistant base metals and alloys using high-temperature sintering under air allows existing thick-film printing electrode materials to be completely replaced from precious metals to base metals. However, when using base metals instead of precious metals, high-temperature sintering is required in a reducing atmosphere to prevent metal oxidation. The method of the present invention first uses a low-cost process to sinter very inexpensive base metals or alloys at high temperatures under air without oxidation, while maintaining excellent electrical properties. Related industries can use existing equipment to sinter under air, i.e., base metal materials can be used instead of precious metal materials, eliminating the need to purchase new equipment and significantly reducing material costs.

[0088] The present invention is a method for producing oxidation-resistant base metals and alloys by using high-temperature sintering under air, which effectively overcomes the drawbacks of the past and allows the electrode materials of existing thick-film printing to be completely changed from precious metals to base metals. Furthermore, very cheap base metals or alloys can be sintered under air at high temperatures without oxidation using a cheap process, while still maintaining excellent electrical properties. Therefore, the present invention is more advanced and more practical, and patent claims are filed in accordance with the law.

[0089] The above is merely a better embodiment of the present invention, and the present invention is not limited thereby. All equivalent changes and modifications made based on the scope of the claims and the contents of the specification related to the present invention are included in the scope of the claims of the present invention. [Brief explanation of the drawings]

[0090] [Figure 1] FIG. 1 is a graph showing the change in weight with increasing temperature in a thermal analysis when copper is added to the aluminum of the present invention. [Figure 2] FIG. 1 is a graph showing the change in weight with increasing temperature in a thermal analysis when nickel is added to aluminum of the present invention. [Figure 3] FIG. 1 is a sintered microstructure diagram when copper is added to the aluminum of the present invention. [Figure 4]FIG. 1 is a sintered microstructure diagram when nickel is added to the aluminum of the present invention. [Figure 5] FIG. 1 is a microstructure diagram of an aluminum alloy sintered when nickel is added to the aluminum of the present invention. [Figure 6] FIG. 2 is a microstructure diagram of sintering when a copper film is coated on an aluminum film of the present invention. [Figure 7] FIG. 2 is a microstructure diagram of sintering when a nickel film is coated on an aluminum film of the present invention. [Figure 8] FIG. 2 is a microstructure diagram of sintering when a copper-nickel film is coated on an aluminum film of the present invention. [Figure 9] FIG. 2 is a microstructure diagram of sintering when coating a manganese copper film on an aluminum film of the present invention. [Figure 10] FIG. 10 is a structural conceptual diagram of the external electrode of a bulk ceramic element manufactured by a new process according to the present invention. [Figure 11] 1 is a structural conceptual diagram of a non-shrinking internal electrode of a multilayer ceramic element manufactured by a new process according to the present invention. [Figure 12] 1 is a structural conceptual diagram of a non-shrinking laminated internal electrode of a multilayer ceramic element manufactured by a new process according to the present invention. [Figure 13] 1 is a structural conceptual diagram of a chip resistor electrode manufactured by a new process according to the present invention. [Figure 14] 1 is a structural schematic diagram of a chip resistor alloy produced by a novel process according to the present invention. [Figure 15] 1 is a structural schematic diagram of a chip resistor alloy produced by a novel process according to the present invention. [Figure 16] 1 is a schematic diagram of a novel base metal alloy chip resistor process according to the present invention. [Figure 17] 1 is a conceptual diagram of a chip resistor alloy structure produced by the novel process of the present invention. [Figure 18] FIG. 1 is a conceptual diagram of the manufacturing process for existing precious metal alloy chip resistors. [Explanation of symbols]

[0091] (The present invention) 11 Ceramic elements 12 Copper aluminum (or nickel aluminum) electrode 13 Copper (or nickel) electrode 14 Aluminum electrode 21 Ceramic Embryogenesis 22 Copper aluminum electrode 23 Nickel-aluminum electrode 24 copper electrode 25 Aluminum electrode 26 Nickel (or nickel-copper) electrodes 27 Aluminum electrode 31 Resistance layer 32 Aluminum copper electrode 33 Aluminum electrode 34 Copper (or copper-nickel) electrode 35 PCB 41 Copper-nickel (or manganese-copper, nickel-chromium) resistance alloy layer 411 Metallic copper powder 412 Metallic nickel powder 413 Copper-nickel alloy powder 414 Metallic manganese powder 415 Copper-coated manganese powder 416 Manganese Copper Alloy Powder 417 Metallic Chromium Powder 418 Nickel-coated chromium powder 419 Nickel-chromium alloy powder 42 Aluminum (or Aluminum-Nickel) Layer 43 Circuit Board 51 PCB 52, 53 Aluminum layer 54 Copper-nickel (or manganese-copper, nickel-chromium) resistance alloy layer (Previously) 61 PCB 62, 63 Noble metal silver electrodes 64 Silver-palladium resistance alloy layer

Claims

1. a layer of aluminum conductor paste film is printed on the top surface of the base metal conductor paste film or base metal mixed paste film by film printing; heat treatment at 500°C to 1450°C under air to convert the base metal conductor paste film or the base metal mixed paste film into a base metal conductive material or a base metal alloy conductive material; The base metal conductor paste film is a metal copper film or a nickel film, The base metal mixed paste film is either a copper-nickel film, a manganese-copper film, or a nickel-chromium film; The highly aerobic nature of the aluminum conductor paste film is utilized to protect the base metal conductor paste film or the base metal mixed paste film, thereby preventing the base metal conductor paste film or the base metal mixed paste film from being oxidized, or the strongly reducing nature of the aluminum conductor paste film is utilized to reduce the oxidized base metal conductor paste film or the base metal mixed paste film, thereby obtaining the base metal conductive material or the base metal alloy conductive material.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

2. The method for producing an oxidation-resistant base metal conductive material or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: printing the base metal conductor paste film on a bulk ceramic element; printing the aluminum conductor paste film on the base metal conductor paste film; The heat treatment is carried out, The base metal conductive material or the base metal alloy conductive material is used as an external electrode of the bulk ceramic element.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

3. The method for producing an oxidation-resistant base metal conductive material or base metal alloy conductive material by sintering under air according to claim 2, further comprising the steps of: The bulk ceramic element comprises: GPS ceramic antenna, Negative temperature coefficient (NTC) thermistors, Positive temperature coefficient (PTC) thermistors, Voltage Dependent Resistor (VDR), or It is a safety capacitor 1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

4. The method for producing an oxidation-resistant base metal or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: a base metal conductor paste film or a base metal mixed paste film is printed on a ceramic raw material compact before firing by film printing, and a layer of aluminum conductor paste film is printed on an upper surface of the printed base metal conductor paste film or base metal mixed paste film; a ceramic raw material compact before firing is formed using the printed base metal conductor paste film or base metal mixed paste film and the aluminum conductor paste film as internal electrodes; subjecting the ceramic raw material compact to the heat treatment; The base metal conductive material or base metal alloy conductive material is used as an internal electrode of a multilayer ceramic element.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

5. The method for producing an oxidation-resistant base metal or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: a base metal conductor paste film or a base metal mixed paste film is printed by film printing on a ceramic raw material compact before firing to form a first layer, a layer of aluminum conductor paste film is printed on the upper surface of the printed base metal conductor paste film or base metal mixed paste film to form a second layer, and a base metal conductor paste film or a base metal mixed paste film is further printed by film printing on the aluminum conductor paste film to form a third layer; forming a ceramic raw material compact before firing using the printed first, second, and third layers as internal electrodes; subjecting the ceramic raw material compact to the heat treatment; The base metal conductive material or base metal alloy conductive material is used as an internal electrode of a multilayer ceramic element.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

6. A method for producing an oxidation-resistant base metal conductive material or base metal alloy conductive material by sintering under air according to claim 4 or claim 5, comprising: When the temperature of the heat treatment is less than 1050°C, the base metal conductor paste film is a metallic copper film; When the temperature of the heat treatment is 1050°C to 1450°C, the base metal conductor paste film or the base metal mixed paste film is a nickel film or a copper-nickel film.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

7. A method for producing an oxidation-resistant base metal conductive material or base metal alloy conductive material by sintering under air according to claim 4 or claim 5, comprising: The multilayer ceramic element comprises: Low temperature co-fired ceramics (LTCC), Multilayer ceramic capacitors (MLCCs), Multilayer ceramic thermistors, Multilayer voltage dependent resistors (VDRs), or It is a multilayer piezoelectric component 1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

8. The method for producing an oxidation-resistant base metal or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: Printing a resistive layer and a base metal conductor paste film or a base metal mixed paste film on a substrate, and connecting the resistive layer and the base metal conductor paste film or the base metal mixed paste film; Furthermore, an aluminum conductor paste film is printed on the upper surface of the printed base metal conductor paste film or base metal mixed paste film, The heat treatment is carried out, The base metal conductive material or base metal alloy conductive material is used as an electrode for a chip resistor.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

9. The method for producing an oxidation-resistant base metal or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: On the substrate, a base metal mixed paste film is printed as a resistive layer, and an aluminum conductor paste film is printed on the base metal mixed paste film; The base metal mixed paste film is one of a copper-nickel film, a manganese-copper film, and a nickel-chromium film; The heat treatment is carried out, The base metal alloy conductive material is used as a resistive layer of a chip resistor.

1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

10. The method for producing an oxidation-resistant base metal or base metal alloy conductive material by sintering under air according to claim 1, further comprising the steps of: Printing the base metal mixed paste film as a resistive layer on a substrate; printing an aluminum conductor paste film on the base metal mixed paste film; The heat treatment is carried out, The base metal mixed paste film is a resistance alloy layer, A part of the aluminum layer on which the aluminum conductor paste film is sintered is removed by laser engraving, and the remaining aluminum layer is used as a terminal electrode. Chip resistor 1. A method for producing an oxidation-resistant conductive base metal material or a base metal alloy conductive material by sintering under air, comprising:

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