Method for manufacturing copper-zinc alloy powder for multilayer ceramic elements capable of being co-fired, copper-zinc alloy powder manufactured using the same, electrode paste containing the same, and multilayer ceramic element

Abstract

The technical gist of the present invention is that it comprises a first step of mixing copper or copper oxide powder with zinc powder to produce a mixed powder, a second step of heat-treating the mixed powder in a reducing atmosphere to produce a copper-zinc alloy powder, a third step of heat-treating the copper-zinc alloy powder in an oxidizing atmosphere to produce a copper oxide-zinc oxide alloy powder, a fourth step of pulverizing the copper oxide-zinc oxide alloy powder to produce a pulverized copper oxide-zinc oxide alloy powder, and a fifth step of heat-treating the pulverized copper oxide-zinc oxide alloy powder in a reducing atmosphere to re-reduce the pulverized copper oxide-zinc oxide alloy powder into a copper-zinc alloy powder, thereby alloying copper and zinc.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a copper-zinc alloy powder for a multilayer ceramic element that can be co-fired, the copper-zinc alloy powder produced from the powder, an electrode paste containing the powder, and a multilayer ceramic element. [Background technology]

[0002] Ceramic elements have fast response and precision, and can be made small and lightweight, which has led to expanded applications in micro-displacement control devices, valves, pumps, etc. However, they have limitations due to their smaller displacement than electrical elements. To overcome this limitation, multi-layer ceramic elements, in which thin ceramics with electrodes are stacked in multiple layers, have been developed.

[0003] Multilayer ceramic elements are manufactured by first cutting ceramic material into thin ceramic shapes, forming electrodes on the surface of the ceramic using a conductive material, and then stacking multiple layers. At this time, since the laminated ceramic has low strength, it is hardened through heat treatment.

[0004] As an electrode material, silver (Ag) has a very low melting point of 961°C, so it is used in solid solutions with palladium (Pd) or platinum (Pt), which have higher melting points, to form silver-palladium (AgPd) or silver-platinum (AgPt). However, because precious metals such as palladium are very expensive, a higher proportion of relatively inexpensive silver is used as an electrode material, but for economic reasons, there are crucial difficulties in mass-producing multilayer ceramic elements.

[0005] There are cases where copper (Cu) or nickel (Ni) is used as the electrode material. The "Multilayer Ceramic Part (KR10-1580350B1)" is a multilayer ceramic part that can improve the connectivity of the internal electrodes by adjusting the content or size of the co-material added to the internal electrode layer and utilizing the high sintering driving force of the co-material, and copper or nickel is used as the internal electrode.

[0006] However, during the alloying process of copper and nickel, segregation, in which copper or nickel elements precipitate in specific areas, tends to occur, resulting in a tendency for copper and nickel to separate. Even if attempts to resolve this issue by modifying the sintering behavior of copper have been successful, there have been limitations to the effectiveness of manufacturing multilayer ceramic elements. In particular, nickel is used as an electrode material in secondary batteries, but its use is difficult due to its high cost. Therefore, there is a need to develop technologies for copper-based alloy powders, electrode pastes containing the same, and multilayer ceramic elements that can maintain stable electrical conductivity using metals less expensive than nickel. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve these problems, and its technical object is to provide a method for manufacturing a copper-zinc alloy powder for a multilayer ceramic element that can be co-fired so that copper and zinc are alloyed and electrical conductivity is stably maintained, a copper-zinc alloy powder manufactured from the same, an electrode paste containing the same, and a multilayer ceramic element. [Means for solving the problem]

[0008] In order to solve the above technical problems, the present invention provides a method for producing a co-fireable copper-zinc alloy powder for a multilayer ceramic element, characterized in that copper and zinc are alloyed, the method comprising: a first step of mixing copper or copper oxide powder with zinc powder to produce a mixed powder; a second step of heat-treating the mixed powder in a reducing atmosphere to produce a copper-zinc alloy powder; a third step of heat-treating the copper-zinc alloy powder in an oxidizing atmosphere to produce a copper oxide-zinc oxide alloy powder; a fourth step of pulverizing the copper oxide-zinc oxide alloy powder to produce a pulverized copper oxide-zinc oxide alloy powder; and a fifth step of heat-treating the pulverized copper oxide-zinc oxide alloy powder in a reducing atmosphere to re-reduce the pulverized copper oxide-zinc oxide alloy powder into a copper-zinc alloy powder.

[0009] In the present invention, the first step is characterized in that the copper or copper oxide powder and the zinc powder are mixed in a weight ratio of 5-9.9:0.1-5.

[0010] In the present invention, the second step is characterized in that the mixed powder is heat-treated at a temperature of 500 to 650° C. in a hydrogen or hydrogen / nitrogen mixed gas atmosphere.

[0011] In the present invention, the third step is characterized in that the copper-zinc alloy powder is heat-treated at a temperature of 500 to 900° C. in an oxygen or air atmosphere.

[0012] In the present invention, the fifth step is characterized in that the pulverized copper oxide-zinc oxide alloy powder is heat-treated in a hydrogen or hydrogen / nitrogen mixed gas atmosphere at a temperature lower than the heat treatment temperature in the second step.

[0013] In order to solve the above-mentioned other technical problems, the present invention provides a copper-zinc alloy powder characterized by being produced by the above-mentioned method.

[0014] In order to solve the above-mentioned other technical problem, the present invention provides an electrode paste comprising an organic vehicle formed by mixing an organic solvent and a binder, and the copper-zinc alloy powder.

[0015] In order to solve the above-mentioned other technical problem, the present invention provides a multilayer ceramic element, characterized in that the electrode paste is printed on a ceramic tape to form a ceramic laminate, and the ceramic laminate is heat-treated in an oxidizing atmosphere and then heat-treated in a reducing atmosphere.

[0016] In the present invention, the ceramic element is formed by the steps of: heat-treating the ceramic laminate in an oxidizing atmosphere at 100 to 650°C to burn out the binder and degreasing, and then heat-treating the sintered ceramic laminate in an oxidizing atmosphere at 800 to 1,100°C, and heat-treating the sintered ceramic laminate in a reducing atmosphere at 100 to 300°C. [Effects of the Invention]

[0017] According to the present invention, which solves the above problems, it is possible to produce a copper-zinc alloy powder that can prevent shrinkage and delamination by controlling the shrinkage rate between dissimilar metals, which can be co-fired even in an oxidizing atmosphere, using dissimilar metals, copper and zinc.In addition, since the copper-zinc alloy powder has a denser structure than pure copper due to the alloying with zinc, it has the effect of improving heat resistance up to 1,050°C.

[0018] In particular, the copper-zinc alloy powder of the present invention maintains stable electrical conductivity compared to bulk copper (Bulk Cu) and expensive silver-palladium (AgPd) materials, and therefore can be used as an electrode for a multilayer ceramic element after manufacturing an electrode paste, instead of expensive silver-palladium (AgPd), thereby improving economic efficiency. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a flowchart showing a method for producing a copper-zinc alloy powder according to the present invention. [Figure 2] 1 is a flowchart showing a method for manufacturing an electrode paste and a multilayer ceramic element according to the present invention. [Figure 3] 1A to 1C are schematic diagrams showing a method for manufacturing electrodes of a multilayer ceramic element according to the present invention. [Figure 4] 1 is an SEM photograph showing changes in the surface of a copper-zinc alloy powder. [Figure 5] 1 is a graph showing a comparison of electrical conductivity depending on electrode materials. DETAILED DESCRIPTION OF THE INVENTION

[0020] Although the present invention can be modified in various ways and can take various forms, the specific embodiments will be described in detail herein, but it should be understood that the invention is not limited to the particular forms disclosed, and that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

[0021] The terms used in this application are merely used to describe specific embodiments and do not limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" and the like are intended to specify the presence of a combination of features, numbers, steps, components, etc. described in the specification, and should be understood not to preclude the presence or possibility of adding one or more other combinations of features, numbers, steps, components, etc.

[0022] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0023] The present invention will be described in detail below with reference to the accompanying drawings, in which: FIG. 1 is a block diagram showing a configuration of a semiconductor device according to an embodiment of the present invention;

[0024] The present invention relates to a method for manufacturing a copper-zinc alloy powder for a multilayer ceramic element that can be co-fired. Figure 1 is a flowchart showing a method for manufacturing the copper-zinc alloy powder according to the present invention. Referring to Figure 1, the copper-zinc alloy powder of the present invention is manufactured by the following steps: a first step (S10) of mixing copper or copper oxide powder with zinc powder to prepare a mixed powder; a second step (S20) of heat-treating the mixed powder in a reducing atmosphere to prepare a copper-zinc alloy powder; a third step (S30) of heat-treating the copper-zinc alloy powder in an oxidizing atmosphere to prepare a copper oxide-zinc oxide alloy powder; a fourth step (S40) of pulverizing the copper oxide-zinc oxide alloy powder to prepare a pulverized copper oxide-zinc oxide alloy powder; and a fifth step (S50) of heat-treating the pulverized copper oxide-zinc oxide alloy powder in a reducing atmosphere to re-reduce the pulverized copper oxide-zinc oxide alloy powder into a copper-zinc alloy powder. The copper and zinc alloy powder are particularly characterized by being alloyed.

[0025] According to the above-described manufacturing method, the first step is to manufacture a mixed powder by mixing copper or copper oxide powder with zinc powder (S10).

[0026] The copper or copper oxide powder and the zinc powder may be mixed in a weight ratio of 5 to 9.9:0.1 to 5. If the copper or copper oxide powder is less than 5 weight ratio or the zinc powder is more than 5 weight ratio, it is difficult to achieve tuning in terms of improving electrical conductivity, and if the copper or copper oxide powder is more than 9.9 weight ratio or the zinc powder is less than 0.1 weight ratio, it may cause shrinkage or delamination between the copper and zinc, which is undesirable.

[0027] Next, the second step is to heat treat the mixed powder in a reducing atmosphere to produce copper-zinc alloy powder (S20).

[0028] The mixed powder is heat-treated at 500-650°C in a hydrogen or hydrogen / nitrogen mixed gas atmosphere. Zinc has a melting point of approximately 419°C, and the minimum melting point must be above that of zinc to form an alloy with copper, preferably 500°C or higher for process efficiency. Reducing heat treatment at temperatures below 500°C results in a long alloying time between copper and zinc, while temperatures above 650°C can lead to deterioration of the physical properties of the copper-zinc alloy powder. Because copper has a high melting point of 1,085°C, heat treatment at 500-650°C in a reducing atmosphere allows zinc, which has a low melting point of approximately 419°C, to melt and encase the copper surface, creating an alloy powder. However, the oxidation rate of zinc is relatively faster than that of copper, which can lead to the formation of an oxide film on the surface of the alloy powder.

[0029] Next, the third step is a step of heat treating the copper-zinc alloy powder in an oxidizing atmosphere to produce copper oxide-zinc oxide alloy powder (S30).

[0030] The copper-zinc alloy powder is heat-treated in an oxygen or air atmosphere at a temperature of 500 to 900°C. To prevent oxidation of the copper-zinc alloy powder, heat treatment must be performed in an oxygen or air atmosphere of at least 500°C. Temperatures above 900°C are undesirable because copper and zinc are over-oxidized.

[0031] Next, the fourth step is to pulverize the copper oxide-zinc oxide alloy powder to produce pulverized copper oxide-zinc oxide alloy powder (S40).

[0032] The copper oxide-zinc oxide alloy powder is pulverized to a particle size of 0.5 to 10 μm. For application as an electrode in a multilayer ceramic element, the powder can be pulverized to particles with a particle size of 0.5 to 10 μm, preferably 1 to 5 μm, and more preferably 1 μm or less.

[0033] Next, the fifth step is a step of heat treating the pulverized copper oxide-zinc oxide alloy powder in a reducing atmosphere to re-reduce the pulverized copper oxide-zinc oxide alloy powder into copper-zinc alloy powder (S50).

[0034] The pulverized copper oxide-zinc oxide alloy powder is stabilized by heat-treating it in a hydrogen or hydrogen / nitrogen mixed gas atmosphere at a temperature relatively lower than the heat-treatment temperature of the second step, thereby removing the oxide film formed on the surface of the copper-zinc alloy powder. Heat treatment can be performed at 100 to 300°C. If the temperature is lower than 100°C, it takes a long time to completely reduce the copper oxide or zinc oxide in oxide form to its metallic form, and a large amount of hydrogen / nitrogen mixed gas must be used, which is a disadvantage in the process. Temperatures above 300°C are not stable enough for re-reduction to copper-zinc alloy powder.

[0035] Meanwhile, an electrode paste and a multilayer ceramic element can be manufactured using the copper-zinc alloy powder manufactured by the above method. Fig. 2 is a flow chart showing a method for manufacturing an electrode paste and a multilayer ceramic element according to the present invention, and Fig. 3 is a schematic diagram showing a method for manufacturing electrodes of a multilayer ceramic element according to the present invention.

[0036] The electrode paste can be composed of an organic vehicle formed by mixing an organic solvent and a binder, and the copper-zinc alloy powder prepared by the above method. The copper-zinc alloy powder mixed with the organic vehicle can be the pulverized copper oxide-zinc oxide alloy powder prepared in the fourth step. The pulverized copper oxide-zinc oxide alloy powder and the organic vehicle are placed in a mixer in a 1:1 weight ratio and mixed at 600-1,000 rpm. The mixture is then mixed in a three-roll mill for a second time, and filtered to obtain the electrode paste.

[0037] The organic vehicle serves to hold the copper oxide-zinc oxide alloy powder together for aggregation. The organic solvent can be one or more selected from the group consisting of PGME (propylene glycol monomethyl ether), terpineol (α, b, d, g), dihydro-terpineol, and dihydro-terpinyl acetate. The binder can be prepared by dissolving 20% ​​by weight of ethyl cellulose in ethanol, and PVB (Polyvinyl Butyral) can also be used in some cases. When preparing the organic vehicle, DOP (di-2-ethylhexyl phthalate) plasticizer, BYK-111 (dispersant), borosilicate glass frit, etc. can also be added.

[0038] Such an organic vehicle can be prepared by mixing an organic solvent and a binder in a weight ratio of 5-9:1-5. If the organic solvent is used in a weight ratio of less than 4, the binder cannot be uniformly mixed, and if the organic solvent is used in a weight ratio of more than 9, the physical properties of the organic vehicle may be impaired. If the binder is used in a weight ratio of less than 1 or more than 5, it is not suitable for forming an electrode paste.

[0039] To manufacture a multilayer ceramic element using such an electrode paste, the electrode paste is screen-printed on a sheet-shaped ceramic tape to form a ceramic laminate, which is then heat-treated in an oxidizing atmosphere and then in a reducing atmosphere.

[0040] The multilayer ceramic element is manufactured by heat-treating the ceramic laminate in an oxidizing atmosphere at 100 to 650°C to burn out the binder and degreasing through organic material burnout, followed by sintering through heat-treating at 800 to 1,100°C in an oxidizing atmosphere, and then stabilizing the sintered ceramic laminate by heat-treating at 100 to 300°C in a reducing atmosphere, thereby reducing the metal oxides to metals and producing the multilayer ceramic element. That is, during the re-reduction heat treatment, oxygen and hydrogen in copper oxide-zinc oxide combine to form water, which evaporates and is reduced to copper-zinc.

[0041] Therefore, in the conventional manufacturing of multilayer ceramic elements, electrode paste is printed on ceramic tape and laminated, and then debinding and sintering are performed in a reducing atmosphere (N2, H2) from the beginning (oxygen partial pressure pO2<10 -13 atm) and re-oxidation heat treatment (oxygen partial pressure pO2<10 -6 Unlike conventional methods requiring special equipment and complicated processes such as gas injection, the multilayer ceramic element of the present invention can be degreased and co-fired in an air atmosphere, and has the advantage that it can be easily manufactured by simply performing a heat treatment in a reducing atmosphere in a post-treatment process.

[0042] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative to aid in understanding the present invention, and the scope of the present invention is not limited to these examples.

[0043] Example 1 Manufacturing of copper-zinc alloy powder Copper oxide powder (Cu2O2, CuO) and zinc (Zn) powder were prepared, and the copper oxide (I) powder and zinc powder were wet mixed in ethanol in a weight ratio of 9:1 to ensure a uniform mixture. The uniformly mixed solution was dried at room temperature or a high temperature below 100°C to obtain a uniformly mixed copper-zinc powder.

[0044] The homogeneously mixed copper-zinc mixed powder was subjected to a reduction heat treatment at a temperature of 600°C in a pure hydrogen atmosphere or a hydrogen / nitrogen mixed gas atmosphere to form a copper-zinc alloy powder.

[0045] The copper-zinc alloy powder was heat-treated at 600°C in an air or oxygen atmosphere to form copper oxide-zinc oxide alloy powder.

[0046] The obtained copper oxide (CuO)-zinc oxide (ZnO) alloy powder was pulverized by ball milling using zirconia balls for 24 hours to obtain copper oxide-zinc oxide alloy powder having an average diameter of 0.5 to 10 μm.

[0047] The pulverized copper oxide-zinc oxide alloy powder was re-reduced to copper-zinc alloy powder by heat treating the pulverized copper oxide-zinc oxide alloy powder in a hydrogen or hydrogen / nitrogen mixed gas atmosphere at an appropriate temperature within the range of 100 to 300°C, which is lower than the temperature used in the reduction heat treatment.

[0048] Electrode paste manufacturing The organic vehicle was prepared by mixing an organic solvent and a binder in a weight ratio of 5-9:1-5. The viscosity characteristics varied depending on the mixing ratio. The organic solvent used was terpineol, and the binder was prepared by dissolving 20% ​​by weight of ethyl cellulose in ethanol.

[0049] The crushed copper oxide-zinc oxide alloy powder and the prepared organic vehicle were mixed in a weight ratio of 1:1 at 700 to 1,000 rpm for 20 seconds or more to prepare an electrode paste.

[0050] Manufacturing of multilayer ceramic elements To obtain a copper-zinc electrode, the electrode paste was printed on a substrate, heat-treated in an air atmosphere at 550°C to burn out the binder and degrease, then heat-treated in an air atmosphere at 950°C to sinter, and then heat-treated again in a hydrogen / nitrogen mixed gas atmosphere at 100-300°C to reduce the copper oxide-zinc oxide to copper-zinc. During the heat treatment process, oxygen and hydrogen in the copper oxide-zinc oxide combined to form water, which evaporated and was reduced to copper-zinc.

[0051] Figure 4 is an SEM photograph showing the surface change of the copper-zinc alloy powder, which shows that the copper-based alloy is formed through the degreasing, sintering, and reduction post-treatment processes of the multilayer ceramic element.

[0052] <Comparative Example 1> In Comparative Example 1, a multilayer ceramic element was manufactured using the same process as in Example 1, but bulk copper (Bulk Cu) was used as the electrode material instead of the copper-zinc alloy.

[0053] <Comparative Example 2> In Comparative Example 2, a multilayer ceramic element was manufactured by the same process as in Example 1, but AgPd was used as the electrode material instead of the copper-zinc alloy.

[0054] 5 is a graph showing a comparison of electrical conductivity depending on the electrode material. Referring to FIG. 5, Comparative Example 1 has an electrical conductivity of 10 8 (Ω·M) -1 Comparative Example 2 is close to 10 7 (Ω·M) -1 However, it can be seen that the copper-zinc alloy electrodes in the multilayer ceramic element of Example 1 have relatively higher electrical conductivity than those in Comparative Example 2. This indicates that in the multilayer ceramic element in which the copper-zinc alloy of the present invention is used as an electrode, shrinkage and delamination between copper and zinc do not occur, and electrical conductivity is stably maintained.

[0055] In summary, the present invention is characterized in that copper or copper oxide powder and zinc powder are mixed, heat-treated in a reducing atmosphere, heat-treated in an oxidizing atmosphere, and then pulverized and heat-treated in a reducing atmosphere, thereby alloying copper and zinc, removing the metal oxide film, and maintaining stable electrical conductivity.

[0056] According to these features, it is possible to produce a copper-zinc alloy powder that can be co-fired even in an oxidizing atmosphere using dissimilar metals of copper and zinc, and that can prevent shrinkage and delamination by controlling the shrinkage rate between the dissimilar metals. Advantageously, this can be used to produce an electrode paste and a multilayer ceramic element.

[0057] In addition, the copper-zinc alloy powder of the present invention maintains stable electrical conductivity compared to bulk copper (Bulk Cu) and silver-palladium (AgPd) materials, and therefore can be used as electrodes for multilayer ceramic elements instead of expensive nickel, which is significant in terms of improving economic efficiency.

[0058] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations are possible by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed herein are for illustrative purposes only and are not intended to limit the technical concept of the present invention. The scope of the present invention should be interpreted by the claims, and all technical concepts within the scope of the claims should be interpreted as being within the scope of the present invention.

Claims

1. a first step of mixing copper or copper oxide powder with zinc powder to produce a mixed powder; a second step of heat-treating the mixed powder in a reducing atmosphere to produce a copper-zinc alloy powder; a third step of heat-treating the copper-zinc alloy powder in an oxidizing atmosphere to produce copper oxide-zinc oxide alloy powder; a fourth step of pulverizing the copper oxide-zinc oxide alloy powder to produce a pulverized copper oxide-zinc oxide alloy powder; a fifth step of heat treating the pulverized copper oxide-zinc oxide alloy powder in a reducing atmosphere to re-reduce the pulverized copper oxide-zinc oxide alloy powder into copper-zinc alloy powder; A method for producing a copper-zinc alloy powder for use in a co-fireable multilayer ceramic element, characterized in that copper and zinc are alloyed.

2. The first step comprises:

2. The method for producing a copper-zinc alloy powder for a co-fireable multilayer ceramic element according to claim 1, wherein the copper or copper oxide powder and the zinc powder are mixed in a weight ratio of 5-9.9:0.1-5.

3. The second step is 2. The method for producing a copper-zinc alloy powder for a multilayer ceramic element capable of being co-fired according to claim 1, characterized in that the mixed powder is heat-treated at a temperature of 500 to 650°C in a hydrogen or hydrogen / nitrogen mixed gas atmosphere.

4. The third step is 2. The method for producing a copper-zinc alloy powder for a co-fired multilayer ceramic element according to claim 1, wherein the copper-zinc alloy powder is heat-treated at a temperature of 500 to 900°C in an oxygen or air atmosphere.

5. The fifth step is 2. The method for producing a copper-zinc alloy powder for a multilayer ceramic element capable of being co-fired according to claim 1, wherein the pulverized copper oxide-zinc oxide alloy powder is heat-treated in a hydrogen or hydrogen / nitrogen mixed gas atmosphere at a temperature lower than the heat treatment temperature in the second step.

6. A copper-zinc alloy powder produced by the method according to any one of claims 1 to 5.

7. an organic vehicle formed by mixing an organic solvent and a binder; and An electrode paste comprising the copper-zinc alloy powder according to claim 6.

8. 10. A multilayer ceramic element comprising: a ceramic tape on which the electrode paste according to claim 7 is printed to form a ceramic laminate; and a heat treatment in an oxidizing atmosphere followed by a heat treatment in a reducing atmosphere.

9. The laminated ceramic element comprises: heat-treating the ceramic laminate in an oxidizing atmosphere at 100 to 650°C to burn out the binder and degreasing, and then sintering the ceramic laminate in an oxidizing atmosphere at 800 to 1,100°C; and 9. The multilayer ceramic element according to claim 8, wherein the multilayer ceramic element is formed by heat treating the sintered ceramic laminate at 100 to 300° C. in a reducing atmosphere.

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