Highly conductive wires and alloys, and new methods for manufacturing electrode terminals

Abstract

The present invention provides highly conductive wires and alloys and methods for fabricating novel electrode terminals. [Solution] Two new material methods can improve the conductivity of thick-film aluminum electrodes, making them comparable to thick-film printed silver electrodes and copper electrodes sintered under a reducing atmosphere. These new materials can also be used to fabricate new types of electrode terminals for multilayer ceramic elements. These materials include those that use chemical oxidation-reduction to replace thick-film aluminum electrodes with highly conductive thick-film metal or alloy electrodes. Alternatively, a thin film is chemically or physically coated on the surface of aluminum particles to form a core shell. Then, through sintering and heating, a laminated metal and aluminum alloy are produced. The alloy is then liquefied, connecting the densely packed aluminum particles to form ultra-highly conductive thick-film printed aluminum electrodes. The new electrode configurations can be used for electrode terminals in multilayer ceramic elements, replacing five-sided electrode terminals manufactured using immersion plating and high-temperature firing with low-temperature two- or three-sided electrode terminals manufactured using printing, wet plating, or chemical plating.

Description

[Technical field]

[0001] The present invention relates to a highly conductive wire or alloy, and a method for manufacturing an electrode terminal of a new type of multilayer ceramic element, in particular to a highly conductive wire or alloy whose thick-film aluminum electrode has a conductivity equivalent to that of a thick-film printed silver electrode or a copper electrode sintered under a reducing atmosphere, and more particularly to a thick-film aluminum electrode (including a substituted metal) replaced by a highly conductive thick-film copper electrode or other metals such as nickel or alloys by chemical oxidation-reduction substitution, and also to a highly conductive wire or other metals such as nickel or alloys that does not require chemical substitution treatment and that has a conductivity equivalent to that of a printed silver electrode sintered under air or a copper electrode sintered under a reducing atmosphere, by simply thick-film printing and sintering an aluminum (including a substituted metal) electrode. The new technology of the material can be applied to a new electrode, and instead of a five-sided electrode terminal by immersion plating or high-temperature firing of an existing passive element multilayer ceramic element, a low-temperature two- to three-sided electrode terminal manufactured by printing, wet plating or chemical plating can be applied. [Background technology]

[0002] On the market, the mainstream material for existing metallization technology is thick-film printed silver electrodes, which can be sintered in air, but the material cost is very high because metallic silver is a precious metal. Alternatively, thick-film printed copper electrodes can be used, which is a low-cost copper material, but metallic copper oxidizes easily when sintered at high temperatures. In a reducing atmosphere, oxidation of the copper electrode can be avoided by nitrogen protection, but the process cost is high. In addition, when ultra-low temperature sintering is performed at temperatures below 200°C, nano silver powder can be used to make nano silver paste to obtain dense, highly conductive silver electrodes, but the price of nano silver powder is ten times that of existing silver powder. As described above, thick-film printing silver paste and nano-silver paste are both precious metal materials, and therefore very expensive. In addition, such base metal conductive thick-film and alloy thick-film printing conductor pastes are produced by processing at high temperatures and in a special reducing atmosphere, which significantly increases production costs and is disadvantageous to market competition. For example, thick-film printing copper paste is sintered in a reducing nitrogen atmosphere and does not oxidize, which results in high process costs.

[0003] Thick-film printed aluminum electrodes can be sintered in air with low process costs, and the raw materials are very cheap. However, because there is a thin layer of aluminum oxide on the surface of the thick-film metallic aluminum powder particles, the metallic aluminum powder of the thick-film printed aluminum electrode cannot be densely shrunk during sintering, and the aluminum oxide layer prevents the aluminum particles from contacting each other. As a result, the conductivity of the thick-film printed aluminum electrode is far lower than that of general thick-film silver electrodes and copper electrodes, and its conductivity is 1 / 500 to 1 / 1000 of that of a thick-film printed silver electrode sintered in air or a copper electrode sintered in a reducing atmosphere. Therefore, the thick-film conductor is only used in solar cells on the existing market as it can reflect light and has a large area.

[0004] As for the electrode configuration, referring to Table 1 below, there are mainly two types of manufacturing technologies for electrode terminals of existing passive elements. One type is a five-sided electrode terminal technology, the structure of which is shown in Figure 17a, in which an internal electrode 1 is deposited inside a ceramic body 2, and both ends become electrode terminals 3. The main process is as shown in Figure 18, in which an integrated molding is performed by an immersion plating process, and then a high-temperature heat treatment is performed. In the case of a copper or nickel conductor paste, a heat treatment process is performed in a reducing atmosphere to prevent oxidation. The other type is a three-sided electrode terminal technology, the structure of which is shown in Figure 17b, and the main process is to use screen printing to manufacture front electrode 4 and back electrode 5, which are then fired, and then side electrode 6 is manufactured by sputtering. The external appearance of the formed electrode terminal is as follows: the first type is an electrode terminal with five sides integrally formed by dipping plating, which easily has a moon-shaped edge, as shown in Figure 19a; the second type is an electrode terminal with three sides formed by printing and sputtering, which has a square shape without a moon-shaped edge, as shown in Figure 19b.

[0005] [Table 1]

[0006] Existing multilayer ceramic capacitor technology has developed toward higher capacitance by utilizing thin dielectric layers and multiple internal electrodes. When multilayer ceramics and internal electrodes are used simultaneously, the shrinkage of the metal electrodes and the ceramic compact does not match, so internal stress is easily generated. When the electrode terminals are fired at high temperatures, the internal stress releases energy, and cracks easily occur in the element. Therefore, the firing temperature of the electrode terminals is preferably as low as possible. Also, the element size of the multilayer ceramic capacitor is becoming smaller, and the electrode terminals must be manufactured with a more regular shape and with greater precision.

[0007] To solve each of the problems in the background art described above, an invention is needed that can improve the conductivity of thick-film printed aluminum electrodes, so that the conductivity of thick-film printed aluminum electrodes is equivalent to that of silver electrodes sintered in air or copper electrodes sintered in a reducing atmosphere, and that combines new materials to laminate ceramic capacitors using a technology similar to that of the three-sided electrode terminals of chip resistors.

[0008] In order to overcome the above drawbacks, the inventors have conducted careful research and, by utilizing scientific theory, have proposed the present invention, which can effectively overcome the above drawbacks and has a rational design. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0009] The main objective of the present invention is to solve the problems of the background art by proposing two new methods for producing highly conductive wires and alloys and new types of electrode terminals, which improve the conductivity of thick-film aluminum electrodes to be equivalent to that of thick-film printed silver electrodes and copper electrodes sintered under a reducing atmosphere.

[0010] Another object of the present invention is to provide a method for manufacturing a highly conductive wire or alloy and a new type electrode terminal by sintering a thick-film printed aluminum electrode, which does not require chemical substitution treatment and has the same conductivity as a silver electrode sintered and printed in air or a copper electrode sintered in a reducing atmosphere. In order to achieve the above object, the method for manufacturing a highly conductive wire or alloy and a new type electrode terminal of the present invention includes laminating a thin metal film on the surface of a plurality of aluminum particles by chemical or physical methods to form a metal structure of an aluminum core and a shell, forming an aluminum shell metal alloy on the metal shell and the outside of the aluminum core by sintering heating, and then heating to a sintering temperature of 300 to 660°C, which is higher than the melting point of the aluminum shell metal alloy, liquefying the aluminum shell metal alloy and connecting the aluminum particles densely accumulated and arranged around it, thereby obtaining a highly conductive thick-film aluminum paste that can manufacture a highly conductive thick-film aluminum electrode without requiring chemical substitution treatment. [Means for solving the problem]

[0011] According to an embodiment of the present invention, the deposited thin metal film is a thin silver film and the aluminum shell metal alloy is an aluminum silver alloy (Ag2Al).

[0012] According to an embodiment of the present invention, the aluminum particles have particle sizes of 5 μm and 2 μm and are arranged so as to be most densely packed.

[0013] According to an embodiment of the present invention, the highly conductive thick film aluminum paste can be printed as surface electrodes on various kinds of dished or block ceramic components, such as safety capacitors, GPS antennas, thermistors (NTC, PTC), varistors, or any components that can be applied with a surface as an electrode.

[0014] According to an embodiment of the present invention, the highly conductive thick film aluminum electrode is applied to dished ceramic elements, metal plates and glass substrates, or as inner electrodes of low temperature co-fired ceramics.

[0015] Yet another object of the present invention is to propose a method for manufacturing highly conductive wires and alloys of base metal conductive thick films and alloy thick films, and new types of electrode terminals, by integrating thick film printing and gold plating deposition technology, and utilizing thick film printing and sintering in the atmosphere, and metal oxidation-reduction deposition technology.

[0016] In order to achieve the above objectives, the present invention proposes a method for manufacturing highly conductive wires and alloys and new types of electrode terminals, in which a thick-film aluminum layer (containing a substitution metal) with a high oxidation potential is thick-film printed, and then immersed in a metal solution with a low oxidation potential, and a chemical oxidation-reduction substitution reaction is carried out while controlling the solution temperature and immersion time, to form a thick-film metal layer with a low oxidation potential.

[0017] According to an embodiment of the present invention, the metal solution is copper sulfate, nickel sulfate, manganese (II) sulfate, chromium sulfate, a silicon compound, or a combination thereof.

[0018] According to an embodiment of the present invention, the thick film metal layer is a thick film copper layer, a thick film nickel layer, a thick film copper-nickel alloy layer, a thick film copper-manganese-nickel alloy layer, or a thick film NiCrSi alloy layer.

[0019] According to an embodiment of the present invention, the thick metal layer is sintered in air to a highly conductive copper electrode or copper die bonding electrode.

[0020] According to an embodiment of the present invention, the copper electrode is applied to the manufacture of plastic soft boards, glass substrates, solar silicon substrates and ceramic substrates from low temperature heat treatment to high temperature sintering, and to the manufacture of new-type electrode terminals of multilayer ceramic capacitors, and the processing temperature of the plastic soft board is a low temperature of 70-200°C, the processing temperature of the glass substrate is a medium temperature of 500-600°C, the processing temperature of the solar silicon substrate is a medium temperature of 500-600°C, while the processing temperature of the ceramic substrate is a high temperature of 850-1000°C.

[0021] According to an embodiment of the present invention, the novel electrode terminal of the multilayer ceramic capacitor is manufactured by using copper or nickel to manufacture the copper or nickel side electrodes of the multilayer ceramic capacitor through displacement plating, and the novel electrode terminals on two or three sides of the multilayer ceramic capacitor are manufactured through a low-temperature side electrode process of the multilayer ceramic capacitor and printing manufacture of the upper and lower electrode terminals of the internal electrodes.

[0022] According to an embodiment of the present invention, the side electrodes of the multilayer ceramic capacitor are fabricated by chemical plating, gold plating and sputtering to form copper or nickel side electrodes of the multilayer ceramic capacitor.

[0023] 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 only, and the present invention is not limited thereto. BEST MODE FOR CARRYING OUT THEINVENTION

[0024] 1 to 16c, which respectively show conceptual diagrams of copper particles replacing aluminum particles in the redox reaction according to the present invention and of copper thick film replacing aluminum thick film, and conceptual diagram of replacement using redox reaction of metal according to the present invention, conceptual diagram of highly conductive copper electrode according to the present invention applied to the front and back surfaces of different substrates, conceptual diagram of thick film aluminum electrode formed by densely accumulating and arranging aluminum particles of different sizes according to the present invention, conceptual diagram of comparison of the configuration of 2-3 side electrode terminal of multilayer ceramic capacitor according to the present invention and 5 side electrode terminal of existing multilayer ceramic capacitor, conceptual diagram of density when side internal electrodes are added to 2-3 side electrode terminal of multilayer ceramic capacitor according to the present invention, conceptual diagram of density when side internal electrodes are added to 2-3 side electrode terminal of multilayer ceramic inductor according to the present invention, conceptual diagram of density when side internal electrodes are added to 2-3 side electrode terminal of low temperature ceramic co-fired LTCC filter according to the present invention, conceptual diagram of conversion of rear aluminum electrode of bifacial solar cell according to the present invention to highly conductive copper electrode, and conceptual diagram of conversion of rear aluminum electrode of bifacial solar cell according to the present invention to highly conductive copper electrode. A conceptual diagram of the photoelectric conversion efficiency of a solar cell being improved by converting the electrode to a copper electrode, a conceptual diagram of the adhesion test results of low-temperature copper die bonding according to the present invention and existing nano silver die bonding, a conceptual diagram of the manufacturing flow of 2-3 side electrode terminals of a multilayer ceramic capacitor according to the present invention, a conceptual diagram of the manufacturing process of electrode terminals of a multilayer ceramic element using low-temperature aluminum paste according to the present invention, a conceptual diagram of the electrode terminals of a multilayer ceramic element according to the present invention being immersed in a copper sulfate solution and replaced with copper electrode terminals, a conceptual diagram of the manufacturing process of gold plating (chemical plating) using side electrodes of a multilayer ceramic capacitor according to the present invention, a conceptual diagram of the configuration of a multilayer ceramic capacitor according to the present invention when the nickel side electrode is lead out by wet chemical treatment using nickel internal electrodes densely packed on the side, a conceptual diagram of 2-3 side electrode terminals of a multilayer ceramic capacitor according to the present invention, a conceptual diagram of the conductivity when a thick-film printed silver-clad aluminum metal paste according to the present invention is sintered at different temperatures, an XRD diagram of the production of Ag2Al with an increase in sintering temperature according to the present invention, and the silver-clad aluminum metal paste according to the present invention,SEM images of the microstructures when sintered at different temperatures. As shown in the figure, the present invention relates to highly conductive wires and alloys and methods for manufacturing new types of electrode terminals, which can be applied to flex board RFID antennas, PCB die bonding, solar cells, electrode terminals of ceramic elements, LED heat dissipation substrates and glass substrates, and proposes two new methods to improve the conductivity of thick-film aluminum electrodes to be equivalent to that of thick-film printed silver electrodes and copper electrodes sintered under reducing atmosphere.

[0025] The first new method is to chemically replace the thick-film aluminum electrode (containing the replacement metal) with a highly conductive thick-film copper electrode. This new method integrates thick-film printing and gold plating deposition technology, and utilizes thick-film printing and sintering under atmospheric conditions, and metal oxidation-reduction deposition technology to fabricate base metal conductive thick films and alloy thick films.

[0026] The above novel method applies the redox reaction of metal to the substitution, as shown in Figures 1 and 2. In Figure 1a, a single aluminum particle 11 with a high oxidation potential is immersed in a metal solution 12 with a low oxidation potential to carry out a redox substitution reaction, and in this embodiment, the aluminum particle 11 is substituted with a copper particle 13. Similarly, in Figure 1b, if a thick-film aluminum layer 21 (containing a substitution metal) with a high oxidation potential printed after a single layer of sintering is immersed in a metal solution 22 with a low oxidation potential, after a certain immersion time, it becomes a thick-film metal layer with a low oxidation potential through a redox substitution reaction, and in this embodiment, the thick-film aluminum layer 21 is substituted with a thick-film copper layer 23.

[0027] Aluminum metal powder is not only relatively cheap, but also has a high oxidation potential, so it can be used as a sacrificial layer after surface pretreatment with hydrofluoric acid. As shown in Figure 2, this thick-film metal aluminum layer 21 has a very high oxidation potential, and can be replaced with a thick-film copper layer 23, a thick-film nickel layer 24, a thick-film copper-nickel alloy layer 25, a copper-manganese-nickel, or a NiCrSi alloy layer by using a low-oxidation potential metal solution 22 that is rich in, for example, copper sulfate, nickel sulfate, manganese (II) sulfate, chromium sulfate, and silicon compounds.

[0028] As shown in Figure 3, by using this new method, highly conductive copper wire can be produced on different substrates, which do not require sintering under a reducing atmosphere, from left to right in the figure, namely ceramics, PET film (thick slices), PET film (thin film), glass substrate and aluminum alloy chassis. The figures in the top row show the front side of the substrate, and the figures in the bottom row show the back side of the substrate.

[0029] The second novel method is the aluminum powder pretreatment of highly conductive thick-film aluminum electrodes. In order to improve the conductivity of the thick-film aluminum electrode, this new method uses a chemical or physical method to laminate a thin metal film 32 on the surface of aluminum particles 31 having a plurality of different particle sizes, forming a core (aluminum) shell (metal) structure; and then, by sintering and heating, an aluminum shell metal alloy 33 is formed on the metal shell and the outside of the aluminum core. The aluminum shell metal alloy is then heated to a sintering temperature of 300 to 660°C, which is the melting point of the aluminum shell metal alloy, to liquefy the aluminum shell metal alloy, thereby densely accumulating and arranging the aluminum particles 31 around the electrode, thereby improving the conductivity of the entire thick-film aluminum electrode. As shown in FIG. 4, in order to obtain the highest conductivity of the thick-film aluminum electrode, aluminum particles 31 having particle sizes of 5 μm and 2 μm are laminated, thereby realizing a densely accumulated arrangement of the thick-film aluminum electrode. As a result, an alloy of metal film aluminum is formed by the laminated metal film 32, and each metal aluminum powder is liquefied and connected, so that the conductivity of the thick-film aluminum electrode is equivalent to that of the mainstream thick-film silver electrodes and copper electrodes on the market.

[0030] The present invention utilizes the above-mentioned new highly conductive material to manufacture electrode terminals of new multilayer ceramic elements, which is a new application form, and thus the existing pentagonal electrode terminal form using immersion plating and high-temperature sintering can be converted into a 2-sided or 3-sided electrode terminal by printing and gold plating or chemical plating deposition.

[0031] The structure, process, materials and features of the new multilayer ceramic capacitor (MLCC) electrode terminal technology according to the present invention and the existing multilayer ceramic capacitor electrode terminal technology are compared as shown in Table 2 and Figure 5, in which Figure 5a shows an electrode terminal of a multilayer ceramic capacitor manufactured using the new multilayer ceramic capacitor electrode terminal technology (similar to the electrode terminal of a chip resistor) according to the present invention, and Figure 5b shows an electrode terminal of a multilayer ceramic capacitor manufactured using the existing multilayer ceramic capacitor electrode terminal technology. As explained by Table 2, the new technology changes the five-sided electrode terminal shape of the existing multilayer ceramic capacitor to the three-sided electrode terminal shape of the existing chip resistor, and the process method and materials used are also changed according to the change in the shape of the electrode terminal.

[0032] [Table 2]

[0033] As can be seen from the above comparison, the process has been changed from the original immersion plating integral molding and sintering heat treatment to front and back electrode printing and simultaneous sintering of the ceramic molded body, and the third electrode terminal on the side is manufactured by low-temperature gold plating and chemical plating or sputtering processes.

[0034] This new 2-3 side electrode terminal technology for multilayer ceramic capacitors has at least four advantages over the existing 5 side electrode terminal technology: 1. By using a printing process instead of a dipping plating process to manufacture a square electrode terminal shape without a lunar border, the quality problem of the electrode terminal shape can be improved, especially in the case of a small-sized multilayer ceramic capacitor. 2. Ultra-low temperature process <100℃ can reduce internal stress, improving the quality problem of cracks caused by the original heat treatment in high temperature reducing atmosphere of electrode terminals. In addition, depending on the density and thin layer of the new electrode terminals, the quality problem of high temperature sintering of copper electrode terminals can be improved by dipping plating the existing copper paste containing glass. 3. The immersion plating process and high-temperature firing process of electrode terminals in a reducing atmosphere used in existing multilayer ceramic capacitors can be omitted, significantly reducing process costs. 4. Instead of thick-film copper conductor paste, copper and nickel chemical solutions can be used, greatly reducing material costs.

[0035] In addition, this new 2- to 3-sided electrode terminal can be applied to, for example, multilayer ceramic elements such as multilayer ceramic capacitors (as in Figures 6a and 6b), multilayer ceramic inductors (as in Figures 7a and 7b), and low-temperature ceramic co-fired LTCC filters (as in Figures 8a and 8b). When screen-printing inner layer electrodes, seed electrodes of side electrodes of electrode terminals with 2 to 3 sides can be produced on both ends of the element, which increases the electrode density of the side electrodes (as in Figures 6b, 7b, and 8b) and is advantageous for producing side electrodes of 2- to 3-sided electrode terminals in a post-process such as gold plating or chemical plating.

[0036] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0037] Embodiment 1: Solar battery Figure 9a shows the rear aluminum electrode of the solar electrode. Through the novel process of the present invention, the original rear aluminum electrode of the bifacial solar cell can be converted into a highly conductive copper electrode, and the conductivity of the electrode is increased, so that the photoelectric conversion efficiency of the solar cell is also improved. Figure 9B shows the best condition and the best front and back surface information of the bifacial solar module. Using the same manufacturing method, a highly conductive aluminum-surface electrode can be printed to replace the existing silver-surface electrode of a solar cell, and the aluminum-surface electrode can be converted into a highly conductive copper-surface electrode by immersing it in a copper sulfate solution. As described above, the novel air-sintered copper-surface electrode of the present invention can be used in place of the silver-surface electrode of the existing solar energy.

[0038] Second embodiment: Die bonding Existing adhesive films for die bonding are mainly made of tin-lead, which is not only environmentally friendly but also has a problem of insufficient thermal conductivity when applied to high-power die bonding. Therefore, in the existing industry, instead of the existing tin-lead die bonding paste, nano silver that can be sintered at low temperature is used. However, the nano silver used as the die bonding paste is expensive. According to the new process of the present invention, low-temperature copper die bonding, which is made by replacing aluminum paste (containing copper sulfate crystals) with highly conductive die bonding copper that is sintered at low temperature under air, can produce copper electrodes at a much lower cost than the existing nano die bonding silver paste (Heraeus) used on the market. In addition, when comparing the characteristics, the following can be seen in FIG. 10a and Table 3. As shown, the experimental values ​​of the properties (e.g., adhesion, thermal conductivity, and electrical conductivity) of the low-temperature copper die bonding of this new process are all equivalent to those of the existing nano silver die bonding. Figure 10b shows the microstructure of the low-temperature copper die bonding (where copper replaces aluminum) of Figure 10a. As shown in Table 4, the adhesion of the low-temperature copper die bonding (where copper replaces aluminum) of the present invention is equivalent to that of the existing nano silver die bonding (Heraeus).

[0039] [Table 3]

[0040] [Table 4]

[0041] Third embodiment: RFID antenna Conventionally, when manufacturing radio frequency identification (RFID) antennas, a polyethylene terephthalate (PET) film is attached to an aluminum foil or copper foil of about 10 μm, and then a RFID antenna is manufactured through a subtractive process such as complicated printing, baking, exposure, development, and etching. Another method uses the new process and material of the present invention to print a thick aluminum paste (containing copper sulfate crystals), bake it, and then perform chemical substitution in a copper sulfate solution for 30 minutes to produce a highly conductive RFID copper antenna (wherein the chemical substitution process is performed by controlling the immersion time to form 0 minutes of aluminum, 5 minutes of a little copper, 10 minutes of partial copper, and 20 minutes of copper). This process is an additive process, so it can reduce waste of materials and the process equipment is simple. The return loss of the antenna characteristics is -24.248 dB, which is better than -14.707 dB of an etched RFID aluminum antenna, as shown in Table 5.

[0042] [Table 5]

[0043] Embodiment 4: Highly conductive aluminum electrodes with pre-treated silver lamination applied to safety capacitors Referring to Figures 11 and 18, comparing the process flow of a multilayer ceramic capacitor with electrode terminals on two or three sides manufactured according to the present invention with the process flow of an existing multilayer ceramic capacitor with electrode terminals on five sides, in the new multilayer ceramic capacitor with electrode terminals on two or three sides according to the present invention, the nickel electrode terminals on the front and back sides are printed and sintered at the same time as the original nickel electrodes are printed and sintered, and instead of the original gold plating process, gold plating or chemical plating is used to manufacture the side electrodes, thereby forming the electrode terminals on two or three sides of the new multilayer ceramic capacitor. This new process eliminates two steps from the original multilayer ceramic capacitor with electrode terminals on five sides: the step of immersion plating with copper paste used to manufacture the original electrode terminals, and step 10 of firing the copper electrode terminals at high temperature in a reducing atmosphere (nitrogen). The electrode terminal process for multilayer ceramic capacitors with electrode terminals on two or three sides involves screen-printing the internal electrodes to create both sides of the front and back electrodes, and then either replacing the copper side electrode with an aluminum electrode, or gold-plating or chemically plating the electrode terminal to create the other side electrode.

[0044] (a) Substitution plating of the copper electrode terminals on the sides with aluminum electrodes First, the aluminum electrode terminals of the multilayer ceramic element are fabricated by low-temperature aluminum paste immersion plating and baking, as shown in Figure 12a; then, the aluminum electrode terminals are immersed in copper sulfate solution to replace the aluminum electrode terminals with copper electrode terminals, as shown in Figure 12b.

[0045] (b) Directly gold-plating or chemically plating the copper or nickel electrode terminals on the sides Using gold plating technology, the multilayer ceramic capacitor is immersed in the cathode of copper sulfate or nickel sulfate solution to oxidize the nickel metal or copper metal of the anode to generate copper ions or nickel ions, as shown in Figure 13. Since the density of the side electrodes of the multilayer ceramic capacitor is higher than that of the cathode, the copper ions or nickel ions are reduced to the side electrodes of the multilayer ceramic capacitor to form the side copper electrodes and side nickel electrodes. Figure 14 is a schematic diagram of the structure of the multilayer ceramic capacitor when the nickel side electrodes are led out by wet chemical processing (gold plating, general chemical plating, or displacement plating) using the nickel internal electrodes densely packed on the sides. At the same time, the three-side nickel electrode terminals of the new multilayer ceramic element are produced by printing the internal nickel electrodes and at the same time producing the nickel electrode terminals on the top and bottom sides, and then using the nickel internal electrodes densely packed on the sides to produce the three-side nickel electrode terminals by wet chemical processing (gold plating, general chemical plating, or displacement plating).

[0046] The electrical tests, mechanical strength tests and solderability tests of the new 2-3 side electrode terminal according to the present invention and the original 5 side electrode terminal are shown in Table 6. The experimental values ​​of the 2-3 side electrode terminal of the multilayer ceramic element are slightly better than the existing 5 side electrode terminal.

[0047] [Table 6]

[0048] Embodiment 5: Pretreated silver-laminated highly conductive aluminum electrodes applied to safety capacitors In the present invention, the laminated thin silver film is chemically substituted to form an aluminum silver core-shell structure on the metallic aluminum powder, and then an aluminum silver alloy (Ag2Al) is formed by heat treatment. The aluminum silver alloy is liquefied to connect the aluminum particles, and the conductivity corresponds to that of the metallic silver electrode. Wherein, referring to FIG. 16a, when the silver-clad aluminum metal paste is thick-printed and sintered at 450°C, 500°C, 550°C, and 600°C, the conductivity is 1x10 -1 Ω*m and 3x10-3 Ω*m, 6x10 -5 Ω*m and 1x10 -5 The resistivity (Tp) of the silver-clad aluminum metal paste is Ω*m. According to the X-ray diffraction (XRD) analysis in FIG. 16b, with the increase in sintering temperature, in addition to metallic aluminum and metallic silver, Ag2Al is generated, and its melting point is about 550°C. As can be seen from the electron microstructure by scanning electron microscopy (SEM) in FIG. 16c, when all the silver-clad aluminum metal pastes are sintered at 550°C and 600°C, the microstructure changes obviously, and the aluminum particles are connected by the formation of Ag2Al phase.

[0049] Table 7 shows the characteristics of the existing silver electrodes used in safety capacitors. The novel highly conductive aluminum electrode of the present invention has a slightly lower conductivity than a general precious metal silver electrode. However, when used as an electrode in a safety capacitor, the dielectric characteristics (C value = 0.35nF and tan δ = 0.92%) and mechanical strength characteristics (attraction force = 1.75kg) of the capacitors manufactured using the general silver electrode and the novel highly conductive aluminum electrode of the present invention are comparable.

[0050] [Table 7]

[0051] Therefore, the main technical features of the present invention are as follows: 1. After thick-film printing of an aluminum electrode (containing copper sulfate crystals), it is immersed in a copper solution, and by controlling the solution temperature and immersion time, chemical oxidation-reduction substitution is carried out to produce a highly conductive copper electrode that can be sintered in air. This copper electrode can be applied to the production of plastic soft boards (low temperature of 70-200°C), glass substrates (medium temperature of 500-600°C), solar silicon substrates (medium temperature of 500-600°C), and ceramic substrates (high temperature of 850-1000°C), from low temperature (70°C) heat treatment to high temperature (1000°C) sintering. 2. If this process is applied to the front and back electrodes of solar cells, copper electrodes can be used instead of the silver on the front and aluminum on the back of existing solar cells, which not only improves the photoelectric conversion efficiency but also significantly reduces material costs. 3. Adhesive film for die bonding: Aluminum or die bonding tin compound paste (containing copper sulfate crystals) is immersed in copper solution, and chemical oxidation-reduction substitution is carried out while controlling the solution temperature and immersion time, and the copper die bonding electrode with high electrical conductivity and high thermal conductivity is sintered in the atmosphere. 4. This process can meet the lead-free environmental requirements when applied to chip die bonding instead of existing tin or tin-lead die bonding paste, and can also be applied to power electronics die bonding packages that require high thermal conductivity. 5. The process applied to the fabrication of RFID antennas has the advantages of low material and process costs, and the properties of the fabricated antennas are superior to those of existing aluminum copper film antennas. 6. The novel high-conductivity copper electrode technology of the present invention can also be applied to medium-temperature glass substrates and high-temperature ceramic substrates. For example, aluminum electrodes are thick-film printed on package glass substrates or LED ceramic heat dissipation substrates at different temperatures, and then immersed in copper solution. While controlling the solution temperature and immersion time, the electrodes are sintered into high-conductivity copper die bonding or copper electrodes in the atmosphere, and chemical oxidation-reduction substitution is carried out. 7. In the present invention, a core-shell structure is formed by covering the surface of aluminum particles with a thin film through chemistry and physics, and then layered metal and aluminum alloy are produced by sintering and heating. The alloy is liquefied and the densely accumulated aluminum particles are connected to realize thick-film printing of ultra-high conductivity aluminum electrodes. This new technology does not require chemical substitution processing, so the conductivity of a silver electrode sintered in air and a copper electrode sintered in a reducing atmosphere is equivalent to that of a copper electrode sintered in an air by ordinary thick-film printing and sintering. 8. The present invention does not require chemical substitution processing, and can print highly conductive thick-film aluminum paste as the surface electrode of each dish-shaped or block-shaped ceramic element, such as safety capacitors, GPS antennas, thermistors (NTC, PTC), and varistors, all of which are applied with the surface as an electrode. Since the conductivity matches that of silver, the element characteristics are equivalent to existing precious metal silver electrodes, but the material cost is greatly reduced. 9. The electrode terminals of the multilayer ceramic element have a 2-3 side electrode terminal configuration, including three sides: a front electrode, a back electrode, and a positive side electrode. This differs from the five-side electrode terminal configuration of conventional multilayer ceramic capacitors, which not only have three sides: a front electrode, a back electrode, and a positive side electrode, but also have electrodes on both the left and right sides. 10. The front and rear electrodes are fabricated by screen printing and sintering, and the positive side electrode is fabricated by low-temperature gold plating or chemical plating (electroless plating) process or sputtering process. 11. Using nickel, copper or silver as material, a conductive paste is screen-printed to produce electrode terminals on both sides, and a third electrode on the side is produced by plating copper, nickel and silver with gold using a chemical solution or by chemical plating. 12. In addition, in order to improve the internal electrode density on the sides of the laminated ceramic element, the internal electrodes of the laminated ceramic element are screen-printed on the ceramic molded body, and at the same time, electrode terminals are screen-printed on the edges of the element to improve the side electrode density, which is advantageous for subsequent chemical processing such as gold plating and chemical plating.

[0052] The differences between the present invention and the existing technology are as follows. 1. Highly conductive copper electrodes can be produced by sintering in air without the need for sintering in a reducing atmosphere, and copper die bonding technology. 2. Highly conductive aluminum electrodes can be manufactured by sintering in air without the need for chemical processing, and aluminum die bonding technology. 3. According to this new technology, the low-temperature, high-conductivity copper electrodes and die bonding properties produced at temperatures below 200°C are equivalent to those of low-temperature, high-conductivity silver electrodes and die bonding produced using existing expensive nano-silver powder paste. 4. The highly conductive thick-film aluminum electrodes of pre-treated laminated metal can be applied to dish-shaped ceramic elements, metal plates, glass substrates, or used as the internal electrodes of low-temperature co-fired ceramics. 5. Instead of the existing five-sided electrode terminals made by immersion plating and high-temperature firing, two- to three-sided electrode terminals made by multilayer ceramic element printing, low-temperature gold plating, and chemical plating can be used.

[0053] This new technology meets low material and process costs by printing and sintering a low-cost aluminum paste (containing copper sulfate crystals) and then replacing it with copper electrodes. The copper electrodes can be used instead of precious metal electrodes, and are primarily used to replace existing screen-printed silver electrodes.

[0054] 1. Green Energy Industry (a) Solar front and back electrodes: for the front and back electrodes of silicon-based solar cells, the copper paste used in screen printing copper electrodes is replaced by the silver paste used in conventional solar screen printing silver front electrodes and silver back electrodes. The average cost of copper paste used in making copper electrodes is one-tenth of that used in making silver electrodes. Moreover, this new copper electrode process can also produce ultra-fine wires (<30μm), thereby improving the efficiency of solar cells. (b) LED heat dissipation ceramic substrate electrode: Using metal wire on LED heat dissipation ceramic substrate (Al2O3, AlN), screen printing copper electrode removal by simple thick film process is replaced by the complex process technology of existing thin film process vacuum sputtering, yellow light and gold plating process. The production cost can be greatly reduced by simplifying the process. 2. Communications Industry (a) Planar inductive electrodes: replacing low-temperature silver electrodes and vacuum-sputtered gold-plated copper electrodes in touch panels. (b) Element or module electrodes fired simultaneously with low-temperature ceramics: Metal electrodes applied to light, thin, short and small multilayer ceramic communication passive elements. By printing, exposure and etching, a planar inductor with a high aspect ratio of metal copper electrodes is produced instead of the conventional multilayer ceramic inductor with silver paste as the internal electrode, thereby significantly reducing both the cost of metal materials and the cost of the process. (c) Touch panel electrodes: Applied to ceramic substrates and ceramic molded bodies, utilizing the ability to manufacture fine lines and the multilayer ceramic process to develop ultra-small communication modules that can meet the technical needs of portable communication products, including being short, light, and thin. 3. Semiconductor packaging industry It is used in wire, pad and die bonding in the packaging industry, especially in power electronics packages that require high thermal conductivity. 4. Passive Component Industry (a) Multilayer ceramic capacitor: Using this new gold plating or chemical plating of copper or nickel electrode technology, the electrode terminals of the multilayer ceramic capacitor can be manufactured. In addition, using copper or nickel substitution plating technology or direct gold plating or chemical plating of copper or nickel, the side electrodes at the boundaries of the multilayer ceramic capacitor can be manufactured as copper or nickel side electrodes. The multilayer ceramic capacitor according to the present invention utilizes nickel internal electrodes and copper or nickel side electrodes to be lead out by chemical wet processing. (b) Chip resistors: This new technology makes it possible to produce ultra-low resistance copper-nickel, copper-manganese-nickel, and NiCrSi alloys. (c) Inductors: This new technology makes it possible to manufacture thin-film inductors with copper electrodes that are fired in air, and chip inductors with copper electrode terminals on three sides. (d) Low Temperature Co-fired Ceramic (LTCC) element: This new technology makes it possible to fabricate surface copper electrodes and three-sided copper electrode terminals for low temperature co-fired ceramic elements with copper electrodes that are fired in air.

[0055] As described above, the method for manufacturing highly conductive wire or alloy material and the method for manufacturing a novel three-sided electrode terminal of a multilayer ceramic element according to the present invention can effectively solve the shortcomings of existing technologies, and by using base metal aluminum material and a highly conductive electrode process manufactured by sintering under air, the needs for low material and process costs can be met, and the method can be applied to various substrates such as plastic soft board (low temperature), glass substrate (medium temperature), solar silicon substrate (medium temperature) and ceramic substrate (high temperature). The two novel material methods correspond to the conductivity of thick-film aluminum electrode and the conductivity of thick-film printed silver electrode or copper electrode sintered under reducing atmosphere. The above-mentioned three-sided new low-temperature electrode terminal process of a multilayer ceramic element can improve the product quality and high material process cost problems of five-sided electrode terminals by immersion plating and high-temperature reducing atmosphere sintering in existing multilayer ceramic elements, and therefore the present invention is more advanced and practical. A patent claim is filed in accordance with the law.

[0056] 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 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 description of the drawings]

[0057] [Figure 1] 1 is a conceptual diagram of the oxidation-reduction reaction of the present invention when aluminum particles are replaced with copper particles and when an aluminum thick film is replaced with a thick copper film, in which a is the replacement of aluminum particles with copper particles and b is the replacement of an aluminum thick film with a thick copper film. [Diagram 2] FIG. 2 is a conceptual diagram showing the case where substitution is performed in the oxidation-reduction reaction of a metal according to the present invention. [Diagram 3] FIG. 2 is a conceptual diagram of the highly conductive copper electrode of the present invention applied to the front and back surfaces of different substrates. [Figure 4] 1 is a conceptual diagram showing how a densely packed array of thick-film aluminum electrodes can be realized by using stacked aluminum particles having different sizes according to the present invention. [Diagram 5] FIG. 1 is a conceptual diagram for comparing the configuration of a two- or three-sided electrode terminal of a multilayer ceramic capacitor according to the present invention with that of a five-sided electrode terminal of an existing multilayer ceramic capacitor, in which a is an electrode terminal having two or three sides of the multilayer ceramic capacitor according to the present invention, and b is an electrode terminal having five sides of the existing multilayer ceramic capacitor. [Figure 6] 1 is a conceptual diagram showing an increase in the density of the internal electrodes on two or three sides of a multilayer ceramic capacitor according to the present invention, in which: a is a multilayer ceramic capacitor, and b is a cross-section of a in which the internal electrode density on the sides is increased. [Figure 7] FIG. 1 is a conceptual diagram of an internal electrode density at two to three sides of a multilayer ceramic inductor according to the present invention, in which a is a multilayer ceramic inductor, b is a cross-section of a where the internal electrode density at the sides is increased, a1 is a coil, a2 is an external electrode, and a3 is a non-magnetic ceramic. [Figure 8] FIG. 1 is a conceptual diagram showing an increase in the internal electrode density of a side of the electrode terminal of the low-temperature ceramics co-fired LTCC filter according to the present invention, in which a is a low-temperature ceramics co-fired LTCC filter, b is a cross-section of a, and the increased internal electrode density of the side is shown. [Figure 9a] This is a conceptual diagram of converting the rear aluminum electrode of a bifacial solar cell into a highly conductive copper electrode. [Figure 9b] This is a conceptual diagram of the time when the photoelectric conversion efficiency of a solar cell is improved after converting the rear aluminum electrode of a bifacial solar cell into a highly conductive copper electrode. The diagram shows the best state of the bifacial solar module and information on the front and back surfaces under this state. [Figure 10a] FIG. 1 is a conceptual diagram of the adhesive strength experimental values ​​of the low-temperature copper die bonding according to the present invention and the existing commercially available nano silver die bonding, in which a1 is low-temperature copper die bonding (when copper replaces aluminum), and a2 is Heraeu. [Figure 10b]FIG. 1 is a microstructure diagram of low temperature copper die bonding (when copper replaces aluminum) according to the present invention, in which b1 is a diode, b2 is copper replacing aluminum, and b3 is a plated substrate. [Figure 11] FIG. 2 is a conceptual diagram showing a manufacturing flow of electrode terminals on two or three sides of a multilayer ceramic capacitor according to the present invention. [Figure 12a] FIG. 2 is an electrode terminal diagram of a multilayer ceramic element manufactured using the low-temperature aluminum paste according to the present invention. [Figure 12b] FIG. 2 is a conceptual diagram showing the process of immersing an electrode terminal of a multilayer ceramic element according to the present invention in a copper sulfate solution and replacing it with a copper electrode terminal, in which the upper diagram shows the surface of the copper electrode terminal and the lower diagram shows a cross-sectional view of the copper electrode terminal. [Figure 13] This is a conceptual diagram of the present invention when manufacturing side electrodes of a multilayer ceramic capacitor by gold plating (chemical plating). [Figure 14] This is a schematic diagram of a multilayer ceramic capacitor according to the present invention, in which nickel internal electrodes are densely packed on the sides and nickel side electrodes are lead out by wet chemical treatment. In this diagram, the left diagram is the surface of the nickel side electrode, and the middle and right diagrams are cross-sectional views of the nickel side electrode. [Figure 15] FIG. 2 is a conceptual diagram of a three-side electrode terminal of the multilayer ceramic capacitor according to the present invention. [Figure 16a] FIG. 2 is a schematic diagram of the electrical conductivity of the thick-film print of the silver-clad aluminum metal paste of the present invention when sintered at different temperatures. [Figure 16b] FIG. 2 is an XRD diagram of Ag2Al produced with increasing sintering temperature in the present invention. [Figure 16c] FIG. 2 is a SEM image of the microstructure of the silver-clad aluminum metal paste of the present invention when sintered under different temperatures. [Figure 17] 1 is a schematic diagram of an existing five-sided multilayer ceramic capacitor and an existing three-sided chip resistor, in which a is a five-sided electrode terminal and b is a two- or three-sided electrode terminal. [Figure 18]This is a conceptual diagram of the manufacturing process for a five-side electrode terminal of an existing multilayer ceramic capacitor. [Figure 19] 1 is a conceptual diagram of an actual sample of an existing five-sided multilayer ceramic capacitor and an existing three-sided chip resistor, in which a is a five-sided electrode terminal with an arrow pointing to a moon-shaped form, and b is a two- to three-sided electrode terminal with an arrow pointing to a square form without a moon-shaped form of the electrode terminal. [Explanation of symbols]

[0058] 11 Aluminum particles 12 Metal Solutions 13 Copper particles 21 Thick aluminum layer 22 Metal Solutions 23 Thick copper layer 24 Thick nickel layer 25 Thick copper-nickel alloy layer 31 Aluminum particles 32 Metal Film 33 Aluminum shell metal alloy 41 Nickel internal electrode 42 Guide copper electrode 43 Copper electrode terminal

Claims

1. A method for producing a multilayer ceramic element, comprising the steps of: When internal electrodes are screen-printed on a ceramic band using a metal paste, external electrodes are also printed using an aluminum paste containing a sulfate of a displacement metal to prepare a ceramic band having electrodes; The ceramic strips having the electrodes are laminated to form a laminated ceramic body having electrodes; The laminated ceramic body having the electrodes is fired in a reducing atmosphere to obtain a laminated ceramic body having fired electrodes; the laminated ceramic body having the fired electrodes is immersed in a sulfuric acid aqueous solution of a sulfate of the replacement metal to generate replacement metal external electrodes in which the external electrodes printed with an aluminum paste containing the sulfate of the replacement metal are replaced with the replacement metal, thereby forming a laminated ceramic body having a replacement metal external electrode; The replacement metal is one or a combination of two or more of copper, nickel, copper-nickel alloy, copper-manganese-nickel alloy, and nickel-chromium-silicon alloy.

1. A method for producing a multilayer ceramic element comprising the steps of:

2. The method for producing a multilayer ceramic element according to claim 1, Furthermore, a side electrode is printed on the side of the laminated ceramic body having the electrode by using an aluminum paste containing a sulfate of the substitution metal.

1. A method for producing a multilayer ceramic element comprising the steps of:

3. The method for producing a multilayer ceramic element according to claim 1, When the internal electrodes are screen-printed on the ceramic band with a metal paste, seeds for the side electrodes are printed in positions corresponding to the ends of the elements. The seed of the side electrode is used as a seed for growing a plating metal, and a side electrode is formed on the laminated ceramic body having the replacement metal external electrode by electroplating.

1. A method for producing a multilayer ceramic element comprising the steps of:

4. A method for fabricating an antenna, comprising the steps of: A circuit wiring pattern is printed on a plastic board or glass substrate using aluminum paste containing sulfates of the substitution metal, and then baked in air. A plastic board or a glass substrate having the circuit wiring pattern is immersed in a sulfuric acid aqueous solution of a sulfate of the substitution metal to generate a circuit wiring pattern in which the circuit wiring pattern printed with an aluminum paste containing the sulfate of the substitution metal is replaced with the substitution metal; The replacement metal is one or a combination of two or more of copper, nickel, copper-nickel alloy, copper-manganese-nickel alloy, and nickel-chromium-silicon alloy. A method for manufacturing an antenna, comprising the steps of:

5. A method for making a solar cell, comprising the steps of: At least one of the front electrode and the back electrode is printed on the solar silicon substrate using an aluminum paste containing a sulfate of a substitution metal, and then baked in air; The solar silicon substrate is immersed in a sulfuric acid aqueous solution of the sulfate of the substitution metal to produce an electrode in which the aluminum paste containing the sulfate of the substitution metal is substituted with the substitution metal; The replacement metal is one or a combination of two or more of copper, nickel, copper-nickel alloy, copper-manganese-nickel alloy, and nickel-chromium-silicon alloy. A method for producing a solar cell comprising the steps of:

6. A die bonding method, comprising: An aluminum paste containing a sulfate of a replacement metal is applied between a semiconductor element and a substrate, baked in air, and immersed in a sulfuric acid aqueous solution of the sulfate of the replacement metal, thereby forming a replacement metal die bonding in which the die bonding paste of the aluminum paste containing the sulfate of the replacement metal is replaced with the replacement metal.

1. A die bonding method comprising the steps of:

Images