KR100991626B1

KR100991626B1 - Copper alloy powder and method for producing the same

Info

Publication number: KR100991626B1
Application number: KR1020107006525A
Authority: KR
Inventors: 야스시 키노; 코지 카지타; 켄지 타마키
Original assignee: 신토고교 가부시키가이샤
Priority date: 2007-10-18
Filing date: 2008-10-20
Publication date: 2010-11-04
Also published as: WO2009051254A1; TW200927959A; JPWO2009051254A1; CN101815799A; KR20100068262A; JP4400696B2; TWI421355B

Abstract

It is excellent in oxidizing property and electrical conductivity, and can arbitrarily set a sintering start temperature, and provides the copper alloy powder which made the production cost comprised from the raw material cost and manufacturing equipment cost cheap. It contains 0.05-3.00 mass% of aluminum, the remainder consists of copper and an unavoidable impurity, and further contains 0.01-0.10 mass% of boron as needed, and granulates by a water spray method.

Description

Copper alloy powder and its manufacturing method {COPPER ALLOY POWDER AND METHOD FOR PRODUCING THE SAME}

This invention relates to the copper alloy powder most suitable for the electrically conductive paste used for an electronic component, and its manufacturing method.

Copper alloy powder is widely used as a material of a conductive paste or a conductive filler used for forming a circuit of an electronic circuit board, filling a through hole, or forming an electrode of a multilayer capacitor. While low electrical resistivity and high oxidation resistance are required, sintering characteristics with a base metal according to the use are required.

For example, when used to form an outer layer circuit of a multilayer capacitor, the sintered compact is not damaged or the electrical resistivity is increased due to oxidation in order to provide an external electrode to the finished sintered compact and to connect the substrate pattern. It is preferable not to oxidize in the atmosphere and to have a lower sintering initiation temperature in order to prevent this. Specifically, the sintering start temperature is approximately 500 ° C. or less, and it is required to have a characteristic excellent in oxidation resistance.

In addition, when used for the formation of an inner layer circuit, since the ceramic dielectric and the internal electrode are sintered at the same time, peeling between the ceramic layer forming the ceramic dielectric and the copper layer forming the internal electrode or the copper layer forming the internal electrode are performed. From the viewpoint of crack prevention, the copper alloy powder has a higher sintering onset temperature and is preferably not oxidized by the atmosphere at the time of sintering. In the present state, since the sintering temperature of the ceramic dielectric is set to approximately 900 to 1100 ° C, a copper alloy powder exhibiting sintering characteristics similar to the sintering shrinkage behavior of the ceramic dielectric is required, and specifically, the sintering start temperature is approximately 500. When the temperature is lower than or equal to 0 ° C, the ceramic dielectric and the internal electrode are easily peeled off or cracks are formed, so the temperature is preferably 700 to 1100 ° C.

As described above, a method of adding an element having an effect of improving the sintering start temperature, the electrical resistivity, and the oxidation resistance to the copper powder with respect to the request of the copper alloy powder used for the conductive paste of the electronic component (for example, Japan Japanese Patent Laid-Open No. 2001-118424, Japanese Patent Laid-Open No. 2001-131655 and Japanese Patent Laid-Open No. 2003-168321, and a method of treating the surface of copper powder (for example, Japanese Patent Publication No. 2006-117959) has been proposed.

The invention of Japanese Patent Laid-Open No. 2001-118424 relates to a copper alloy powder for a conductive paste used for forming an external electrode of a multilayer ceramic capacitor, and has an average particle diameter of Sn or Zn added as a material sintered at a lower temperature than pure copper. The copper alloy powder which is 0.1-1.0 micrometer is disclosed. However, since the sintering start temperature is not described, the electrical resistivity is slightly high at 8 to 21 µΩ · cm, and since the addition amount of Sn and Zn is required in a large amount in the range of 5 to 50% by weight, it is necessary to reduce the material cost. It is difficult.

The invention of Japanese Patent Laid-Open No. 2001-131655 relates to a copper alloy powder for conductive paste used for internal electrode formation of a multilayer ceramic capacitor having an average particle diameter of 0.1 to 1.0 µm, and has an electrical resistivity of 1.7 to 4.5 µΩ · cm. In order to make the sintering start temperature higher than the sintering start temperature of pure copper, one or more types of Ag, Cr, and Zr are added. In the said Example, the sintering start temperature of the pure copper powder whose average particle diameter is 1 micrometer is 200 degreeC, The sintering start temperature of the copper alloy powder of this invention is 210-270 by adding 0.1-20 weight% of the said additives. It is rising to ° C. However, when using for internal electrodes, it is necessary to make said sintering start temperature higher temperature, and since additive additives Ag, Cr, and Zr are expensive elements, it is difficult to reduce material cost.

The invention of Japanese Patent Laid-Open No. 2003-168321 relates to a copper alloy powder for conductive paste used for internal electrode formation of a multilayer ceramic capacitor having an average particle diameter of 0.1 to 1.0 µm, which is the same as that of Patent Document 2, wherein the electrical resistivity is 1.8. It is excellent at -2.5 microohm * cm, and in order to make sintering start temperature higher than the sintering start temperature of pure copper, 1 or more types of Ta and W are added. In the said Example, while the sintering start temperature of the pure copper powder whose average particle diameter is 0.5 micrometer is 200 degreeC, the sintering start temperature of the copper alloy powder of the said invention is 500-760 by adding 0.1-20 weight% of the said additives. It raises to C and improves significantly. However, since Ta and W are expensive elements, it is difficult to reduce material costs.

The invention of Japanese Laid-Open Patent Publication No. 2006-117959 is for use in forming an outer layer circuit, an inner layer circuit, and a via in a multilayer ceramic substrate, and a surface containing a nitrogen-containing heterocyclic compound is preferred to provide an average particle diameter. More specifically, the present invention relates to a copper powder having a thickness of 0.1 to 10.0 µm, wherein the nitrogen-containing heterocyclic compound is coated on the surface of the copper powder as a means for making the sintering start temperature higher than that of pure copper. In the above embodiment, the sintering start temperature of the pure copper powder having an average particle diameter of 1.5 μm and 3 μm is about 500 ° C., and the sintering start temperature of the copper alloy powder of the present invention is raised to 700 ° C. or more to greatly improve. Doing. However, it does not exceed 800 degreeC.

As mentioned above, although the copper alloy powder used for the electrically conductive paste of the electronic component disclosed by the prior art is all improved with respect to oxidation resistance, sintering start temperature, and electrical resistivity by the element to add, the material cost of the additional element is It is preferable to reduce the temperature and further increase the sintering start temperature.

The present invention has a low production cost in which the material cost of the elements to be added and the equipment cost of the assembling means are inexpensive, the electrical resistance is small, the oxidation resistance is excellent, and the high temperature region in which the sintering start temperature cannot be obtained in the prior art (electron In the case of sintering to the dielectric material of the component, it is required to provide a copper alloy powder that can be easily adjusted to around 1000 ° C.

The present invention made in order to solve the above problems, the copper alloy powder characterized by containing aluminum (Al) 0.05 ~ 3.00% by weight, the remainder is made of copper and unavoidable impurities as a first invention, When the content of aluminum is less than 0.05% by weight, the sintering start temperature can be lowered, but the oxidation start temperature is also lowered and the oxidation resistance is greatly reduced. Moreover, oxidation resistance improves when content of aluminum exceeds 3.00 weight%, but since electric resistivity exceeds a tolerance or reaches melting | fusing point without sintering, it is not suitable for an electronic material use. In addition, the said unavoidable impurity consists of Ag, Au, As, Bi, Sn, Pb, Ni, Te, Se, S, Fe, P, Mg, Zn, etc. If the sum total of these impurities is 0.05 weight% or less, There is no problem in carrying out the invention.

Furthermore, copper alloy powder characterized by containing 0.05-3.00 weight% of aluminum (Al) and 0.01-0.10 weight% of boron (B) is made into 2nd invention, About the content of the said boron, this inventor etc. In Japanese Patent Application Laid-Open No. 2008-95169 (filed Oct. 16, 2006), the application of boron as an element deoxidizing molten metal without increasing the electrical resistivity was described. In the present invention, the effect of increasing the sintering start temperature and the improvement of the oxidation resistance is less than the effect of the addition of aluminum, but the effect of the boron content is lower than the effect of the addition of aluminum. It is evident that it is an effective element for finely adjusting the oxidation resistance, and if the boron content is less than 0.01% by weight, the deoxidation effect is not sufficiently obtained. Since the material ratio increases because the excess is saturated, the content thereof is preferably in the range of 0.01 to 0.10% by weight.

The copper alloy powder according to the first or second invention has an average particle diameter in the range of 0.2 to 10.0 μm, wherein the copper alloy powder is a third invention. In the case of following the (atomize) method, the powder having an average particle diameter of less than 0.2 µm has a low yield even if a classification step is provided, and the powder having an average particle diameter of 10.0 µm or more has a lower granulation rate and is 0.2 to The range of 10.0 micrometers is preferable.

In addition, 0.05-3.00 weight% of aluminum is added to copper independently, or 0.05-3.00 weight% of aluminum and 0.01-0.10 weight% of boron are compounded, and the addition content is changed and the said sintering start temperature is changed. The copper alloy which makes it possible to make big adjustment of the sintering start temperature by the change of the addition content of aluminum, and fine adjustment of the sintering start temperature by the change of the addition content of boron in the range of 360 degreeC-1050 degreeC. The manufacturing method of powder is 4th invention.

Furthermore, the copper alloy powder according to any one of the first to third inventions is granulated by a water spray method, and the fifth method is a method for producing a copper alloy powder, wherein the fifth invention is based on boron. The addition of a trace amount also deoxidizes the molten metal together with the fine adjustment of the sintering start temperature. Therefore, it is not a gas spraying method which is expensive in equipment and difficult to assemble fine particles, but a high pressure water powder which is inexpensive in equipment cost and suitable for assembling fine particles. Judicial law is available. That is, since the copper alloy powder is easy to oxidize in the water injection method suitable for granulation of fine particles, it has been conventionally assembled by the gas injection method in an atmosphere which prevents oxidation. As a result, the equipment for assembling is complicated and expensive. According to the present invention, since deoxidation can be effectively carried out by the addition of a small amount of boron, the copper alloy powder of fine particles having a low oxygen concentration can be granulated. Therefore, it becomes possible to simplify the installation for assembling.

The copper alloy powder of this invention is small in electrical resistivity, excellent in oxidation resistance, and changes sintering start temperature by 360 degreeC by changing the addition content in the case where an additive is made into the aluminum single body or the compound of aluminum and boron. Since it can adjust in the range of -1050 degreeC, it can use for both the external electrode material and internal electrode material of a multilayer ceramic capacitor, for example. In addition, since the molten metal can be effectively deoxidized by the addition of a small amount of boron, it can be produced using a water spraying method in which the equipment cost is inexpensive.

This application is based on patent application No. 2007-271770 for which it applied on October 18, 2007 in Japan, The content forms a part as content of this application.

In addition, the present invention will be more fully understood by the following detailed description. However, detailed description and specific Example are preferred embodiment of this invention, and are described only for the purpose of description. This is because various changes and modifications are apparent to those skilled in the art from the above detailed description.

Applicants have no intention of offering any of the described embodiments to the public, and any of the disclosed variations, alternatives, which may not be included in the language of the claims, are part of the invention under equality.

In the description of the present specification or claims, the use of nouns and the same directives should be construed to include both the singular and the plural unless specifically indicated otherwise or unless clearly indicated by the context. The use of all illustrative or exemplary terms (eg, "etc.") provided herein is merely intended to facilitate describing the present invention, and the scope of the present invention unless specifically stated in the claims. It is not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS The test figure which shows the relationship between the temperature and expansion shrinkage rate which were implemented in order to understand the sintering start temperature of Example 1, Example 4, and Comparative Example 1 shown in Table 1. FIG.
FIG. 2 is a test chart showing the relationship between the weight change of the powder according to the temperature rise performed in order to understand the oxidation initiation temperature of Example 1, Example 4 and Comparative Example 1 shown in Table 1. FIG.

After granulating the copper alloy powder of the present invention by a water spray method having a hydraulic pressure of 100 MPa and a water quantity of 100 L / min, an air flow classifier (Nissei Engineering Co., Ltd .: Turbo Classifier) turbo classifier)) to collect a powder having an average particle diameter of 1.6 mu m, sintering start temperature, oxidation start temperature and electrical resistivity are measured, and the results are shown in Table 1.

Example

Regarding the sintering start temperature, when the content of aluminum is increased from 0.05% by weight to 3.00% by weight than Examples 1 to 5 shown in Table 1, the sintering start temperature tends to increase in proportion to the content of the aluminum. When the content of aluminum is 0.05% by weight (Example 1), the sintering start temperature of pure copper (Comparative Example 1) is lower than the sintering start temperature (510 ° C), and when the content of aluminum is 0.1 to 3.00% by weight, the sintering start temperature of pure copper Higher. In Comparative Example 3 in which the content of aluminum exceeds 3.00% by weight, since the melting point is reached without confirming the sintering start, the upper limit of the aluminum content is 3.00% by weight.

In order to confirm the expansion shrinkage rate with respect to the temperature performed in order to understand a sintering start temperature, what is necessary is just to confirm the change of the expansion shrinkage rate from the shrinkage which arises when sintering starts. The measuring method applies pressure to an alloy powder to produce a green compact, and measures the relationship between the height of the green compact and the temperature by a thermomechanical measuring device (Legaq: Termo Plus2 / TMA). The temperature at which the green compact started shrinkage was taken as the sintering start temperature.

Of the examples and comparative examples shown in Table 1, as a representative example of Example 1 (Al content: 0.05% by weight), Example 4 (Al content: 1.00% by weight), Comparative Example 1 (Al content: 0.00% by weight) The test was done and the result was shown in FIG. From this figure, in Example 1 and Example 4, the temperature of the point where the expansion shrinkage rate falls to the negative side rather than the straight line extended from 0% to the right side extends to the sintering start temperature (360 degreeC, 970 degreeC) In Comparative Example 1, the temperature at which the point expands once, rises to the positive side, and contracts and descends from the straight line is the sintering start temperature (510 ° C).

In addition, with respect to oxidation start temperature, when aluminum content is 0.05 weight% or more, it raises remarkably than Comparative Examples 1-2 shown in Table 1 which is less than 0.05 weight%, and since oxidation resistance is improved, the minimum of aluminum content is 0.05 Weight percent is preferred.

To understand the oxidation start temperature, an oxide layer is formed on the surface of the material when it is heated and oxidized, and the weight of the material increases by the weight of the oxide layer, so the temperature at the point where the increase in weight starts. . The measuring method measured the weight in nitrogen stream by the differential thermal balance (Leaque make: TermoPlus2 / TG-DTA), and made the temperature which the weight increase rate exceed 0.02% as oxidation start temperature.

In the test of the said sintering start temperature, the oxidation start temperature of Example 1, Example 4, and Comparative Example 1 shown in Table 1 which were represented as a representative example was implemented, and the result was shown in FIG. In this figure, the temperature at which the point at which each curve (Example 1, Example 4, Comparative Example 1) starts to rise from the weight increase (%) = 0 is substantially the oxidation start temperature (280 ° C, 420 ° C, 150 ° C). The oxidation start temperature (280 degreeC, 420 degreeC) of Example 1 and Example 4 is all higher than the oxidation start temperature (150 degreeC) of Comparative Example 1, and it turned out that it is excellent in the oxidation resistance which is hard to oxidize.

Moreover, regarding electrical resistivity, as shown in Table 1, Examples 1-5 whose content of aluminum is 0.05-3.00 weight%, and content of aluminum are the range of 0.05-3.00 weight%, and content of boron is 0.01. Also in any of Examples 6-10 which set it as -0.10 weight%, it is within 6 times of pure copper (comparative example 1), and is within an acceptable range practically.

As a measuring method, the bulk sample was produced and the method of measuring by the DC 4-terminal method was used.

In addition, the oxygen concentration in the molten metal in the assembling process of the copper alloy powder used for manufacturing the electronic component is preferably lower as it is lower, so as to suppress oxidation of the electrode and an increase in the electrical resistance value. As for the oxygen concentration of the copper alloy powder, 0.3 wt% or less is preferable. Table 1 also shows oxygen concentrations in Examples and Comparative Examples.

The measurement of the said oxygen concentration was measured using the gas analyzer (EMGA-2200 by Horiba Corporation).

In the above, the characteristics of aluminum as an additive of the copper alloy powder have been described. By adding aluminum, a very thin (a few tens of ohms) and a dense oxide film (aluminum oxide / Al ₂ O ₃ ) are formed on the surface of the copper alloy powder. Therefore, it is also possible to reduce the electrical conduction between the powders and to slow down the progress of oxidation at a high temperature.

In addition, regarding the effect which boron was added, the electrical resistivity is not increased by Examples 6-8 which made the content of aluminum constant at 0.05 weight%, and increased the content of boron in the range of 0.01 to 0.1 weight%. It is judged that fine adjustment is possible by slightly increasing the sintering start temperature. Furthermore, even when compared with Example 9 in which the aluminum content was 1.00% by weight and the boron content was 0.05% by weight, and the content of aluminum was the same as that in Example 9, which is the same as in Example 9, the sintering was not increased without increasing the electrical resistivity. Fine adjustment was possible by slightly increasing the onset temperature. Moreover, when the effect which added 0.01 weight% of boron to the copper alloy whose content of aluminum is the same amount (0.05 weight%) was examined by comparing Example 1 and Example 6, there was no effect of raising the sintering start temperature. , The oxygen concentration dropped from 0.29% by weight to 0.16% by weight, and there was an effect of removing oxygen (= deoxidation effect). This is presumed to be the result of the addition of boron combined with oxygen in the molten metal.

Furthermore, when comparing the comparative example 4 which made the aluminum content 0.05 weight% and the boron content 0.30 weight%, and the Example 8 which made the content of boron 0.10 weight%, sintering starts regardless of content of boron. Since no change was found in temperature, oxidation start temperature, and electrical resistivity, the upper limit and content of boron were 0.10 wt% in consideration of economical efficiency. In addition, whether or not to further add boron to the addition of aluminum may be appropriately determined depending on the required values such as the particle size of the granulated powder, the sintering start temperature, and the like, and the particle size of the powder is fine for the deoxidation effect. The more you can expect the effect.

Further, an external electrode was formed by applying a conductive paste prepared by adding an organic binder or the like to the copper alloy powder of Example 1 on both ends of the multilayer ceramic capacitor sintered by alternately laminating and sintering a dielectric powder made of barium titanate. Then, as a result of sintering through a process such as drying, peeling and cracking did not occur and a uniform bonding state was obtained.

In addition, as a result of test fabrication of the internal electrode using the copper alloy powder of Example 9 in a multilayer ceramic capacitor obtained by laminating and sintering a dielectric powder made of barium titanate, the sintering temperature was set to 1050 ° C. No deformation or crack caused by excessive shrinkage of the internal electrode made of copper alloy powder occurred.

As mentioned above, the copper alloy powder of this invention arbitrarily selects the sintering start temperature in the very wide range of 360-1050 degreeC, suppressing the increase of electrical specific resistance within the practical range by aluminum or the composite addition of aluminum and boron. Since it can set, it can use for both the external electrode and internal electrode of a multilayer ceramic capacitor as copper alloy powder for electrically conductive pastes, respectively. Moreover, it is excellent in oxidation resistance and can be manufactured in low cost by the water spraying method.

TABLE 1

Since the copper alloy powder which concerns on this invention is excellent in oxidation resistance and electrical conductivity compared with the conventional copper alloy powder, and can be set to arbitrary sintering start temperature, the use field can be expanded significantly and the alloy to add Since the production cost which consists of the raw material cost of an element (aluminum, boron) and the installation cost of the water injection method which can be employ | adopted as a granulation method can be made cheap, industrial value is very large.

Claims

Copper alloy powder for electrically conductive pastes containing 0.05-3.00 mass% of aluminum (Al) and 0.01-0.10 mass% of boron (B), and remainder consists of copper and an unavoidable impurity.

The method of claim 1,
Copper alloy powder for electrically conductive pastes whose average particle diameter is the range of 0.2-10.0 micrometers.

0.05-3.00 mass% aluminum and 0.01-0.10 mass% boron are compositely added to copper, The manufacturing method of the copper paste powder for electrically conductive pastes whose sintering start temperature is the range of 360 degreeC-1050 degreeC.

The copper alloy powder for electrically conductive pastes of Claim 1 or 2 is granulated by the water atomization method, The manufacturing method of the copper alloy powder for electrically conductive pastes characterized by the above-mentioned.

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