KR102581070B1 - Method of manufacturing conductive powder with improved film density and conductive powder produced therefrom - Google Patents

Abstract

The present invention includes ((A) disposing a seed layer on the surface of an insulator core by dry sputtering; and (B) disposing a plating layer on the surface of the seed layer by electroless plating; Disclosed is a method for producing conductive powder with improved film density, the thickness of which is smaller than that of the plating layer, and the conductive powder produced thereby.

Description

Method for manufacturing conductive powder with improved film density and conductive powder with improved film density manufactured thereby {METHOD OF MANUFACTURING CONDUCTIVE POWDER WITH IMPROVED FILM DENSITY AND CONDUCTIVE POWDER PRODUCED THEREFROM}

The present invention relates to a method for producing conductive powder with improved membrane density and to the conductive powder with improved membrane density produced thereby. Specifically, the present invention relates to a manufacturing method for manufacturing conductive powder with improved film density by coating the surface of glass powder, which is an insulator, with silver (Ag, Silver), a conductive metal.

This invention was developed through the Gyeonggi-do Small and Medium Business Development Support Project of the Gyeonggi-do Economic and Science Promotion Agency (Project number: PJ20210140, Research project name: Development of a conductive gasket using Ag coated glass filler, Host organization: MS Corporation Co., Ltd., Research period: 2021.05. It was derived from research conducted as part of the project (01~2021.12.31).

Until recently, electronic devices such as smartphones, tablet PCs, and laptop computers have gradually become lighter and shorter, and even now, research is being conducted to develop materials that can be made lighter and thinner while still performing at par with existing products. It is actively progressing.

Conventionally, silver (Ag, Silver) powder is mainly used as a conductive powder in the electronic component materials industry because it provides high reliability. Meanwhile, silver (Ag, silver) is an expensive precious metal, and its price fluctuates repeatedly depending on the international situation. As an alternative, the development of alternative materials has continued, and as an alternative, powder with a core-shell structure has been developed. The development of conductive powder with excellent price-performance ratio is in progress.

Among these core-shell structure powders, a representative example is silver-coated copper powder. Copper powder is attracting attention in the materials industry due to its excellent conductivity and low price. However, due to its vulnerability to oxidation, it has the problem of reduced reliability when used as a material for smart electronic devices that require high reliability.

As an alternative to this, by applying glass powder instead of copper as the core and then coating the glass core with silver, it was possible to prevent the problem of resistance increasing due to oxidation by copper.

However, conventional silver-coated copper powder is manufactured using an electroless plating method. Therefore, the manufacturing process must go through at least 5 to 6 steps, and in some cases, expensive catalysts are used and a high concentration of environmental wastewater is generated. In addition, in terms of physical properties, the adhesion between the glass powder as the core and the silver coating layer as the shell is weak, so the silver coating layer easily falls off from the core during the physical dispersion process for paste production.

Meanwhile, in the past, in order to increase the surface activity of the conductive powder (Core (glass)-Shell (silver)), conductive powder was manufactured by coating tin with a catalyst and then making a high-concentration alkali silver plating solution. There are problems in that the activity of silver plating is low due to low activity, a uniform silver plating layer cannot be formed, and free silver is precipitated, making electrical conductivity weak.

Republic of Korea Public Patent No. 10-2012-0099587 Republic of Korea Public Patent No. 10-2007-0013982 Republic of Korea Public Patent No. 10-2010-0064429

The purpose of the present invention is to provide a conductive powder that has a core-shell structure composed of glass and silver and can achieve excellent performance at a low price by taking advantage of the advantages of glass and silver.

In addition, the purpose of the present invention is to provide a conductive powder that can improve reliability by maintaining excellent electrical conductivity and dispersibility without fear of functional deterioration due to oxidation even after contact with air for a long period of time.

In addition, the present invention aims to provide a conductive powder that is economical by reducing the number of process steps and can solve the problem of environmental wastewater generated by eliminating the process of treating glass with an acidic solution during the manufacturing process.

Meanwhile, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly apparent to those skilled in the art from the description below. It will be understandable.

A method of manufacturing conductive powder with improved film density according to an embodiment of the present invention includes the steps of (A) disposing a seed layer on the surface of an insulator core by dry sputtering; and (B) disposing a plating layer on the surface of the seed layer by electroless plating; It includes, and the thickness of the seed layer may be smaller than the thickness of the plating layer.

Additionally, the seed layer and the plating layer may be made of the same metal.

Additionally, the seed layer may be coated with angstrom-scale metal particles, and the plating layer may be coated with nano-scale metal particles.

Additionally, the ratio of the thickness of the seed layer to the thickness of the plating layer may be 1:4 to 1:30.

Additionally, in step (A), the seed layer may have a thickness of 10 nm to 50 nm.

Additionally, in step (B), the thickness of the plating layer may be 0.2 ㎛ to 3 ㎛.

Additionally, (C) surface treating the surface of the plating layer to improve dispersibility; and (D) drying the surface-treated conductive powder.

Meanwhile, the method for manufacturing conductive powder with improved film density according to an embodiment of the present invention includes a non-conducting core; A seed layer disposed on the surface; and a plating layer disposed on the surface of the seed layer, wherein the thickness of the seed layer may be smaller than the thickness of the plating layer.

Additionally, the seed layer may be formed on the surface of the insulator core through dry sputtering, and the plating layer may be formed on the surface of the seed layer through electroless plating.

Additionally, the seed layer and the plating layer may be made of the same metal.

Additionally, the seed layer may be coated with angstrom-scale metal particles, and the plating layer may be coated with nano-scale metal particles.

Additionally, the ratio of the thickness of the seed layer to the thickness of the plating layer may be 1:4 to 1:30.

Additionally, the seed layer may have a thickness of 10 nm to 50 nm.

Additionally, the thickness of the plating layer may be 0.2 ㎛ to 3 ㎛.

In addition, to improve dispersibility, a coating layer disposed on the surface of the plating layer may be further included.

According to an embodiment of the present invention, by having a core-shell structure composed of glass and silver, excellent performance can be achieved at a low price by utilizing the advantages of glass and silver.

In addition, according to an embodiment of the present invention, there is no concern about functional deterioration due to oxidation even in contact with air for a long time, and reliability can be improved by maintaining excellent electrical conductivity and dispersibility.

In addition, according to an embodiment of the present invention, it is economical by reducing the number of process steps, and the problem of environmental wastewater generation can be solved by eliminating the process of treating glass with an acidic solution during the manufacturing process.

Meanwhile, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below. You will be able to.

1 is a flow chart sequentially showing a method for manufacturing conductive powder according to an embodiment of the present invention;
Figure 2 is a cross-sectional view schematically showing the conductive powder produced by the method for producing conductive powder according to an embodiment of the present invention;
Figures 3 and 4 are SEM images schematically showing conductive powder produced by the method for producing conductive powder according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following embodiments. This example is provided to more completely explain the present invention to those skilled in the art. Therefore, the shapes of elements in the drawings are exaggerated to emphasize clearer explanation.

In order to clarify the solution to the problem to be solved by the present invention, the configuration of the invention will be described in detail with reference to the accompanying drawings based on preferred embodiments of the present invention, and the reference numbers to the components in the drawings will be the same. Components are given the same reference numbers even if they are in different drawings, and it is stated in advance that components of other drawings can be cited when necessary when explaining the relevant drawings.

Figure 1 is a flow chart sequentially showing a method for producing conductive powder according to an embodiment of the present invention, and Figure 2 is a cross-sectional view schematically showing the conductive powder produced by the method for producing conductive powder according to an embodiment of the present invention. 3 and 4 are SEM images schematically showing the conductive powder produced by the method for producing conductive powder according to an embodiment of the present invention.

First, referring to Figure 1, the method for manufacturing conductive powder according to an embodiment of the present invention includes a core preparation step (S10), a seed layer placement step (S20), a plating layer placement step (S30), and a surface treatment step (S40). and a drying step (S50).

In the core preparation step (S10), the raw materials are measured and charged at a level equivalent to 10 to 20 vol% of the barrel area in the chamber to prepare the core 110.

The core 110 is preferably spherical, but may have various shapes and is not limited to this in the present invention.

Here, the raw materials of the core 110 are non-conducting particles, and include silicon dioxide (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc peroxide (ZnO ₂ ), hydroxyapatite, yttria (Y ₂ O ₃ ), and YAG (Y ₃ Al ₅ O ₁₂ ), titanium dioxide (TiO ₂ ), calcium phosphate, bioglass, zirconia (ZrO ₂ ), Yttria stabilized zirconia (YSZ), dysprosia (Dy ₂ O ₃ ), gadoli Niarium (Gd ₂ O ₃ ), Ceria (CeO ₂ ), Gadolinia-Ceria (GDC, Gadolinia doped Ceria), Magnesia (MgO), Barium Titanate (BaTiO ₃ ), Nickel Manganate (NiMn ₂ O ₄ ), Potassium It may be selected from at least one of the group consisting of sodium niobate (KNaNbO ₃ ), bismuth potassium titanate (BiKTiO ₃ ), and bismuth sodium titanate (BiNaTiO ₃ ).

Meanwhile, this insulator core is not limited to the types of materials other than the particles described above, and various types of glass powder can be used.

Meanwhile, this insulator core preferably has an average particle size (D) of 3 ㎛ to 100 ㎛.

Meanwhile, in the core preparation step (S10), a dispersion medium can be added for excellent dispersion effect of the raw materials, and the medium can be charged at 5 to 15 vol% of the barrel area.

Here, the type of medium is not limited, but it is desirable to use a material with a density 2 to 4 times higher than the density of the above-mentioned raw materials. In the present invention, it is possible to use stainless steel powder, emery powder, or a mixture of stainless steel powder and emery powder.

In the seed layer placement step (S20), the seed layer 120 may be placed on the surface of the core 10 prepared in the core preparation step (S10) through dry sputtering.

Here, in the dry sputtering process, a metered seed layer raw material is charged into a rotating barrel, the barrel is rotated in an atmosphere in which an inert gas (e.g., argon) is injected and plasma is generated, and the target of the metal to be coated is selected. This is a process in which ions are eluted from and settle on the surface of the base material (core).

The target material of the seed layer 120 may be silver (Ag) or nickel (Ni).

Meanwhile, the thickness (T1) of the seed layer 120 may range from 10 nm to 50 nm. In other words, Angstrom, ) units of metal (silver) ions are seated on the base material, forming excellent film density, and adhesion to the base material can be improved.

Here, if the thickness (T1) of the seed layer 120 is less than 10 nm, the electromotive force is lowered, and there is a problem that the activity of silver plating is reduced during wet plating (electroless plating) performed later, and the If the thickness (T1) exceeds 50 nm, electromotive force is excellent, but excessive waste of money occurs in terms of manufacturing cost.

In the plating layer placement step (S30), the plating layer 130 may be placed on the surface of the seed layer 120 using wet electroless plating.

In other words, the silver layer formed in this way with excellent film density is called a seed layer. By forming an additional silver layer using a wet electroless plating method on the seed layer formed with strong adhesion, electrical conductivity characteristics are further improved.

In the plating layer arrangement step (S30), the silver coating process can be performed directly without a pretreatment process for surface activation for silver plating. Here, the silver compound used in the wet process may be an acidic type silver compound consisting of silver nitrate (AgNO ₃ ), silver sulfate (Ag ₂ SO ₄ ), etc., and is used to form a plating solution atmosphere of pH 1-2. Acidic substances such as nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), and hydrochloric acid (HCl) are added, a reducing agent is added, and a plating layer 130 is added on the surface of the seed layer 120 formed by dry coating. It can be placed as .

Here, the ratio of the thickness T1 of the seed layer 120 and the thickness T2 of the plating layer 130 may be 1:4 to 1:30.

That is, the plating layer 130 additionally formed on the surface of the seed layer 120 through the plating layer arrangement step (S30) may have a size of 0.2 μm to 3 μm.

Meanwhile, it may be reasonable to form the thickness at 0.4㎛ to 2㎛ in terms of electrical conductivity characteristics and manufacturing costs. In addition, when the plating layer 130 is formed to a thickness of 1 ㎛ or more by wet coating, irregular silver irregularities are formed, and mutual irregular contact points are formed when neighboring conductive powders come into contact, further improving electrical conduction characteristics.

Meanwhile, the purpose of the seed layer 120 is to increase the activity of the plating layer 130 and eliminate a separate activation process or catalyst process. Since the higher the electromotive force, the plating activity improves, the optimal effect is achieved at the above-mentioned ratio. can do.

Here, the plating layer arrangement step (S30) implements excellent electrical conductivity by increasing the thickness of the layers 122 and 130 made of conductive metal (silver) based on the seed layer 120 formed through a dry sputtering process.

Through this, electrical conduction characteristics can be improved by increasing the thickness of the same material, and the thickness can be increased through a cheaper wet process separately from the expensive sputtering process, thereby lowering the process cost.

In addition, the sputtering process has the problem of increasing the defect rate by increasing the possibility of non-uniformity and cracks in the coating layer as the coating thickness increases due to particle coating in the angstrom unit. In the present invention, the thickness of the product is increased by a wet process after the sputtering process. Reliability can be improved.

Meanwhile, the size of the nuclear particles coated in the seed layer 120 formed by sputtering and the plating layer 130 formed by a wet process may be different, so a boundary may exist between the seed layer 120 and the plating layer 130.

Specifically, the wet electroless plating method produces nano-scale nuclei precipitation and coating, and the sputtering process produces angstrom-scale coating, so the adhesion between the seed layer 120 and the plating layer 130 is reduced due to this interface. does not occur.

In the conventional wet electroless plating process, there is a pretreatment process to increase the binding force of the catalyst by floating the positive charge on the surface of the base material, then seat the catalyst, and increase the activity of the catalyst. However, in the embodiment according to the present invention, the pretreatment process can be eliminated. Therefore, it is possible to form a metal plating layer immediately after the dry sputtering process.

That is, the embodiment according to the present invention can reduce the generation of large amounts of environmental wastewater by eliminating the pretreatment process, and can also achieve a reduction in manufacturing costs by not using expensive catalysts.

In addition, in embodiments according to the present invention, wet electroless plating is performed in an acidic atmosphere, which can suppress problems caused by agglomeration of particles caused by an alkaline base. Here, the electroless plating method is based on an acidic plating method of pH 1 to 2, and plating can be performed by adding a metal compound to the required plating thickness.

In the surface treatment step (S40), a coating layer 140 may be formed on the surface of the conductive powder 100 formed up to the plating layer 130 with an organic material.

Through this, the manufactured conductive powder 100 is prevented from being oxidized by moisture, and the dispersion effect with the resin can be improved through the conductive powder 100 when producing paste.

Meanwhile, the present invention does not limit the type of additive to improve the dispersibility of the manufactured conductive powder 100, and it is possible to use a commonly used dispersant.

Thereafter, in the drying step (S50), the surface-treated conductive powder 100 is washed and then dried. Here, drying can be done with hot air or vacuum drying, and drying is preferably performed in a nitrogen atmosphere. Specifically, the drying temperature is preferably 150°C to 300°C.

Meanwhile, of course, this set temperature can be optimally changed depending on the size of the conductive powder 100 and the thickness of the multiple coating layers.

<Example>

70g of glass powder with an average particle diameter of 30㎛ is charged into a rotating barrel, and plasma is generated while injecting argon (Ar) gas to elute silver ions from the silver target, thereby forming silver ions on the surface of the glass powder. Attach to form a seed layer.

A 50nm silver seed layer is coated on the surface of the glass powder.

Afterwards, in a wet process (electroless silver plating), 31.6 g of silver nitrate (AgNO ₃ ) and 1 liter of pure water were stirred, sulfuric acid was added to adjust pH to 1-2, and a reducing agent was added to reduce silver particles on the silver seed layer. By precipitation, the silver layer is formed to have a thickness of 0.7 μm to 1 μm.

Afterwards, an organic material for surface treatment is added to treat the surface of the particles to improve dispersion, then washed with pure water and dried to complete the conductive particles.

<Comparative example>

70g of copper powder with an average particle diameter of 30㎛ was prepared by electroless plating method. In the first step, a degreasing and peeling process was performed to remove the passivation layer on the surface of the copper powder. After charging 70g of copper powder into 10ml of degreasing and stripping agent and 600ml of pure water, stirred for 10 minutes, decanted the peeled copper powder into 47.4g of silver nitrate (AgNO3) and EDTA-2Na as a chelating agent adjusted to pH 2~3 using sulfuric acid. Add 35 g of Ascorbic Acid to 1.5 L of water, stir for 20 minutes, and perform decantation to prepare silver-plated copper powder. The prepared copper powder was dried in a dry oven in an N2 atmosphere for 120 minutes.

<Characteristics Evaluation>

As described above, the characteristics of the examples are described in the following [Table 1], and the characteristics of the comparative example were analyzed and described in the following [Table 2], and the powder was left at 30°C for 3hr, 6hr, 9hr, 12hr, and 24hr. The resistance measurement characteristics are described in [Table 3] below.

Apparent Density Tap Density electrical conductivity Powder size (㎛) D10 D50 D90 Avg. 1.2g/ ^cm3 1.8g/ ^cm3 7x10 ^-3 ohm/cm 20 35 58 41

Apparent density
Apparent Density tap density
Tap Density electrical conductivity Powder size (㎛) D10 D50 D90 Avg. 1.8g/ ^cm3 2.5g/ ^cm3 5x10 ^-4 ohm/cm 18 30 55 34

3hr 6hrs 9hr 12hrs 24hrs Example 8x10 ^-3 ohm/cm 9x10 ^-3 ohm/cm 2x10 ^-2
ohm/cm 5x10 ^-2
ohm/cm 8x10 ^-2
ohm/cm Comparative example 6x10 ^-3 ohm/cm 4x10 ^-2
ohm/cm 3x10 ^-1
ohm/cm 8x10 ^-1
ohm/cm 15
ohm/cm

Copper powder (comparative example) was also coated with the same silver content as the glass powder (example). As can be seen in [Table 1] and [Table 2], the comparative example (Ag coated copper powder) was coated with copper as the core. (Cu (Copper)) was oxidized by heat, and the resistance increased as the time the powder was exposed to heat increased. On the other hand, in the example (Ag coated glass powder), the core glass powder suffered heat shock (Damage). ), it can be seen that the increase in resistance of the powder is caused by oxidation of silver in the simple silver layer, so the increase in resistance is not large.

The above detailed description is illustrative of the present invention. Additionally, the foregoing is intended to illustrate preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, changes or modifications can be made within the scope of the inventive concept disclosed in this specification, a scope equivalent to the written disclosure, and/or within the scope of technology or knowledge in the art. The written examples illustrate the best state for implementing the technical idea of the present invention, and various changes required for specific application fields and uses of the present invention are also possible. Accordingly, the detailed description of the invention above is not intended to limit the invention to the disclosed embodiments. Additionally, the appended claims should be construed to include other embodiments as well.

100: Conductive powder
110: core
120: Seed layer
130: Plating layer
140: Coating layer

Claims (15)

(A) disposing a seed layer on the surface of the insulator core; and
(B) disposing a plating layer on the surface of the seed layer; Including,
The seed layer is formed by dry sputtering and the plating layer is formed by electroless plating,
The thickness of the seed layer is smaller than the thickness of the plating layer,
The material of the seed layer and the plating layer is silver (Ag),
A method of producing a conductive powder with improved film density, wherein the seed layer has a thickness in the range of 10 nm to 50 nm.
delete According to clause 1,
The seed layer is coated with metal particles in Angstrom units,
A method of manufacturing a conductive powder with improved film density in which the plating layer is coated with nano-scale metal particles.
According to clause 1,
A method of manufacturing a conductive powder with improved film density wherein the ratio of the thickness of the seed layer to the thickness of the plating layer is 1:4 to 1:30.
delete According to clause 1,
In step (B) above,
A method of producing a conductive powder with improved film density wherein the thickness of the plating layer is 0.2㎛ to 3㎛.
According to clause 1,
(C) surface treating the surface of the plating layer to improve dispersibility; and
(D) A method for producing conductive powder with improved film density, further comprising drying the surface-treated conductive powder.
non-conducting core;
a seed layer disposed on the surface of the insulator core; and
It includes a plating layer disposed on the surface of the seed layer,
The thickness of the seed layer is smaller than the thickness of the plating layer,
The seed layer is formed on the surface of the insulator core by dry sputtering,
The plating layer is formed on the surface of the seed layer by electroless plating,
The material of the seed layer and the plating layer is silver (Ag),
A conductive powder with improved film density wherein the seed layer has a thickness ranging from 10 nm to 50 nm.
delete delete According to clause 8,
The seed layer is coated with metal particles in Angstrom units,
The plating layer is a conductive powder with improved film density coated with nano-scale metal particles.
According to clause 8,
A conductive powder with improved film density wherein the ratio of the thickness of the seed layer to the thickness of the plating layer is 1:4 to 1:30.
delete According to clause 8,
A conductive powder with improved film density wherein the thickness of the plating layer is 0.2 ㎛ to 3 ㎛.
According to clause 8,
Conductive powder further comprising a coating layer disposed on the surface of the plating layer to improve dispersibility.