KR102193224B1 - Conductive powder mixture of different kind of shape for electromagnetic wave shielding and Method for manufacturing the same and Paint composition having the same - Google Patents

Abstract

The present invention relates to a heterogeneous conductive powder mixture for shielding electromagnetic waves, a method of preparing the same, and a paint composition comprising the same. The conductive powder mixture is prepared by mixing dendritic silver plating copper powder including dendritic copper powder and a silver-plating layer laminated on the surface of the dendritic copper powder with flake silver plating copper powder including flake copper powder and a silver-plating layer laminated on the surface of the flake copper powder. The heterogeneous conductive powder mixture for shielding electromagnetic waves according to the present invention is configured by mixing dendritic copper powder and flake copper powder that have microstructures with different shapes, and thus has a low porosity rate and has a lot of contact points between the copper powder, thereby providing excellent electromagnetic wave shielding effect when dispersed in a polymer resin as a conductive filler. In addition, the method of preparing a mixture according to the present invention is configured in a way that the dendritic copper powder and the flake copper powder are repeatedly mixed during a preparation process to minimize pores, and thus, the mixture exhibits reduction in electrical resistance and excellent electromagnetic wave shielding effect. Moreover, a paint composition according to the present invention has a dense film and small electrical resistance, thereby providing excellent electrical conductivity and electromagnetic wave shielding effect.

Description

TECHNICAL FIELD [Conductive powder mixture of different kind of shape for electromagnetic wave shielding and Method for manufacturing the same and paint composition having the same]

The present invention relates to a conductive powder that can be used as a filler for electromagnetic wave shielding, and more particularly, a method for manufacturing a mixture and a mixture of heterogeneous conductive powder for electromagnetic wave shielding having a dendrite-type copper powder and a flake-type copper powder as a basic material, and the mixture It relates to a paint composition including.

The full-scale start of 5G communication services along with the 4th industry is not an exaggeration to say that it is a signal of the generalization of cutting-edge smart systems, and the performance of electronic devices is constantly improving. For example, recently released personal smartphones not only implement virtual reality (VR) or augmented reality (AR), but also have the capability to exchange large amounts of information at a very high speed.

As the spread of such state-of-the-art electronic devices gradually expands, what is becoming an issue is, first of all, a problem of malfunction due to unnecessary electromagnetic waves occurring inside the electronic devices and technologies related to effective blocking of electromagnetic waves leaking out of the electronic devices.

One of several technologies for blocking electromagnetic waves generated from electronic devices and discharging heat is a conductive paste. The conductive paste is a conductive filler dispersed in an insulating polymer resin, and is usually implemented in the form of a thin sheet and serves to block electromagnetic waves and emit heat while applied to the surface of an electronic component. The performance of the conductive paste may vary depending on the content or electrical and physical properties of the conductive filler dispersed therein, and the thickness of the paste itself.

As the conductive filler, gold or silver or nickel or copper powder has been conventionally used. That is, the metal powder is dispersed in a polymer resin to form a conductive paste. Silver has low electrical resistance and good electromagnetic wave shielding performance, and is mainly applied in the form of flakes. In addition, copper has a problem of oxidation, but recently, as products with improved reliability through antioxidant treatment have been released, the amount of use has increased.

However, when the metal powder is used alone, it has a problem due to its specific gravity. In other words, because of its high specific gravity, it is easily settled in the polymer resin and the layers are separated, thereby reducing workability and lowering the uniformity of the coating film.

In addition, the conductive paste to which the metal powder is applied has a non-dense, non-uniform internal structure, and has many micropores. As a result, the electrical resistance increases and the electromagnetic wave shielding rate decreases significantly. In order to solve this problem, the content of the metal powder is increased or the coating thickness is increased, but the improvement effect is insignificant.

Meanwhile, Korean Patent Publication No. 10-0695564 discloses a silicone paste composition and an electromagnetic wave shielding gasket. The disclosed paste composition has a configuration in which 35 to 70% by weight of conductive metal particles having an apparent density of 1 g/cc or less, a tap density of 1.5 g/cc or less, a silver content of 8 to 22%, and an average particle diameter of 15 to 50 μm are applied.

However, for the conductive metal particles having the above density and size specifications, it is difficult to manufacture a conductive paste having uniform dispersibility, and in the case of a dispensing product having a three-dimensional shape, the filling efficiency of the voids between particles is not large, so the electromagnetic wave shielding efficiency It also has a problem that it is not good. In addition, the silver plating alone cannot properly prevent the oxidation of the powder, and as time passes, the electrical conduction characteristics and the electromagnetic wave shielding efficiency are inevitably deteriorated.

Domestic Patent Publication No. 10-0695564 (Silicone paste composition and electromagnetic wave shielding gasket)

The present invention has been created to solve the above problems, and has low porosity and good electrical conductivity, and when dispersed in a polymer resin as a conductive filler, it is possible to provide an excellent electromagnetic wave shielding effect. It is an object of the present invention to provide a method and a paint composition including the mixture.

The dissimilar conductive powder mixture for electromagnetic wave shielding of the present invention as a solution to the above object is a dendrite type silver plated copper comprising a dendrite type copper powder and a silver plated layer laminated on the surface of the dendrite type copper powder. Powder; A flake-type copper powder and a flake-type silver-plated copper powder consisting of a silver-plated layer laminated on the surface of the flake-type copper powder are mixed and dispersed in a polymer resin to provide conductivity, and the dendrite-type silver-plated copper powder and flakes On the silver-plated layer of the silver-plated copper powder, a protective layer is further laminated to protect the silver-plated layer to prevent oxidation, and the protective layer includes; It is a laminate of any one of sodium stearate, calcium stearate, magnesium stearate, and potassium stearate.
In addition, the mixing ratio of the dendrite-type silver-plated copper powder and flake-type silver-plated copper powder per 100 parts by weight of the dendrite-type silver-plated copper powder and flake-type silver-plated copper powder mixture, the dendrite-type silver-plated copper powder is 70 to 90 parts by weight, Flaky silver-plated copper powder is 10 to 30 parts by weight.
In addition, the average particle size of the dendrite-type silver-plated copper powder is 60 to 80 µm, the surface area is 2000 to 2900 cm ² /g, and the silver forming the silver-plated layer is 5 to 15 parts by weight per 100 parts by weight of the dendrite-type copper powder. .
In addition, the average particle size of the flake-type silver-plated copper powder is 55 to 75 μm, the surface area is 2500 to 3000 cm ² /g, and the silver constituting the silver plating layer is 5 to 15 parts by weight per 100 parts by weight of the flake-type copper powder.
In addition, the method for producing a mixture of different conductive powders for shielding electromagnetic waves of the present invention as a means of solving the problems for achieving the above object includes a weighing step of weighing dendrite-type copper powder and flake-type copper powder, respectively; A degreasing step of adding and stirring the dendrite-type copper powder and flake-type copper powder weighed through the weighing step together with ultrapure water and a degreasing agent into a degreasing tank and stirring them; A washing step of washing the mixed powder having the degreasing step completed with ultrapure water; The mixed powder after the washing step is put into a silver plating bath, and a silver plating layer is formed on the surface of the dendrite-type copper powder and flake-type copper powder using a silver nitrate (AgNO ₃ )-based silver precursor, but the substitution plating layer and the reduction plating layer are sequentially As a process of lamination, in the silver plating bath, ultrapure water, based on 1 liter of ultrapure water, silver nitrate (AgNO ₃ ) 8 to 10 wt%/L, reducing agent 12 to 16 wt%/L, complexing agent 5 to 8 wt%/L, dispersant 0.2 to 0.7 In the state in which wt%/L was added, 30% of the total silver content was consumed to proceed with substitution plating to form a silver-substituted plating layer on the surface of the copper powder, and then the remaining 70% of the silver precursor was used. A silver plating step of reducing and depositing silver on the substitution plating layer to form a silver reduction plating layer covering the silver substitution plating layer; A surface treatment step of laminating a protective layer on the silver plating layer after completion of the silver plating step; And a drying step of drying the powder mixture having the surface treatment step completed after washing with water.
In addition, the surface treatment step; This is a process of coating a surface treatment agent containing any one of sodium stearate salt, calcium stearate salt, magnesium stearate salt, and potassium stearate salt on the silver plating layer.
In addition, the paint composition of the present invention as a means of solving the problems for achieving the above object includes: a dendrite-type silver-plated copper powder comprising a dendrite-type copper powder and a silver-plated layer laminated on the surface of the dendrite-type copper powder; It is composed by mixing flake-type copper powder and flake-type silver-plated copper powder consisting of a silver-plated layer laminated on the surface of the flake-type copper powder, and is dispersed in a polymer resin to impart conductivity, and the dendrite-type silver-plated copper powder and flakes On the silver-plated layer of the silver-plated copper powder, a protective layer is further laminated to protect the silver-plated layer to prevent oxidation, and the protective layer includes; Dissimilar conductive powder mixture for electromagnetic wave shielding, which is a stack of any one of sodium stearate, calcium stearate, magnesium stearate, and potassium stearate; It includes a polymer resin that maintains contact between the conductive powder mixtures in a mixed state with the electromagnetic wave shielding heterogeneous conductive powder mixture and provides adhesion to external substrates.

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The heterogeneous conductive powder mixture for electromagnetic wave shielding of the present invention made as described above is composed of a mixture of dendrite-type copper powder and flake-type copper powder having different shapes of microstructure, so that the porosity is low and the contact points between the copper powders are very large, When dispersed in a polymer resin as a filler, an excellent electromagnetic wave shielding effect can be provided.

In addition, the method for preparing the mixture of the present invention maximizes dispersibility because dendrite-type copper powder and flake-type copper powder are repeatedly mixed during the manufacturing process, thereby minimizing voids, reducing electrical resistance and exhibiting excellent electromagnetic shielding effects. .

In addition, the coating composition of the present invention provides excellent electrical conductivity and electromagnetic wave shielding effect because the coating film is dense and electrical resistance is low.

1 is a block diagram illustrating a method of manufacturing a mixture of heterogeneous conductive powders for shielding electromagnetic waves according to an embodiment of the present invention.
2 is a diagram schematically showing the manufacturing method shown in FIG. 1.
3 is a view briefly showing a paint composition containing a mixture prepared by a method for producing a mixture according to an embodiment of the present invention.
4 is a cross-sectional view taken along line AA of FIG. 3.

Hereinafter, an embodiment according to the present invention will be described in more detail with reference to the accompanying drawings.

Basically, in the heterogeneous conductive powder mixture of the present invention, a dendritic type copper powder and a flake type copper powder are mixed multiple times, and a silver plated layer and a protective layer on the surface of the mixed copper mixed powder Is coated.

Such a powder mixture is introduced and dispersed in a polymer resin such as silicone to impart electrical conductivity and electromagnetic wave shielding ability to the polymer resin. Polymer resins having electromagnetic wave shielding capabilities are coating compositions and are applied in various ways to objects generating electromagnetic waves. For example, it can be applied by thin film application, extrusion or injection method.

The copper itself in the dendrite-type copper powder and the flake-type copper powder is the same, but the shape is different. What is called a heterogeneous conductive powder means that the shape is different.

As described later, the dendrite-type copper powder and the flake-type copper powder mixture perform complementary functions in an entangled state, have numerous contact points inside, and maintain excellent thixotropic (shape retention). Therefore, when the copper powder mixture is used to prepare a coating composition for shielding electromagnetic waves, excellent workability, high density of the coating film, no sagging, and excellent electromagnetic shielding effect having a low resistance value can be realized.

The dissimilar conductive powder mixture for shielding electromagnetic waves of the present invention includes a dendrite copper powder, a silver plated layer laminated on the surface of the dendrite copper powder, and a surface that prevents oxidation of the silver plated layer and greatly improves the dispersibility of the powder. A dendrite type silver-plated copper powder comprising a treatment layer; It is composed by mixing flake-type silver-plated copper powder consisting of a flake-type copper powder, a silver-plated layer laminated on the surface of the flake-type copper powder, and a surface treatment layer that prevents oxidation of the silver-plated layer and greatly improves the dispersibility of the powder. , It is dispersed in a polymer resin to provide conductivity.

FIG. 1 is a block diagram illustrating a method of manufacturing a mixture of different conductive powders for shielding electromagnetic waves according to an embodiment of the present invention, and FIG. 2 is a diagram schematically showing the manufacturing method shown in FIG. 1.

As shown, the method of manufacturing a mixture of heterogeneous conductive powders for electromagnetic wave shielding according to the present embodiment includes a weighing step 101, a mixing step 103, a degreasing step 105, a washing step 107, and a silver plating step 109. , A surface treatment step 111, a washing step 113, and a drying step 115.

First, the weighing step 101 is a process of weighing the dendrite-type copper powder 11a and the flake-type copper powder 11b, respectively. An electronic balance 21 can be used for weighing copper powder.

The weight ratio of the dendrite-type copper powder (11a) and the flake-type copper powder (11b) measured at this time is 70wt% to 90wt% of the dendrite copper powder (11a), 10wt% to 30wt% of the flake copper powder (11b) to be. For example, when 75g of dendrite-type copper powder (11a) is used, 25g of flake-type copper powder is used, and when 87g of dendrite-type copper powder is used, 13g of flake-type copper powder is used.

In other words, per 100 parts by weight of a mixture of dendrite-type copper powder (11a) and flake-type copper powder (11b), 70 to 90 parts by weight of dendrite-type copper powder (11a), and flake-type copper powder (11b) It has an input ratio of 10 to 30 parts by weight.

If the dendrite-type copper powder 11a and the flake-type copper powder 11b are weighed through the weighing step 101, the two copper powders 11a are mixed through the mixing step 103. The method of the mixing step 103 may be any method. In some cases, the mixing step 103 may be omitted.

The subsequent degreasing step 105 is a process in which dendrite-type copper powder 11a and flake-type copper powder 11b are added to the degreasing tank 23 together with ultrapure water and a degreasing agent, and stirred with a stirrer 25. Through the degreasing step 105, various contaminants adhering to the surface of the copper powders 11a and 11b are washed away with ultrapure water. As the degreasing agent, a general metal degreasing agent may be used, and the stirring time may be adjusted according to the situation. Stirring time may be, for example, 10 minutes or less.

The degreasing step 105 is for the purpose of degreasing, but provides a side effect of evenly mixing the dendrite type copper powder 11a and the flake type copper powder 11b. Since the quality of the powder mixture according to the present embodiment varies depending on the mixing degree of the dendrite-type copper powder (11a) and the flake-type copper powder (11b), the degreasing step 105 is a step for improving the quality of the powder mixture. It is also.

Through the degreasing step 105, the flake-type copper powder 11b is evenly dispersed among the dendrite-type copper powders 11a.

After the degreasing step 105 is completed, the washing step 107 is performed. The water washing step 107 is a process of removing the degreasing agent by putting the copper powders 11a and 11b, which have been mixed and degreasing, on the filter plate 27 and adding ultrapure water. The washing method can also be changed in various ways.

Subsequently, a silver plating step 109 is performed. In the silver plating step 109, a mixed powder consisting of dendrite-type copper powder (11a) and flake-type copper powder (11b) is put together with a plating solution (33) in a silver plating bath (31), and a silver plating layer is formed on the surface of the copper powder. It is a process. The silver plated layer plays a role in preventing oxidation of copper and maximizing electrical conductivity. In addition, the plating solution 33 contains water, a silver precursor, a reducing agent, a complexing agent, and a dispersing agent.

The silver plating step 109 is performed using a silver precursor based on silver nitrate. For example, based on 1 liter of water, silver nitrate (AgNO ₃ ) 8 to 10 wt%/L, reducing agent 12 to 16 wt%/L, complexing agent 5 to 8 wt%/L, and dispersing agent 0.2 to 0.7 wt%/L were put together for 20 minutes To 30 minutes.

The above-described additive material causes a substitution reaction on the copper surface to form a substitution plating layer first, and when the substitution plating layer becomes a thickness at the level of consuming 30 wt% of the total silver content, when the substitution with copper is no longer made, the remaining 70wt% of the silver precursor causes a reduction action to reduce and precipitate silver.

Through the silver plating step 109, the dendrite-type copper powder 11a becomes a dendrite-type silver-plated copper powder 13a, and the flake-type copper powder 11b becomes a flake-type silver-plated copper powder 13b. The dendrite type silver plated copper powder and the flake type silver plated copper powder are shown in [Reference Picture 1] and [Reference Picture 2].

Silver in the silver plating layer (14 in FIG. 4) formed through the silver plating step 109 is 5 to 15 parts by weight per 100 parts by weight of the copper powder. In other words, it is 5 to 15 parts by weight per 100 parts by weight of the dendrite copper powder, and 5 to 15 parts by weight per 100 parts by weight of the flake-type copper powder.

[Reference photo 1] Dendritic silver-plated copper powder]

[Reference photo 2] Flake type silver-plated copper powder]

The dendritic silver-plated copper powder 13a has an average particle size of 60 to 80 µm, a surface area of 2000 to 2900 cm ² /g, and an apparent density of 1.2 to 1.5 g/cm ³ . In addition, the flake-type silver-plated copper powder 13b has an average particle size of 55 to 75 μm, a surface area of 2500 to 3000 cm ² /g, and an apparent density of 0.3 to 0.6 g/cm ³ .

Subsequently, the surface treatment step 111 is a process of adding and reacting a dendrite type silver plated copper powder 13a, a flake type silver plated copper powder 13b, ultrapure water, and a surface treatment agent 35 into the silver plating bath 31. As the surface treatment agent 35, one selected from sodium stearate salt, calcium stearate salt, and magnesium stearate salt may be used. The surface treatment agent 35 is coated on the silver plating layer 14 to form the protective layer 15.

The surface treatment step 111 is performed by adding 0.1 to 5% wt/L of the surface treatment agent 35 based on 1 liter of ultrapure water and reacting for 1 to 10 minutes.

A powder mixture 16 is obtained through the surface treatment step 111. The powder mixture 16 is a mixture of a dendrite silver-plated copper powder 13a coated with a protective layer 15 and a flake silver-plated copper powder 13b.

After the surface treatment step 111 is followed by washing the surface of the powder mixture 16 through the washing step 113, all processes are finished through the drying step 115.

The drying step 115 is a process of placing the powder mixture 16 in the drying device 37 and drying the moisture. The drying method of the drying step can be applied in various ways. For example, natural drying, dry air drying, and heat drying methods can be applied.

The conductive powder mixture 16 prepared through the above process includes a dendrite-type copper powder, a dendrite-type silver-plated copper powder comprising a silver-plated layer laminated on the surface of the dendrite-type copper powder, and a flake-type copper powder, It is composed by mixing flake-type silver-plated copper powder consisting of a silver-plated layer laminated on the surface of the flake-type copper powder, and is dispersed in a polymer resin 17 to form a paint composition 18 and impart conductivity to the paint composition.

In addition, the mixing ratio of the dendrite-type silver-plated copper powder and flake-type silver-plated copper powder per 100 parts by weight of the dendrite-type silver-plated copper powder and flake-type silver-plated copper powder mixture, the dendrite-type silver-plated copper powder is 70 to 90 parts by weight, Flakes-type silver-plated copper powder is 10 to 30 parts by weight,

The dendrite-type silver-plated copper powder has an average particle size of 60 to 80 μm, a surface area of 2000 to 2900 cm2/g, and the silver constituting the silver plating layer is 5 to 15 parts by weight per 100 parts by weight of the dendrite-type copper powder.

In addition, the average particle size of the flake-type silver-plated copper powder is 55 to 75 μm, the surface area is 2500 to 3000 cm2/g, and the silver forming the silver-plated layer is 5 to 15 parts by weight per 100 parts by weight of the flake-type copper powder.

In addition, on the silver plating layer of the dendrite silver-plated copper powder and the flake silver-plated copper powder, a protective layer 14 to protect the silver plating layer is further laminated, and the protective layer is sodium stearate, calcium stearate. It consists of any one of a salt (Calcium stearate), a magnesium stearate salt (Magnesium stearate), and a potassium stearate salt (Potassium stearate).

FIG. 3 is a schematic view of a paint composition 18 including a conductive powder mixture 16 manufactured by a method for manufacturing a mixture according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3.

As shown in FIG. 3, the paint composition 18 has the physical properties of a paste, and can be applied to the substrate 41 using, for example, a dispenser 39. The substrate 41 may be an electromagnetic wave generating component or an electromagnetic wave shielding case.

The paint composition 18 is a mixture obtained by mixing the conductive powder mixture 16 described above with a polymer resin 17. The mixing ratio of the polymer resin 17 and the powder mixture 16 is 55 to 80 wt%: 20 to 45 wt%. That is, per 100 parts by weight of the paint composition 18, the polymer resin 17 is 20 to 45 parts by weight, and the powder mixture 16 is 55 to 80 parts by weight.

The polymer resin 17 maintains contact between the conductive powder mixtures in a mixed state with the conductive powder mixture 16 and provides adhesion to the external substrate 41.

In particular, the conductive powder mixture 16 is formed by entangled dendrite-type copper powder and flake-type copper powder, and effectively blocks the leakage of electromagnetic waves by covering the voids of the dendrite-type copper powder with flake-type copper powder.

In addition, as mentioned above, since the paint composition 18 has a complex internal structure of dendrite and flakes and has excellent thixotropic properties, the height (H) of the paint composition in the first applied state is It can be kept as it is. For reference, when spherical copper powder is applied as a conductive filler, the height (H) is not properly maintained by the weight of the copper powder itself.

Implementation Example 1) Evaluation of electromagnetic wave shielding efficiency characteristics of a paint prepared by silver coating before mixing two shapes of silver coated copper powder

A silver plated layer was formed on the dendrite-type copper powder and the flake-type copper powder, respectively, and then mixed. The mixture was dispersed in a silicone resin for 1 hour, and then bar-coated on a PET film to a thickness of 300 µm. After that, the physical properties were measured while drying at room temperature for 24 hours. Electrical resistance was measured using a multimeter and a jig for measuring a resistance of 250 g, and the electromagnetic shielding rate was measured in a frequency range of 30 MHz to 1.5 GHz by making a round specimen with a diameter of 133 mm.

Implementation Example 2) Evaluation of electromagnetic wave shielding efficiency characteristics of a paint prepared by mixing two shapes of copper powder and then coating silver

The dendrite-type copper powder and the flake-type copper powder were first mixed and coated with silver. After that, the mixture was dispersed in a silicone resin for 1 hour, and then bar-coated to a thickness of 300㎛ on a PET film. After that, the physical properties were measured in a state of drying at room temperature for 24 hours. The electrical resistance measurement method is the same as in Example 1).

Embodiment 2) is prepared according to the method for producing a mixture covered through the detailed description of the present invention.

Comparative Example 1) The contents of the prior art document (Korean Patent Publication No. 10-0695564) described above were reproduced, and silver-coated copper powder was used by applying a product of Mitsui mining in Japan. The reason is to reproduce as much as possible the silver-coated copper powder of the density described in the prior art.

Comparative Example 2) The sales product manufactured by the applicant of the prior art document was reproduced.

Materials used Manufacturer and characteristics Implementation Example 1 Implementation Example 2 Comparative Example 1 Comparative Example 2 7%Ag/Cu
Dendritic + flake type
(Mixed after manufacturing alone) Our company
50% 7%Ag/Cu
Dendritic + Flake type
(Silver plating after mixing copper) “
50% 20%Ag/Cu
Dendritic type
Average particle diameter 18μm Mitsui mining
(Japan) 55% 10%Ag/Cu
Dendritic type
Average particle diameter 35μm “ 55% Silicone resin Shin-Etsu 25% 25% 20% 20% solvent Daejeonghwa Gold 20% 20% 20% 20% Hardener KCC 1.5% 1.5% 1.5% 1.5% Adhesive - 2.5% 2.5% 2.5% 2.5% catalyst - One% One% One% One% Coating thickness (㎛) 330 310 310 320 Surface resistance (m-ohm) 21 10 40 200 Storage stability (14 days) Good Good Good Bad Electromagnetic shielding rate 100 112 80 60

As can be seen from Table 1 above, in the case of Examples 1 and 2 in which the dendrite-type copper powder and the flake-type copper powder were mixed, the electromagnetic wave shielding rate was measured to be high.

In particular, the electromagnetic wave shielding rate of the paint prepared by silver coating after mixing copper powder (Implementation Example 2) was measured higher than that of the paint prepared by silver coating (Implementation Example 1) 2 before mixing the copper powder. . This result is because, in the manufacturing step of the conductive powder mixture, the process of mixing the dendrite-type copper powder and the flake-type copper powder is repeated through the mixing step 103, the degreasing step 105, and the surface treatment step 111. to be.

As described above, the present invention has been described in detail through specific embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible by those of ordinary skill within the scope of the technical idea of the present invention.

11a: Dendritic copper powder 11b: Flaky copper powder
13a: dendrite silver-plated copper powder 13b: flake silver-plated copper powder
15: protective layer 16: powder mixture
17; polymer resin 18; paint composition
21: electronic scale 23: degreasing tank
25: agitator 27: filter plate
31: silver plating tank 33: plating amount
35: surface treatment agent 37: drying device
39: dispenser 41: description

Claims (10)

A dendrite-type silver-plated copper powder comprising a dendrite-type copper powder and a silver-plated layer laminated on the surface of the dendrite-type copper powder;
A flake-type copper powder and a flake-type silver-plated copper powder composed of a silver-plated layer laminated on the surface of the flake-type copper powder are mixed, and are dispersed in a polymer resin to provide conductivity,
On the silver plated layer of the dendrite type silver plated copper powder and flake type silver plated copper powder, a protective layer for protecting the silver plated layer to prevent oxidation is further laminated,
The protective layer is;
Dissimilar conductive powder mixture for electromagnetic wave shielding, which is a laminate of any one of sodium stearate, calcium stearate, magnesium stearate, and potassium stearate. The method of claim 1,
The mixing ratio of the dendrite type silver plated copper powder and the flake type silver plated copper powder,
Per 100 parts by weight of a mixture of dendrite-type silver-plated copper powder and flake-type silver-plated copper powder, 70 to 90 parts by weight of dendrite-type silver-plated copper powder, and 10 to 30 parts by weight of flake-type silver-plated copper powder. The method of claim 2,
The dendritic silver-plated copper powder has an average particle size of 60 to 80 µm, a surface area of 2000 to 2900 cm ² /g,
Silver forming the silver plated layer, 5 to 15 parts by weight per 100 parts by weight of the dendrite-type copper powder is a heterogeneous conductive powder mixture for shielding electromagnetic waves. The method of claim 2,
The flake-type silver-plated copper powder has an average particle size of 55 to 75 μm, a surface area of 2500 to 3000 cm ² /g,
Silver forming the silver-plated layer, 5 to 15 parts by weight per 100 parts by weight of flake-type copper powder, heterogeneous conductive powder mixture for electromagnetic wave shielding. delete delete A weighing step of weighing dendrite-type copper powder and flake-type copper powder, respectively;
A degreasing step of adding and stirring the dendrite-type copper powder and flake-type copper powder weighed through the weighing step together with ultrapure water and a degreasing agent into a degreasing tank and stirring them;
A washing step of washing the mixed powder having the degreasing step completed with ultrapure water;
The mixed powder after the washing step is put into a silver plating bath, and a silver plating layer is formed on the surface of the dendrite-type copper powder and flake-type copper powder using a silver nitrate (AgNO ₃ )-based silver precursor, but the substitution plating layer and the reduction plating layer are sequentially As a process of lamination, in the silver plating bath, ultrapure water, based on 1 liter of ultrapure water, silver nitrate (AgNO ₃ ) 8 to 10 wt%/L, reducing agent 12 to 16 wt%/L, complexing agent 5 to 8 wt%/L, dispersant 0.2 to 0.7 In the state in which wt%/L was added, 30% of the total silver content was consumed to proceed with substitution plating to form a silver-substituted plating layer on the surface of the copper powder, and then the remaining 70% of the silver precursor was used. A silver plating step of reducing and depositing silver on the substitution plating layer to form a silver reduction plating layer covering the silver substitution plating layer;
A surface treatment step of laminating a protective layer on the silver plating layer after completion of the silver plating step;
A method of manufacturing a heterogeneous conductive powder mixture for shielding electromagnetic waves comprising a drying step of drying the powder mixture having the surface treatment step completed after washing with water. delete The method of claim 7,
The surface treatment step;
A method for producing a mixture of different conductive powders for electromagnetic wave shielding, which is a process of coating a surface treatment agent containing any one of sodium stearate, calcium stearate, magnesium stearate, and potassium stearate on the silver plating layer. A dendrite-type silver-plated copper powder comprising a dendrite-type copper powder and a silver-plated layer laminated on the surface of the dendrite-type copper powder; It is composed by mixing flake-type copper powder and flake-type silver-plated copper powder consisting of a silver-plated layer laminated on the surface of the flake-type copper powder, and is dispersed in a polymer resin to impart conductivity, and the dendrite-type silver-plated copper powder and flakes On the silver-plated layer of the silver-plated copper powder, a protective layer is further laminated to protect the silver-plated layer to prevent oxidation, and the protective layer includes; Dissimilar conductive powder mixture for electromagnetic wave shielding, which is a stack of any one of sodium stearate, calcium stearate, magnesium stearate, and potassium stearate;
A coating composition comprising a polymer resin that maintains contact between the conductive powder mixture in a mixed state with the electromagnetic wave shielding heterogeneous conductive powder mixture and provides adhesion to an external substrate.

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