KR102054676B1 - EMI shielding material for circuit board and manufacturing method of PCB using the same - Google Patents

Abstract

The present invention relates to an electromagnetic wave shielding material which is laminated on the surface of a circuit board to shield electromagnetic waves. The electromagnetic shielding material comprises a sponge-type ultra-thin copper foil made of different metals, and a conductive adhesive layer bonded to the sponge-type ultra-thin copper foil. The conductive adhesive layer comprises a polymer resin, conductive filler and conductive polymer. It is possible to improve an electromagnetic wave shielding effect.

Description

Electromagnetic shielding material for circuit board using sponge type copper foil and manufacturing method of circuit board using same {EMI shielding material for circuit board and manufacturing method of PCB using the same}

The present invention relates to an electromagnetic shielding material for a circuit board and a method for manufacturing the circuit board using the same, and more particularly, the surface area of the metal foil is increased, thereby improving adhesion and electromagnetic shielding efficiency, and providing various functions including a dissimilar metal layer. The present invention relates to an electromagnetic shielding material for a circuit board and a method of manufacturing a circuit board using the same.

Recently, due to the remarkable development of information and communication technology, the information transmission speed and processing capacity are greatly improved while various communication devices are miniaturized and lightweight. If electromagnetic waves emitted from a communication device flow into the circuit of another device, it may cause problems such as malfunction of the device. Recently, 5G communication devices that expect faster transmission speeds use higher frequency bands than conventional communication technologies, and the need for electromagnetic shielding is increasing with the increase of such frequencies.

Existing electromagnetic shielding technology is a metal can that shields electromagnetic waves by covering the entire substrate with a metal shield in the form of a box. However, this metal can has a limitation in reducing the size and thickness of the device because it covers the entire substrate at once. Accordingly, a shielding technology for covering an ultra-thin metal for electromagnetic wave blocking on a semiconductor package itself has emerged. A representative technique for forming an ultra-thin metal is sputtering. Sputtering is a method in which a thin film is deposited on a target surface by applying a physical force to a metal material using plasma. Sputtering has the advantage of being able to form a high-density shielding film and easily controlling the film quality, but has a disadvantage of high process cost because it uses a vacuum process.

The plating method is a technique of forming a metal film on the surface of the insulator or the conductor by using an electroless or electrolytic method, and the process cost is lower than that of the sputtering method because it is a wet process rather than a vacuum process. Recently, many efforts have been made to develop an electromagnetic shielding material using a plating method having a relatively low process cost compared to the sputtering method.

 As a prior document regarding the film for electromagnetic wave shield, there is a Korean Patent No. 1607552. The prior document discloses a technique related to an electromagnetic shielding sheet which is difficult to cause physical destruction of the metal layer even after repeated bending or sliding, including a bellows-shaped metal layer and a conductive adhesive layer. However, the prior art includes a process for separately controlling the roughness of the lower surface in order to form a metal layer having a bellows-shaped cross section, which has disadvantages in terms of process cost and process stability.

Therefore, there is a great need for the development of an electromagnetic shielding material capable of reducing the connection resistance and maintaining high adhesion while the process is simple.

Therefore, the first problem to be solved by the present invention is to increase the surface area of the conductive layer to improve the adhesion and electromagnetic shielding effect, and further improved circuit boards, such as improved magnetic shielding function, durability, including the dissimilar metal layer It is to provide an electromagnetic shielding material for.

The second problem to be solved by the present invention is to provide a method for manufacturing a circuit board using the electromagnetic shielding material for the circuit board.

In order to achieve the first object, the present invention is an electromagnetic shielding material laminated on the surface of a circuit board to shield electromagnetic waves, comprising a sponge-type metal foil made of different metals, and a conductive adhesive layer bonded to the sponge-type metal foil. In addition, the conductive adhesive layer provides an electromagnetic shielding material for a circuit board comprising a polymer resin, a conductive filler and a conductive polymer.

According to one embodiment of the present invention, the content of the conductive adhesive layer is preferably 30 to 60% by weight of epoxy resin, urethane resin or acrylic resin, 1 to 10% by weight of conductive filler and 10 to 50% by weight of conductive polymer.

According to another embodiment of the present invention, the sponge-like metal foil has a surface roughness of Ra in the range of 0.30 to 1.00 micrometers, Rz in the range of 0.50 to 2.00 micrometers, and the specific surface area increase rate of the non-porous metal layer is 200 to 400%. The porosity is preferably 5 to 40%.

According to another embodiment of the present invention, the sponge-type metal foil made of the heterogeneous metal is made of a first metal and a sponge-type metal layer formed to include a plurality of open pores, and the first metal and other metals And a coating layer formed on the entire surface of the sponge-like metal layer.

According to another embodiment of the present invention, the coating layer may include metal protrusions in the form of round protrusions.

According to another embodiment of the present invention, the coating layer may include acicular metal protrusions.

According to another embodiment of the invention, the conductive polymer may be at least one selected from the group consisting of polypyrrole, polyaniline, poly acetylene, poly thiophene.

In order to achieve the second object of the present invention, there is provided a carrier, forming a release layer on the carrier, forming an electroless plating layer on the release layer, and forming a porous layer on the discontinuous metal layer. Forming an electroplating layer, forming a metal coating layer on the open surface of the porous electroplating layer, bonding the porous electroplating layer on which the metal coating layer is formed to the surface of the electromagnetic wave shielding object, the carrier and the release layer It provides a method of manufacturing an electromagnetic shielding circuit board comprising the step of removing, and forming a conductive adhesive layer on the porous electroplating layer formed with the metal coating layer.

According to one embodiment of the present invention, the conductive adhesive layer may be filled in the pores of the porous electroplating layer.

According to another embodiment of the present invention, the content of the conductive adhesive layer is preferably 30 to 60% by weight epoxy resin, 1 to 10% by weight conductive filler and 10 to 50% by weight conductive polymer.

According to another embodiment of the present invention, the metal coating layer may include metal protrusions in the form of round protrusions.

According to another embodiment of the present invention, the metal coating layer may include acicular metal protrusions.

According to another embodiment of the present invention, the porous electroplating layer has a surface roughness of Ra in the range of 0.30 to 1.00 micrometers, Rz in the range of 0.50 to 2.00 micrometers, the specific surface area increase rate compared to the non-porous metal layer is 200 ~ 400% It is preferable that the porosity is 5 to 40%.

The electromagnetic shielding material for a circuit board of the present invention has the following effects.

1. Since the metal layer of the carrier metal foil has a sponge-like structure, the pores on the surface and the inside function as anchors and release passages of residual gas components, thereby improving adhesion to the polymer resin.

2. The sponge-type structure of the carrier metal foil has high specific surface area to improve the electromagnetic shielding performance, and has high conductivity and noise reduction effect when applied to the electromagnetic shielding material of the printed circuit board.

3. The dissimilar metal layer composed of rounded protrusions or needle-shaped metal protrusions coated on the sponge-type metal foil can further increase the surface area of the sponge-type metal foil to improve the electromagnetic shielding efficiency.

4. When the dissimilar metal layer coated on the sponge-type metal foil is made of tin, silver, gold, etc. having higher conductivity than the material of the sponge-type metal foil, the grounding performance can be improved with a relatively low connection resistance, and ferromagnetic properties such as nickel In case of the material, it is advantageous to improve the magnetic shielding performance. In case of the metal such as palladium, gold, and titanium, it is advantageous to provide surface reliability. In the case of the ternary alloy such as CuNiCo, the aforementioned effects can be simultaneously obtained. Has the effect.

5. The electromagnetic shielding material for circuit boards has the effect of reducing the overall thickness of the material because the adhesion to the conductive adhesive layer is improved by the pores of the sponge-type metal foil, and the components of the conductive adhesive layer are filled in the pores of the sponge-type metal foil. .

6. The conductive adhesive layer includes a metal filler having ferromagnetic properties such as nickel to improve the magnetic field shielding effect.

7. Since the conductive polymer is included in the components of the conductive adhesive layer, the conductive polymer is easily filled in the pores of the sponge-type metal foil, thereby improving the conductivity of the sponge-type metal foil and the conductive adhesive layer.

8. Since the process for forming the sponge type metal foil is sequentially performed by the formation of the discontinuous island type electroless plating layer and the growth of the electroplating layer starting from the island type electroless plating layer, the sponge type is controlled only by the control of the plating process conditions. Metal foil can be formed.

Figure 1 shows in sequence the manufacturing process of the electromagnetic shielding material for a circuit board of the present invention.
Figure 2 shows in sequence the process of producing a carrier metal foil of the present invention.
Figure 3 illustrates the process of manufacturing an electromagnetic shielding material for a circuit board using the carrier metal foil of the present invention sequentially.
4 is an electron micrograph of an electronic vehicle shielding material for a circuit board manufactured according to Examples and Comparative Examples.
FIG. 5 is an electron micrograph of a sponge type ultrathin, a sponge type ultrathin with needle protrusions, and a sponge type ultrathin with round protrusions applied to an electromagnetic wave shielding material for a circuit board of the present invention.

The present invention is an electromagnetic shielding material laminated on the surface of the circuit board to shield electromagnetic waves, comprising a sponge-type metal foil made of different metals, and a conductive adhesive layer bonded to the sponge-type metal foil, the conductive adhesive layer is a polymer resin And a conductive filler and a conductive polymer.

The carrier metal foil used for the electromagnetic wave shielding material of the present invention includes a metal foil having a sponge-like structure. Sponge-shaped metal foil structure has a number of pores formed on the surface and the inside, improve the electromagnetic shielding performance due to the increase in surface area, improve the adhesion to the resin layer, such as conductive adhesive layer by the role of pores, the electromagnetic shielding performance and adhesion It has the effect of reducing the thickness of the electromagnetic shielding layer due to the improvement.

The sponge type metal foil, which is one component of the electromagnetic wave shielding material of the present invention, may be formed of different kinds of metals. Some of the different metals may be a sponge-like metal layer formed to include a plurality of open pores, and some of the other metals may be a coating layer formed on the surface of the sponge-like metal layer. The coating layer may be formed on the entire surface exposed to the outside of the sponge-like metal layer. For example, the coating layer may be formed on the entire surface of the pores formed therein and the surface exposed to the outside in the sponge-like metal layer.

The coating layer may be a continuous layer or may be a layer formed discontinuously in a portion in the form of a protrusion. The protrusion-like metal layer may be in the form of a rounded protrusion such as a spherical shape or a hemisphere in which a portion is cut off, or a needle-shaped metal protrusion having a needle shape or a sharp cross section.

The sponge-type metal layer and the coating layer constituting the sponge-type metal foil may be made of different kinds of metals, and the different types of metals may be pure metals made of different elements or alloys of two or more metal elements. .

The coating layer formed on the surface of the sponge-type metal foil may have an effect of increasing the reliability of the electromagnetic shielding material. When the sponge-like metal foil is made of copper, the coating layer may be made of metals such as tin, silver, and gold, which may contribute to the improvement of low connection resistance and grounding performance, and the magnetic field shielding when the coating layer is made of ferromagnetic material such as nickel. It can contribute to the improvement of performance, and when made of metals such as palladium, gold, and titanium can give higher surface reliability.

When the coating layer formed on the surface of the sponge-type metal foil is not a continuous film but has a discontinuous protrusion, it has an effect of increasing the surface area of the sponge-type metal foil. The electromagnetic wave shielding performance may be improved by increasing the surface area, and the coating film having a protrusion shape along with the pores of the sponge-type metal foil may also function as an anchor to further improve the interfacial adhesion.

The carrier metal foil used for the electromagnetic wave shielding material of the present invention includes a metal foil in the form of a sponge formed on the carrier and the release layer. The carrier functions as a medium for transferring the metal foil to the electromagnetic wave shielding object, and the release layer functions to facilitate separation of the release layer and the metal film in the process of removing the carrier. The metal foil has a porous structure, and forms a non-continuous island type electroless plating film, and performs electroplating by applying a current to the electroless plating film. At this time, as the electroplating film grows in the island-type electroless plating film spaced apart, the connection is made with the electroplating film that grows adjacent to each other, and a sponge metal foil having a very high porosity is grown through this process.

It is important to control the conditions of electroless plating and electroplating in the process of manufacturing the carrier metal foil used for the electromagnetic wave shielding material of this invention.

In electroless plating, nucleation on the release layer by the electroless plating solution and growth of the nucleus into an island form are continuously performed, and electroless plating is stopped before a continuous film is formed. Control of the above conditions can be implemented by adjusting the concentration of the electroless plating solution, electroless plating time, plating temperature and the like.

In the electromagnetic wave shielding material for a circuit board of the present invention, a conductive adhesive layer is further formed on the metal foil constituting the carrier metal foil. The conductive adhesive layer performs a function of improving the electromagnetic shielding performance by the electrical conductivity of the conductive adhesive layer. The conductive adhesive layer used for the electromagnetic wave shielding material of the present invention contains a conductive polymer. The conductive polymer may be polypyrrole, polyaniline, polyacetylene, polythiophene, or the like as the polymer resin having conductivity. The inclusion of a conductive polymer in the conductive adhesive layer of the electromagnetic wave shielding material of the present invention relates to a sponge type metal foil. In the sponge-type metal foil, pores are formed therein. When the conductive adhesive constituting the conductive adhesive layer is applied onto the sponge-type metal foil, the polymer resin, the conductive filler, and the conductive polymer included in the conductive adhesive penetrate the pores of the sponge-type metal foil. The conductive material penetrating the pores of the sponge-type metal foil improves the conductivity of the sponge-type metal foil and blocks the possibility that electromagnetic wave shielding is not performed in the high density of pores of the sponge-type metal foil. That is, the inside of the pores may be filled with a conductive filler or a conductive polymer to absorb additional electromagnetic waves in a region through which the electromagnetic waves can pass. The conductive filler may penetrate the pores of the sponge-like metal foil along the flow of the polymer resin or the conductive polymer, but if the pores are small in size or the conductive filler is blocking the inlet of the pores, the conductive filler may penetrate into some of the pores. You may not be able to. At this time, since the conductive polymer is a liquid material, it has the advantage of easily penetrating the pores. Another reason for including the conductive polymer as a component of the conductive adhesive is to reduce the connection resistance of the sponge type metal foil and the conductive adhesive layer. When only the polymer resin and the conductive filler are included in the conductive adhesive layer, the contact area between the conductive filler and the sponge-type metal foil may be small, thereby increasing the connection resistance between the two layers. However, when the conductive adhesive layer is included in the conductive adhesive layer as in the present invention, the contact resistance may be greatly reduced while surrounding the conductive polymer, the sponge-type metal foil, and the conductive filler. As a result, in the case where a part of the sponge type metal foil is grounded, the connection resistance of the sponge type metal foil and the conductive adhesive layer is reduced, and the electromagnetic wave shielding efficiency can be increased.

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

Figure 1 shows in sequence the manufacturing process of the electromagnetic shielding material for a circuit board of the present invention.

Referring to Figure 1, first prepare a carrier. The carrier functions as a means for transferring the porous metal foil formed by electroless plating and electrolytic plating to the electromagnetic wave shielding surface. The carrier may be in the form of a polymer film, a metal foil, or a polymer film and a metal foil bonded to each other. However, the surface of the carrier on which the electroless plating layer is formed is preferably metal. This is because the carrier should act as an electrode in the electrolytic plating process after the electroless plating. In the case where the electroless plating layer and the electrolytic plating layer are copper, the metal carrier is preferably aluminum. Since aluminum reacts with oxygen in the air to form a natural oxide film, an electroplating film is not formed on an aluminum oxide surface or a release layer other than the island-type electroless plating layer in the electrolytic plating process.

Next, a release layer is formed on a carrier. The release layer may be made of a metal compound, and specifically, may be a nickel or cobalt-based compound. The release layer is formed by degreasing the aluminum carrier with 10 to 100 g / L nickel chloride (more preferably 30 to 60 g / L nickel chloride) and 10 to 50 g / L cobalt chloride (more preferably 20 to 30 g / L cobalt chloride). ), 100 to 200 g / L calcium chloride (more preferably 130 to 160 g / L calcium chloride), less than 50 ppm PEG-based surfactant, less than 10 ppm iron compound reducing agent is deposited in a release layer forming solution 1 ~ in an electroless manner A release layer having a thickness of 10 nm (more preferably 3 to 7 nm) can be formed, wherein the temperature of the solution is preferably 30 to 50 ° C. and the treatment time is 2 to 3 minutes. The release layer is preferably thin so that electric charge can be transferred to the island-type electroless plating layer due to the tunneling effect when a voltage is applied to the metal carrier. It is preferable that the thickness of a release layer exists in the range of 5-10 nanometers.

Subsequently, electroless plating is performed on the release layer. Electroless plating should be stopped before a continuous film is formed on the release layer, and the higher the island-type copper film density (number of copper islands per unit area) formed by electroless plating, the larger the pore size in subsequent electroplating steps. Becomes smaller. The electroless plating process involves 50 to 100 g / L copper salt (more preferably 70 to 80 g / L copper salt), 70 to 150 g / L complexing agent (more preferably 90 to 120 g / L) on the aluminum carrier on which the release layer is formed. L complexing agent), caustic soda, potassium hydroxide can be deposited in an electroless copper plating solution consisting of a pH adjusting agent to form a copper island, wherein the electroless copper plating working conditions are 30 seconds to 2 minutes at a temperature of 30 ~ 50 ℃ It is desirable to deposit

Subsequently, the first metal electrolytic plating film is grown on the release layer on which the electroless plating layer is partially formed. In the electrolytic copper plating process, since electrolytic plating is not performed on the aluminum carrier and the release layer, copper plating is performed only on the surface of copper particles formed by electroless copper plating, and copper grown from neighboring copper particles meets to form a porous copper film. The conditions of the electrolytic copper plating is preferably such that the thickness of the porous copper foil has a thickness of 1 to 5 micrometers. If the thickness of the copper foil is less than 1 micrometer, the strength is too low, so the applicability is lowered and the copper foil thickness is 5 micrometers. If it exceeds, the advantage which an ultra-thin copper foil has disappeared. Electrolytic copper plating processes include 100-150 g / L copper sulfate (more preferably 120-130 g / L copper sulfate), 100-150 g / L sulfuric acid (more preferably 120-130 g / L sulfuric acid), less than 50 ppm hydrochloric acid, other varnishes, An electrolytic copper plating solution consisting of a leveler was used, and electrolytic copper plating was carried out at a current density of 1.4ASD at room temperature to form a copper foil having fine pores having a thickness of about 3 μm.

Subsequently, second metal plating is performed on the first metal electrolytic plating film. The second metal plating forms a needle-like copper film by electroless plating on the surface of the first metal electrolytic plating film, or forms a metal protrusion of a round projection consisting of copper-nickel-cobalt by electroplating on the surface of the first metal electroplating film. do. It is preferable that the coating layer (or protrusion) made of the second metal plating has a thickness of 0.1 to 2 micrometers, and more preferably 0.1 to 1 micrometer.

Subsequently, the sponge-like metal foil on which the second metal plating is made is bonded to the insulating layer. The sponge type metal foil can be used as an electromagnetic wave shielding material, and for this purpose, the sponge type metal foil is bonded to the surface of the electromagnetic wave shielding object. The electromagnetic shielding object may be a printed circuit board, and in this case, the insulating layer to which the sponge-type metal foil is bonded may be a surface layer of the printed circuit board. Conductive adhesive may be used for bonding, and the conductive adhesive may be applied on the insulating layer or on the sponge metal foil.

The carrier is then removed. Removal of the carrier can be performed by the function of the release layer. When the carrier is removed, the sponge-like metal foil is bonded onto the insulating layer of the electromagnetic wave shielding object. Some areas of the sponge metal foil may be grounded.

Finally, the carrier is removed to form a conductive or insulating layer on the exposed sponge metal foil. The conductive layer can be a conductive adhesive layer. The conductive adhesive layer can be bonded while electrically conductive on the sponge-like metal foil. The conductive adhesive layer functions to shield electromagnetic waves together with the grounded sponge-shaped metal foil.

The conductive adhesive layer includes a polymer resin, a conductive filler and a conductive polymer, and the polymer resin may be epoxy resin, urethane resin or acrylic resin. The mixing ratio is preferably 30 to 60% by weight of epoxy resin, 1 to 10% by weight of conductive filler, and 10 to 50% by weight of conductive polymer. The conductive filler may be at least one selected from the group consisting of copper (Cu), silver (Ag), gold (Au), nickel (Ni), palladium (Pd), tin (Sn), and titanium (Ti). Double tin, silver and gold are advantageous for improving grounding performance with relatively low connection resistance, nickel is advantageous for improving magnetic field shielding performance using ferromagnetic materials, and palladium, gold and titanium are advantageous for providing high surface reliability. The conductive polymer may include at least one selected from the group consisting of polypyrrole, polyaniline, polyacetylene, polythiophene, or a copolymer thereof.

Figure 2 shows in sequence the process of producing a carrier metal foil of the present invention.

Referring to Figure 2, first prepare a carrier. The carrier has a form in which a metal foil 102 is stacked on a polymer film 101 such as PET. In the case where the electroless plating layer and the electrolytic plating layer are made of copper, the metal foil is preferably made of a metal other than copper, and may be aluminum foil.

Subsequently, a release layer 103 is formed on the metal foil. The release layer may be made of an inorganic material or an organic material, and may be a nickel or cobalt-based compound. The thickness of the release layer is preferably a thin thickness in which charge can be transferred by the tunneling effect in consideration of the use of a metal foil as an electrode in electroplating.

Next, electroless plating is performed on the release layer 103. Electroless plating proceeds only until the formation of a discontinuous film and an electroless plating island 104 is formed over the release layer.

Next, electrolytic plating is performed. Electroplating is carried out using the metal foil 102 as an electrode, in which the electrolytic plating is carried out only on the electroless plating island 104 while current flows through the electroless plating island 104 through the thin release layer. 105a) is formed, and electroplating is not performed on the release layer. This is because aluminum is used as a metal carrier. Since aluminum is formed with a natural oxide film in the air, plating is not performed on the surface during electroplating, and nickel or cobalt oxide / nitride, which is extremely low in electrical conductivity, is not a pure metal. Plating is also not performed on the release layer. In the electrolytic copper plating process, plating is performed only on copper plated particles formed of electroless copper plating. Electrolytic copper formed on spaced apart copper plated particles meets electrolytic copper formed on neighboring copper plated particles to form a porous copper foil. At this time, the properties of the porous copper foil is affected by the electroless copper plating conditions and the electrolytic copper plating conditions, the pore size of the porous copper foil is mainly affected by the electroless copper plating conditions. If the electroless copper plating time is set short, relatively large pores are formed, and if the electroless copper plating time is set long, relatively small pores are formed. The pore size (diameter) of the porous copper foil is preferably in the range of 0.1 to 40 micrometers, more preferably in the range of 1 to 30 micrometers, and more preferably in the range of 3 to 20 micrometers. If the pore size of the copper foil is less than 0.1 micrometer, it is difficult to control the porous physical properties, and if it exceeds 40 micrometers, the strength of the copper foil is too low. At this time, since the size of the pores is observed based on the surface of the copper foil, the thickness of the copper foil may be smaller than the size of the pores, but the pores may have a larger value than this.

Subsequently, a dissimilar metal coating layer 105b is formed on the surface of the porous electroplating layer 105a. The dissimilar metal coating layer is formed on the entire surface of the porous electroplating layer. In addition to the surface exposed to the outside, the dissimilar metal coating layer is formed on the surface exposed to the inside of the pores. The dissimilar metal coating layer may be a continuous layer as shown in the figure, but may be a layer formed discontinuously in part in the form of a protrusion. The protrusion-like metal layer may be in the form of a rounded protrusion such as a spherical shape or a hemisphere in which a portion is cut off, or a needle-shaped metal protrusion having a needle shape or a sharp cross section.

Next, the release layer 103 is separated from the sponge metal foil layer 110. Through the separation process of the release layer, the polymer film 101 and the metal foil 102 are removed together.

FIG. 3 sequentially shows a process of manufacturing an electronic vehicle shielding material for a circuit board using the carrier metal foil of the present invention.

Referring to FIG. 3, first, a carrier metal foil composed of a carrier 201, a release layer 202, and a sponge type metal foil layer 210, and an electromagnetic wave shielding object are prepared. The sponge-type metal foil layer may be made of a porous electroplating layer and a dissimilar metal coating layer formed on a surface thereof. The electromagnetic shielding object may be a printed circuit board. In this case, the electromagnetic shielding object includes an insulating layer 301, and an adhesive layer 302 is formed on the insulating layer 301.

Subsequently, the sponge-like metal foil layer 201 of the carrier metal foil is bonded to the adhesive layer 302 under the insulating layer 301. The sponge-like metal foil layer 201 has a porous structure, and when protrusions are formed on the surface, the surface area is further increased, so that the contact area with the adhesive layer 302 is greatly increased, and thus the adhesion and bonding strength are very excellent.

Next, the carrier 201 and the release layer 202 of the carrier metal foil are removed. At this time, one surface of the sponge-like metal foil layer 210 from which the carrier and the release layer is removed is combined with the adhesive layer 302, and the other surface is exposed to the outside while maintaining the porous structure.

Subsequently, a conductive adhesive layer 401 is formed under the sponge-type metal foil layer 210 that is exposed to the outside. The conductive adhesive layer 401 is applied using a conductive adhesive, which includes a non-conductive vibration damper such as an epoxy resin, urethane resin or acrylic resin, a conductive filler and a conductive polymer. The conductive adhesive cures after application to protect the surface of the sponge-like metal foil layer, and is electrically connected to the grounded sponge-like metal foil layer to perform an electromagnetic shielding function together. The conductive adhesive penetrates the pores formed in the sponge-like metal foil layer, and a part of the conductive adhesive layer is filled in the sponge-type metal foil layer, and a portion forms a film on the surface of the sponge-type metal foil layer. The present invention is characterized in that the conductive polymer used in the process of manufacturing the electromagnetic shielding material includes a conductive polymer, which is associated with the porous structure of the sponge-type metal foil layer.

Since the sponge-type metal foil constituting the electromagnetic wave shielding material of the present invention has a porous structure, the surface area is very wider than that of the non-porous membrane, so that the efficiency of absorbing electromagnetic waves is increased. However, since the sponge-type metal foil does not have a uniform structure, some regions may have a region where electromagnetic waves can pass through pores. The conductive filler included in the conductive adhesive serves to block the possibility of electromagnetic waves penetrating into the pores. In this respect, the average pore of the sponge-like metal foil is preferably in the range of 1 to 30 micrometers, more preferably in the range of 3 to 20 micrometers. Despite the average pore diameter, some pores may be smaller than a few micrometers, which is the typical size of the conductive filler included in the conductive adhesive, in which case the conductive filler may not be filled inside the pores. . At this time, the conductive polymer can be easily filled even in the small pores that can not penetrate the conductive filler can compensate for the electromagnetic wave weakening area. When the sponge-type metal foil is composed of a sponge-type metal layer made of a first metal and a dissimilar metal coating layer formed on the surface of the sponge-type metal layer, the average pore diameter of the sponge-type metal layer is reduced by the dissimilar metal coating layer. In this case, the function of the conductive polymer included in the conductive adhesive may be further increased.

Another function of the conductive polymer is to help the electrical connection between the sponge metal foil and the conductive filler. Since the sponge type metal foil is grounded, the conductive filler must also be electrically connected to the sponge type metal foil to contribute to the improvement of the electromagnetic shielding performance. In the state where the conductive adhesive layer does not contain the conductive polymer and only the conductive filler is included, the dispersed conductive filler should be in contact with the sponge-type metal foil, and the contact area between the conductive filler and the sponge-type metal foil is small and the electrical space between the conductive fillers is small. The connection is also vulnerable. When the conductive adhesive contains a conductive polymer, the conductive polymer may mediate the electrical connection between the sponge-type metal foil and the conductive filler and the electrical connection between the conductive fillers. By the medium of the conductive polymer, the conductivity of the conductive adhesive layer and the conductivity of the sponge-type metal foil and the conductive adhesive layer can be improved.

In FIG. 3, a separate adhesive is applied to the lower portion of the insulating layer in order to bond the carrier metal foil to the electric vehicle shielding object. Alternatively, the spherical metal foil can be directly bonded to the insulating layer using a conductive adhesive layer formed on the lower portion of the sponge-type metal foil. It is possible. In this case, a conductive layer is formed on the surface of the electromagnetic wave shielding object in the order of a conductive adhesive layer and a sponge type metal foil.

Hereinafter, the present invention will be described in more detail using examples.

Example 1-1 (carrier metal foil production)

In order to effectively remove contaminants such as organic substances on the surface of the aluminum carrier, YMT degreasing agent (Al clean 193) was prepared by diluting, and degreased at a temperature of 30 to 50 ° C. for 2 to 5 minutes. Subsequently, the degreased aluminum carrier was electrolessly deposited in a release layer forming solution consisting of 45 g / L nickel chloride, 25 g / L cobalt chloride, 150 g / L calcium chloride, less than 50 ppm PEG-based surfactant, and less than 10 ppm iron compound reducing agent. In this manner, a 5 nm thick release layer was formed. At this time, the temperature of the solution was treated for 2 minutes at a temperature of 40 ℃. Subsequently, copper islands were formed by depositing an electroless copper plating solution composed of a pH adjusting agent such as 75 g / L copper salt, 110 g / L complexing agent, caustic soda and potassium hydroxide on the aluminum carrier on which the release layer was formed. Electroless copper plating working conditions were deposited for 20 seconds at a temperature of 40 ℃. Subsequently, electroplating was carried out on the copper islands formed using electroless copper plating. Electrolytic plating was performed using an electrolytic copper plating solution consisting of 125g / L copper sulfate, 125g / L sulfuric acid, less than 50ppm hydrochloric acid, other brightening agents, and leveler, and electrolytic copper plating with a current density of 1.4ASD at room temperature to about 3㎛ thickness. Far copper foil having fine pores was formed.

Example 1-2 (carrier metal foil manufacture)

Carrier metal foil was prepared in the same manner as in Example 1-1 except that the electroless plating time was 40 seconds in the electroless copper plating copper particle forming step.

Example 1-3 (carrier metal foil manufacture)

Carrier metal foil was prepared in the same manner as in Example 1-1 except that the electroless plating time was set to 1 minute 30 seconds in the electroless copper plating copper particle forming step.

Example 1-4 (carrier metal foil manufacture)

Carrier metal foil was prepared in the same manner as in Example 1-1 except that the electroless plating time was 2 minutes in the electroless copper plating copper particle forming step.

Example 1-1-1 (carrier metal foil manufacture)

In the same manner as in Example 1-1, after preparing the Far East foil having the fine pores, the Far East foil having the fine pores by electroplating was formed on the surface of the copper-nickel-cobalt ternary alloy. In the process of forming the coating layer, first, a plating solution containing 20 g / L CuSO 4, 10 g / L NiSO 4, 20 g / L CoSO 4, and 60 g / L citric acid was prepared. First, the base plating was performed for about 7 seconds at a current density of 6ASD at room temperature using the ternary alloy plating solution. Thereafter, the same plating solution was used to perform nodule plating for about 7 seconds at a current density of 30 ASD at room temperature.

Example 1-2-1 (carrier metal foil production)

In the same manner as in Example 1-2, the copper foil having fine pores was manufactured, and then a coating layer made of a copper-nickel-cobalt ternary alloy was formed in the same manner as in Example 1-1-1.

Example 1-3-1 (carrier metal foil production)

In the same manner as in Example 1-3, after preparing the Far Copper Foil having fine pores, a coating layer made of a copper-nickel-cobalt ternary alloy was formed in the same manner as in Example 1-1-1.

Example 1-4-1 (carrier metal foil manufacture)

In the same manner as in Example 1-4, a copper foil having fine pores was manufactured, and a coating layer made of a copper-nickel-cobalt ternary alloy was formed in the same manner as in Example 1-1-1.

Example 1-3-2 (carrier metal foil manufacture)

In the same manner as in Example 1-3, after preparing the Far East foil having the fine pores, the Far East foil having the fine pores by electroless plating was formed on the surface of the coating layer made of a needle-like copper projection. The process of forming the coating layer is as follows. First, a pre-dip was performed by treating 20 ml of sulfuric acid (61.5%) for 20-40 sec, followed by 30 ml / L of Cata 855 Cata 855 catalyst of YMT, 90 ml / L of sulfuric acid (61.5%). Palladium was adsorbed on the surface of the substrate by treating at 30-35 ° C. for 2-5 minutes. Then, sodium hypophosphite was used as a reducing agent. The pretreated polymer substrate was immersed in a plating solution at 30-40 ° C. for 5-20 minutes to form a copper seed. The plating solution was prepared by adding distilled copper sulfate, sodium hydroxide and pyridazine.

Comparative Example 1 (carrier metal foil production)

Carrier metal foil was prepared in the same manner as in Example 1-1 except that the electroless plating time was 5 minutes in the electroless copper plating copper particle formation step. The electroplated film formed at this time was a continuous film without pores.

Evaluation example 1 (measurement of pore diameter, roughness, specific surface area increase rate, and porosity of sponge type metal foil)

Examples 1-1, 1-2, 1-3, 1-4, 1-1-1, 1-2-1, 1-3-1, 1-4-1, 1-3-2 and comparative example The cross section of the sponge-like metal foil of the carrier metal foil prepared according to 1 was observed with an electron microscope to measure the average diameter, roughness, specific surface area increase rate and porosity of the pores. The results are as shown in Table 1 below, in the case of Examples 1-1, 1-2, 1-3, 1-4 and Comparative Example 1 in which no needleless electroless copper plating layer or three-way metal plating layer was formed, The longer the copper plating time, the smaller the pore size, and the roughness, specific surface area increase rate, and porosity also changed. In addition, as can be seen in Table 2, Example 1-1-1, 1-2-1, 1-3-1, 1-4-1, 1-3-2 with a needleless electroless copper plating layer or a three-way metal plating layer formed In the case of, the pore size was slightly smaller, but the longer the electroless copper plating time was, the smaller the pore size was. The roughness, specific surface area increase rate, and porosity also changed.

5 is a sponge type metal foil planar electron micrograph (A) of a carrier metal foil prepared according to Example 1-3, and a sponge type metal foil having a needleless electroless copper foil coating layer prepared according to Example 1-3-1. A planar electron micrograph ((B)), a sponge-shaped metal foil planar electron micrograph (B) formed with rounded protrusions of ternary metals prepared according to Example 1-3-2 was presented.

Example 1-1 Example 1-2 Example 1-3 Example 1-4 Comparative Example 1 Average diameter of pores 34.7 micrometer 24.6 micrometer 12.8 micrometer 5.2 micrometer No pore Roughness Ra 0.65 micrometer 0.62 micrometer 0.44 micrometer 0.34 micrometer 0.28 micrometer Roughness Rz 1.62 micrometer 1.25 micrometer 1.19 micrometer 0.82 micrometer 0.55 micrometer Specific Surface Area Growth Rate 267% 272% 320% 326% 161% Porosity 26% 27% 30% 29% 4.7%

Example 1-1-1 Example 1-2-1 Example 1-3-1 Example 1-4-1 Example 1-3-2 Average diameter of pores 33.9 micrometers 23.1 micrometer 11.9 micrometer 3.2 micrometer 12.2 micrometer Roughness Ra 0.65 micrometer 0.60 micrometer 0.45 micrometer 0.33 micrometer 0.25 micrometer Roughness Rz 1.70 micrometer 1.26 micrometer 1.20 micrometer 1.01 micrometer 0.62 micrometer Specific Surface Area Growth Rate 312% 326% 350% 358% 366% Porosity 26% 27% 29% 28% 28%

Example 2-1 (Manufacture of Electromagnetic Wave Shielding Material)

The epoxy adhesive was apply | coated on the polyimide film, and the sponge type metal foil of carrier metal foil manufactured by Example 1-1 was adhere | attached. Subsequently, the carrier was removed, and a conductive adhesive consisting of 50% by weight of epoxy resin, 5% by weight of silver filler, and 45% by weight of polypyrrole was applied onto the sponge-shaped metal foil to proceed with curing. The average diameter of the silver filler was 10 micrometers.

Example 2-2 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-2 was used.

Example 2-3 (Production of Electromagnetic Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-3 was used.

Example 2-4 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-4 was used.

Example 2-1-1 (Manufacture of Electromagnetic Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-1-1 was used.

Example 2-2-1 (production of an electromagnetic shielding material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-2-1 was used.

Example 2-3-1 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-3-1 was used.

Example 2-4-1 (production of an electromagnetic shielding material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-4-1 was used.

Example 2-3-2 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil prepared in Example 1-3-2 was used.

Comparative Example 2-1 (Manufacture of Electromagnetic Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the carrier metal foil manufactured by Comparative Example 1 was used.

Comparative Example 2-2 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Example 2-1, except that the components of the conductive adhesive were 95% by weight of epoxy resin and 45% by weight of polypyrrole.

Comparative Example 2-3 (Manufacture of Electromagnetic Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Comparative Example 2-2, except that the carrier metal foil prepared in Example 2-2 was used.

Comparative Example 2-4 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Comparative Example 2-2, except that the carrier metal foil prepared in Example 2-3 was used.

Comparative Example 2-5 (Manufacture of Electromagnetic Wave Shielding Material)

An electromagnetic wave shielding material was manufactured in the same manner as in Comparative Example 2-2, except that the carrier metal foil prepared in Example 2-4 was used.

Evaluation Example 2 (Adhesion Test)

The adhesion of the prepared electromagnetic shielding material was applied to the test method specified in IPC-TM 650d. First, a test piece was fabricated by press laminating the prepared electromagnetic shielding material and the printed circuit board at 170 degrees for 1 hour. Then, the printed circuit board was fixed, and the insulation layer of the laminated electromagnetic shielding material was peeled off at 90 degrees to confirm the result value. At this time, the insulating layer width of the electromagnetic shielding material to confirm the adhesion was 1 cm. Example 2-1, 2-2, 2-3, 2-4, 2-1-1, 2-2-1, 2-3-1, 2-4-1, 2-3-2, comparative example The adhesion between polyimide and electrolytic copper foil was tested in the electromagnetic shielding material of 2-1. The results can be seen in Table 3 below. In the case of 2-1, 2-2, 2-3, 2-4 and Comparative Example 2-1, the electromagnetic shielding material in which the sponge-type electrolytic copper foil was formed was formed without the pores of electrolytic copper foil as in Comparative Example 2-1. It was evaluated that the adhesion was excellent compared to the.

In addition, as can be seen in Table 4, Example 2-1-1, 2-2-1, 2-3-1, 2-4-1, 2-3- with needle-shaped electroless copper plating layer or ternary metal plating layer formed In case 2 it can be seen that the adhesion is increased compared to when the needleless electroless copper plating layer or the three-way metal plating layer is not formed.

Example 2-1 Example 2-2 Example 2-3 Example 2-4 Comparative Example 2-1 Adhesion 0.84kgf / cm 0.79kgf / cm 0.89kgf / cm 0.59kgf / cm 0.24kgf / cm

Example 2-1-1 Example 2-2-1 Example 2-3-1 Example 2-4-1 Example
2-3-2 Adhesion 1.09kgf / cm 1.10kgf / cm 1.21kgf / cm 0.86kgf / cm 1.15kgf / cm

Evaluation Example 3 (observing electron microscope of pore site)

The pores of the sponge type metal foil were observed using the electron microscope about the electromagnetic wave shielding material of Example 2-1, 2-2, 2-3, 2-4, and the comparative example 2-2. Referring to FIG. 4, in Examples 2-1, 2-2 and Comparative Example 2-2 in which the average pore diameter of the sponge-type metal foil is relatively large, it can be confirmed that the conductive filler penetrates the pores and is filled, and the average pore diameter is In relatively small Examples 2-3 and 2-4, it was confirmed that the conductive filler was not filled in some pores and was empty. Although not observed separately by electron microscopic images, the pores of the sponge-type metal foil of the embodiments are filled with an epoxy resin and a conductive polymer, and Comparative Example 2-2 is filled with only an epoxy resin without a conductive polymer.

Evaluation Example 4 (Connection Resistance Measurement)

Example 2-1, 2-2, 2-3, 2-4, 2-1-1, 2-2-1, 2-3-1, 2-4-1, 2-3-2, comparative example In order to evaluate the connection resistance between the conductive adhesive layer and the electrolytic copper foil in the electromagnetic shielding materials of 2-1, 2-2, 2-3, 2-4, and 2-5, the electrical resistance of 10 regions of the conductive adhesive layer was measured. . Table 5 and Table 6 below show the average resistance value measured in each of the Examples and Comparative Examples and the resistance value measured the largest of the ten areas. Referring to Table 5, the average connection resistance of Examples 2-1, 2-2, 2-3, and 2-4 is smaller than that of Comparative Examples 2-2, 2-3, 2-4, and 2-5. Was measured. This is considered to be due to the conductive polymer contained in the conductive adhesive layer of the embodiments. The maximum connection resistance value showed a similar tendency, but in Comparative Examples 2-4 and 2-5, the difference between the average connection resistance value and the maximum connection resistance value was large. In the case of Comparative Examples 2-4 and 2-5, it is considered that the connection resistance is largely measured because a region in which the conductive filler is not filled is included in the relatively small pores. However, in Examples 2-3 and 2-4 including small pores in the same range, even if the pores are not filled with the conductive filler, the conductive polymer is filled, so it is considered that the variation between regions is not large.

In addition, referring to Table 6, Example 2-1-1, 2-2-1, 2-3-1, 2-4-1, 2-3-2 in which a needleless electroless copper plating layer or a three-way metal plating layer were formed It can be seen that in the case of having a needle-like electroless copper plating layer or a three-way metal plating layer has a similar average connection resistance value.

Example 2-1 Example 2-2 Example 2-3 Example 2-4 Comparative Example 2-1 Comparative Example 2-2 Comparative Example 2-3 Comparative Example 2-4 Comparative Example 2-5 Average connection resistance 0.034Ω 0.037Ω 0.035Ω 0.038Ω 0.033Ω 0.042 Ω 0.054Ω 0.067Ω 0.071Ω Connection resistance 0.041Ω 0.043Ω 0.044Ω 0.042 Ω 0.037Ω 0.048Ω 0.067Ω 0.089Ω 0.098Ω

Example 2-1-1 Example 2-2-1 Example 2-3-1 Example 2-4-1 Example 2-3-2 Average connection resistance 0.035Ω 0.034Ω 0.035Ω 0.037Ω 0.036Ω Connection resistance 0.041Ω 0.042 Ω 0.045Ω 0.042 Ω 0.044Ω

Evaluation example 4 (high temperature heat resistance measurement)

The surface state of the specimens prepared on the molten metal melted Sn-Ag-Cu series solder was observed. The solder melt temperature was 288 degrees, 300 degrees and 320 degrees, and the time was repeated three times for 10 seconds. The solder floating test of the insulating layer to which the electromagnetic shielding material manufactured according to Example 2-3, Example 2-3-1, or Example 2-3-2 was applied was performed by the above method. As a result of the test, in the insulating layer to which the electromagnetic wave shielding material prepared according to Examples 2-3-1 and 2-3-2 in which the needleless electroless copper plating layer or the three-way metal plating layer were formed, the appearance was improved at temperatures of 288 degrees and 320 degrees. Although no defect was found, in Example 2-3, where the needleless electroless copper plating layer or the three-way metal plating layer was not formed, a partial failure was found even at a temperature of 300 degrees.

Looking at the evaluation results for the above examples and comparative examples once again, (1) Examples 2-1 to 2-4 and Comparative Examples 2-2 to 2-5 containing a sponge-type metal foil, non-porous Adhesion was found to be superior to Comparative Example 2-1 including a metal film, and (2) Examples 2-1, 2-2, 2-3, and 2-4 including a conductive polymer in a conductive adhesive layer did not. It was shown that it was superior in the average value and the deviation of connection resistance than Example 2-2, 2-3, 2-4, 2-5. (3) Comparative Examples 2-4 and 2-5 in which the conductive filler was not filled in some of the pores due to the small pore size were found to have a large average connection resistance and deviation, but the conductive adhesive contained the conductive polymer. In Examples 2-3 and 2-4, the average connection resistance and the variation were not large due to the function of the conductive polymer. In addition, in the case of Examples 2-1-1, 2-2-1, 2-2-3, 2-2-4, and 2-3-2 in which the needleless electroless copper plating layer or the three-way metal plating layer were formed, the needleless electroless Adhesion was improved as compared with the case where the copper plating layer or the ternary metal plating layer was not formed, but the connection resistance was not significantly different.

The above description has been made using the embodiments of the technical idea of the present invention, and those skilled in the art to which the present invention pertains various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

101: polymer film 102: metal foil
103: release layer 104: electroless plating island
105a: porous electroplating layer 105b: dissimilar metal coating layer
110: sponge type metal foil layer 201: carrier
202: release layer 210: sponge type metal foil layer
301: insulating layer 302: adhesive layer
401: conductive adhesive layer

Claims (12)

In the electromagnetic shielding material laminated on the surface of the circuit board to shield the electromagnetic wave,
Sponge type metal foil composed of different metals; And
And a conductive adhesive layer bonded to the sponge metal foil.
The conductive adhesive layer includes a polymer resin, a conductive filler and a conductive polymer,
The sponge-type metal foil has a surface roughness of Ra in the range of 0.30 to 1.00 micrometers and Rz in the range of 0.50 to 2.00 micrometers. Electromagnetic shielding material for a circuit board. The method according to claim 1,
The content of the conductive adhesive layer is 30 to 60% by weight epoxy resin, urethane resin or acrylic resin, 1 to 10% by weight conductive filler and 10 to 50% by weight conductive polymer, the electromagnetic shielding material for a circuit board. delete The method according to claim 1,
Sponge-type metal foil made of the heterogeneous metal,
A sponge-like metal layer formed of a first metal and formed to include a plurality of open pores; And
And a coating layer formed entirely on the open surface of the sponge-type metal layer, the metal being different from the first metal. The method according to claim 4,
The coating layer is an electromagnetic shielding material for a circuit board, characterized in that it comprises a metal projection of the round projection. The method according to claim 4,
The coating layer is electromagnetic wave shielding material for a circuit board, characterized in that it comprises a needle-like metal projection. The method according to claim 1,
The conductive polymer is at least one selected from the group consisting of polypyrrole, polyaniline, polyacetylene, polythiophene electromagnetic shielding material for a circuit board. Providing a carrier;
Forming a release layer on the carrier;
Forming an electroless plating layer on the release layer;
Forming a porous electroplating layer on the electroless plating layer;
Forming a metal coating layer on the open surface of the porous electroplating layer;
Bonding the porous electroplating layer having the metal coating layer to the surface of the electromagnetic wave shielding object;
Removing the carrier and the release layer; And
And forming a conductive adhesive layer on the porous electroplating layer on which the metal coating layer is formed.
The porous electroplating layer has a surface roughness of Ra in the range of 0.30 to 1.00 micrometers, Rz in the range of 0.50 to 2.00 micrometers, and the specific surface area increase rate is 200 to 400% and the porosity is 5 to 40% compared to the nonporous metal layer. Method of manufacturing a shielding circuit board. The method according to claim 8,
The conductive adhesive layer is a manufacturing method of the electromagnetic shielding circuit board, characterized in that filled in the pores of the porous electroplating layer. The method according to claim 8,
The content of the conductive adhesive layer is 30 to 60% by weight epoxy resin, 1 to 10% by weight conductive filler and 10 to 50% by weight conductive polymer, the method of manufacturing a circuit board for electromagnetic shielding. The method according to claim 8,
The metal coating layer is a manufacturing method of the electromagnetic shielding circuit board, characterized in that it comprises a metal projection of the round projection form. The method according to claim 8,
The metal coating layer is a manufacturing method of the electromagnetic shielding circuit board, characterized in that it comprises a needle-like metal projection.

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