TWI699409B - Conductive composition for electromagnetic shielding, electromagnetic shielding layer formed of the same, circuit board laminate comprising the same, and method of forming electromagnetic shielding layer - Google Patents

Abstract

A conductive composition for electromagnetic shielding, an electromagnetic shielding layer formed of the same, a circuit board laminate comprising the same, and a method of forming the electromagnetic shielding layer are disclosed. The conductive composition for electromagnetic shielding includes a conductive powder, an epoxy resin, a curing agent, and a solvent, wherein the conductive powder includes a silver powder and nickel-coated carbon nanotubes.

Description

Conductive composition for electromagnetic shielding, electromagnetic shielding layer formed therefrom, circuit board laminate containing it, and method for forming electromagnetic shielding layer

The present invention relates to a conductive composition for electromagnetic shielding, an electromagnetic shielding layer formed therefrom, a circuit board laminate containing the same, and a method of forming an electromagnetic shielding layer.

Recently, with the rapid development of communication technology, high integration and high precision of electronic devices can be achieved. However, the high integration and high precision of electronic devices cause serious electromagnetic interference problems. For example, electromagnetic wave interference occurs between adjacent circuits closely arranged in a highly integrated electronic device, thereby causing failure of the electronic device, or electromagnetic waves emitted from the electronic device cause failure of other precision electronic devices adjacent to it.

In addition, due to the increasing controversy regarding the physical hazards of electromagnetic waves based on various studies, the studies have shown that electromagnetic waves emitted from electronic devices can weaken the immune function by increasing the temperature of biological tissue cells caused by thermal reactions, or Have adverse effects on the body (such as genetic changes, etc.), so electromagnetic shielding is urgently needed.

At present, electromagnetic shielding is achieved by electroless plating, vacuum deposition, conductive paste, etc. Plating (electroless plating) requires high costs and complicated manufacturing processes, and can cause environmental pollution. Vacuum deposition also requires high costs and has long-term reliability issues. Therefore, various studies have been conducted to develop a conductive paste that can be applied to the surface of a shielding target by spraying.

Typical conductive paste has the disadvantage of low shielding efficiency in the low frequency band of 1 GHz or less. Although various attempts have been made to solve this problem by providing conductive pastes containing various components, such conductive pastes have a problem of reducing overall electromagnetic shielding efficiency by increasing electrical resistance or deteriorating dispersibility.

Therefore, there is a need for conductive paste that has good electromagnetic shielding efficiency not only in a low frequency range but also in a wide electromagnetic wave range and is suitable for spray injection.

An example of the background art is disclosed in Korean Patent Registration No. 10-0871603.

An object of the present invention is to provide a conductive composition for electromagnetic shielding, an electromagnetic shielding layer formed therefrom, a circuit board laminate containing the same, and a method of forming an electromagnetic shielding layer. It can ensure good electromagnetic shielding efficiency in a low frequency range and a wide electromagnetic wave range.

Another object of the present invention is to provide a conductive composition for electromagnetic shielding, an electromagnetic shielding layer formed therefrom, a circuit board laminate containing the same, and a method of forming an electromagnetic shielding layer, the conductive composition having Good dispersibility to improve electromagnetic shielding efficiency and suitable for jet injection.

The above and other objects of the present invention can be achieved by the embodiments of the present invention described below.

One aspect of the present invention relates to a conductive composition for electromagnetic shielding.

In some embodiments, the conductive composition for electromagnetic shielding includes conductive powder, epoxy resin, curing agent and solvent, wherein the conductive powder includes silver powder and nickel-coated carbon nanotubes.

The silver powder and the nickel-coated carbon nanotube may be present in a weight ratio of 60:1 to 6000:1.

The nickel-coated carbon nanotube may be present in the conductive composition for electromagnetic shielding in an amount of 0.01% by weight (wt%) to 3% by weight.

The nickel-coated carbon nanotube may contain 5% to 50% by weight nickel.

The carbon nanotube may have an average particle size of 0.5 to 20 microns and an average length of 1 to 200 microns.

The silver powder may be present in the conductive composition for electromagnetic shielding in an amount of 20% to 80% by weight.

The conductive powder may further include at least one of gold (Au), aluminum (Al), palladium (Pd), nickel (Ni), platinum (Pt), and copper (Cu).

Another aspect of the present invention relates to an electromagnetic shielding layer.

In some embodiments, the electromagnetic shielding layer may be formed of a conductive composition for electromagnetic shielding.

The electromagnetic shielding layer may have an electromagnetic shielding rate of 50 decibels (dB) to 100 decibels in a frequency range of 30 MHz to 1.5 GHz.

When measured at a thickness of 10 microns, the electromagnetic shielding layer may have a sheet resistance of 50 milliohms/□ or less than 50 milliohms/□.

Another aspect of the present invention relates to a circuit board laminate.

In some embodiments, the circuit board laminate may include an encapsulation layer formed on the circuit board; and an electromagnetic shielding layer formed on the encapsulation layer.

Another aspect of the present invention relates to a method of forming an electromagnetic shielding layer.

In some embodiments, the method of forming an electromagnetic shielding layer may include: injecting a conductive composition for electromagnetic shielding into a shielding target to be shielded by the electromagnetic shielding layer, and then curing the conductive composition.

The curing may be performed at a temperature of 100°C to 250°C.

The present invention provides a conductive composition for electromagnetic shielding, an electromagnetic shielding layer formed therefrom, a circuit board laminate containing the same, and a method for forming an electromagnetic shielding layer. The conductive composition is not only in the low frequency range Moreover, it can ensure good electromagnetic shielding efficiency in a wide electromagnetic wave range, has good dispersibility to improve electromagnetic shielding efficiency, and is suitable for injection injection.

Hereinafter, embodiments of the present invention will be explained in detail. It should be understood that the present invention is not limited to the following embodiments, but can be implemented in different ways.

It should be understood that the following embodiments are provided to complete the disclosure and enable those skilled in the art to thoroughly understand the present invention. In addition, it should be understood that those skilled in the art can make various modifications, changes, and alterations without departing from the spirit and scope of the present invention.

Unless the context clearly indicates otherwise, the singular forms "一 (a, an)" and "the (the)" used herein are intended to also include the plural forms. In addition, when the term "comprises, comprising, includes, and/or including" is used in this specification, it specifically indicates the existence of the features, integers, steps, operations, elements, components, and/or groups thereof, However, the existence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof is not excluded.

As used herein, "X to Y" representing a specific value range means "greater than or equal to X and less than or equal to Y". Conductive composition for electromagnetic shielding

The conductive composition for electromagnetic shielding according to an embodiment of the present invention includes conductive powder, epoxy resin, curing agent and solvent. (A) Conductive powder

In one embodiment, the conductive powder includes silver powder and nickel-coated carbon nanotubes.

The silver powder is used to impart conductivity to the shielding layer and may have an average particle diameter D _{50 of} 20 micrometers or less, for example, 0.1 micrometers to 20 micrometers, specifically 0.1 micrometers to 10 micrometers. Within this average particle size range, the conductive composition has a good balance between electrical resistance and durability. In addition, silver powder can be provided in a flake shape to improve electrical resistance and electromagnetic shielding efficiency.

In the conductive composition for electromagnetic shielding, the silver powder may be present in an amount of 20% to 80% by weight, specifically 25% to 70% by weight, more specifically 30% to 70% by weight.

The nickel-coated carbon nanotube contained in the conductive composition for electromagnetic shielding can further improve the electromagnetic shielding efficiency, especially in the low frequency range (for example, 1 GHz or less than 1 GHz). When the conductive composition contains only nickel powder, the conductive composition has high electrical resistance, thereby causing deterioration of the overall electromagnetic shielding efficiency in a wide frequency range, and when the conductive composition contains carbon nanotubes that are not coated with nickel, The improvement of the electromagnetic shielding efficiency of the conductive composition in the low frequency range is not significant. In addition, the conductive composition prepared using nickel-coated graphite has the problems of degraded dispersibility and high resistance, and the conductive composition prepared using graphene and carbon fiber cannot improve the electromagnetic shielding efficiency.

The conductive composition for electromagnetic shielding according to the present invention includes nickel-coated carbon nanotubes, thereby improving the electromagnetic shielding efficiency while maintaining the overall electromagnetic shielding efficiency in a wide frequency range.

The nickel-coated carbon nanotube may contain 5 to 50% by weight of nickel, specifically 10 to 50% by weight of nickel. Within this content range of nickel, the conductive composition for electromagnetic shielding can improve the electromagnetic shielding efficiency while maintaining the overall electromagnetic shielding efficiency in a wide frequency range.

The carbon nanotube may have an average particle size of 0.5 to 20 microns, specifically 1 to 10 microns, and an average length of 1 to 200 microns, specifically 5 to 100 microns. Within these ranges, the nickel-coated carbon nanotubes may have a reduced particle size or a reduced length after dispersion. Within this particle size range, carbon nanotubes can have good dispersibility and are suitable for jet injection.

The carbon nanotube may include at least one of a single-walled carbon nanotube (SWCNT) and a multi-walled carbon nanotube (MWCNT).

It can be prepared by mixing single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) with a weight ratio of 1:1000 to 1:10, specifically 1:100 to 1:10 Carbon nanotubes. In this case, carbon nanotubes have good dispersibility and low electrical resistance.

In the conductive composition for electromagnetic shielding, there may be an amount of 0.01% to 3% by weight, specifically 0.01% to 2% by weight, more specifically 0.05% to 1% by weight of nickel-coated Carbon nanotubes. Within this content range, the conductive composition used for electromagnetic shielding can improve the electromagnetic shielding efficiency in the low frequency range.

Carbon nanotubes coated with silver powder and nickel can be 60:1 to 6,000:1, specifically 90:1 to 3,000:1, more specifically 90:1 to 3000:1, 90:1 to 1000:1 or A weight ratio of 100:1 to 1000:1 exists. Within this weight ratio range, the conductive composition used for electromagnetic shielding can improve electromagnetic shielding efficiency in low frequency ranges while maintaining electromagnetic shielding efficiency in other frequency ranges.

In another embodiment, the conductive powder may further include at least one of gold (Au), aluminum (Al), palladium (Pd), nickel (Ni), platinum (Pt), and copper (Cu) to improve its properties . In the conductive composition for electromagnetic shielding, the metal powder additionally added to the conductive powder may be 0.1% to 50% by weight, specifically 1% to 40% by weight, more specifically 10% to 30% by weight The amount exists. (B) Epoxy resin

The epoxy resin enables the conductive composition to form an electromagnetic shielding layer. In addition, epoxy resin can impart adhesion strength to the shielding target shielded by the electromagnetic shielding layer.

The epoxy resin may include at least one of the following: butyl glycidyl ether type epoxy resin, cresyl glycidyl ether type epoxy resin, phenyl glycidyl ether type epoxy resin, nonylphenyl glycidyl ether type Epoxy resin, butyl phenyl glycidyl ether type epoxy resin, 2-ethylhexyl glycidyl ether type epoxy resin, bisphenol F diglycidyl ether type epoxy resin, bisphenol A diglycidyl ether type ring Oxygen resin, 1,6-hexanediol diglycidyl ether type epoxy resin, 1,4-butanediol diglycidyl ether type epoxy resin, alicyclic diglycidyl ether type epoxy resin, naphthalene type ring Oxygen resin, dicyclopentadiene epoxy resin, silicone modified epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A modified phenol novolac type epoxy Resin, epoxy resin containing liquid bismaleimide, trimethylolpropane triglycidyl ether type epoxy resin, polyalicyclic epoxy resin, triglycidyl isocyanurate epoxy resin, additive Diglycidyl ether type epoxy resin of aminophenol, N,N,N',N'-tetraglycidyl-4,4'-methylene bisaniline resin, polyoxetane resin, tri- (Hydroxyphenyl) ethane glycidyl ether type epoxy resin, solid cresol novolac type epoxy resin, and bismaleimide epoxy resin.

In one embodiment, the epoxy resin may include a first epoxy resin having a weight average molecular weight (Mw) of 1,000 to 100,000 and a second epoxy resin having a weight average molecular weight (Mw) of 10 to less than 1,000.

In this case, the electromagnetic shielding film formed of the conductive composition may have improved adhesion to the shielding target to be shielded by the electromagnetic shielding film and may exhibit good durability.

The first epoxy resin and the second epoxy resin may be present in a weight ratio of 0.25:1 to 4:1, specifically 0.4:1 to 2.5:1. Within this range, the conductive composition can optimize the adhesive strength of the electromagnetic shielding film.

In the conductive composition for electromagnetic shielding, the epoxy resin may be present in an amount of 1% to 35% by weight, specifically 3% to 32.5% by weight. Within this content range, the electromagnetic shielding film formed of the conductive composition can exhibit good adhesion strength and durability. (C) Curing agent

The curing agent may be selected from any typical curing agent as long as the curing agent enables the epoxy resin to be completely cured. Specifically, the curing agent may include a melamine compound, an imidazole compound, and a triphenylphosphine compound. These curing agents can be selected from commercially available products, for example, for imidazole compounds, PN-23, PN-40 (Ajinomoto Precision Technology Co., Ltd.), 2P4MZ, 2MA-OK, 2MAOK-PW, 2P4MHZ, 2MZ-H (Shikoku Chemical Co., Ltd) and TPP-K and TPP-MK (Hokko Chemical Industry Co., Ltd.). These curing agents can be used alone or in combination.

In the conductive composition for electromagnetic shielding, the curing agent may be present in an amount of 0.01% to 5% by weight, specifically 0.1% to 5% by weight. Within this content range, the curing agent enables the epoxy resin to be fully crosslinked, and can improve the thermal resistance and storage stability. (D) Solvent

The solvent may include at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol , 2-pentanol, 3-pentanol, 3-methyl-1-butanol, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol, diethylene glycol, triethylene glycol, glycerin , 2-methoxyethanol, 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol and 2-(2-methoxyethoxy)ethanol.

In the conductive composition for electromagnetic shielding, there may be a balance, specifically 5 to 60 wt%, specifically 20 to 60 wt% of solvent. For example, there may be a balance of solvent in addition to the amounts of other components.

The conductive composition used for electromagnetic shielding may further include a binder resin. The binder resin may include at least one of epoxy resin, acrylic resin, urethane resin, and cellulose resin. In the conductive composition for electromagnetic shielding, the binder resin may be present in an amount of 1% to 20% by weight, specifically 1% to 10% by weight.

In addition to the above-mentioned components, the conductive composition according to the present invention may further include typical additives to improve fluidity, process characteristics and stability. The additives may include dispersants, thixotropic agents, plasticizers, viscosity stabilizers, defoamers, pigments, ultraviolet (UV) stabilizers, antioxidants, and coupling agents. These additives can be used alone or in combination. In the conductive composition for electromagnetic shielding, the additive may be present in an amount of 0.01% to 5% by weight, but it is not limited to this. Electromagnetic shielding layer

The electromagnetic shielding layer according to an embodiment of the present invention may be formed of a conductive composition for electromagnetic shielding. Specifically, the electromagnetic shielding layer according to the embodiment may be formed by injecting a conductive composition into a shielding target using a sprayer, and then curing at 100°C to 250°C or 150°C to 250°C for 1 minute to 60 minutes. In addition, the injection amount of the conductive composition can be adjusted according to the required thickness.

The electromagnetic shielding layer may have an electromagnetic shielding rate of 50 decibels to 100 decibels, specifically 60 decibels to 90 decibels in the frequency range of 30 MHz to 1.5 GHz. In this case, the electromagnetic shielding layer has good electromagnetic shielding efficiency in the low frequency range (for example, 1 GHz or less than 1 GHz).

When measured at a thickness of 10 microns, the electromagnetic shielding layer may have 50 milliohms/□ or less than 50 milliohms/□, for example, 10 milliohms/□ to 50 milliohms/□, specifically 10 milliohms/□ to Sheet resistance of 40 milliohms/□. The electromagnetic shielding layer may have a thickness of 10 microns or less, for example, 1 to 10 microns, specifically 3 to 8 microns. Within this thickness range, the electromagnetic shielding layer may have 50 milliohms/□ or less than 50 milliohms/□, for example, 10 milliohms/□ to 50 milliohms/□, specifically 10 milliohms/□ to 40 milliohms/□ □The sheet resistance. Within this sheet resistance range, the electromagnetic shielding layer shows good shielding efficiency in a wide frequency range.

Fig. 1 is a schematic diagram of a circuit board laminate according to an embodiment of the present invention. 1, a circuit board laminate according to an embodiment of the present invention includes a circuit board 10; an encapsulation layer 20 formed on the circuit board 10; and an electromagnetic shielding layer 30 formed on the encapsulation layer 20. The encapsulation layer may be formed of any epoxy resin composition used to encapsulate semiconductor devices without limitation. For example, the encapsulation layer may be formed of a composition including epoxy resin, curing agent, curing accelerator, inorganic filler, and the like.

The electromagnetic shielding layer 30 may be formed on at least one surface of the circuit board 10. Specifically, the electromagnetic shielding layer may include an electromagnetic shielding layer according to another aspect of the present invention. For example, the electromagnetic shielding layer can be formed by injecting a conductive composition for electromagnetic shielding into the circuit board using a sprayer. The electromagnetic shielding layer according to the present invention not only has good electromagnetic shielding efficiency in a low frequency range and a wide electromagnetic range, but also enables conductive particles to have good dispersibility, thereby improving electromagnetic shielding efficiency.

The circuit board may include a printed circuit board or a flexible circuit board. Method of forming electromagnetic shielding layer

A method of forming an electromagnetic shielding layer according to an embodiment of the present invention includes: injecting a conductive composition for electromagnetic shielding into a shielding target to be shielded by the electromagnetic shielding layer, and then curing the conductive composition.

Injection can be performed by jet injection. Jet injection has advantages such as low cost, simple process and high productivity.

The conductive composition for electromagnetic shielding according to the present invention has a viscosity suitable for spray injection and ensures good dispersion of conductive powder during injection.

The curing may be performed at 100°C to 250°C, specifically 110°C to 250°C. Specifically, curing can be performed in an oven at this curing temperature for 30 minutes or more.

Next, the present invention will be explained in more detail with reference to some examples. However, it should be noted that these examples are provided for illustration only and should not be seen as limiting the present invention in any way. A description of details that are obvious to those familiar with this technology will be omitted. Instance

The details of the components used in the examples and comparative examples are as follows. (A) Conductive powder (a-1) Silver powder: SF29 (D ₅₀ : 4.2 microns, AMES Co., Ltd.) (a-2) Nickel-coated carbon nanotubes (nickel content : 20% by weight, average particle size: 13 microns, average length: 20 microns, Kumho Petrochemical Co., Ltd.) (a-3) Nickel powder: T255 (Vale Inco. )) (a-4) Carbon nanotubes without nickel coating: K-North (Nanos) 100P, (Kumho Petrochemical Co., Ltd.) (a-5) Graphite: MSG-15P (BTR New Energy Materials Co., Ltd.) (BTR New Energy Materials Inc.)) (a-6) Graphene: Multilayer graphene ink in N-methylpyrrolidone (Mexplorer Co., Ltd.) (B) Ring Oxygen resin (b-1) epoxy resin: E4275 (Mw = 60,000, Mitsubishi Chemical Co., Ltd.) (b-2) epoxy resin: YD-115CA (Mw = 400, Guodu (Kukdo Chemical Co., Ltd.) (C) Curing agent: 2P4MHZ-PW (Shikoku Chemical Co., Ltd.) (D) Solvent (d-1) Propylene glycol monomethyl ether acetate (Sanchun Chemical Co., Ltd.) (Samchun Chemical Co., Ltd.)) (d-2) Dipropylene glycol monomethyl ether (Sanchun Chemical Co., Ltd.) Examples 1 to 2 and Comparative Examples 1 to 4

The above-mentioned components were uniformly mixed in the amount listed in Table 1 in a mixer. Then, a sprayer was used to inject the mixture onto an epoxy molding compound (EMC) and cured at 200° C. for 10 minutes to form an electromagnetic shielding layer with a thickness of 10 microns. <Table 1>

Each of the electromagnetic shielding layers was evaluated for the following properties, and the evaluation results are shown in Table 2. Property evaluation

(1) Sheet resistance (unit: milliohm/□): The sheet resistance at a thickness of 10 microns was measured by the 4-point probe method, and the measurement results are shown in Table 2.

(2) Electromagnetic shielding rate (unit: decibels (dB)): According to Korea Standard (KS) C 0304:1998, the electromagnetic shielding rate was measured using network analyzer E5071C and shielding effect test fixture EM-2107A. Table 2

As shown in Table 2, the electromagnetic shielding layer formed of the conductive composition for electromagnetic shielding according to the present invention has good resistance and is in a wide frequency range, especially in a low frequency range (for example, 1 GHz or less than 1 GHz). ) Has further improved electromagnetic shielding efficiency.

In contrast, the electromagnetic shielding layer formed of the conductive composition of Comparative Example 1 to Comparative Example 4 prepared without using nickel-coated carbon nanotubes has reduced electromagnetic shielding efficiency in the overall frequency range (30 MHz to 1 GHz) .

Specifically, the electromagnetic shielding layer formed of the conductive composition of Comparative Example 1 containing only nickel powder suffers from a decrease in the electromagnetic shielding rate in the overall frequency range (30 MHz to 1 GHz) due to an increase in electrical resistance, and is not used The electromagnetic shielding layer formed by the conductive composition of Comparative Example 2 prepared from nickel-coated carbon nanotubes showed an insignificant increase in electromagnetic shielding efficiency in the low frequency range.

In addition, the electromagnetic shielding layer formed of the conductive composition of Comparative Example 3 prepared using graphite suffers from deterioration in dispersibility and has high resistance to reduce electromagnetic shielding efficiency, and is formed of the conductive composition of Comparative Example 4 prepared using graphene The electromagnetic shielding layer showed an insignificant increase in electromagnetic shielding efficiency.

Although some embodiments have been described herein with reference to the drawings and tables, the present invention is not limited by these embodiments and can be achieved in various ways. In addition, those skilled in the art should understand that various modifications, variations, and alterations can be made without departing from the spirit and scope of the present invention. Therefore, these embodiments are given for illustration only and should not be regarded as limiting the present invention in any way.

10‧‧‧Circuit board 20‧‧‧Encapsulation layer 30‧‧‧Electromagnetic shielding layer

Fig. 1 is a schematic diagram of a circuit board laminate according to an embodiment of the present invention.

10‧‧‧Circuit board

20‧‧‧Encapsulation layer

30‧‧‧Electromagnetic shielding layer

Claims (13)

A conductive composition for electromagnetic shielding, comprising: conductive powder; epoxy resin; curing agent; and solvent, wherein the conductive powder includes silver powder and nickel-coated carbon nanotubes. The conductive composition for electromagnetic shielding according to the first item of the patent application, wherein the silver powder and the nickel-coated carbon nanotubes are present in a weight ratio of 60:1 to 6000:1. The conductive composition for electromagnetic shielding as described in the first item of the scope of patent application, wherein the nickel-coated carbon is present in the conductive composition for electromagnetic shielding in an amount of 0.01% to 3% by weight Nanotube. The conductive composition for electromagnetic shielding according to the first item of the scope of patent application, wherein the nickel-coated carbon nanotube contains 5 to 50% by weight of nickel. The conductive composition for electromagnetic shielding described in the first item of the patent application, wherein the carbon nanotubes have an average particle size of 0.5 to 20 microns and an average length of 1 to 200 microns. The conductive composition for electromagnetic shielding according to the first item of the scope of patent application, wherein the silver powder is present in the conductive composition for electromagnetic shielding in an amount of 20% to 80% by weight. The conductive composition for electromagnetic shielding as described in item 1 of the scope of patent application, wherein the conductive powder includes gold (Au), aluminum (Al), palladium (Pd), nickel (Ni), platinum (Pt) and At least one of copper (Cu). An electromagnetic shielding layer is formed of the conductive composition for electromagnetic shielding as described in any one of items 1 to 7 of the scope of patent application. The electromagnetic shielding layer according to item 8 of the scope of patent application, wherein the electromagnetic shielding layer has an electromagnetic shielding rate of 50 decibels to 100 decibels in the frequency range of 30 MHz to 1.5 GHz. The electromagnetic shielding layer according to item 8 of the scope of patent application, wherein when measured at a thickness of 10 microns, the electromagnetic shielding layer has a sheet resistance of 50 milliohms/□ or less than 50 milliohms/□. A circuit board laminate includes: an encapsulation layer formed on a circuit board; and an electromagnetic shielding layer as described in item 8 of the scope of patent application, formed on the encapsulation layer. A method for forming an electromagnetic shielding layer includes: injecting the conductive composition for electromagnetic shielding as described in any one of items 1 to 7 of the scope of patent application into a shielding target to be shielded by the electromagnetic shielding layer, Then, the conductive composition is cured. The method described in item 12 of the scope of patent application, wherein the curing is performed at a temperature of 100°C to 250°C.

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