TW202146507A - Electroconductive composition - Google Patents

Abstract

Provided is an electroconductive composition that has good shielding properties against electromagnetic waves of 100 MHz to 1 GHz, and excellent filling properties for a trench portion formed in a molded resin. An electroconductive composition comprising 400-600 parts by mass of an electroconductive filler with respect to 100 parts by mass of an epoxy resin containing 5-20 parts by mass of a dimer acid-type epoxy resin, wherein the electroconductive filler contains an electroconductive filler (A) having an average particle size (D50) of 5-8 [mu]m as measured by a laser diffraction scattering-type particle size distribution measurement technique, and an electroconductive filler (B) having an average particle size (D50) of 2-3 [mu]m, and the content ratio ((A):(B)) by mass of the electroconductive filler (A) and the electroconductive filler (B) is 97:3 to 50:50.

Description

conductive composition

The present invention relates to a conductive composition having excellent shielding properties.

In electronic devices such as mobile phones and tablet terminals, a system-in-package (SIP) is being pursued, which is based on the requirements of miniaturization and high functionality, and multiple semiconductor chips are integrated into one package as a system. Play a role.

This system-in-package has been increasing the assembly density of electronic components in order to take into account both the miniaturization, weight reduction and high functionality of electronic equipment. However, if the packing density is increased, the number of electronic components affected by electromagnetic waves will also increase, which may cause functional errors due to interference between adjacent electronic components.

As a method of preventing interference between electronic components, there is a known method in which a groove (groove) is formed between electronic components sealed with a mold resin, and the groove is buried with a conductive paste, so as to prevent the interference between electronic components. A shield layer (so-called compartment shield) is formed between the parts and the electronic parts.

In order to obtain sufficient shielding properties by the above method, it is necessary to fill the bottom surface of the groove with the conductive paste, and it is necessary to add a solvent to the conductive paste to reduce the viscosity of the conductive paste.

However, in the case where the viscosity of the conductive paste has been reduced by adding a solvent, when the conductive paste is thermally cured, the solvent may volatilize, and voids may be generated in the cured material of the conductive paste ( Bubble). If voids are formed in the cured product, there is a possibility that electromagnetic waves cannot be sufficiently shielded.

Further, as a method of reducing the viscosity of the conductive paste, in addition to adding a solvent, it is considered to reduce the content of the conductive filler, but if the content of the conductive filler is reduced, the shielding properties tend to deteriorate. On the other hand, when the content of the conductive filler is increased in order to improve the shielding properties, the fillability of the groove portion formed in the mold resin tends to deteriorate. That is, the shielding characteristics and the fillability to the grooves are trade-off characteristics, and it is required to improve these characteristics in a balanced manner.

prior art literature Patent Literature Patent Document 1: Japanese Patent Laid-Open No. 2004-55543 Patent Document 2: Japanese Patent Laid-Open No. 2016-126878 Patent Document 3: Japanese Patent No. 4037619

Summary of Invention The problem to be solved by the invention The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide a conductive composition which has good shielding properties against electromagnetic waves of 100 MHz to 1 GHz, and which is excellent in filling properties of grooves formed in a mold resin.

In addition, although Patent Documents 1 to 3 describe conductive pastes, they do not describe shielding properties and fillability of grooves formed in mold resins.

means of solving problems The conductive composition of the present invention contains 400 to 600 parts by mass of a conductive filler with respect to 100 parts by mass of the epoxy resin containing 5 to 20 parts by mass of the dimer acid-type epoxy resin; The conductive fillers contain: conductive fillers (A) with an average particle size (D50) of 5~8 μm measured by laser diffraction scattering particle size distribution measurement method, and conductive fillers (A) with an average particle size (D50) of 2~3 μm ( B), and the content ratio ((A):(B)) of the said conductive filler (A) and the said conductive filler (B) is 97:3~50:50 in mass ratio.

Among them, the above-mentioned dimer acid type epoxy resin can be a glycidyl modified compound of dimer acid.

Among them, the above epoxy resin may contain a glycidylamine type epoxy resin and a glycidyl ether type epoxy resin.

effect of invention According to the electroconductive composition of the present invention, it is excellent in filling properties of the grooves formed in the mold resin, and can prevent interference between electronic components due to electromagnetic waves of 100 MHz to 1 GHz.

As described above, the conductive composition of the present invention is set to contain 400 to 600 parts by mass of conductive filler with respect to 100 parts by mass of epoxy resin containing 5 to 20 parts by mass of dimer acid-type epoxy resin; The conductive fillers contain: conductive fillers (A) with an average particle size (D50) of 5~8 μm measured by laser diffraction scattering particle size distribution measurement method, and conductive fillers (A) with an average particle size (D50) of 2~3 μm ( B), and the content ratio ((A):(B)) of the conductive filler (A) and the conductive filler (B) is 97:3 to 50:50 in terms of mass ratio.

Although the use of this conductive composition is not particularly limited, it is suitably used in a system-in-package as a shielding layer formed between electronic parts sealed with a molded resin.

Epoxy resins other than dimer acid-type epoxy resins may be those having one or more epoxy groups in the molecule, and two or more of them may be used in combination. Specific examples include: bisphenol A type epoxy resin, brominated epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, alicyclic epoxy resin, glycidylamine type epoxy resin, Glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, heterocyclic epoxy resins, etc., among them, glycidylamine type epoxy resins, glycidyl Ether-type epoxy resins are preferred.

The epoxy equivalent of the epoxy resin other than the dimer acid type epoxy resin is not particularly limited, but is preferably 1500 g/eq or less, more preferably 20 to 1000 g/eq. When the epoxy equivalent is within the above range, it is easy to obtain a conductive composition having a good balance of heat resistance, viscosity, and adhesion.

Dimer acid-type epoxy resins are epoxy resins with one or more epoxy groups in the molecule and those that have been modified by dimer acid, such as glycidyl acid of dimer acid. As an example of a modified compound etc., you may use 2 or more types together. As the resin, for example, those represented by the following general formulae (1) and (2) can be used.

[Chemical formula 1]

In formulas (1) and (2), n1 to n5 each independently represent an integer of 3 to 9.

n1 represents an integer of 3 to 9, preferably an integer of 4 to 8, more preferably 5 to 7, particularly preferably 7. n2 represents an integer of 3 to 9, preferably an integer of 5 to 9, more preferably 7 or 8, particularly preferably 7. n3 represents an integer of 3 to 9, preferably an integer of 4 to 8, more preferably 6 or 7, particularly preferably 6. n4 represents an integer from 3 to 9. n5 represents an integer of 3 to 9, preferably an integer of 4 to 8, more preferably 5 or 6, particularly preferably 5.

By containing the dimer acid-type epoxy resin, the viscosity and thixotropic index (TI value) of the conductive composition tend to be low, and it is easy to obtain excellent filling properties for the grooves formed in the molding resin.

Although the epoxy equivalent of the dimer acid-type epoxy resin is not particularly limited, it is preferably 80 to 1500 g/eq, more preferably 200 to 1000 g/eq. When the epoxy equivalent is within the above range, it is easy to obtain a conductive composition having a good balance of heat resistance, viscosity, and adhesion.

The conductive filler (A) has an average particle size of 5 to 8 μm, has good dispersibility, can prevent aggregation, and has good connectivity and shielding properties with the ground circuit of the package.

The conductive filler (B) can fill the gap between conductive fillers with an average particle size of 5 to 8 μm with an average particle size of 2 to 3 μm, thereby improving the shielding performance against electromagnetic waves of 100 MHz to 1 GHz and obtaining low viscosity. the conductive composition.

The content of the conductive filler is not particularly limited as long as it is 400 to 600 parts by mass with respect to 100 parts by mass of the epoxy resin, but it is preferably 450 to 550 parts by mass. Within the above range, it is easy to obtain a conductive composition having shielding properties and excellent fillability to the grooves formed in the mold resin.

The content ratio ((A):(B)) of the conductive filler (A) and the conductive filler (B) is not particularly limited as long as the mass ratio is 97:3 to 50:50, but is preferably 95: 5~70:30.

The conductive filler (A) and the conductive filler (B) are preferably copper powder, silver powder, gold powder, silver-coated copper powder or silver-coated copper alloy powder, and one of them may be used alone or two of them may be used in combination As mentioned above, from the viewpoint of cost reduction, copper powder, silver-coated copper powder, or silver-coated copper alloy powder is more preferable.

The silver-coated copper powder has copper powder and a silver layer or a silver-containing layer that coats at least a part of the copper powder particles, and the silver-coated copper alloy powder has copper alloy powder and a silver layer that coats at least a part of the copper alloy particles or those with silver layers. The copper alloy particles are, for example, the content of nickel is 0.5 to 20 mass %, the content of zinc is 1 to 20 mass %, the remainder is composed of copper, and the remaining copper may contain unavoidable impurities. By using the copper alloy particles having the silver coating layer in this way, a shielding package excellent in shielding properties and discoloration resistance can be easily obtained.

Examples of the shape of the conductive filler (A) include platelet-shaped (scaly), dendritic, spherical, fibrous, and indeterminate (polyhedral), but a lower resistance value and better shielding properties can be obtained by From the viewpoint of a higher shielding layer and improved fillability, spherical shape is preferable.

Moreover, when the conductive filler (A) is spherical, the tap density (tap density) of the conductive filler (A) is preferably 3.5 to 7.0 g/cm ³ . When the tap density is within the above range, the conductivity of the shielding layer tends to be better.

Examples of the shape of the conductive filler (B) include flakes (scaly), dendritic, spherical, fibrous, and indefinite (polyhedron), but lower resistance and shielding properties are obtained by From the viewpoint of a higher shielding layer and improved fillability, spherical shape is preferable.

Moreover, when the conductive filler (B) is spherical, the tap density of the conductive filler (B) is preferably 4.0 to 7.0 g/cm ³ . When the tap density is within the above range, the conductivity of the shielding layer tends to be better.

An epoxy resin hardener can be used for the electroconductive composition of this invention. As an epoxy resin hardener, a phenol type hardener, an imidazole type hardener, an amine type hardener, a cation type hardener, etc. are mentioned. These may be used individually by 1 type, and may use 2 or more types together.

As a phenol type hardening|curing agent, a phenol novolak, a naphthol type compound, etc. are mentioned, for example.

Examples of imidazole-based curing agents include imidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and 1-benzyl yl-2-phenylimidazole, 2-ethyl-4-methyl-imidazole, 1-cyanoethyl-2-undecylimidazole.

Examples of the amine-based curing agent include aliphatic polyamines such as diethylenetriamine and triethylenetetramine; aromatic polyamines such as m-phenylenediamine, diaminodiphenylmethane, and diaminediphenylene, and the like. .

Examples of the cationic curing agent include onium-based compounds represented by the following: amine salts of boron trifluoride, p-methoxybenzenediazonium hexafluorophosphate, diphenyl iodonium hexafluorophosphate, triphenyl base perionium, tetra-n-butylphosphonium tetraphenyl borate, tetra-n-butylphosphonium-o,o-diethyldithiophosphate, etc.

The content of the hardener is preferably 0.3 to 40 parts by mass, more preferably 0.5 to 35 parts by mass, relative to 100 parts by mass of the epoxy resin. When the content of the curing agent is 0.3 parts by mass or more, the conductive composition is sufficiently cured, the conductivity becomes good, and a shielding layer with excellent shielding effect is easily obtained, and when the content of the curing agent is 40 parts by mass or less, it is easy to store Conductive composition with excellent stability.

Known additives such as defoaming agents, thickeners, adhesives, fillers, flame retardants, and colorants can be added to the conductive composition of the present invention within a range that does not impair the purpose of the invention.

In order to enable the conductive composition to be coated on the groove of the package by dispensing and vacuum printing, the conductive composition of the present invention is preferably one with low viscosity and low thixotropic index (TI value). .

Here, the so-called dispensing method is a method in which the conductive composition is extruded from the tip of a syringe-shaped nozzle and applied. In addition, the so-called vacuum printing method is: as stencil printing, using a screen with chemical fibers spread on a plate, and optically producing a screen film on the screen to block the meshes other than the necessary lines. The printing plate is a method of printing on the printing surface of the object to be printed under the plate by rubbing ink through the holes of the plate film under vacuum.

The viscosity of the conductive composition of the present invention should be appropriately adjusted according to the application and the machine used for coating. Although it is not particularly limited, in general terms, the temperature of the conductive composition is preferably 25°C. 600 dPa·s or less, more preferably 500 dPa·s or less. If it is less than 600 dPa·s, the nozzle clogging in the dispensing method and the clogging of the mesh in the vacuum printing method are not easy to occur, and it is easy to obtain excellent filling properties for the grooves. The measurement method of viscosity can follow JISK7117-1, and it can measure at 10 rpm with the rotor No. 7 with a single cylindrical rotational viscometer (so-called B type or BH type viscometer). In addition, as long as it is a viscosity that can be measured by a single cylindrical rotational viscometer, it does not matter how low it is.

The thixotropic index (TI value) of the conductive composition of the present invention should be appropriately adjusted according to the application and the machine used for coating. Although not particularly limited, it is preferably 4.5 or less as a general standard. When the TI value is 4.5 or less, it is easy to obtain excellent fillability to the groove portion, and the surface is easy to become smooth when applied by a vacuum printing method, and bumps are not easily formed. In this way, a low profile of the system-in-package can be achieved, and space can be effectively utilized in the device in which the system-in-package is assembled. Here, the TI value can be calculated by the following formula. TI value=(viscosity measured at 2rpm)/(viscosity measured at 20rpm)

The conductive composition of the present invention preferably contains no solvent from the viewpoint of preventing generation of voids.

Example Hereinafter, the content of the present invention will be described in detail based on examples, but the present invention is not limited to the following. In addition, the following "part" or "%" shall be regarded as the quality standard unless otherwise stated.

Examples and Comparative Examples With respect to 100 parts by mass of the epoxy resin shown below, a conductive filler and a curing agent were blended and mixed at the ratios described in Tables 1 to 4 to obtain a conductive composition. The details of each component used are as follows.

・Epoxy resin (a): Epoxypropylamine type epoxy resin, "EP-3905S" manufactured by ADEKA, epoxy equivalent = 95 g/eq ・Epoxy resin (b): glycidyl ether type epoxy resin, "ED502" manufactured by ADEKA, epoxy equivalent = 320 g/eq ・Dimer acid type epoxy resin: In the above formula (2), n1=7, n2=7, n4=4, and n5=5 were used.

・Conductive filler (a): Silver-coated copper particles, D50=10μm, spherical ・Conductive filler (b): Silver-coated copper particles, D50=8μm, spherical ・Conductive filler (c): Silver-coated copper particles, D50=6μm, spherical ・Conductive filler (d): Silver-coated copper particles, D50=5μm, spherical ・Conductive filler (e): Silver particles, D50=4μm, spherical ・Conductive filler (f): Silver-coated copper particles, D50=3μm, spherical ・Conductive filler (g): Silver particles, D50=2μm, spherical ・Conductive filler (h): Silver particles, D50=1μm, spherical

・Hardener (a): Imidazole-based hardener, "2E4MZ" manufactured by Shikoku Chemical Industry Co., Ltd. ・Hardener (b): Phenol novolac-based hardener, "TAMANOL 758" manufactured by Arakawa Chemical Industry Co., Ltd.

The evaluation of the electroconductive composition of the said Example and the comparative example was performed as follows. The results are shown in Tables 1 to 4.

(1) Viscosity of the conductive composition According to JIS K7117-1, the viscosity at 25 degreeC of the electroconductive composition obtained above was measured by the single cylinder rotational viscometer (so-called B-type viscometer) using the rotor No. 7 at 10 rpm.

(2) Thixotropic Index (TI value) In accordance with JIS K7117-1, the viscosity at 25°C of the conductive composition obtained above was measured with a single cylindrical rotational viscometer (so-called B-type viscometer) using rotor No. 7 at 2 rpm and 20 rpm. The obtained viscosity value was substituted into the following formula, and the TI value was calculated|required. TI value=(viscosity measured at 2rpm)/(viscosity measured at 20rpm)

(3) Electric field shielding characteristics (100MHz, 1GHz) In accordance with IEC62333-1 and IEC62333-2, the shielding properties against electromagnetic waves of 100MHz and 1GHz were evaluated by the KEC method. The measurement conditions are set as a gas environment with a temperature of 25 °C and a relative humidity of 30 to 50%.

After printing the conductive composition obtained above with a Bar Film Applicator (manufactured by BYK-Gardner) on a polyimide film having a thickness of about 100 μm, it was heated at 80° C. for 60 minutes and further heated at 160° C. for 60 minutes. It was hardened to form a coating film with a thickness of about 150 μm. The obtained coating film was cut out into a square of 15 cm as sample 1.

FIG. 1 is a schematic diagram showing the configuration of a system used in the KEC method. The system used in the KEC method is composed of an electromagnetic wave shielding effect measuring device 211a, a spectrum analyzer 221, an attenuator 222 for 10dB attenuation, an attenuator 223 for 3dB attenuation, and a preamplifier 224.

In addition, as the spectrum analyzer 221, U3741 manufactured by Advantest Co., Ltd. was used. In addition, HP8447F made by Agilent Technologies was used as a preamplifier.

Two measuring jigs 213 facing each other are provided in the electric field wave shielding effect evaluation device 211a. The sample 1 to be measured is set so as to be held between the measurement jigs 213 and 213 . The measurement jig 213 adopts the size distribution of a TEM cell (Transverse Electro Magnetic Cell), and is formed into a structure that is symmetrically divided in a plane perpendicular to the direction of the transmission axis. However, in order to prevent a short circuit due to the insertion of the sample 1 , the flat-shaped central conductor 214 is disposed with a gap between each of the measurement jigs 213 .

In the KEC method, first, the signal output from the spectrum analyzer 221 is input to the measuring jig 213 on the transmission side through the attenuator 222 . Next, after the signal received by the measuring jig 213 on the receiving side is passed through the attenuator 223 and amplified by the preamplifier 224 , the signal level is measured by the spectrum analyzer 221 . In addition, the spectrum analyzer 221 outputs the attenuation amount when the sample 1 is installed in the electromagnetic wave shielding effect measuring device 211a based on the state in which the sample 1 is not installed in the electromagnetic wave shielding effect measuring device 211a.

As for the evaluation of the shielding effect of the electromagnetic wave of 100 MHz, those with an attenuation amount of 70 dB or more were evaluated as being excellent in the shielding effect. In the evaluation of the shielding effect of electromagnetic waves of 1 GHz, those with an attenuation of 63 dB or more were evaluated as being excellent in the shielding effect.

(4) Filling of dispensing method Using the sample substrate shown in FIG. 2 , a sample 2 for measurement was produced by the dispensing method. As a sample substrate, the ground circuit 11 is formed on the substrate 10 , the substrate 10 and the ground circuit 11 are sealed by the mold resin 12 , and the groove portion 13 is formed in the mold resin 12 . Using a dispenser "S2-920N-P" and a valve "DV-8000" manufactured by Nordson ASYMTEK, a conductive composition was applied to the groove portion 13 of the sample substrate shown in FIG. 2 under the following dispensing conditions to obtain sample 2. Next, the obtained sample 2 was hardened by heating at 80° C. for 60 minutes and further heating at 160° C. for 60 minutes. About the obtained sample 2, the groove part 13 was observed before hardening and after hardening using the X-ray penetration apparatus "Y.Cheetah μHD" made by YXLON International, and the presence or absence of voids was confirmed under the following measurement conditions. Those with no voids were regarded as having excellent filling properties and evaluated as "○", and those with voids were regarded as poor in filling properties and evaluated as "x".

＜Dispensing Conditions＞ Valve temperature: 60℃ Substrate temperature: 60℃ Nozzle inner diameter: 100μm Dispensing interval: 100μm Dispensing speed: 1.2mm/sec <Measurement conditions> Voltage: 50kV Current: 80μA Power: 4W

(5) Mass production of dispensing method When the above-mentioned sample 2 was produced, when the nozzle was not clogged, it was rated as "○" as being excellent in mass productivity, and when the nozzle was clogged, it was rated as "x" as being poor in mass productivity.

(6) Fillability of vacuum printing method Using the sample substrate shown in FIG. 3 , a sample 3 for measurement was produced by a vacuum printing method. As a sample substrate, the ground circuit 11 is formed on the substrate 10 , the substrate 10 and the ground circuit 11 are sealed by the mold resin 12 , and the groove portion 13 is formed in the mold resin 12 . Using a vacuum printer "VE-700" manufactured by Toray Engineering Co., Ltd., the conductive composition was applied to the groove portion 13 of the sample substrate shown in FIG. 3 under the following printing conditions to obtain Sample 3. Next, the obtained sample 3 was hardened by heating at 80° C. for 60 minutes and further heating at 160° C. for 60 minutes. About the obtained sample 3, the groove part 13 was observed under the following measurement conditions before hardening and after hardening using the X-ray penetrating apparatus "Y. Those with no voids were regarded as having excellent filling properties and evaluated as "○", and those with voids were regarded as poor in filling properties and evaluated as "x".

＜Printing Conditions＞ Printing pressure: 0.5MPa Scraper angle: 10° Scraper speed: 15mm/sec Clearance: 2.0mm Vacuum degree: 0.13kPa Urethane scraper hardness: 80 degrees <Measurement conditions> Voltage: 50kV Current: 80μA Power: 4W

(7) Mass production of vacuum printing method When the above-mentioned sample 3 was produced, those without clogging of the mesh of the printing plate of the vacuum printing machine were regarded as excellent in mass productivity and evaluated as "○", and those with clogging of the mesh were regarded as the amount of The productivity was poor and evaluated as "X".

(8) Top view of vacuum printing method It was evaluated whether or not the mold resin 12 and the conductive composition filled in the groove 13 formed a smooth surface in the opening of the groove 13 formed in the above-mentioned sample 3. Specifically, when the difference between the surface formed of the mold resin 12 and the surface formed of the conductive composition was less than 30 μm, the plane appearance was considered to be excellent and evaluated as “◯”, and when the difference was 30 to 60 μm, the plane appearance was considered to be poor. It was evaluated as "Δ" when it was poor, and when it was 61 μm or more, it was considered as poor in plan view appearance and evaluated as “×”.

[Table 1]

[Table 2]

[table 3]

[Table 4]

From the results shown in Table 1, Examples 1-1 to 1-4 in which the content of the dimer acid-type epoxy resin is within the predetermined range are excellent in any evaluation results. On the other hand, Comparative Example 1-1 is an example of an acid-type epoxy resin that does not contain dimer, and its conductive composition has high viscosity and TI value. Sex is bad. Moreover, in the vacuum printing method, the top view appearance is also slightly inferior. In addition, Comparative Example 1-2 is an example in which the content of the dimer acid-type epoxy resin exceeds the upper limit value, and the electric field shielding properties of 100 MHz and 1 GHz are poor.

From the results shown in Table 2, Examples 2-1 to 2-4 in which the content ratio of the conductive filler (A) and the conductive filler (B) are within the predetermined range are excellent in any evaluation results. . On the other hand, Comparative Example 2-1 is an example in which the conductive filler (A) is contained alone as the conductive filler, and the electric field shielding property of 100 MHz is poor. Comparative Examples 2-2 and 2-3 are examples in which the content ratio of the conductive filler (A) and the conductive filler (B) is outside the predetermined range, and their isoviscosity and TI value are high, and they are used in the dispensing method and the vacuum printing method. In any of them, the filling property was poor. Moreover, in the vacuum printing method, the top view appearance is also slightly inferior.

Comparative Example 2-4 is an example in which the conductive filler (B) is contained alone as the conductive filler, and the shielding property against 100 MHz is poor. Moreover, the TI value of the electroconductive composition was high, and the planar appearance in the vacuum printing method was inferior.

From the results shown in Table 3, Examples 3-1 and 3-2 in which the total amount of the conductive fillers were within the predetermined range were excellent in any evaluation results. On the other hand, Comparative Example 3-1 was an example in which the total amount of the conductive fillers was less than the lower limit value, and the shielding properties against 100 MHz and 1 GHz were poor. Comparative Example 3-2 is an example in which the total amount of the conductive filler exceeds the upper limit, the viscosity of the conductive composition is high, and the filling property is poor in any of the dispensing method and the vacuum printing method. In addition, the TI value of the conductive composition was high, and the top-view appearance in the vacuum printing method was slightly inferior.

From the results shown in Table 4, Examples 4-1 to 4-3 containing the conductive filler (A) and the conductive filler (B) were excellent in any evaluation results. On the other hand, Comparative Example 4-1 is an example in which a conductive filler having an average particle diameter smaller than the lower limit of the average particle diameter of the conductive filler (A) is contained in place of the conductive filler (A), and the conductive composition is The viscosity is high, and the filling property is poor in either the dispensing method or the vacuum printing method. Moreover, in the vacuum printing method, the top view appearance is also slightly inferior.

Comparative Example 4-2 is an example in which a conductive filler with an average particle size exceeding the upper limit of the average particle size of the conductive filler (A) is contained instead of the conductive filler (A), and the shielding properties for 100 MHz and 1 GHz are poor. . In addition, because the average particle size of the conductive filler is large, the nozzle is blocked in the dispensing method, and in the vacuum printing method, the grid of the printing plate of the vacuum printing machine is blocked, any amount of Fertility is poor.

Comparative Example 4-3 is an example in which a conductive filler with an average particle size smaller than the lower limit of the average particle size of the conductive filler (B) is contained instead of the conductive filler (B), and the viscosity of the conductive composition is high, Fillability was poor in either the dispensing method or the vacuum printing method. Moreover, in the vacuum printing method, the top view appearance is also slightly inferior.

Comparative Example 4-4 is an example in which a conductive filler having an average particle diameter exceeding the upper limit of the average particle diameter of the conductive filler (B) is contained instead of the conductive filler (B), and the shielding properties against 100 MHz are poor.

211a: Electric field wave shielding effect evaluation device 213: Measuring jig 214: Center conductor 221: Spectrum Analyzer 222: Attenuator 223: Attenuator 224: Preamplifier 10: Substrate 11: Ground circuit 12: Molding resin 13: Groove

FIG. 1 is a diagram showing the configuration of a system used in the KEC method. FIG. 2 is a schematic cross-sectional view of a sample substrate for evaluating the fillability and mass-producibility of the conductive composition in the dispensing method. 3 is a schematic cross-sectional view of a sample substrate used for evaluating the fillability, mass productivity, and top-view appearance of the conductive composition in a vacuum printing method.

Claims (3)

A conductive composition containing 400-600 parts by mass of a conductive filler relative to 100 parts by mass of an epoxy resin containing 5-20 parts by mass of a dimer acid-type epoxy resin; The above-mentioned conductive fillers include: conductive fillers (A) with an average particle size (D50) of 5 to 8 μm measured by a laser diffraction scattering particle size distribution measurement method, and conductive fillers (A) with an average particle size (D50) of 2 to 3 μm filler (B), and The content ratio ((A):(B)) of the said conductive filler (A) and the said conductive filler (B) is 97:3-50:50 in mass ratio. The conductive composition according to claim 1, wherein the dimer acid-type epoxy resin is a glycidyl modified compound of dimer acid. The conductive composition according to claim 1 or 2, wherein the epoxy resin contains a glycidylamine type epoxy resin and a glycidyl ether type epoxy resin.

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