JP7369031B2 - Paste composition and method for manufacturing electronic component device - Google Patents

Description

The present invention relates to a paste composition, and more particularly to a paste composition that can be applied between narrowed bumps, and a method for manufacturing an electronic component device using the same.

Conventionally, an area bump array package, which is a package having a two-dimensional bump arrangement, has been known as a substrate on which elements are mounted in an array (Patent Document 1).
In recent years, miniaturization of elements has progressed, and elements with a side size of 200 μm or less, such as 50 μm or 10 μm, have been proposed. These elements are typically mini-LEDs or micro-LEDs of, for example, 50 μm or 10 μm, and are arranged in an array as RGB pixels on a display substrate.

For example, a micro LED array display device in which a plurality of micro LED pixels are arranged on one micro LED panel is known (Patent Document 2). When a conventional flip-chip bonding process is used to package micro-LEDs, the reduced solder bump size increases the current density and thermal energy density per bump connection, reducing the reliability of the flip solder connection. Furthermore, as the distance between adjacent solder bumps becomes finer, there is a risk that a solder bridge phenomenon may occur between adjacent solder bumps due to wetting and spreading of solder during solder reflow.

Therefore, a method is known in which a hemispherical solder cap is formed in order to prevent the expansion phenomenon of the solder joint (Patent Document 3).

Japanese Patent Application Publication No. 11-233559 JP2019-68082A Japanese Patent Application Publication No. 2018-166224

However, even the method of Patent Document 3 does not improve solder reflow.

The present disclosure provides an optimal paste composition for realizing a highly reliable area bump array package.

The present disclosure uses a paste composition having a specific yield value, viscosity, and thixometry ratio to form an array of m vertically by n horizontally (m and n are each independently from 10 to 1000) bumps for electrode connection. It has been found that good reliability can be obtained by forming the film into a shape. Furthermore, the inventors have discovered that by mounting an element component having two or more electrodes on the electrode connection bumps and heating and curing the same, an electronic component mounted in an area array can be obtained, and the present invention has been completed.

That is, the present disclosure relates to the following.
[1] A paste composition comprising (A) a thermosetting compound, (B) a radical initiator, (C) silver particles, and (D) silver powder, the paste composition comprising the (C) component and the (D) ) component is 85 to 95% by mass of the entire paste composition, yield value is 100 to 200 Pa, viscosity at 2 rpm is 20 to 60 Pa・s, thixotropic ratio at 25°C (viscosity at 2 rpm) /20 rpm) of 3 to 6.
[2] The thermosetting compound (A) includes (A1) epoxidized polybutadiene, and (A2) a (meth)acrylic acid ester compound or (meth)acrylamide compound having a hydroxy group, and the (A1) component and the above-mentioned (A2) component is 5:95 to 55:45, the thickness or short axis of the above-mentioned (C) silver particles is 1 to 200 nm, and the average particle diameter of the above-mentioned (D) silver powder is The paste composition according to the above [1], wherein the paste composition is greater than 0.2 μm and less than or equal to 20 μm, and the content ratio of the component (C) and the component (D) is 10:90 to 50:50 in mass ratio. .
[3] The paste composition according to [1] or [2] above, wherein the component (C) includes (C1) plate-shaped silver particles, and the component (D) includes (D1) flaky silver powder.
[4] The above component (C) further includes (C2) spherical silver particles, and the content ratio of the component (C1) to the component (C2) is from 100:0 to 50:50 in terms of mass ratio. The paste composition according to [3].
[5] Using the paste composition according to any one of [1] to [4] above, silver bumps with a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed on a substrate with a gap of 50 μm between each bump. ~200μm, printing m vertically x n horizontally (m and n are each independently 10 to 1000) to form an array, and arranging element parts having two or more electrodes on the bumps. A method for manufacturing an electronic component device including a mounting process.

According to the present disclosure, it is possible to provide a paste composition with good adhesion and conductivity, and an electronic component with excellent reliability using the paste composition. Further, according to the paste composition of the present disclosure, bumps having a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed, each with a gap of 50 to 200 μm, m vertically×n horizontally (m, n are Even when formed in an array (10 to 1000 each independently), unlike solder paste, it does not wet and spread during reflow, so it forms a highly reliable bump group with no risk of short circuits occurring between bumps. can do.

Hereinafter, the present disclosure will be described in detail with reference to one embodiment.
In addition, in this disclosure, "(meth)acrylic" means acrylic and/or methacryl, and "(meth)acrylate" means acrylate and/or methacrylate.

<Paste composition>
One embodiment of the paste composition of the present disclosure is a paste composition containing (A) a thermosetting compound, (B) a radical initiator, (C) silver particles, and (D) silver powder, the paste composition comprising: The value is 100 to 200 Pa, the viscosity at a rotation speed of 2 rpm is 20 to 60 Pa·s, and the thixotropic ratio (viscosity at 2 rpm/viscosity at 20 rpm) at 25° C. is 3 to 6. Further, the total content of the component (C) and the component (D) is 85 to 95% by mass of the entire paste composition.

(A) Thermosetting Compound The thermosetting compound (A) used in this embodiment is not particularly limited, but includes (A1) epoxidized polybutadiene, and/or (A2) (meth)acrylic acid having a hydroxy group. It may be an ester compound or a (meth)acrylamide compound.
The epoxidized polybutadiene (A1) used in this embodiment is a compound obtained by modifying polybutadiene with epoxy, and may be an epoxidized polybutadiene having an epoxy equivalent of 50 to 500 (g/eq). When the epoxy equivalent is 50 g/eq or more, the viscosity does not increase too much and the workability of the paste composition becomes good, and when it is 500 g/eq or less, the adhesive strength under heat can be improved.
Note that the epoxy equivalent was determined by the perchloric acid method. As the epoxidized polybutadiene (A1), one having a hydroxyl group in the molecule may be used.

Examples of the epoxidized polybutadiene (A1) include Epolead PB4700 and GT401 (both trade names) commercially available from Daicel Corporation, and JP-100 and JP-200 (both commercially available from Nippon Soda Co., Ltd.). (product name) can be used.
By containing the epoxidized polybutadiene (A1), the paste composition of the present embodiment can improve the adhesion of the electrode to the chip component terminal.

The epoxidized polybutadiene (A1) may have a number average molecular weight of 500 to 10,000. When the number average molecular weight is within the above range, adhesiveness is good and the viscosity can be controlled to an appropriate level, resulting in good workability.
Note that the number average molecular weight is a value measured by gel permeation chromatography using a standard polystyrene calibration curve.

(A2) The (meth)acrylic acid ester compound or (meth)acrylamide compound having a hydroxy group used in this embodiment is a (meth)acrylate or (meth)acrylate compound having one or more (meth)acrylic groups in one molecule, respectively. It is (meth)acrylamide and contains a hydroxy group.

Here, the (meth)acrylate having a hydroxy group can be obtained by reacting a polyol compound with (meth)acrylic acid or a derivative thereof. A known chemical reaction can be used for this reaction. For the (meth)acrylate having a hydroxy group, acrylic ester or acrylic acid is usually used in an amount of 0.5 to 5 times the mole of the polyol compound.

Furthermore, (meth)acrylamide having a hydroxy group can be obtained by reacting an amine compound having a hydroxy group with (meth)acrylic acid or a derivative thereof. The method of producing (meth)acrylamide by reacting a (meth)acrylic ester with an amine compound requires that amine, cyclopentadiene, alcohol, etc. Generally, a protective group is added to the double bond in advance, and the protective group is removed by heating after the amidation is completed.

By incorporating a hydroxy group into the (meth)acrylic acid ester compound or (meth)acrylamide compound, sintering properties due to the reduction effect are promoted and adhesiveness is improved during electrode formation.

Moreover, the hydroxy group here is an alcoholic group in which the hydrogen atom of an aliphatic hydrocarbon group is substituted. The content of the hydroxy groups may be 1 to 50 in one molecule. When the content of hydroxyl groups is within the above range, sinterability is not inhibited due to excessive hardening, and sinterability can be promoted.

Examples of the (meth)acrylic acid ester compound or (meth)acrylamide compound having such a (A2) hydroxy group include compounds represented by the following general formulas (1) to (4).

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a divalent aliphatic hydrocarbon group having 1 to 100 carbon atoms or an aliphatic hydrocarbon group having a cyclic structure.)

(In the formula, R ¹ and R ² each represent the same as above.)

(In the formula, R ¹ represents the same as above, and n represents an integer from 1 to 50.)

(In the formula, R ¹ and n each represent the same as above.)

As the (meth)acrylic acid ester compound or (meth)acrylamide compound having a hydroxy group (A2), the compounds shown in the general formulas (1) to (4) described above may be used alone or in combination of two or more. can be used. Note that the number of carbon atoms of R ² in general formulas (1) and (2) may be 1 to 100 or 1 to 36. When the number of carbon atoms in R ² is within the above range, sinterability is not inhibited due to excessive hardening.

Furthermore, the blending ratio of the component (A1) and the component (A2) may be (A1):(A2)=5:95 to 55:45 in mass ratio, or 15:85 to 50: It may be 50. When each of the components (A1) and (A2) is within the above range, the adhesion of electronic components is good and the connection resistance is kept low. When the component (A1) is 5% by mass or more, the adhesion is good, and when the component (A2) is 45% by mass or more, the connection resistance is good.

Note that as the thermosetting compound (A), thermosetting compounds other than the components (A1) and (A2) can also be used. Examples of thermosetting compounds that can be used here include epoxy resins, bismaleimide resins, polybutadiene resins (excluding component (A1)), and phenol resins. However, the thermosetting compounds other than the components (A1) and (A2) may be 20% by mass or less, and may be 10% by mass or less, when the thermosetting compound (A) is 100% by mass. It's okay.

The content of the thermosetting compound (A) may be 0.1 to 10% by mass, 0.2 to 8% by mass, 0.5 to 8% by mass, based on the entire paste composition. It may be 5% by mass. (A) When the content of the thermosetting compound is 0.1% by mass or more, good adhesiveness can be obtained, and when the content is 10% by mass or less, good conductivity can be obtained.

(B) Radical Initiator The (B) radical initiator used in this embodiment can be used without particular limitation as long as it is a polymerization catalyst that is normally used in radical polymerization.

The radical initiator (B) has a decomposition start temperature of 40 to 140°C in a rapid heating test (a test to measure the decomposition start temperature when 1 g of sample is placed on an electric heating plate and heated at 4°C/min). It may be. When the decomposition start temperature is 40°C or higher, the paste composition has good storage stability at room temperature, and when it is 140°C or lower, a suitable curing time is obtained.
The decomposition start temperature is defined as the temperature at which the mass of the sample decreases by 1% with respect to the mass before heating.

Specific examples of the radical initiator (B) that satisfies the above conditions include 1,1-bis(t-butylperoxy)-2-methylcyclohexane, t-butylperoxyneodecanoate, dicumyl peroxide. etc. These may be used alone or in combination of two or more to control curability.

The content of the radical initiator (B) may be 0.1 to 10 parts by mass based on 100 parts by mass of the thermosetting compound (A). (B) When the content of the radical initiator is 0.1 parts by mass or more, curability is good, and when it is 10 parts by mass or less, the change in viscosity of the paste composition over time does not become too large, and workability is good. becomes.

(C) Silver particles The (C) silver particles used in this embodiment are not particularly limited, but the thickness or short diameter of the (C) silver particles may be 1 to 200 nm, or 1 to 100 nm. It's okay. (C) When the thickness or breadth of the silver particles is 1 nm or more, the workability of the paste composition can be improved, and when it is 200 nm or less, the sinterability is good and the volume resistance of the connection bump is lowered. be able to.
The thickness or short diameter of the silver particles (C) is measured by data processing an observed image obtained by a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

Examples of the shape of the silver particles (C) include spherical, plate-shaped, dendritic, rod-shaped, and wire-shaped. (C) When the shape of the silver particle is a plate type, the thickness only needs to satisfy the above range, and when the shape of the silver particle is spherical, dendritic, rod-like, or wire-like, the cross-sectional diameter It is sufficient that the shortest diameter (breadth diameter) in satisfies the above range. Here, in the present disclosure, the thickness of plate-shaped silver particles refers to the minimum distance between a pair of planes.
Examples of the (C) silver particles include (C1) plate-shaped silver particles, (C2) spherical silver particles, and the like.

The silver particles (C) may be used alone or in combination of two types. When using two kinds of silver particles (C) in combination, (C1) plate-shaped silver particles and (C2) spherical silver particles may be used together. The content ratio of (C1) plate-shaped silver particles and (C2) spherical silver particles may be (C1):(C2)=100:0 to 50:50, or 100:0 to 70, in terms of mass ratio. :30 may be sufficient. By containing the component (C1) at 50% by mass or more, the paste composition of this embodiment has a thixotropic ratio within the range described below, stable shape retention after printing, and a plurality of electrode connection bumps arranged at a narrow pitch. Even when printed, good insulation properties can be obtained.

Unlike spherical nanoparticles, the plate-shaped silver particles (C1) are plate-shaped particles with a uniform thickness that are obtained by growing a single metal crystal face, and generally have a size on the order of microns. The thickness is approximately several nanometers, and the shape is a triangular plate, a hexagonal plate, or a truncated triangular plate. Further, the upper surface in the thickness direction may be widely covered with the [111] plane.
(C1) Since plate-shaped silver particles tend to stack up in the short axis direction, m vertically x horizontally n bumps (m and n are each independently 10 to 1000) are printed in an array. This has the advantage of reducing the variation in bump height when bumping. There is also the advantage that the connection resistance value after the paste composition is cured can be lowered.

(C1) The plate-shaped silver particles may have a center particle diameter of 0.3 to 15 μm. In an embodiment of the present disclosure, by setting the center particle diameter of the plate-shaped silver particles within the above range, dispersibility in the resin component can be improved. Here, the central particle diameter refers to a 50% integrated value (50% particle diameter) in a volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size distribution analyzer.

Further, the thickness of the plate-shaped silver particles (C1) may be 10 to 200 nm, or may be 10 to 100 nm. The thickness is measured by data processing an observed image acquired by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Furthermore, the average thickness of the plate-shaped silver particles (C1) may be within the above range. The average thickness is calculated as a number average thickness as follows.

(C1) The thicknesses measured from the observation images of [n+1] plate-shaped silver particles (n+1 is, for example, about 50 to 100) are arranged in order from the thickest to the thinnest, and the range (maximum thickness: x ₁ , minimum thickness: x _n+1 ) is divided into n sections, and each thickness section is defined as [x _j , x _j+1 ] (j=1, 2, . . . , n). The division in this case is equal division on a logarithmic scale. Further, the representative thickness in each thickness section based on the logarithmic scale is expressed by the following formula.

Furthermore, if r _j (j=1, 2,..., n) is the relative amount (difference %) corresponding to the interval [x _j , x _j+1 ], and the sum of all intervals is 100%, then the logarithmic scale The above average value μ can be calculated using the following formula.

Since μ is a numerical value on a logarithmic scale and does not have a thickness unit, 10 ^μ , that is, 10 to the μ power, is calculated to return it to a thickness unit. This 10 ^μ is the number average thickness.

Further, the long side in the direction perpendicular to the thickness direction may be within the range of 8 to 150 times the thickness, or may be 10 to 50 times the thickness. Furthermore, the short side in the direction perpendicular to the thickness direction may be within the range of 1 to 100 times the thickness, or may be 3 to 50 times the thickness.

(C1) Plate-shaped silver particles can be self-sintered at 100 to 250°C. By containing silver particles that self-sinter at temperatures of 100 to 250°C, the fluidity of the silver particles improves during heat curing, resulting in more contact points between the silver particles and the area of the contact points. becomes larger, and the conductivity is significantly improved. Since the lower the self-sintering temperature, the better the sinterability, the sintering temperature of the plate-shaped silver particles (C1) may be 100 to 200°C.
Note that the term "self-sinterable" here means that the material can be sintered by heating at a temperature lower than the melting point without applying pressure or adding additives.

Examples of such (C1) plate-shaped silver particles include M612 (product name; center particle diameter 6 to 12 μm, particle thickness 60 to 100 nm, melting point 250° C.) manufactured by Tokusen Kogyo Co., Ltd., M27 (product name; center Particle size: 2 to 7 μm, particle thickness: 60 to 100 nm, melting point: 200°C), M13 (product name; center particle size: 1 to 3 μm, particle thickness: 40 to 60 nm, melting point: 200°C), N300 (product name: center particle size: 0. 3 to 0.6 μm, particle thickness of 50 nm or less, melting point of 150° C.), etc. These plate-shaped silver particles may be used alone or in combination. In particular, in order to improve the filling rate, (C1) plate-type silver particles are replaced with silver particles having a relatively large particle size such as M27 and M13 among the above-mentioned plate-type silver particles, and a plate-type silver particle having a particle size such as N300. You may use a combination of small ones.

(C1) Plate-shaped silver particles may have a particle thickness of 200 nm or less, a tap density (TD) of 3.0 to 7.0 g/cm ³ , and a specific surface area (BET) of 2.0 to 6.0 m ² /g. good. When the tap density is within the range, a good connection resistance value is obtained.
The tap density can be measured using a tap density measuring device. Further, the specific surface area can be measured by a BET one-point method using nitrogen adsorption using a specific surface area measuring device.

The spherical silver particles (C2) may have an average particle diameter of 10 to 200 nm. (C2) Spherical silver particles are usually formed by providing a coating layer of an organic compound on the metal surface of silver particles, or by dispersing the silver particles in an organic compound. This form prevents the metal surfaces of the contained silver particles from coming into direct contact with each other, thereby suppressing the formation of aggregates of silver particles and creating a state in which the silver particles are individually dispersed. It can be held with
The average particle diameter of the (C2) spherical silver particles is measured by data processing an observed image obtained by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Furthermore, the average particle diameter of the spherical silver particles (C2) may be within the range of the thickness or breadth of the silver particles (C) described above. The average particle diameter is calculated as the number average particle diameter of the particle diameters measured from 50 to 100 observed images of (C2) spherical silver particles. The average value of the number average particle diameter may be calculated in the same manner as the calculation of the average thickness.

The coating layer on the surface of the (C2) spherical silver particles or the organic compound in which the (C2) spherical silver particles are dispersed include organic compounds having nitrogen, carbon, and oxygen as constituent elements with a molecular weight of 20,000 or less, specifically amino acids. An organic compound having a functional group such as a group or a carboxy group is used.
The organic compound containing a carboxyl group used here includes one or more organic compounds selected from organic carboxylic acids having a molecular weight of 110 to 20,000, such as hexanoic acid, heptanoic acid, octanoic acid, nonane Examples include carboxylic acids such as decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, eicosanoic acid, docosanoic acid, 2-ethylhexanoic acid, oleic acid, linoleic acid, linolenic acid, and terminal dipropionic acid polyethylene oxide. Further, as the organic compound, a carboxylic acid derivative of the above-mentioned carboxylic acid can also be used.

In addition, examples of the organic compound having an amino group used here include alkyl amines, such as butylamine, methoxyethylamine, 2-ethoxyethylamine, hexylamine, octylamine, 3-butoxypropylamine, nonylamine, dodecylamine, etc. Primary amines such as amines, hexadodecylamine, octadecylamine, cocoamine, tallowamine, hydroxylated tallowamine, oleylamine, laurylamine, stearylamine, and 3-aminopropyltriethoxysilane, dicocoamine, dihydrogenated tallowamine, and distearyl. Secondary amines such as amines, and tertiary amines such as dodecyldimethylamine, didodecylmonomethylamine, tetradecyldimethylamine, octadecyldimethylamine, cocodimethylamine, dodecyltetradecyldimethylamine, and trioctylamine, and others. Examples include diamines such as naphthalene diamine, stearylpropylene diamine, octamethylene diamine, nonane diamine, diamine-terminated polyethylene oxide, triamine-terminated polypropylene oxide, and diamine-terminated polypropylene oxide.

If the molecular weight of the organic compound that coats or disperses the spherical silver particles (C2) is 20,000 or less, the organic compound is likely to be detached from the surface of the silver particles, and after the paste is baked, it will not be present in the cured product. The organic compound is less likely to remain, and as a result, conductivity can be improved. Further, the lower limit of the molecular weight may be 50 or more. When the molecular weight is 50 or more, the storage stability of the silver particles can be improved.

(C2) The spherical silver particles may have a mass ratio of 90:10 to 99.5:0.5 between the silver particles and the organic compound that coats or disperses the silver particles. When the mass ratio of the organic compound is 0.5% by mass or more, there is little aggregation of silver particles, and when it is 10% by mass or less, it is possible to make it difficult for the organic compound to remain in the cured product after firing, and the As a result, electrical conductivity and thermal conductivity become good.

(D) Silver powder The (D) silver powder used in this embodiment has a larger particle size than the (C) silver particles, and is silver powder as an inorganic filler added to the resin adhesive to impart conductivity. Good to have.
By containing the silver powder (D) in combination with the silver particles (C), the connection resistance value can be reduced.
(D) The silver powder may have an average particle diameter of more than 0.2 μm and 20 μm or less, or 1 to 10 μm.
The average particle diameter of the silver powder (D) refers to a 50% integrated value (50% particle diameter) in a volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size distribution measuring device.

Moreover, examples of the shape of the silver powder (D) include flake, spherical, resin, rod, wire, and plate shapes.
Examples of the silver powder (D) include (D1) flaky silver powder, (D2) spherical silver powder, and the like.
One type of silver powder (D) may be used, or two types may be used in combination.

The silver powder (D) may be a combination of (D1) flaky silver powder and (D2) spherical silver powder.
The content ratio of the component (D1) and the component (D2) may be (D1):(D2)=50:50 to 100:0 in terms of mass ratio. When the paste composition of this embodiment contains 50% by mass or more of the component (D1), the yield value falls within the range described below and the plate release property becomes good. Even if the bumps are printed at pitch, short circuits between bumps will not occur.

The content ratio of the component (C) and the component (D) may be a mass ratio of component (C):component (D)=10:90 to 50:50, or 10:90 to 30:70. It may be. When the content ratio is within the above range, the paste composition has both a yield value and a viscosity within the ranges described below, has stable shape retention after printing, and can print a plurality of electrode connection bumps at a narrow pitch. Good insulation properties can also be obtained. When the content ratio of the component (C) is 10% by mass or more, the paste composition exhibits excellent sinterability and thus has a low volume resistivity. In the paste composition, when the content ratio of the component (C) is 50% by mass or less, the volumetric shrinkage due to sintering becomes small, so that the printed bump height is stabilized.

The total content of the component (C) and the component (D) is 85 to 95% by mass, and may be 90 to 94% by mass, based on the entire paste composition. If the total content of the component (C) and the component (D) is less than 85% by mass, the conductivity may be poor, and if it exceeds 95% by mass, the adhesiveness may be poor.

(E) Solvent The paste composition of this embodiment may further contain a solvent. The solvent used in this embodiment may be an alcohol or ester having a boiling point of 200 to 220°C and a flash point of 90 to 130°C from the viewpoint of workability after printing.
(E) The solvent may be an alcoholic solvent with a boiling point of 200° C. or higher, from the viewpoint of high solubility of the resin and less likely to cause uneven coating due to solvent volatilization. Examples of alcoholic solvents with a boiling point of 200°C or higher include diethylene glycol, triethylene glycol, 1,3-butanediol, glycerin, benzyl alcohol, dipropylene glycol, 1,4-butanediol, 2,2,4-trimethyl 1 , 3-pentanediol monoisobutyrate, ethylene glycol mono-2-ethylhexyl ether, dihydroterpineol, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, terpineol, diethylene glycol butyl methyl ether, isodecanol, isotridecanol or ethylene glycol mono Examples include hexyl ether.

(E) From the viewpoint of workability, the content of the solvent may be 0.1 to 10% by mass based on the entire paste composition. Further, by appropriately adjusting the content of the solvent (E) within the above range, the viscosity of the paste composition can be set within the range described below.

In addition to the above-mentioned components, the paste composition of the present embodiment may contain curing accelerators, rubber, silicone, etc., which are generally blended in this type of composition, as necessary, to the extent that the effects of the present embodiment are not impaired. Additives such as stress reducing agents such as, coupling agents such as titanate coupling agents, adhesion agents, pigments, dyes, antifoaming agents, surfactants, diluents and the like may be appropriately contained. Each of these additives may be used alone or in combination of two or more.

The total content of components (A) to (D) contained in the paste composition of the present embodiment may be 90% by mass or more, 94% by mass or more, or 96% by mass or more. There may be.

(Preparation of paste composition)
The paste composition of this embodiment is prepared by thoroughly mixing each of the components (A) to (D) described above, additives such as a coupling agent, a solvent, etc., which are added as necessary. Next, the paste composition of this embodiment is prepared by kneading the mixed resin composition using a disperser, a kneader, a three-roll mill, or the like. Finally, the paste composition of this embodiment can be prepared by defoaming the kneaded resin composition.

(Yield value of paste composition)
The paste composition of this embodiment has a yield value of 100 to 200 Pa, and may be 120 to 180 Pa. If the breakdown value is less than 100 Pa, the stability during mounting will be poor, and the reliability of the resulting electronic component may be reduced. On the other hand, if the yield value exceeds 200 Pa, the leveling property during heating and melting may be reduced, and the reliability of the obtained electronic component may be reduced. Further, when the yield value is within the range, plate release properties are good and electronic components having a uniform height level when a plurality of electronic components are mounted side by side can be obtained.
Here, the yield value is the minimum stress required to cause the paste composition to flow, and is defined as the loading force or shear force at which the paste composition begins to flow.
The yield value can be determined, for example, by measuring shear stress at a given shear rate using an E-type viscometer (3° cone), and by drawing a Casson plot of the shear rate and shear stress. Specifically, it can be measured by the method described in Examples.

(Viscosity of paste composition)
The paste composition of this embodiment has a viscosity of 20 to 60 Pa·s at a rotational speed of 2 rpm, and may be 20 to 50 Pa. If the viscosity is less than 20 Pa·s, there is a risk that the wetting and spreading during printing will become too large and the reliability of the obtained electronic component will decrease. On the other hand, if the viscosity exceeds 60 Pa·s, there is a risk that the mounting performance of electronic components may deteriorate. Furthermore, when the viscosity is within the range, variations in the height of printed bumps can be reduced.
The viscosity is a value measured at 25° C. using an E-type viscometer (3° cone). Specifically, it can be measured by the method described in Examples.

(Thixotropic properties of paste composition)
The thixotropic ratio (viscosity at 2 rpm/viscosity at 20 rpm) of the paste composition of the present embodiment at 25° C. is 3 to 6, and may be 4 to 5. When the thixometry ratio is less than 3, the wettability during printing becomes too large, which may reduce the reliability of the resulting electronic component. On the other hand, if the thixometry ratio exceeds 6, there is a risk that the mounting performance of electronic components may deteriorate. Furthermore, when the thixotropic ratio is within the range, there is no risk of short circuits due to wetting and spreading even when a plurality of bumps are printed.
The thixotropic ratio can be measured using, for example, an E-type viscometer (3° cone), and specifically can be measured by the method described in Examples.

The paste composition of this embodiment has good adhesion and conductivity, and does not spread during reflow unlike solder paste, so it can be used as a highly reliable bump without the risk of short circuits occurring between bumps. can form a group. Furthermore, by using the paste composition of this embodiment, it is possible to provide electronic components with excellent reliability.

<Method for manufacturing electronic components>
The method for manufacturing an electronic component device according to the present embodiment includes forming silver bumps with a diameter of 50 to 200 μm and a height of 10 to 50 μm on a substrate using the above-mentioned paste composition with a gap of 50 to 200 μm. , a process of printing m vertically x n horizontally (m and n are each independently 10 to 1000) to form an array, and a process of arranging and mounting element parts having two or more electrodes on the bumps. has.
By using the paste composition of this embodiment, the mounted element components can have good leveling properties.

An array is a state in which element parts are arranged in multiple rows and columns according to a predetermined pattern, and the intervals in the row and column directions are the same or different, such as a checkerboard arrangement, a honeycomb pattern, etc. This is a staggered arrangement like this.
Element parts are parts used in electronic circuits, and include chips such as MEMS, semiconductor elements, resistors, and capacitors. Semiconductor elements include discrete semiconductors such as transistors, diodes, LEDs, and thyristors, as well as ICs, LSIs, etc. includes integrated circuits. LEDs include so-called mini LEDs and micro LEDs.

The conditions for heat curing the paste composition may be at 150 to 250° C. for 30 to 90 minutes. When the heat curing conditions are within the above range, the adhesion is good and the connection resistance value is low.

As a method for forming silver bumps at regular intervals on a substrate, known methods such as a stamping method, a dispensing method, and a printing method can be used. A metal mask with holes made in a metal plate may be used as the printing plate.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way.

(Examples 1 to 6, Comparative Examples 1 to 4)
Each component was mixed according to the formulation shown in Table 1 and kneaded with a roll to obtain a paste composition. The obtained paste composition was evaluated by the method described below. The results are also shown in Table 1. The materials used in Examples and Comparative Examples had the following characteristics.

[(A) Thermosetting compound]
・(A1) Thermosetting compound: Epoxidized polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: JP-200, molecular weight 2,200, epoxy equivalent 230 g/eq)
・(A2) Thermosetting compound: Hydroxyethyl acrylamide (manufactured by KJ Chemicals Co., Ltd., product name: HEAA (registered trademark))

[(B) Radical initiator]
・Dicumyl peroxide (manufactured by NOF Corporation, product name: Parkmil (registered trademark) D; decomposition temperature in rapid heating test: 126°C)

[(C) Silver particles]
・(C1) Plate-shaped silver particles: M13 (trade name, manufactured by Tokusen Kogyo Co., Ltd.; central particle diameter: 2 μm, thickness: 50 nm or less)
The central particle diameter of the plate-shaped silver particles (C1) is such that the cumulative volume is 50% in the particle size distribution measured using a laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation, product name: SALAD-7500nano). It was determined from the particle size (50% particle size, D50).
The thickness of the (C1) plate-shaped silver particles was calculated as the average value of the particle thicknesses measured from 50 observed images of the (C1) plate-shaped silver particles obtained by a transmission electron microscope (TEM).
・(C2) Spherical silver particles: Ag nano powder-1 (trade name, manufactured by DOWA Electronics Co., Ltd., average particle diameter: 20 nm)
The average particle diameter of the (C2) spherical silver particles was calculated as the number average particle diameter of the particle diameters measured from 50 observed images of the (C2) spherical silver particles obtained by a transmission electron microscope (TEM).

[(D) Silver powder]
・(D1) Flake-like silver powder: TC-506C (product name, manufactured by Tokuriki Honten Co., Ltd., average particle size: 4.0 μm)
・(D2) Spherical silver powder: Ag-HWQ2.5 (trade name, manufactured by Fukuda Metal Foil and Powder Industries Co., Ltd., average particle size: 2.5 μm)
The average particle diameter of the silver powder (D) is the particle diameter at which the cumulative volume is 50% in the particle size distribution measured using a laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation, product name: SALAD-7500nano). It was determined from the 50% particle size (D50).

[(E) Solvent]
・Butyl carbitol (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

<Evaluation method>
(1) Viscosity Value at a temperature of 25°C and a rotation speed of 2 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate rotor: 3° x R17.65) was measured.

(2) Thixometry ratio Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate rotor: 3° x R17.65), at 25°C, rotation speeds of 2 rpm and 20 rpm. The viscosity at 2 rpm was measured, and the ratio of the viscosity at 2 rpm to 20 rpm (viscosity at 2 rpm/viscosity at 20 rpm) was defined as the thixotropic ratio.

(3) Yield value Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate rotor: 3° x R17.65), a shear rate of 1 ( 1/s), 2 (1/s), 4 (1/s), 10 (1/s), 20 (1/s), 40 (1/s), 100 (1/s), 200 (1 /s) was measured. The shear rate and shear stress were plotted on a Casson plot, and the yield value was calculated.

(4) Room temperature adhesion After bonding a 0.25 mm x 0.1 mm LED to a printed evaluation board using a paste composition by heating it at 200°C for 1 hour, an adhesive strength measuring device manufactured by Seishin Shoji Co., Ltd. was used. The adhesive strength at 25° C. was measured using the following method.

(5) Adhesion under heat A 1 mm x 1 mm LED chip was mounted on a silver-plated frame using a paste composition, and heat-cured in an oven at 200° C. for 60 minutes. The obtained electronic component was laterally pushed at 20 mm/min, and the shear strength was measured using a bond tester device (manufactured by Nordson DAGE, model number Nordson DAGE 4000Plus), and the load at which it broke was taken as the bonding strength (N).

(6) Volume resistivity The paste composition was applied to a glass substrate (thickness: 1 mm) to a size of 5 mm x 50 mm and a thickness of 30 μm by screen printing, and cured at a temperature of 200° C. for 60 minutes. The electrical resistance of the resulting wiring was measured using a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product name "MCP-T600") by a four-terminal method, and evaluated according to the following evaluation criteria.
[Evaluation criteria]
〇: Less than 1×10 ^-5 Ω・cm ×: 1×10 ⁻⁵ Ω・cm or more

(7) Mounting Evaluation (7-1) Printability On the print evaluation board, 40×50 electrode groups were formed using 0.1 mm electrodes at 0.1 mm intervals. Connection bumps with a diameter of 60 μm and a thickness of 20 μm were printed on the electrodes using the paste composition. The printed shape was observed with a magnifying glass (magnification: 100 times) and evaluated according to the following evaluation criteria.
[Evaluation criteria]
〇: No abnormality △: There is some scratching or bleeding, but it is at a level that does not cause any practical problems. ×: There is a defective shape or chipping.

(7-2) Reliability After mounting 1000 0.25 mm x 0.1 mm LEDs with two electrodes on a printed evaluation board, they were bonded by heating at 200°C for 1 hour using a paste composition. After that, the presence or absence of a short circuit was visually confirmed and evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: No short circuit occurred. ×: Short circuit occurred. In Comparative Examples 1, 2, and 4, reliability tests were not conducted because the connection bumps were poorly formed or missing, or the volume resistance value exceeded the reference value.

The paste compositions of Examples 1 to 6 have a yield value of 100 to 200 Pa, a viscosity at a rotation speed of 2 rpm of 20 to 60 Pa·s, and a thixotropic ratio (viscosity at 2 rpm/viscosity at 20 rpm) at 25° C. of 3 to 6. It was confirmed that both had good adhesion, low volume resistivity, and excellent mounting performance.
On the other hand, in Comparative Example 1, in which the viscosity at a rotation speed of 2 rpm exceeds 60 Pa·s, and in Comparative Example 2, in which the yield value exceeds 200 Pa and the viscosity at a rotation speed of 2 rpm exceeds 60 Pa·s, the printability of micro bumps is poor, and the connection Shape defects or defects occurred due to bump printing fading. Further, Comparative Example 1 and Comparative Example 4 in which the thixotropic ratio was less than 3 had high volume resistivities of 1×10 ⁻⁵ Ω·cm or more. Furthermore, in Comparative Example 3, in which the yield value was 100 Pa and the viscosity at a rotational speed of 2 rpm was less than 20 Pa·s, a short circuit occurred, which was thought to be due to wetting and spreading of the paste composition.

Claims (3)

A paste composition comprising (A) a thermosetting compound, (B) a radical initiator, (C) silver particles, and (D) silver powder,
The total content of the component (C) and the component (D) is 85 to 95% by mass of the entire paste composition,
The yield value is 100 to 200 Pa, the viscosity at a rotation speed of 2 rpm is 20 to 60 Pa・s, and the thixotropic ratio (viscosity at 2 rpm/viscosity at 20 rpm) at 25° C. is 3 to 6.
The thermosetting compound (A) includes (A1) epoxidized polybutadiene, and (A2) a (meth)acrylic acid ester compound or (meth)acrylamide compound having a hydroxy group,
The blending ratio of the component (A1) and the component (A2) is 5:95 to 55:45,
The content ratio of the component (C) and the component (D) is 10:90 to 50:50 in mass ratio,
The component (C) includes (C1) plate-shaped silver particles, the component (D) includes (D1) flaky silver powder,
The (C) silver particles contain 50% by mass or more of the (C1) component,
The silver powder (D) contains 50% by mass or more of the component (D1),
The plate-type silver particles (C1) have a center particle diameter of 0.3 to 15 μm and a thickness of 10 to 100 nm,
The silver powder (D) is a paste composition having an average particle size of 1 to 10 μm. 2. The method according to claim 1, wherein the component (C) further includes (C2) spherical silver particles, and the content ratio of the component (C1) and the component (C2) is 100:0 to 50:50 in terms of mass ratio. Paste composition as described. Using the paste composition according to claim 1 or 2, silver bumps with a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed on a substrate in a matrix of m vertically x horizontally with a gap of 50 to 200 μm. An electronic component device comprising a step of printing n bumps (m and n are 10 to 1000 each independently) to form an array, and a step of arranging and mounting element parts having two or more electrodes on the bumps. Production method.