JP2021107475A - Paste composition, and method for producing electronic component device - Google Patents

Abstract

To provide a paste composition having excellent adhesion and conductivity and an electronic component that uses the paste composition and has excellent reliability.SOLUTION: A paste composition contains (A) a thermosetting compound, (B) a radical initiator, (C) silver particles, and (D) silver powder, the total content of the (C) component and the (D) component being 85-95 mass% of the total mass of the paste composition. The paste composition has a yield value of 100-200 Pa, a viscosity of 20-60 Pa s at the number of revolutions of 2 rpm, and a thixotropic ratio at 25°C (viscosity at 2 rpm/viscosity at 20 rpm) of 3-6.SELECTED DRAWING: None

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 paste composition.

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

For example, there is known a micro LED array display device in which a plurality of micro LED pixels are arranged on one micro LED panel (Patent Document 2). When a normal flip-chip bonding process is used to mount a micro LED, the size of the solder bumps is reduced, which increases the current density and thermal energy density per bump connection and reduces the reliability of the flip solder connection. Further, since the distance between the adjacent solder bumps is miniaturized, a solder bridge phenomenon may occur between the adjacent solder bumps due to the wet spread of the solder during solder reflow.

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

JP-A-11-233559 JP-A-2019-68082 JP-A-2018-166224

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

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

In the present disclosure, m x horizontal n (m and n are independently 10 to 1000) electrode connection bumps are arranged using a paste composition having a specific yield value, viscosity, and thixo ratio. It was found that good reliability can be obtained by forming the shape. Further, it has been found that an electronic component mounted in an area array can be obtained by mounting an element component having two or more electrodes on the electrode connecting bump and heat-curing the component component, which has been completed.

That is, the present disclosure relates to:
[1] A paste composition containing (A) a thermosetting compound, (B) a radical initiator, (C) silver particles, and (D) silver powder, wherein the component (C) and the component (D) are described. ) The total content with the components is 85 to 95% by mass of the whole 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 viscosity ratio at 25 ° C. (viscosity at 2 rpm). A paste composition having a viscosity (viscosity of / 20 rpm) of 3 to 6.
[2] The (A) thermosetting compound contains (A1) epoxidized polybutadiene and (A2) a (meth) acrylic acid ester compound or a (meth) acrylamide compound having a hydroxy group, and the (A1) component. The compounding ratio of the compound (A2) and the component (A2) is 5:95 to 55:45, the thickness or minor axis of the silver particles (C) is 1 to 200 nm, and the average particle size of the silver powder (D) is. The paste composition according to the above [1], which is larger than 0.2 μm and 20 μm or less, and the content ratio of the component (C) to the component (D) is 10:90 to 50:50 in terms of mass ratio. ..
[3] The paste composition according to the above [1] or [2], wherein the component (C) contains (C1) plate-type silver particles, and the component (D) contains (D1) flaky silver powder.
[4] The component (C) further contains (C2) spherical silver particles, and the content ratio of the component (C1) to the component (C2) is 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 having a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed on a substrate, and each gap is 50. A process of printing m × n (m and n are 10 to 1000 independently of each other) to form an array at ~ 200 μm, and element components having two or more electrodes arranged side by side on the bump. A method of manufacturing an electronic component device having a mounting process.

According to the present disclosure, it is possible to provide a paste composition having good adhesion and conductivity, and an electronic component having 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 provided, each having a gap of 50 to 200 μm, and m vertical × n horizontal (m, n are: Even if they are formed independently in an array of 10 to 1000), they do not get wet and spread during reflow unlike solder paste, so that a group of highly reliable bumps is formed without a risk of short circuit between bumps. can do.

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

<Paste composition>
One aspect 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, and yields. The values are 100 to 200 Pa, the viscosity at a rotation speed of 2 rpm is 20 to 60 Pa · s, and the chixo ratio (viscosity at 2 rpm / viscosity at 20 rpm) at 25 ° C. is 3 to 6. 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 (A) thermosetting compound used in the present embodiment is not particularly limited, but is (A1) epoxidized polybutadiene and / or (A2) a (meth) acrylic acid having a hydroxy group. It may be an ester compound or a (meth) acrylamide compound.
The (A1) epoxidized polybutadiene used in the present embodiment is a compound obtained by epoxidizing polybutadiene, 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, the workability of the paste composition becomes good, and when it is 500 g / eq or less, the adhesive strength at the time of heat can be improved.
The epoxy equivalent was determined by the perchloric acid method. As the (A1) epoxidized polybutadiene, one having a hydroxyl group in the molecule may be used.

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

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

The (meth) acrylic acid ester compound or (meth) acrylamide compound having a (A2) hydroxy group used in the present embodiment is a (meth) acrylate 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. As the (meth) acrylate having a hydroxy group, 0.5 to 5 times the molar amount of acrylic acid ester or acrylic acid is usually used with respect to the polyol compound.

Further, (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. In the method for producing (meth) acrylamide by reacting a (meth) acrylic acid ester with an amine compound, amine, cyclopentadiene, alcohol, etc. are used because the double bond of the (meth) acrylic acid ester is extremely reactive. It is common to add a protecting group to the double bond in advance and heat it after the completion of amidation to remove the protecting group.

By including the hydroxy group in the (meth) acrylic acid ester compound or the (meth) acrylamide compound, the sinterability due to the reducing effect is promoted at the time of electrode formation, and the adhesiveness is improved.

Further, the hydroxy group referred to here is an alcoholic group in which the hydrogen atom of the aliphatic hydrocarbon group is substituted. The content of the hydroxy group may be 1 to 50 in one molecule. When the content of the hydroxy group is within the above range, the sinterability is not hindered by excessive curing, and the sinterability can be promoted.

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

（式中、Ｒ^１は水素原子又はメチル基を表し、Ｒ^２は炭素数１〜１００の２価の脂肪族炭化水素基又は環状構造を持つ脂肪族炭化水素基を表す。）

(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.)

（式中、Ｒ^１及びＲ^２はそれぞれ前記と同じものを表す。）

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

（式中、Ｒ^１は前記と同じものを表し、ｎは１〜５０の整数を表す。）

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

（式中、Ｒ^１及びｎはそれぞれ前記と同じものを表す。）

(Wherein, R ¹ and n represent the same meanings as respectively defined above.)

As the (meth) acrylic acid ester compound or the (meth) acrylamide compound having the (A2) hydroxy group, the compounds represented by the above general formulas (1) to (4) may be used alone or in combination of two or more. Can be used. ^{The carbon number of R 2} in the general formulas (1) and (2) may be 1 to 100 or 1 to 36. The number of carbon atoms of R ² sinterability is not inhibited by the curing excessive in said range.

Further, the blending ratio of the component (A1) and the component (A2) may be (A1) :( A2) = 5: 95 to 55:45 in terms of mass ratio, and 15:85 to 50: It may be 50. When each component of the component (A1) and the component (A2) is within the above range, the adhesion of the electronic component is good and the connection resistance is suppressed to be 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, good connection resistance is obtained.

As the thermosetting compound (A), a thermosetting compound other than the components (A1) and (A2) can also be used. Examples of the thermosetting compound that can be used here include an epoxy resin, a bismaleimide resin, a polybutadiene resin (excluding the component (A1)), a phenol resin, and the like. However, the thermosetting compound other than the component (A1) and the component (A2) may be 20% by mass or less, or 10% by mass or less, when the (A) thermosetting compound is 100% by mass. You may.

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

(B) Radical Initiator The (B) radical initiator used in the present embodiment is not particularly limited as long as it is a polymerization catalyst usually used for radical polymerization.

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

Specific examples of the (B) radical initiator satisfying the above conditions include, for example, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, t-butylperoxyneodecanoate, and dicumyl peroxide. And so on. These may be used alone or in combination of two or more in order to control the curability.

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

(C) Silver particles The (C) silver particles used in the present embodiment are not particularly limited, but the thickness or minor axis of the (C) silver particles may be 1 to 200 nm, and may be 1 to 100 nm. You may. (C) When the thickness or minor axis 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 minor axis of the silver particles (C) is measured by data processing an observation image acquired by a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

Examples of the shape of the silver particles (C) include a spherical shape, a plate type, a dendritic shape, a rod shape, and a wire shape. Here, when the shape of the silver particles (C) is a plate type, the thickness may satisfy the above range, and when the shape is spherical, dendritic, rod-shaped, or wire-shaped, the cross-sectional diameter thereof is sufficient. It suffices that the shortest diameter (minor diameter) in is satisfied with the above range. Here, in the present disclosure, the thickness of the plate-shaped silver particles means the minimum distance between a pair of planes.
Examples of the (C) silver particles include (C1) plate-type silver particles and (C2) spherical silver particles.

As the silver particles (C), one type may be used, or two types may be used in combination. When two types of (C) silver particles are used in combination, (C1) plate-type silver particles and (C2) spherical silver particles may be used in combination. The content ratio of the (C1) plate-type silver particles to the (C2) spherical silver particles may be (C1) :( C2) = 100: 0 to 50:50, and 100: 0 to 70 in terms of mass ratio. : 30 may be used. The paste composition of the present embodiment contains the component (C1) in an amount of 50% by mass or more, so that the thixo ratio is in the range described later, the shape retention after printing is stable, and a plurality of electrode connection bumps are formed at a narrow pitch. Good insulation can be obtained even when printed.

Unlike spherical nanoparticles, the (C1) plate-type silver particles are plate-shaped particles having a uniform thickness obtained by growing one metal crystal plane large, and generally have a size on the order of microns. It has a thickness of about several nanometers and has shapes such as a triangular plate, a hexagonal plate, and a truncated triangular plate. Further, the upper surface in the thickness direction may be widely covered with the [111] plane.
(C1) Since the plate-type silver particles tend to be stacked in the minor axis direction, m vertical × n horizontal (m and n are independently 10 to 1000) electrode connection bumps are printed in an array. There is an advantage that the variation in bump height can be reduced. In addition, there is an advantage that the connection resistance value after curing of the paste composition can be lowered.

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

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

(C1) The thickness measured from [n + 1] (n + 1 is, for example, about 50 to 100) observation images of plate-type silver particles are arranged in order from thick to thin, and the range (maximum thickness: x) is arranged. _1. Minimum thickness: x _{n + 1} ) is divided into n, and the sections of each thickness are [x _j , x _{j + 1} ] (j = 1, 2, ..., N). The division in this case is an 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.

Further _{, assuming that r j} (j = 1, 2, ..., N) is _{a relative quantity (difference%) corresponding to the interval [x j} , x _{j + 1} ] and the total of all intervals is 100%, it is a logarithmic scale. The average value μ above can be calculated by the following formula.

Since μ is a numerical value on a logarithmic scale and has no unit as thickness, 10 ^μ, that is, 10 μ power is calculated in order to return to the unit of thickness. This 10 ^μ is the number average thickness.

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

(C1) Plate-type silver particles can be self-sintered at 100 to 250 ° C. By containing the silver particles that are self-sintered at 100 to 250 ° C. in this way, the fluidity of the silver particles during thermosetting is improved, and as a result, the number of contacts between the silver particles is increased and the area of the contacts is increased. Is increased, and the conductivity is significantly improved. Since the lower the self-sintering temperature is, the better the sinterability is, the sintering temperature of the (C1) plate-type silver particles may be 100 to 200 ° C.
Here, self-sintering means that sintering is performed by heating at a temperature lower than the melting point without applying pressure or additives.

Examples of such (C1) plate-type silver particles include M612 (trade name; center particle diameter 6 to 12 μm, particle thickness 60 to 100 nm, melting point 250 ° C.) and M27 (trade name; center) manufactured by Toxen Industries, Ltd. Particle size 2-7 μm, particle thickness 60-100 nm, melting point 200 ° C.), M13 (trade name; center particle size 1-3 μm, particle thickness 40-60 nm, melting point 200 ° C.), N300 (trade name; center particle size 0. 3 to 0.6 μm, particle thickness 50 nm or less, melting point 150 ° C.) and the like. These plate-type silver particles may be used alone or in combination. In particular, in order to improve the filling rate, the (C1) plate-type silver particles are, for example, among the above-mentioned plate-type silver particles, silver particles having a relatively large particle size such as M27 and M13 have a particle size such as N300. Small ones may be used in combination.

(C1) Plate-type silver particles 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 in the above 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 the BET one-point method by 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. The (C2) spherical silver particles are usually formed by providing a coating layer made of an organic compound on the metal surface of the silver particles, or by dispersing the silver particles in the organic compound. In such a form, since the contained silver particles can be prevented from directly contacting their metal surfaces, it is possible to suppress the formation of agglomerates of silver particles, and the silver particles are individually dispersed. Can be held at.
The average particle size of the (C2) spherical silver particles is measured by data processing an observation image acquired by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Further, the average particle size of the (C2) spherical silver particles may be within the range of the thickness or the minor axis of the (C) silver particles described above. The average particle size is calculated as the number average particle size of the particle size measured from 50 to 100 observation 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 that disperses the (C2) spherical silver particles is an organic compound having nitrogen, carbon, or oxygen having a molecular weight of 20,000 or less as constituent elements, specifically, amino. An organic compound having a functional group such as a group or a carboxy group is used.
Examples of the organic compound containing a carboxy group used here include one or more organic compounds selected from organic carboxylic acids having a molecular weight of 110 to 20,000, and examples thereof include hexanoic acid, heptanic acid, octanoic acid, and nonane. Examples thereof include carboxylic acids such as acids, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, eicosanoic acid, docosanoic acid, 2-ethylhexanoic acid, oleic acid, linoleic acid, linolenic acid and polyethylene oxide terminal dipropionic acid. Further, as the organic compound, a carboxylic acid derivative of the above-mentioned carboxylic acid can also be used.

Examples of the organic compound having an amino group used here include alkylamines, butylamines, methoxyethylamines, 2-ethoxyethylamines, hexylamines, octylamines, 3-butoxypropylamines, nonylamines and dodecyls. Primary amines such as amines, hexadodecylamines, octadecylamines, cocoamines, tallowamines, tallowamine hydroxides, oleylamines, laurylamines, stearylamines, and 3-aminopropyltriethoxysilane, dicocoamines, dihydrogenated tallowamines, and distearyls. Secondary amines such as amines, as well as tertiary amines such as dodecyldimethylamine, didodecylmonomethylamine, tetradecyldimethylamine, octadecyldimethylamine, cocodimethylamine, dodecyltetradecyldimethylamine, and trioctylamine, and others. Examples thereof include diamines such as naphthalenediamine, stearylpropylenediamine, octamethylenediamine, nonanediamine, terminal diamine polyethylene oxide, triamine-terminal polypropylene oxide, and diamine-terminal polypropylene oxide.

When the molecular weight of the organic compound that coats or disperses the (C2) spherical silver particles is 20,000 or less, the organic compound is likely to be desorbed from the surface of the silver particles, and after the paste is fired, it is contained in the cured product. The organic compound is less likely to remain, and as a result, conductivity can be enhanced. 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, the aggregation of silver particles is small, and when it is 10% by mass or less, the organic compound can be prevented from remaining in the cured product after firing. As a result, the conductivity and thermal conductivity are improved.

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

Examples of the shape of the silver powder (D) include flakes, spheres, resins, rods, wires, and plates.
Examples of the (D) silver powder include (D1) flake-shaped silver powder and (D2) spherical silver powder.
As the silver powder (D), one type may be used, or two types may be used in combination.

The (D) silver powder may be used in combination with (D1) flake-shaped silver powder and (D2) spherical silver powder.
The content ratio of the component (D1) to the component (D2) may be (D1) :( D2) = 50:50 to 100: 0 in terms of mass ratio. When the paste composition of the present embodiment contains 50% by mass or more of the component (D1), the yield value is in the range described later and the plate release property is good. Therefore, a plurality of electrode connection bumps are narrowed in an array. Even when printing at a pitch, short circuits between bumps do not occur.

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

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 with respect to 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 inferior, and if it exceeds 95% by mass, the adhesiveness may be inferior.

(E) Solvent The paste composition of the present embodiment may further contain a solvent. The solvent used in this embodiment may be an alcohol or an 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.
The solvent (E) may be an alcohol solvent having a boiling point of 200 ° C. or higher from the viewpoint of having high solubility of the resin and making coating unevenness due to volatilization of the solvent less likely to occur. Examples of the alcohol solvent having a boiling point of 200 ° C. or higher include diethylene glycol, triethylene glycol, 1,3-butanediol, glycerin, benzyl alcohol, dipropylene glycol, 1,4-butanediol, and 2,2,4-trimethyl1. , 3-Pentanediol monoisobutyrate, ethylene glycol mono-2-ethylhexyl ether, dihydroterpineol, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, tarpineol, diethylene glycol butylmethyl ether, isodecanol, isotridecanol or ethylene glycol mono Hexyl ether and the like can be mentioned.

The content of the solvent (E) may be 0.1 to 10% by mass with respect to the entire paste composition from the viewpoint of workability. 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 later.

In addition to the above components, the paste composition of the present embodiment contains a curing accelerator, rubber, and silicone, which are generally blended in this type of composition, if necessary, as long as the effects of the present embodiment are not impaired. Such as a low stress agent, a coupling agent such as a titanate coupling agent, an adhesion imparting agent, a pigment, a dye, an antifoaming agent, a surfactant, a diluent and the like can be appropriately contained. Each of these additives may be used alone or in combination of two or more.

The total content of the 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)
In the paste composition of the present embodiment, first, the above-mentioned components (A) to (D), additives such as a coupling agent, and a solvent, which are blended as necessary, are sufficiently mixed. Next, in the paste composition of the present embodiment, the mixed resin composition is kneaded by a disperse, a kneader, a three-roll mill or the like. Finally, the paste composition of the present embodiment can be prepared by defoaming the kneaded resin composition.

(Yield value of paste composition)
The paste composition of the present embodiment has a yield value of 100 to 200 Pa and may be 120 to 180 Pa. If the yield value is less than 100 Pa, the stability at the time of mounting is inferior, and the reliability of the obtained electronic component may be lowered. On the other hand, if the yield value exceeds 200 Pa, the leveling property at the time of heating and melting may decrease, and the reliability of the obtained electronic component may decrease. Further, when the yield value is within the above range, the plate release property is good, and an electronic component 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 make the paste composition flow, and is defined as a load force or a shearing force at the time when the paste composition starts to flow.
The yield value can be obtained by, for example, measuring the shear stress at an arbitrary shear rate using an E-type viscometer (3 ° cone) and performing a Casson plot of the shear rate and the shear stress. Specifically, it can be measured by the method described in Examples.

(Viscosity of paste composition)
The paste composition of the present embodiment has a viscosity of 20 to 60 Pa · s at a rotation speed of 2 rpm, and may be 20 to 50 Pa. If the viscosity is less than 20 Pa · s, the wett spread during printing becomes too large, and the reliability of the obtained electronic component may decrease. On the other hand, if the viscosity exceeds 60 Pa · s, the mountability of electronic components may deteriorate. Further, when the viscosity is in the above range, the variation in the height of the print bump 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.

(Chixosis of paste composition)
The paste composition of the present embodiment has a thixo ratio (viscosity of 2 rpm / viscosity of 20 rpm) at 25 ° C. of 3 to 6, and may be 4 to 5. If the chixo ratio is less than 3, the wett spread during printing may become too large and the reliability of the obtained electronic component may decrease. On the other hand, if the chixo ratio exceeds 6, the mountability of electronic components may deteriorate. Further, if the chixo ratio is within the above range, there is no possibility of a short circuit due to wetting and spreading even if a plurality of bumps are printed.
The thixo 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 the present embodiment has good adhesion and conductivity, and unlike solder paste, it does not get wet and spread during reflow, so that there is no possibility of a short circuit occurring between bumps, and the bumps have good reliability. A group can be formed. Further, by using the paste composition of the present embodiment, it is possible to provide an electronic component having excellent reliability.

<Manufacturing method of electronic parts>
In the method for manufacturing an electronic component device of the present embodiment, silver bumps having a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed on a substrate by using the above-mentioned paste composition, and the gaps between them are 50 to 200 μm. , M vertical × n horizontal (m and n are independently 10 to 1000) to form an array, and element components having two or more electrodes are mounted side by side on the bump. Has.
By using the paste composition of the present embodiment, good leveling property can be obtained for the mounted element component.

The array shape means a state in which element parts are arranged in a plurality of rows and columns according to a determined pattern, and the intervals in the row direction and the column direction are the same or different. It is a staggered arrangement such as.
Element components are components used in electronic circuits, including chips such as MEMS, semiconductor elements, resistors and capacitors, and semiconductor elements include discrete semiconductors such as transistors, diodes, LEDs and thyristors, as well as ICs and LSIs. Integrated circuits are included. LEDs include so-called mini LEDs and micro LEDs.

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

As a method of forming silver bumps on the substrate at equal intervals, a known method such as a stamping method, a dispensing method, or a printing method can be used. The printing plate may use a metal mask having holes in the metal plate.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these examples.

(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 Corporation, trade name: JP-200, molecular weight 2,200, epoxy equivalent 230 g / eq)
(A2) Thermosetting compound: Hydroxyethyl acrylamide (manufactured by KJ Chemicals Co., Ltd., trade name: HEAA (registered trademark))

[(B) Radical initiator]
-Dikumil Peroxide (manufactured by NOF CORPORATION, trade name: Park Mill (registered trademark) D; decomposition temperature in rapid heating test: 126 ° C)

[(C) Silver particles]
(C1) Plate-type silver particles: M13 (trade name, manufactured by Toxen Industries, Ltd .; center particle diameter: 2 μm, thickness: 50 nm or less)
The central particle size of the (C1) plate-type silver particles has an integrated volume of 50% in the particle size distribution measured using a laser diffraction type particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name: SALAD-7500 nano). It was determined from the particle size (50% particle size, D50).
The thickness of the (C1) plate-type silver particles was calculated as an average value of the particle thicknesses measured from 50 observation images of the (C1) plate-type silver particles acquired by a transmission electron microscope (TEM).
(C2) Spherical silver particles: Ag nano powder-1 (trade name, manufactured by DOWA Electronics Co., Ltd., average particle size: 20 nm)
The average particle size of the (C2) spherical silver particles was calculated as the number average particle size of the particle sizes measured from 50 observation images of the (C2) spherical silver particles acquired by a transmission electron microscope (TEM).

[(D) Silver powder]
(D1) Flaky silver powder: TC-506C (trade 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 Powder Industry Co., Ltd., average particle size: 2.5 μm)
The average particle size of the silver powder (D) is a particle size (integrated volume of 50%) measured using a laser diffraction type particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name: SALAD-7500 nano). It was determined from 50% particle size, D50).

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

<Evaluation method>
(1) Viscosity A 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 type rotor: 3 ° × R17.65). Was measured.

(2) Chixo ratio Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate type rotor: 3 ° x R17.65), the rotation speed is 2 rpm and 20 rpm at 25 ° C. 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 taken as the ticko ratio.

(3) Yield value Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate type rotor: 3 ° x R17.65), the shear rate is 1 at a temperature of 25 ° C. 1 / s), 2 (1 / s), 4 (1 / s), 10 (1 / s), 20 (1 / s), 40 (1 / s), 100 (1 / s), 200 (1) The shear stress of / s) was measured. The shear rate and the shear stress were Casson-plotted, and the yield value was calculated.

(4) Adhesiveness at room temperature Adhesion A 0.25 mm × 0.1 mm LED is heated at 200 ° C. for 1 hour to bond it to a print evaluation substrate using the paste composition, and then an adhesive strength measuring device manufactured by Seishin Shoji Co., Ltd. is used. The adhesive strength at 25 ° C. was measured using.

(5) Adhesion during heat A 1 mm × 1 mm LED chip was mounted on a silver-plated frame using a paste composition, and heat-cured at 200 ° C. for 60 minutes in an oven. The obtained electronic component was laterally pressed 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 the time of fracture was defined as the fixing strength (N).

(6) Volume resistivity The paste composition was applied to a glass substrate (thickness 1 mm) to a size of 5 mm × 50 mm and a thickness of 30 μm by a screen printing method, and cured at a temperature of 200 ° C. for 60 minutes. The obtained wiring was evaluated by the following evaluation criteria by measuring the electrical resistance by the 4-terminal method using a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product name "MCP-T600").
[Evaluation criteria]
〇: 1 × 10 ^-5 Ω ・ cm or less ×: 1 × 10 ^-5 Ω ・ cm or more

(7) Mounting Evaluation (7-1) Printability On the print evaluation substrate, 40 × 50 electrode groups were formed at 0.1 mm intervals using 0.1 mm electrodes. A connection bump having a diameter of 60 μm and a thickness of 20 μm was printed on the electrode 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 △: Some blurring or bleeding, but there is no problem in practical use ×: Poor shape or defect

(7-2) Reliability After mounting 1000 LEDs of 0.25 mm × 0.1 mm having two electrodes on a print evaluation substrate, 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]
〇: No short circuit occurred ×: Short circuit occurred In Comparative Examples 1, 2 and 4, the reliability test was not performed 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 satisfying a yield value of 100 to 200 Pa, a viscosity of 20 to 60 Pa · s at a rotation speed of 2 rpm, and a thixo ratio (viscosity of 2 rpm / viscosity of 20 rpm) at 25 ° C. It was confirmed that all of them have good adhesion, low volume resistivity, and excellent mountability.
On the other hand, in Comparative Example 1 in which the viscosity at a rotation speed of 2 rpm exceeds 60 Pa · s and 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 the minute bumps is inferior and the connection is made. A shape defect or a defect occurred due to the printing blur of the bump. Further, in Comparative Example 1 and Comparative Example 4 in which the chixo ratio was less than 3, the volume resistivity was as high as 1 × 10 ^-5 Ω · cm or more. Further, in Comparative Example 3 in which the yield value was 100 Pa and the viscosity at a rotation speed of 2 rpm was less than 20 Pa · s, a short circuit which was considered to be due to the wet spread of the paste composition occurred.

Claims (5)

A paste composition containing (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.
A paste composition having a yield value of 100 to 200 Pa, a viscosity of 20 to 60 Pa · s at a rotation speed of 2 rpm, and a thixo ratio (viscosity of 2 rpm / viscosity of 20 rpm) at 25 ° C. The (A) thermosetting compound contains (A1) epoxidized polybutadiene and (A2) a (meth) acrylic acid ester compound or a (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 thickness or minor axis of the (C) silver particles is 1 to 200 nm, and the average particle size of the (D) silver powder is larger than 0.2 μm and 20 μm or less.
The paste composition according to claim 1, wherein the content ratio of the component (C) to the component (D) is 10:90 to 50:50 in terms of mass ratio. The paste composition according to claim 1 or 2, wherein the component (C) contains (C1) plate-type silver particles, and the component (D) contains (D1) flaky silver powder. According to claim 3, the component (C) further contains (C2) spherical silver particles, and the content ratio of the component (C1) to the component (C2) is 100: 0 to 50:50 in terms of mass ratio. The paste composition described. Using the paste composition according to any one of claims 1 to 4, silver bumps having a diameter of 50 to 200 μm and a height of 10 to 50 μm are formed on a substrate, each having a gap of 50 to 200 μm, and a length m. An electron having a step of printing x horizontal n (m and n are 10 to 1000 independently of each other) to form an array, and a step of arranging and mounting element components having two or more electrodes on the bump. Manufacturing method of parts equipment.