JP7181964B2 - Conductive composition containing solder and method for manufacturing electronic substrate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conductive composition and a method for manufacturing an electronic substrate.

Conventionally, a high-melting point solder alloy having a melting point of 280° C. or higher has been used for joining a power semiconductor element and an electrode. High melting point solder alloys can be used to form joints that have high shear strength even when exposed to high temperatures. High melting point solder alloys include tin-lead solder alloys, tin-lead-antimony solder alloys, and lead-silver solder alloys. These high-melting-point solder alloys all contain lead, and their use tends to be restricted in consideration of the environment.
Therefore, there is a need for a solder alloy that is a high melting point solder alloy and does not contain lead, for example, contains 6% to 70% by weight of tin, less than 50% by weight of copper, and the balance is substantially antimony. A solder alloy consisting of is proposed (for example, Patent Document 1).

JP 2003-290976 A

However, the solder alloy described in Patent Document 1 is not sufficient in terms of solder wettability to copper. On the other hand, it has also been proposed to join a power semiconductor element and an electrode using a silver paste composed of silver powder and a thermosetting resin. However, the method using silver paste has a problem in terms of manufacturing cost.

The present invention provides a conductive composition capable of forming a bond having high shear strength even when exposed to high temperatures (e.g., 250° C. or higher, or 270° C. or higher), and a method for producing an electronic substrate using the same. for the purpose.

In order to solve the above problems, the present invention provides the following conductive composition and method for producing an electronic substrate.
The solder-containing conductive composition of the present invention contains conductive particles containing solder powder and a flux composition, wherein the conductive particles contain (A) tin and have a melting point of 130° C. or higher. (B) a solder powder having a temperature of 230° C. or less, and (B) having a spherical shape, an average particle diameter of less than 1 μm, and a melting point of 300° C. or more; (C) first metal particles that are incorporated into the compound and can increase the melting point of the intermetallic compound; and a bimetallic particle, and the amount of the component (B) is 5% by mass or more and 50% by mass or less with respect to 100% by mass of the total amount of the component (B) and the component (C). , wherein the flux composition contains (D) an activator.

In the conductive composition of the present invention, the component (A) is tin-silver-copper-based or tin-bismuth-based solder alloy silver particles, and the average particle size of the component (A) is It is preferably 10 μm or more and 30 μm or less.
In the electrically conductive composition of the present invention, the amount of component (A) to be blended is preferably 20% by mass or more and 70% by mass or less with respect to 100% by mass of the electrically conductive particles.
In the conductive composition of the present invention, the blending amount of the component (B) is 5% by mass or more and 50% by mass or less with respect to 100% by mass of the total amount of the component (B) and the component (C). is preferably
In the electrically conductive composition of the present invention, the shape of the component (C) is preferably flaky.

A method for manufacturing an electronic substrate of the present invention is a method of manufacturing an electronic substrate using the conductive composition of the present invention, comprising a coating step of coating the conductive composition on an electrode of a wiring substrate; A mounting step of mounting an electronic component on the conductive composition, and a bonding step of heating at a temperature higher than the melting point of the component (A) to bond the electrode and the electronic component. is a method characterized by

The reason why the conductive composition of the present invention can form a bond having high shear strength even when exposed to high temperatures is not necessarily clear, but the present inventors speculate as follows.
That is, in the conductive composition of the present invention, (A) the solder powder containing tin and having a melting point of 130° C. or more and 230° C. or less is used not only for wiring of electronic substrates and electrodes of electronic components, but also (B ) first metal particles having an average particle size of less than 1 μm and a melting point of 300° C. or higher; and (C) second metal particles having an average particle size of 1 μm or more and 20 μm or less and a melting point of 300° C. or higher. to form a solder joint. By this solder joint, the resistance value of the joint can be made sufficiently low. Also, during soldering, an intermetallic compound is formed between the solder and the metal, but since the component (B) is fine particles with an average particle size of less than 1 μm, it is incorporated into the intermetallic compound. Since this intermetallic compound contains a large amount of the component (B), its melting point becomes high. A plurality of particles of the component (C) having a melting point of 300° C. or higher are joined to at least a portion between the wiring of the electronic substrate and the electrode of the electronic component via an intermetallic compound having a high melting point. A columnar portion is formed. This columnar portion has a melting point of 300° C. or higher, so even if it is exposed to a high temperature of 300° C. and component (A) around the columnar portion melts, the columnar portion does not melt and the shear strength increases. can be maintained. The present inventors presume that the effects of the present invention are achieved as described above.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a conductive composition capable of forming a bond having high shear strength even when exposed to high temperatures, and a method for manufacturing an electronic substrate using the same.

[Conductive composition]
First, the conductive composition of this embodiment will be described. The conductive composition of the present embodiment contains conductive particles and a flux composition, which will be described below. The conductive particles also contain (A) solder powder, (B) first metal particles, and (C) second metal particles, which will be described below.

[(A) component]
The (A) solder powder used in this embodiment is a solder powder containing tin and having a melting point of 130° C. or higher and 230° C. or lower. As the solder alloy in this solder powder, an alloy containing tin (Sn) as a main component is preferable. In addition, having tin as a main component means that the content of tin in the component (A) is 50% by mass or more (preferably 70% by mass or more, more preferably 90% by mass or more). In addition, the second elements of this alloy include silver (Ag), copper (Cu), zinc (Zn), bismuth (Bi), indium (In) and antimony (Sb). Furthermore, other elements (third and subsequent elements) may be added to this alloy, if necessary. Other elements include copper, silver, bismuth, indium, antimony, cobalt (Co), chromium (Cr), nickel (Ni), germanium (Ge), iron (Fe) and aluminum (Al).
Component (A) is preferably lead-free solder powder. Here, the lead-free solder powder means powder of solder metal or alloy to which lead is not added. However, the presence of lead as an unavoidable impurity in lead-free solder powder is allowed, but in this case, the amount of lead is preferably 300 ppm by mass or less.

Specific examples of lead-free solder powder include Sn—Ag, Sn—Ag—Cu, Sn—Cu, Sn—Ag—Bi, Sn—Bi, Sn—Ag—Cu—Bi, Sn—Sb, Sn -Zn-Bi, Sn-Zn, Sn-Zn-Al, Sn-Zn-Bi-Al, Sn-Ag-Bi-In, Sn-Ag-Cu-Bi-In-Sb, In-Ag and the like . Among these, Sn--Ag--Cu based solder alloys are preferred from the viewpoint of strength of solder joints, and 96.5Sn/3Ag/0.5Cu solder alloys are particularly preferred. The melting point of the Sn--Ag--Cu solder is usually 200.degree. C. or higher and 230.degree. C. or lower. Among these, from the viewpoint of a low melting point, Sn—Bi based solder alloys are preferred, and 42Sn/58Bi solder alloys are particularly preferred. The melting point of Sn--Bi solder is usually 130.degree. C. or higher and 170.degree. C. or lower. When using such a low-melting-point solder powder, the reflow temperature can be lowered, so that wiring boards with a low glass transition temperature can be used, and the heat load on electronic components can be reduced.

The average particle size of component (A) is preferably 10 μm or more and 30 μm or less, more preferably 15 μm or more and 25 μm or less, from the viewpoint of solder meltability. The average particle size can be measured with a dynamic light scattering particle size measuring device.

The amount of component (A) is preferably 30% by mass or more and 70% by mass or less, more preferably 35% by mass or more and 65% by mass or less, relative to 100% by mass of the conductive particles, and 40% by mass. % or more and 60% by mass or less is particularly preferable. (A) If the compounding quantity of a component is more than the said minimum, solder meltability can be improved further. On the other hand, if the blending amount of component (A) is equal to or less than the above upper limit, the shear strength at high temperatures can be further improved.

[(B) component]
The (B) first metal particles used in this embodiment are metal particles having an average particle diameter of less than 1 μm and a melting point of 300° C. or higher. If the average particle size of component (B) is 1 μm or more, it cannot be incorporated into the intermetallic compound in solder joints. Also, if the melting point of the component (B) is less than 300°C, the shear strength at high temperatures will be insufficient.

As the component (B), known metal particles can be appropriately used as long as they are electrically conductive metal particles. Component (B) includes silver particles, copper particles and nickel particles. Among these, silver particles and copper particles are preferred, and silver particles are more preferred. These may be used individually by 1 type, and may be used in mixture of 2 or more types.
The shape of component (B) is not particularly limited, and may be spherical, flaky, or needle-like. Among these shapes, a spherical shape is preferable from the viewpoint of facilitating incorporation into an intermetallic compound in solder joint.
The average particle size of the component (B) is preferably 10 nm or more and 900 nm or less, more preferably 100 nm or more and 800 nm or less, from the viewpoint of facilitating incorporation into the intermetallic compound in solder joint.

From the viewpoint of shear strength at high temperatures, the amount of component (B) is preferably 3% by mass or more and 40% by mass or less, and 5% by mass or more and 35% by mass or less with respect to 100% by mass of the conductive particles. more preferably, and particularly preferably 6% by mass or more and 30% by mass or less.

[(C) Component]
The second metal particles (C) used in this embodiment are metal particles having an average particle diameter of 1 μm or more and 20 μm or less and a melting point of 300° C. or more. If the average particle size of the component (C) is 1 μm or more and 20 μm or less, the shear strength at high temperatures can be improved. Also, if the melting point of the component (C) is less than 300°C, the shear strength at high temperatures will be insufficient.

As the component (C), known metal particles can be appropriately used as long as they are electrically conductive metal particles. Component (C) includes silver particles, copper particles and nickel particles. Among these, silver particles are preferred. These may be used individually by 1 type, and may be used in mixture of 2 or more types.
The shape of component (C) is not particularly limited, and may be spherical, flaky, or needle-like. Among these shapes, the flake shape is preferable from the viewpoint of further improving the shear strength at high temperatures.
The average particle size of component (C) is preferably 2 μm or more and 15 μm or less, preferably 2 μm or more and 10 μm or less, and 3 μm or more and 7 μm or less, from the viewpoint of further improving shear strength at high temperatures. is more preferred.

The amount of component (C) is preferably 15% by mass or more and 60% by mass or less, preferably 17% by mass or more, relative to 100% by mass of the conductive particles, from the viewpoint of further improving the shear strength at high temperatures. It is more preferably 50% by mass or less, and particularly preferably 20% by mass or more and 45% by mass or less.

In the conductive composition of the present embodiment, the amount of component (B) is 5% by mass or more and 50% by mass or less with respect to 100% by mass of the total amount of components (B) and (C). , more preferably 10% by mass or more and 40% by mass or less, and particularly preferably 15% by mass or more and 30% by mass or less. (B) If the compounding quantity of a component is more than the said minimum, shear strength can be improved further. On the other hand, if the blending amount of the component (B) is equal to or less than the above upper limit, the solder meltability and shear strength can be further improved.

[Flux composition]
The conductive composition of the present embodiment contains the flux composition described below and the conductive particles. Moreover, the flux composition used in the present embodiment contains (D) an activator described below.

The amount of the flux composition is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, and 20% by mass with respect to 100% by mass of the conductive composition. % or more and 40 mass % or less is particularly preferable. When the amount of the resin composition is less than 10% by mass (when the amount of the conductive particles is more than 90% by mass), the flux composition as a binder is insufficient, so that the flux composition and the conductive particles On the other hand, when the amount of the flux composition exceeds 50% by mass (when the amount of the conductive particles is less than 50% by mass), the resulting conductive composition is used. , it tends to be difficult to obtain sufficient conductivity.

[(D) Component]
Examples of the (D) activator used in this embodiment include organic acids, non-dissociative activators comprising non-dissociable halogenated compounds, and amine-based activators. These activators may be used singly or in combination of two or more. Among these, organic acids and amine-based activators (halogen-free) are preferably used from the viewpoint of environmental measures and the viewpoint of suppressing corrosion in soldered parts, and organic acids are used. is more preferable.

Examples of organic acids include monocarboxylic acids, dicarboxylic acids, and other organic acids.
Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, margaric acid, stearic acid, and tuberculostearic acid. , arachidic acid, behenic acid, lignoceric acid, and glycolic acid.
Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid.
Other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

The non-dissociation type activator includes non-salt organic compounds to which halogen atoms are covalently bonded. The halogenated compound may be a compound formed by a covalent bond of each single element of chlorine, bromine and fluorine, such as chloride, bromide and fluoride, but any two or all of chlorine, bromine and fluorine may be may be a compound having a covalent bond of These compounds preferably have a polar group such as a hydroxyl group or a carboxyl group, such as a halogenated alcohol or a halogenated carboxyl compound, in order to improve the solubility in an aqueous solvent. Examples of halogenated alcohols include 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, and brominated alcohols such as tribromoneopentyl alcohol, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and In addition, compounds similar to these may be mentioned. Halogenated carboxyl compounds include iodinated carboxyl compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid, 2-chlorobenzoic acid, and Chlorinated carboxyl compounds such as 3-chloropropionic acid, brominated carboxyl compounds such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid, and other like compounds. .

Amine-based surfactants include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, and diethylamine), and organic or inorganic acid salts such as aminoalcohols (hydrochloric acid, sulfuric acid, and hydrobromic acid)), amino acids (glycine, alanine, aspartic acid, glutamic acid, valine, etc.), amide compounds, and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salts (such as hydrochloride, succinate, adipate, and sebacate), triethanolamine, monoethanolamine, and hydrobromides of these amines.

The amount of component (D) is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, based on 100% by mass of the flux composition. It is particularly preferable that the amount is not less than 35% by mass and not more than 35% by mass. (D) If the compounding quantity of a component is more than the said minimum, solderability can further be improved. On the other hand, if the blending amount of the component (D) is equal to or less than the above upper limit, the flux residue can be sufficiently suppressed.

[(E) Component]
The flux composition used in the present embodiment preferably further contains (E) a rosin-based resin from the viewpoint of solder meltability. The (E) rosin-based resin used here includes rosins and rosin-based modified resins. Rosins include gum rosin, wood rosin and tall oil rosin. Rosin modified resins include disproportionated rosin, polymerized rosin, hydrogenated rosin (completely hydrogenated rosin, partially hydrogenated rosin, and unsaturated organic acid (unsaturated aliphatic monobasic base such as (meth)acrylic acid). aliphatic unsaturated dibasic acids such as α,β-unsaturated carboxylic acids such as fumaric acid and maleic acid, unsaturated carboxylic acids having an aromatic ring such as cinnamic acid, etc.). Examples include hydrogenated modified rosin (also referred to as "hydrogenated acid-modified rosin") and derivatives thereof. These rosin-based resins may be used singly or in combination of two or more.

When component (E) is used, its content is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 30% by mass or less, relative to 100% by mass of the flux composition. It is preferably 15% by mass or more and 20% by mass or less, particularly preferably. When the amount of the component (E) is at least the above lower limit, it is possible to prevent the copper foil surface of the soldering land from oxidizing and make it easier for molten solder to wet the surface, thereby improving the so-called solderability. On the other hand, if the blending amount of the component (E) is equal to or less than the above upper limit, the amount of residual flux can be sufficiently suppressed.

[(F) Component]
From the viewpoint of printability, etc., the flux composition used in the present embodiment preferably further contains (F) a solvent. As the (F) solvent used here, a known solvent can be appropriately used. As such a solvent, it is preferable to use a solvent having a boiling point of 170° C. or higher.
Examples of such solvents include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyldiglycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, octanediol, phenyl glycol, diethylene glycol mono Hexyl ether, tetraethylene glycol dimethyl ether, diisopropyl sebacate, dibutyl maleate, and the like. One type of these solvents may be used alone, or two or more types may be mixed and used.

When component (F) is used, its content is preferably 10% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, based on 100% by mass of the flux composition. It is preferably 40% by mass or more and 50% by mass or less, particularly preferably. If the blending amount of the solvent is within the above range, the viscosity of the conductive composition to be obtained can be appropriately adjusted to an appropriate range.

[(G) Component]
The flux composition used in the present embodiment may further contain (G) a thixotropic agent from the viewpoint of printability. The (G) thixotropic agent used here includes hydrogenated castor oil, polyamines, polyamides, bisamides, dibenzylidene sorbitol, kaolin, colloidal silica, organic bentonite, glass frit and the like. Among these, polyamides are preferable from the viewpoint of suppression of heat sagging. These thixotropic agents may be used singly or in combination of two or more.

When component (G) is used, its content is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 8% by mass or less, relative to 100% by mass of the flux composition. preferable. When the blending amount is at least the above lower limit, sufficient thixotropic properties can be obtained, and sagging can be sufficiently suppressed. Further, if the blending amount is equal to or less than the above upper limit, the thixotropy is too high, and printing defects do not occur.

[Other ingredients]
In addition to the (D) component, (E) component, (F) component and (G) component, the flux composition used in the present embodiment may optionally contain other additives and further resins. can be added. Other additives include antifoaming agents, antioxidants, modifiers, matting agents, foaming agents, curing accelerators, and the like. Other resins include polyimide resins and the like.

[Method for producing conductive composition]
The conductive composition of the present embodiment can be produced by blending the above-described flux composition and the above-described conductive particles in the predetermined ratio and stirring and mixing.

[Method for manufacturing electronic substrate]
Next, a method for manufacturing the electronic substrate of this embodiment will be described.
The method for manufacturing an electronic substrate according to the present embodiment is a method for manufacturing an electronic substrate using the conductive composition described above, and is a method comprising a coating step, a mounting step, and a bonding step, which will be described below.

In the application step, the conductive composition is applied onto electrodes of a wiring substrate having wiring.
The wiring board may be a rigid board or a flexible board. Also, the wiring board may be a metal frame. The base material of the wiring board is not particularly limited, and known base materials can be used as appropriate.
Metals for the wiring include copper, silver, and gold. Also, the wiring can be formed by a vapor deposition method, a plating method, or the like.
Moreover, the application device includes a screen printer, a metal mask printer, a dispenser, a jet dispenser, and the like.
The thickness of the coating film is preferably 10 μm or more and 1000 μm or less, more preferably 30 μm or more and 500 μm or less, and particularly preferably 50 μm or more and 200 μm or less.

In the mounting step, an electronic component is mounted on the conductive composition.
Electronic parts include power semiconductor elements, chips, package parts, and the like. According to the conductive composition of the present embodiment described above, a bond having high shear strength can be formed even when exposed to high temperatures. Therefore, even a power semiconductor element that operates at a high temperature can be suitably bonded.
As the mounting device, a known mounting device can be used as appropriate.

In the bonding step, the electrode and the electronic component are bonded by heating at a temperature higher than the melting point of the component (A).
A known heating furnace can be appropriately used as the heating furnace.
As for the heating conditions, the heating temperature is preferably higher than the melting point of component (A) and 350° C. or lower, and preferably 1° C. or higher than the melting point of component (A) and 320° C. or lower. More preferably, it is higher than the melting point of component (A) by 5°C or more and 300°C or less. If the heating temperature is within the above range, solder joints can be formed, and there is little adverse effect on electronic components mounted on the electronic substrate.
The heating time is preferably 10 seconds or more and 10 minutes or less, more preferably 20 seconds or more and 5 minutes or less, and particularly preferably 30 seconds or more and 2 minutes or less. If the heating time is within the above range, solder joints can be formed, and there is little adverse effect on electronic components mounted on the electronic substrate.

According to the method for manufacturing the electronic substrate of the present embodiment as described above, it is possible to form a bond having a high shear strength even when exposed to high temperatures.
It should be noted that the conductive composition and the method for producing an electronic substrate of the present invention are not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. be.

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Materials used in Examples and Comparative Examples are shown below.
((A) component)
Solder powder A: particle diameter 10-30 μm (average particle diameter 20 μm), solder melting point 217-220° C., solder composition 96.5 Sn/3.0 Ag/0.5 Cu
Solder powder B: particle size 10 to 30 μm (average particle size 20 μm), solder melting point 139° C., solder composition 42Sn/58Bi
((B) component)
First metal particles: silver powder (spherical), average particle size 0.8 μm, trade name “AG-2-1C”, manufactured by DOWA (Component (C))
Second metal particles A: Silver powder (flake shape), average particle size 6.8 μm, trade name “AgC-2242”, manufactured by Fukuda Metal Foil & Powder Co., Ltd. Second metal particle B: Silver powder (flake shape), average Particle diameter is 3.5 μm, trade name “FA-8-1”, DOWA secondary metal particles C: silver powder (flaky), average particle diameter is 4.4 μm, trade name “AgC-A”, Fukuda Second metal particles D manufactured by Metal Foil & Powder Co., Ltd.: Silver-coated copper powder (10% silver), average particle size 15 μm, trade name “ACAX-2”, manufactured by Mitsui Kinzoku Mining Co., Ltd. ((D) component)
Active agent A: glutaric acid Active agent B: diglycolic acid (component (E))
Rosin-based resin: Hydrogenated acid-modified rosin, trade name “Pine Crystal KE-604”, manufactured by Arakawa Chemical Industries, Ltd. ((F) component)
Solvent A: Hexyldiglycol (diethylene glycol monohexyl ether)
Solvent B: diisopropyl sebacate (component (G))
Thixotropic agent: trade name "Gelol D", manufactured by Shin Nippon Rika Co., Ltd.

[Example 1]
5% by mass of rosin resin, 2% by mass of activator A, 8% by mass of activator B, 4% by mass of solvent A, 10% by mass of solvent B, and 1% by mass of thixotropic agent are placed in a container and mixed using a planetary mixer. A flux composition was obtained.
After that, 11% by mass of the resulting flux composition, 30% by mass of solder powder A, 10% by mass of the first metal particles and 30% by mass of the second metal particles A (100% by mass in total) were put into a container, and rolled into a triple roll. A conductive composition was prepared by mixing and dispersing.
Then, the resulting conductive composition was printed on a copper plate using a mask (thickness: 100 μm) having a pattern corresponding to the electrodes. After that, electronic components (copper chip components, size: 2 mm × 2 mm, thickness: 0.5 mm) are mounted, heat treatment is performed at 300 ° C. for 1 minute, the electronic components are bonded to the copper plate, and the evaluation board was made.

[Examples 2 to 6 and Comparative Examples 1 to 5]
A conductive composition was obtained in the same manner as in Example 1, except that each material was blended according to the composition shown in Table 1 below.
Then, for Examples 2 to 4 and 6 and Comparative Examples 1 to 5, electronic components were bonded to substrates in the same manner as in Example 1, except that the obtained conductive compositions were used.
For Example 5, an electronic component was bonded to a substrate in the same manner as in Example 1 except that the obtained conductive composition was used and the heat treatment conditions were changed to 160° C. for 1 minute.

<Evaluation of conductive composition>
The conductive composition was evaluated (solder meltability, shear strength at 25° C., shear strength at 250° C.) by the following methods. Table 1 shows the results obtained.
(1) Solder Meltability A sample was obtained by printing a conductive composition on a copper plate using a mask (thickness: 100 μm) having a circular pattern with a diameter of 0.5 mm. After heating this sample at 300° C. for 1 minute in a nitrogen atmosphere, it was cooled to room temperature and the surface of the sample was observed with a magnifying glass (magnification: 100 times). Then, solderability was evaluated according to the following criteria.
◯: A smooth metallic luster is observed in 90% or more of the total area.
Δ: Smooth metallic luster is observed in 50% or more and less than 90% of the total area.
x: Less than 50% of the total area has a smooth metallic luster.
(2) Shear Strength at 25° C. The chip component on the substrate for evaluation was peeled off with a bond tester (manufactured by Nordson Advanced Technologies, Inc.), and the shear strength (unit: N) at that time was measured. In addition, the measurement was performed at room temperature (25° C.). Then, the shear strength at 25°C was evaluated according to the following criteria.
○: Shear strength is 10 N or more.
Δ: The shear strength is 1N or more and less than 10N.
x: The shear strength is less than 1N.
(3) Shear strength at 250 ° C. While heating the chip parts on the evaluation substrate to 250 ° C., peeled with a bond tester (manufactured by Nordson Advanced Technologies, Inc.), and measured the shear strength (unit: N) at that time. did. Then, the shear strength at 250° C. was evaluated according to the following criteria.
○: Shear strength is 10 N or more.
Δ: The shear strength is 1N or more and less than 10N.
x: The shear strength is less than 1N.

As is clear from the results shown in Table 1, when the conductive composition of the present invention was used (Examples 1 to 6), solder meltability, shear strength at 25 ° C., and shear strength at 250 ° C. All turned out to be good. Therefore, it was confirmed that the conductive composition of the present invention can form a bond having high shear strength even when exposed to high temperature (250° C.).

The conductive composition of the present invention can be particularly suitably used as a technique for mounting electronic components on electronic substrates such as printed wiring boards of electronic equipment.

Claims (7)

A conductive composition containing conductive particles containing solder powder and a flux composition,
The conductive particles are (A) a solder powder containing tin and having a melting point of 130° C. or more and 230° C. or less, and (B) being spherical, having an average particle size of less than 1 μm, and having a melting point of 300° C. That is, at the time of soldering, the first metal particles that can be incorporated into the intermetallic compound with the component (A) and can increase the melting point of the intermetallic compound, and (C) flakes, second metal particles having an average particle size of 2 μm or more and 20 μm or less and a melting point of 300° C. or more;
The blending amount of the component (B) is 5% by mass or more and 50% by mass or less with respect to the total amount of 100% by mass of the component (B) and the component (C),
The amount of the component (C) is 15% by mass or more and 50% by mass or less with respect to 100% by mass of the conductive particles,
The flux composition contains (D) an activator and (E) a rosin-based resin,
The component (D) contains an organic acid,
The amount of the flux composition is 10% by mass or more and 50% by mass or less with respect to 100% by mass of the conductive composition.
A solder-containing conductive composition characterized by: In the solder-containing conductive composition according to claim 1,
A solder-containing conductive composition, wherein the flux composition is a flux composition (excluding thermosetting flux). In the solder-containing conductive composition according to claim 1 or claim 2,
The solder-containing conductive composition, wherein the flux composition further contains (F) a solvent. In the solder-containing conductive composition according to any one of claims 1 to 3,
A solder-containing conductive composition, wherein the flux composition further contains (G) a thixotropic agent. In the solder-containing conductive composition according to any one of claims 1 to 4,
The component (A) is tin-silver-copper-based or tin-bismuth-based solder alloy silver particles, and
A solder-containing conductive composition, wherein the component (A) has an average particle size of 10 μm or more and 30 μm or less. In the solder-containing conductive composition according to any one of claims 1 to 5,
A solder-containing conductive composition, wherein the compounding amount of the component (A) is 20% by mass or more and 70% by mass or less with respect to 100% by mass of the conductive particles. A method for producing an electronic substrate using the solder-containing conductive composition according to any one of claims 1 to 6,
A coating step of coating the solder-containing conductive composition on the electrodes of the wiring substrate;
A mounting step of mounting an electronic component on the solder-containing conductive composition;
and a bonding step of bonding the electrode and the electronic component by heating at a temperature higher than the melting point of the component (A).