JP2021141068A - Solder containing conductive composition and method for manufacturing electronic substrate - Google Patents

Abstract

To provide a conductive composition capable of forming a bond having high shear strength even when exposed to a high temperature.SOLUTION: A solder containing conductive composition includes conductive particles including a solder powder and a flux composition. The conductive particles comprises: (A) a solder powder including tin and having a melting point of 130°C or more and 230°C or less; (B) first metal particles spherical, having an average particle size of less than 1 μm and a melting point of 300°C or more, incorporated into an intermetallic compound with the (A) component when solder-bonding and capable of enhancing the melting point of the intermetallic compound; and (C) second metal particles flake-like and 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 mixture amount of the (B) component is 5 mass% or more and 50 mass% or less to 100 mass% of the total amount of the (B) component and the (C) component, and the flux composition includes (D) an activator.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a conductive composition and 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. By using a high melting point solder alloy, a bond having high shear strength can be formed even when exposed to a high temperature. Examples of the refractory solder alloy include tin-lead solder alloys, tin-lead-antimon solder alloys, and lead-silver solder alloys. Since all of these refractory solder alloys contain lead, their use tends to be restricted due to environmental considerations.
Therefore, a solder alloy that is a high melting point solder alloy and does not contain lead is required. For example, it contains 6% by mass to 70% by mass of tin and less than 50% by mass of copper, and the balance is substantially antimony. A solder alloy comprising the above has been proposed (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2003-290976

However, the solder alloy described in Patent Document 1 is not sufficient in terms of solder wettability with respect to copper. On the other hand, it has also been proposed to join a power semiconductor device and an electrode by 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 a high temperature (for example, 250 ° C. or higher, or 270 ° C. or higher), and a method for manufacturing an electronic substrate using the conductive composition. The purpose is.

In order to solve the above problems, the present invention provides the following methods for producing a conductive composition and an electronic substrate.
The solder-containing conductive composition of the present invention contains conductive particles containing solder powder and a flux composition, and the conductive particles contain (A) tin and have a melting point of 130 ° C. or higher. Solder powder having a temperature of 230 ° C. or lower and (B) spherical, having an average particle diameter of less than 1 μm and having a melting point of 300 ° C. or higher, are intermetallic with the component (A) at the time of solder joining. First metal particles that can be incorporated into a compound and can raise the melting point of this intermetallic compound, and (C) flakes, an average particle size of 2 μm or more and 20 μm or less, and a melting point of 300 ° C. or more. It contains two metal particles, and 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). , The flux composition is characterized by containing (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 large. It is preferably 10 μm or more and 30 μm or less.
In the conductive composition of the present invention, the blending amount of the component (A) is preferably 20% by mass or more and 70% by mass or less with respect to 100% by mass of the 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 preferable.
In the conductive composition of the present invention, the shape of the component (C) is preferably flakes.

The method for manufacturing an electronic substrate of the present invention is a method for manufacturing an electronic substrate using the conductive composition of the present invention, which comprises a coating step of applying the conductive composition onto an electrode of a wiring board. A mounting step of mounting an electronic component on the conductive composition and a joining step of joining the electrode and the electronic component by heating at a temperature higher than the melting point of the component (A) are provided. It is a method characterized by.

According to the conductive composition of the present invention, the reason why a bond having high shear strength can be formed even when exposed to a high temperature is not always clear, but the present inventors presume as follows.
That is, in the conductive composition of the present invention, the solder powder containing (A) tin and having a melting point of 130 ° C. or higher and 230 ° C. or lower is not only the wiring of the electronic substrate and the electrodes of the electronic parts, 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 more. Including and, a solder joint is formed. By this solder joint, the resistance value of the joint portion can be sufficiently lowered. Further, at the time of solder bonding, an intermetallic compound is formed between the solder and the metal, but since the component (B) is fine particles having an average particle diameter 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. Then, a plurality of particles of the component (C) having a melting point of 300 ° C. or higher are bonded to at least a part 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 part is formed. Since this columnar portion has a melting point of 300 ° C. or higher, even if the columnar portion is exposed to a high temperature of 300 ° C. and the component (A) around the columnar portion melts, the columnar portion does not melt and the shear strength is increased. Can be maintained. As described above, the present inventors presume that the above-mentioned effect of the present invention is achieved.

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 a high temperature, and a method for manufacturing an electronic substrate using the conductive composition.

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

[(A) component]
The solder powder (A) 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. The term "tin as the 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). Examples of the second element of this alloy include silver (Ag), copper (Cu), zinc (Zn), bismuth (Bi), indium (In) and antimony (Sb). Further, other elements (third element and later) may be added to this alloy as needed. Other elements include copper, silver, bismuth, indium, antimony, cobalt (Co), chromium (Cr), nickel (Ni), germanium (Ge), iron (Fe) and aluminum (Al).
The component (A) is preferably lead-free solder powder. Here, the lead-free solder powder refers to a solder metal or alloy powder to which lead is not added. However, it is permissible for lead to be present as an unavoidable impurity in the lead-free solder powder, but in this case, the amount of lead is preferably 300 mass ppm or less.

Specific examples of the lead-free solder powder include Sn-Ag, Sn-Ag-Cu, Sn-Cu, Sn-Ag-Bi, Sn-Bi, Sn-Ag-Cu-Bi, Sn-Sb, and 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 can be mentioned. .. Among these, from the viewpoint of the strength of the solder joint, a Sn—Ag—Cu based solder alloy is preferable, and a 96.5 Sn / 3Ag / 0.5Cu solder alloy is particularly preferable. The melting point of the Sn—Ag—Cu-based solder is usually 200 ° C. or higher and 230 ° C. or lower. Among these, from the viewpoint of low melting point, Sn—Bi-based solder alloys are preferable, and 42Sn / 58Bi solder alloys are particularly preferable. The melting point of the Sn—Bi-based solder is usually 130 ° C. or higher and 170 ° C. or lower. When such a low melting point solder powder is used, the reflow temperature can be lowered, so that it can be applied to a wiring substrate having a low glass transition temperature, and the heat load on electronic components can be reduced.

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

The blending amount of the 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, and 40% by mass with respect to 100% by mass of the conductive particles. It is particularly preferable that it is% or more and 60% by mass or less. When the blending amount of the component (A) is at least the above lower limit, the solder meltability can be further improved. On the other hand, if the blending amount of the component (A) is not more than the upper limit, the shear strength at high temperature can be further improved.

[(B) component]
The first metal particles (B) used in the present 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 the component (B) is 1 μm or more, it cannot be incorporated into the intermetallic compound in the solder bonding. Further, if the melting point of the component (B) is less than 300 ° C., the shear strength at a high temperature becomes insufficient.

As the component (B), known metal particles can be appropriately used as long as they are conductive metal particles. Examples of the component (B) include silver particles, copper particles, nickel particles and the like. Among these, silver particles and copper particles are preferable, and silver particles are more preferable. One of these may be used alone, or two or more thereof may be mixed and used.
The shape of the component (B) is not particularly limited, and examples thereof include a spherical shape, a flake shape, and a needle shape. Among these shapes, a spherical shape is preferable from the viewpoint of facilitating incorporation into the intermetallic compound in solder bonding.
The average particle size of the component (B) is preferably 10 nm or more and 900 nm or less, and more preferably 100 nm or more and 800 nm or less, from the viewpoint of facilitating incorporation into the intermetallic compound in the solder bonding.

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

[(C) component]
The second metal particles (C) used in the present 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. When the average particle size of the component (C) is 1 μm or more and 20 μm or less, the shear strength at high temperature can be improved. Further, if the melting point of the component (C) is less than 300 ° C., the shear strength at a high temperature becomes insufficient.

As the component (C), any known metal particle can be used as long as it is a conductive metal particle. Examples of the component (C) include silver particles, copper particles, nickel particles and the like. Among these, silver particles are preferable. One of these may be used alone, or two or more thereof may be mixed and used.
The shape of the component (C) is not particularly limited, and examples thereof include a spherical shape, a flake shape, and a needle shape. Among these shapes, a flake shape is preferable from the viewpoint of further improving the shear strength at high temperature.
The average particle size of the 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 the shear strength at high temperature. Is more preferable.

The blending amount of the component (C) is preferably 15% by mass or more and 60% by mass or less, preferably 17% by mass or more, with respect to 100% by mass of the conductive particles, from the viewpoint of further improving the shear strength at high temperature. 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 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 the component (B) and the component (C) of 100% by mass. Is more preferable, and it is 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. When the blending amount of the component (B) is at least the above lower limit, the shear strength can be further improved. On the other hand, when the blending amount of the component (B) is not more than the above upper limit, the solder meltability and the 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. In addition, the flux composition used in this embodiment contains the activator (D) described below.

The blending 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. It is particularly preferable that it is% or more and 40% by mass or less. When the blending amount of the resin composition is less than 10% by mass (when the blending amount of the conductive particles exceeds 90% by mass), the flux composition as a binder is insufficient, so that the flux composition and the conductive particles are used. On the other hand, when the blending amount of the flux composition exceeds 50% by mass (when the blending amount of the conductive particles is less than 50% by mass), the obtained conductive composition is used. If so, it tends to be difficult to obtain sufficient conductivity.

[(D) component]
Examples of the (D) activator used in the present embodiment include an organic acid, a non-dissociative activator composed of a non-dissociative halogenated compound, and an amine-based activator. One of these activators may be used alone, or two or more thereof may be mixed and used. Among these, from the viewpoint of environmental measures and the viewpoint of suppressing corrosion at the soldered portion, it is preferable to use an organic acid or an amine-based activator (which does not contain halogen), and an organic acid is used. Is more preferable.

Examples of the organic acid include monocarboxylic acids, dicarboxylic acids and the like, as well as 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, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tubercrostearic acid. , Arakidic acid, behenic acid, lignoseric acid, and glycolic acid.
Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeric 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, anis acid, citric acid, picolin acid and the like.

Examples of the non-dissociative activator include non-salt organic compounds in 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 chlorinated compound, brominated compound and fluoride, but any two or all of chlorine, bromine and fluorine may be used. It may be a compound having a covalent bond of. In order to improve the solubility in an aqueous solvent, 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. Examples of the halogenated alcohol include 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, and the like. And brominated alcohols such as tribromoneopentyl alcohols, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and Other compounds similar to these can be mentioned. The carboxylated carboxyl compounds include carboxyl compounds iodide such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranic acid, 2-chlorobenzoic acid, and Examples thereof include carboxyl chloride 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 similar compounds. ..

Amine-based activators include amines (such as polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, and diethylamine, and organic or inorganic acid salts such as aminoalcohol (hydrochloride, sulfuric acid, etc.). And hydrobromic acid, etc.)), amino acids (glycine, alanine, aspartic acid, glutamate, and valine, etc.), amide compounds, and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salts (such as hydrochlorides, succinates, adipates, and sebacates), triethanolamine, monoethanolamine, In addition, hydrobromide of these amines and the like can be mentioned.

The blending amount of the 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 it is by mass% or more and 35% by mass or less. When the blending amount of the component (D) is at least the above lower limit, the solderability can be further improved. On the other hand, when the blending amount of the component (D) is not more than the above upper limit, the flux residue can be sufficiently suppressed.

[(E) component]
The flux composition used in this embodiment preferably further contains (E) a rosin-based resin from the viewpoint of solder meltability and the like. Examples of the (E) rosin-based resin used here include rosins and rosin-based modified resins. Examples of rosins include gum rosin, wood rosin and tall oil rosin. Examples of the rosin-based modified resin include disproportionated rosins, polymerized rosins, hydrogenated rosins (fully hydrogenated rosins, partially hydrogenated rosins, and aliphatic unsaturated monobases such as unsaturated organic acids ((meth) acrylic acids). An unsaturated organic acid that is a modified rosin of an aliphatic unsaturated dibasic acid such as α, β-unsaturated carboxylic acid such as acid, fumaric acid and maleic acid, and an unsaturated carboxylic acid having an aromatic ring such as cinnamic acid). Examples thereof include hydrogenated additives of modified rosin (also referred to as "hydrophobic acid-modified rosin") and derivatives thereof. One of these rosin-based resins may be used alone, or two or more thereof may be mixed and used.

When the component (E) is used, the blending amount thereof is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 30% by mass or less with respect to 100% by mass of the flux composition. It is preferable, and it is particularly preferable that it is 15% by mass or more and 20% by mass or less. When the blending amount of the component (E) is at least the above lower limit, it is possible to improve the so-called solderability, which prevents oxidation of the copper foil surface of the soldered land and makes it easier for the molten solder to get wet on the surface. On the other hand, when the blending amount of the component (E) is not more than the above upper limit, the amount of flux residue can be sufficiently suppressed.

[(F) component]
The flux composition used in the present embodiment preferably further contains (F) a solvent from the viewpoint of printability and the like. As the solvent (F) 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 a solvent include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyldiglycol, 1,5-pentanediol, methylcarbitol, butylcarbitol, octanediol, phenylglycol, and diethylene glycol mono. Examples thereof include hexyl ether, tetraethylene glycol dimethyl ether, diisopropyl sebacate, and dibutyl maleate. One of these solvents may be used alone, or two or more of these solvents may be mixed and used.

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

[(G) component]
The flux composition used in the present embodiment may further contain a (G) thixo agent from the viewpoint of printability and the like. Examples of the (G) thixotropic agent used here include hardened castor oil, polyamines, polyamides, bisamides, dibenzylideneacetone sorbitol, kaolin, colloidal silica, organic bentonite, and glass frit. Among these, polyamides are preferable from the viewpoint of suppressing heating sagging. One of these thixogens may be used alone, or two or more thereof may be mixed and used.

When the component (G) is used, the blending amount thereof is preferably 1% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 8% by mass or less with respect to 100% by mass of the flux composition. preferable. When the blending amount is at least the above lower limit, sufficient thixophilicity can be obtained and sagging can be sufficiently suppressed. Further, if the blending amount is not more than the above upper limit, the tincture property is too high and printing failure does not occur.

[Other ingredients]
In addition to the components (D), (E), (F) and (G), the flux composition used in the present embodiment includes, if necessary, other additives and further resins. Can be added. Examples of other additives include antifoaming agents, antioxidants, modifiers, matting agents, foaming agents, curing accelerators and the like. Examples of other resins include polyimide resins.

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

[Manufacturing method of electronic board]
Next, a method for manufacturing the electronic substrate of the present embodiment will be described.
The method for manufacturing an electronic substrate of the present embodiment is a method for manufacturing an electronic substrate using the above-mentioned conductive composition, and is a method including a coating step, a mounting step, and a joining step described below.

In the coating step, the conductive composition is coated on the electrodes of the wiring board having the wiring.
The wiring board may be a rigid board or a flexible board. Further, the wiring board may be a metal frame. The base material of the wiring board is not particularly limited, and a known base material can be appropriately used.
Wiring metals include copper, silver, and gold. Further, the wiring can be formed by a vapor deposition method, a plating method, or the like.
Further, examples of the coating apparatus include a screen printing machine, a metal mask printing machine, 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 process, electronic components are mounted on the conductive composition.
Examples of electronic components include power semiconductor devices, chips, and package components. According to the conductive composition of the present embodiment described above, a bond having high shear strength can be formed even when exposed to a high temperature. Therefore, even a power semiconductor device whose operating temperature becomes high can be suitably bonded.
Further, as the mounting device, a known mounting device can be used as appropriate.

In the joining step, the electrode and the electronic component are joined by heating at a temperature higher than the melting point of the component (A).
As the heating furnace, a known heating furnace can be appropriately used.
As the heating conditions, the heating temperature is preferably higher than the melting point of the component (A) and 350 ° C. or lower, and 1 ° C. or higher and 320 ° C. or lower than the melting point of the component (A). It is more preferable that the temperature is 5 ° C. or higher and 300 ° C. or lower, which is higher than the melting point of the component (A). When the heating temperature is within the above range, a solder bond can be formed, and there is little adverse effect on the 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, a solder joint can be formed, and there is little adverse effect on the electronic components mounted on the electronic substrate.

According to the method for manufacturing an electronic substrate of the present embodiment as described above, a bond having high shear strength can be formed even when exposed to a high temperature.
The method for producing the conductive composition and the electronic substrate of the present invention is not limited to the above-described embodiment, and modifications and improvements within the range in which the object of the present invention can be achieved 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. The materials used in Examples and Comparative Examples are shown below.
(Ingredient (A))
Solder powder A: Particle size is 10 to 30 μm (average particle size is 20 μm), solder melting point is 217 to 220 ° C, solder composition is 96.5 Sn / 3.0 Ag / 0.5 Cu.
Solder powder B: Particle size is 10 to 30 μm (average particle size is 20 μm), solder melting point is 139 ° C, and solder composition is 42 Sn / 58 Bi.
(Component (B))
First metal particles: silver powder (spherical), average particle size 0.8 μm, trade name “AG2-1C”, manufactured by DOWA (component (C))
Second metal particles A: silver powder (flake-shaped), average particle size is 6.8 μm, trade name "AgC-2242", second metal particles B manufactured by Fukuda Metal Foil Powder Industry Co., Ltd .: silver powder (flake-shaped), average Particle size is 3.5 μm, trade name “FA-8-1”, DOWA second metal particle C: silver powder (flakes), average particle size is 4.4 μm, trade name “AgC-A”, Fukuda Second metal particles D manufactured by Metal Foil Powder Industry Co., Ltd .: Silver-coated copper powder (10% silver), average particle diameter 15 μm, trade name “ACAX-2”, manufactured by Mitsui Metal Mining Co., Ltd. ((D) component)
Activator A: Glutaric acid Activator B: Diglycolic acid (component (E))
Rosin-based resin: Hydrogenated acid-modified rosin, trade name "Pine Crystal KE-604", manufactured by Arakawa Chemical Industry Co., Ltd. ((F) component)
Solvent A: Hexyl diglycol (diethylene glycol monohexyl ether)
Solvent B: Diisopropyl sebacate ((G) component)
Chixo agent: Brand name "Gelall D", manufactured by Shin Nihon Rika Co., Ltd.

[Example 1]
5% by mass of rosin-based 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 chixo agent were put into a container and mixed using a planetary mixer. A flux composition was obtained.
Then, 11% by mass of the obtained flux composition, 30% by mass of the 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 put into three rolls. To prepare a conductive composition by mixing and dispersing.
Then, the obtained conductive composition was printed on the copper plate using a mask (thickness: 100 μm) having a pattern corresponding to the electrodes. After that, an electronic component (copper chip component, size: 2 mm × 2 mm, thickness: 0.5 mm) is mounted, heat-treated at 300 ° C. for 1 minute, and the electronic component is joined to a copper plate to form an evaluation substrate. Was produced.

[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, in Examples 2 to 4 and 6 and Comparative Examples 1 to 5, the electronic components were bonded to the substrate in the same manner as in Example 1 except that the obtained conductive composition was used.
In Example 5, the obtained conductive composition was used, and the electronic components were bonded to the substrate in the same manner as in Example 1 except that the heat treatment conditions were changed at 160 ° C. for 1 minute.

<Evaluation of conductive composition>
The evaluation of the conductive composition (solder meltability, shear strength at 25 ° C., shear strength at 250 ° C.) was carried out by the following method. The results obtained are shown in Table 1.
(1) A sample was obtained by printing a conductive composition on a solder-meltable copper plate using a mask (thickness: 100 μm) having a circular pattern with a diameter of 0.5 mm. This sample was heated at 300 ° C. for 1 minute in a nitrogen atmosphere, cooled to room temperature, and the surface of the sample was observed with a magnifying glass (magnification: 100 times). Then, the solder bondability was evaluated according to the following criteria.
◯: A smooth metallic luster is observed in an area of 90% or more of the whole area.
Δ: A smooth metallic luster is observed in an area of 50% or more and less than 90% of the whole area.
X: A smooth metallic luster is observed in an area of less than 50% of the total area.
(2) The chip component on the shear strength evaluation substrate at 25 ° C. was peeled off with a bond tester (manufactured by Nordson Advanced Technology Co., Ltd.), and the shear strength (unit: N) at that time was measured. 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: Shear strength is 1N or more and less than 10N.
X: Shear strength is less than 1N.
(3) Shear strength at 250 ° C While heating the chip parts on the evaluation board to 250 ° C, peel them off with a bond tester (manufactured by Nordson Advanced Technology), and measure the shear strength (unit: N) at that time. bottom. Then, the shear strength at 250 ° C. was evaluated according to the following criteria.
◯: Shear strength is 10 N or more.
Δ: Shear strength is 1N or more and less than 10N.
X: 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), the solder meltability, the shear strength at 25 ° C, and the shear strength at 250 ° C were determined. Everything turned out to be good. Therefore, according to the conductive composition of the present invention, it was confirmed that a bond having high shear strength can be formed even when exposed to a high temperature (250 ° C.).

The conductive composition of the present invention can be particularly preferably used as a technique for mounting an electronic component on an electronic substrate such as a printed wiring board of an electronic device.

Claims (7)

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 higher and 230 ° C. or lower, and (B) spherical, having an average particle diameter of less than 1 μm and a melting point of 300 ° C. As described above, at the time of solder bonding, the first metal particles which are incorporated into the intermetallic compound with the component (A) and can raise the melting point of the intermetallic compound and (C) flakes are formed. Contains secondary 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 100% by mass of the total amount of the component (B) and the component (C).
A solder-containing conductive composition, wherein the flux composition contains (D) an activator. In the solder-containing conductive composition according to claim 1,
A solder-containing conductive composition, wherein the flux composition further contains (E) a rosin-based resin. In the solder-containing conductive composition according to claim 1 or 2.
A solder-containing conductive composition, wherein the flux composition further contains (F) a solvent. 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 thixo agent. 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 characterized in that the average particle size of the component (A) is 10 μm or more and 30 μm or less. The solder-containing conductive composition according to any one of claims 1 to 5.
A solder-containing conductive composition, wherein the blending 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 manufacturing an electronic substrate using the solder-containing conductive composition according to any one of claims 1 to 6.
A coating step of applying the solder-containing conductive composition onto the electrodes of the wiring board, and
A mounting process for mounting electronic components on the solder-containing conductive composition, and
A method for manufacturing an electronic substrate, which comprises a joining step of joining the electrode and the electronic component by heating at a temperature higher than the melting point of the component (A).