JPH1031912A - Solderable electroconductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solderable conductive paste which maintains such fundamental traits as oxidation resistance, anti-migration property, bonding strength, printing performance, and anti-sedimenting property, wherein particularly the solderability is enhanced to the same degree as a copper foil. SOLUTION: A copper alloy powder expressed by Agx Cuy is used, having a region whose silver concentration of the facial part of each particle is higher than the mean silver concentration of particles, where such condition should be met that 0.001<=x<=0.4, 0.6<=y<=0.999, and x+y=1 by atomic ratio. From this powder a conductive paste is formed, which contains 100 parts by wt. copper alloy powder having mean particle size between 5-35μm, one or more sorts of resin binder, a solvent, and 0.001-10 parts by wt. higher aliphatic acid and/or higher aliphatic ester to be added as a solderability improving agent. A coating film is formed with this conductive paste.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste used for a printed wiring material or an electronic component, such as a paper phenol resin substrate, a glass epoxy resin substrate, a paper epoxy resin substrate, an alumina substrate, a glass substrate or a metal substrate. For circuit board, chip resistor electrode, ceramic capacitor external electrode, tantalum capacitor external electrode, aluminum electrolytic capacitor case fixing, hybrid IC, foot connecting parts to through hole, IT
Conductivity that enables direct soldering that can provide a coating film with good conductivity and solderability by applying and curing by screen printing, dipping, transfer, dispenser, etc. for O-glass electrodes etc. The present invention relates to a paste and a conductive coating film thereof. More specifically, it has excellent oxidation resistance and migration resistance on the surface of the coating film, maintains printability, adhesion strength to the substrate, and sedimentation resistance of the conductive powder. The present invention relates to a solderable conductive paste having both excellent solder wettability and high solder erosion resistance, and a conductive coating film formed by applying or printing this paste and then curing.

[0002]

2. Description of the Related Art Generally, conductive pastes have been widely used in industrial applications from the viewpoint of cost advantages due to their wide application area and simplification of processes. Among them, phenolic resin, organic resin binder such as epoxy resin and melamine resin, and conductive paste composed of silver, copper, carbon and other conductive powder and solvent, etc., the material is inexpensive, wide application range It has low adverse effects on other base materials or components due to low-temperature curing.Since circuit formation and electrode formation can be performed without using plating, the process can be simplified and no harmful waste liquid is generated. Therefore, it is a material with a high degree of attention because it can reduce environmental problems.

[0003] Solderable conductive pastes using organic resin binders include silver, copper,
It is known to use silver-plated copper powder, and a combination of these with a solvent and various additives has been devised so as to form a paste that can be soldered.

[0004]

Each of the known conductive pastes has the following drawbacks. First, paste using silver powder,
Although good conductivity is obtained, the diffusion rate of silver into the solder is inherently high, so that solder is easily eroded and solder dewetting occurs before a sufficient solder fillet is formed. As a result, there is a problem that satisfactory adhesive strength and electrical connection cannot be obtained. Further, in the case of a conductor circuit using silver paste, there is a serious problem that a device is broken due to a short circuit due to silver migration. In addition, the paste using copper powder is inexpensive as a material, but when the coating is heated and cured, a powder having a high oxidizing activity is used. An oxide film is formed on the surface, and the wettability of the solder is easily impaired as the conductivity decreases. Attempts to add an antioxidant or a metal chelating agent to a paste used for copper powder (for example, see JP-A-61-31)
454, JP-A-3-77202, JP-A-6
However, in this case, the powder surface is oxidized with the lapse of time after being formed into a coating film, and the conductivity and the solder wettability are reduced. In addition, obstacles such as a decrease in adhesive strength with the resin and a reduction in shelf life also occur. A paste using a powder obtained by plating silver on the surface of a copper powder is known. However, the production cost of the powder is high, and even though only a small amount of silver is present on the surface, the migration of the powder is still high. There is a problem, and all the characteristics have not yet been satisfied in a well-balanced manner.

[0005] As a means for solving these problems, the present applicant has proposed a general formula of Ag _x Cu _y (where
0.001 ≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999, x
+ Y = 1 (atomic ratio)), using a copper alloy powder characterized by having a region where the silver concentration on the particle surface is higher than the average silver concentration and has a region where the silver concentration increases toward the particle surface. Pastes (for example, JP-A-4-345701 and JP-A-6-023582), which are disclosed as techniques for compensating the above-mentioned disadvantages of silver and copper. According to these technologies, the powder itself has high oxidation resistance and migration resistance, so additives that compensate for the defects can be omitted as much as possible, and compared to conventional conductive pastes using silver or copper powder. The characteristics are well-balanced.

By the way, these existing solderable conductive pastes have the same solder wettability and solder erosion resistance as tin plating or solder plating on copper foil on printed circuit boards and component electrodes. There is no present. As described above, conductive paste is widely used industrially.In general, industrial soldering in the electronic / electrical equipment industry mainly involves component electrode surfaces or through-holes plated with metal such as tin or solder. It is performed for the purpose of directly soldering to a copper foil or the like on a printed circuit board. At this time, in order to ensure the reliability of the soldering, for example, in the case of flow soldering using a tin-lead eutectic solder, it is preferable to go through a soldering process of 235 to 260 ° C. for several seconds to several tens of seconds. In the case of using solder or special solder, more stringent soldering conditions are applied at present. In this case, with the existing solderable conductive paste, solder dewetting of the coating surface due to solder erosion is likely to occur, thereby resulting in insufficient fillet formation, lowering of the adhesive strength of the solder surface, and There is also a problem that electrical connection cannot be established. Therefore, with respect to solder wettability and solder erosion, the emergence of a solderable conductive paste having characteristics similar to those of the above-mentioned copper foil and metal plating has been desired.

[0007] The object of the present invention is exactly at this point, and as a solution to this problem, a solderable conductive paste such as oxidation resistance, migration resistance, adhesive strength, printability, and sedimentation resistance. It is an object of the present invention to provide a solderable conductive paste which maintains its performance, and in particular, improves the solder wettability and the resistance to solder erosion to the level of a copper foil.

[0008]

Means for Solving the Problems In view of such problems, the present inventors have made intensive studies and found that the general formula Ag _x Cu
_y (However, 0.001 ≦ x ≦ 0.4, 0.6 ≦ y ≦
0.999, x + y = 1 (atomic ratio)), and the average particle diameter of the copper alloy powder is 5 to 5 in the copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particles. Copper alloy powder 100 having a size of 35 μm
1 part by weight of a conductive paste containing at least one kind of resin binder and a solvent, wherein the solder contains 0.001 to 10 parts by weight of a higher fatty acid and / or a higher fatty acid ester as a solderability improver. It has been found that the above problem can be solved by using a conductive paste that can be attached, and the present invention has been completed.

That is, the present invention is as follows. (1) General formula Ag _x Cu _y (where 0.001 ≦ x
≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1 (atomic ratio)), and 100 weight parts of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particles. Part and a conductive paste containing at least one or more resin binders and a solvent, in which a higher fatty acid or a higher fatty acid ester is used as a solderability improver.
A solderable conductive paste containing 0 parts by weight. (2) General formula Ag _x Cu _y (where 0.001 ≦ x
≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1 (atomic ratio)), and 100 weight parts of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particles. And a conductive paste containing at least one or more types of resin binders and solvents, wherein 0.001 to 10 parts by weight of a higher fatty acid and a higher fatty acid ester are contained as a solderability improver. Conductive paste. (3) General formula Ag _x Cu _y (where 0.001 ≦ x
≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1 (atomic ratio)), and 100 weight parts of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particles. And a conductive paste containing at least one or more resin binders and a solvent, wherein the solderable conductive paste contains 0.001 to 10 parts by weight of a higher fatty acid ester as a solderability improver. . (4) The solderable conductive paste according to any one of claims 1 to 3, wherein the copper alloy powder has an average particle size of 5 to 35 µm. (5) A solderable conductive coating film obtained by applying or printing the conductive paste according to any one of claims 1 to 4 on a base material and then curing.

Hereinafter, the present invention will be described in detail. The copper alloy powder used in the present invention is preferably prepared by a gas atomizing method described in JP-A-6-260015, which has already been disclosed by the present applicant. It is preferable to make it. At this time, the oxygen contained in the gas is
It is preferably at most 2%, more preferably at most 0.1%.

Further, the silver content x of the copper alloy powder used in the present invention
If less than 0.001, sufficient oxidation resistance and solderability cannot be obtained, and if more than 0.4, migration resistance and solder erosion resistance cannot be obtained, and the adhesive strength on the solder surface And the cost of the powder increases. The preferred range of the amount x of silver is 0.005 ≦ x ≦ 0.3, and more preferably 0.02 ≦ x0.25. In the copper alloy powder used in the present invention, the silver concentration on the powder surface is higher than the average silver concentration, and the silver concentration on the surface is 1.4 of the average silver concentration.
It is at least 2.1 times, more preferably at least 2.1 times.
As the silver concentration on the surface and near the surface of the copper alloy powder,
X-ray photoelectron spectroscopy analyzer ESCALAB2 manufactured by UK VG
Using a 00-X type, the surface silver concentration at a depth of about 50 ° from the surface was determined. The silver concentration at this time was Ag3
This is obtained by comparing peaks of d _5/2 (Kα line of Al) and Cu3p (Kα line of Mg). The average silver concentration was determined by dissolving a sample in concentrated nitric acid and using a high-frequency inductively coupled plasma emission spectrometer (Seiko Electronics Co., Ltd.)
JY38P-P2).

It is essential that the average particle diameter of the copper alloy powder used in the present invention is in the range of 5 to 35 μm. 5
If it is less than μm, during soldering, the copper alloy particles on the surface of the cured coating film will melt into the solder alloy layer and be eaten by the solder phase, and the time for dewetting will be extremely short. For this reason, in order to impart solder erosion resistance comparable to that of metal foil such as copper foil, it is desirable to use as large an average particle diameter as conductive powder as possible, but when using as a conductive paste, If it is 35 μm or more, although the time during which the particles on the surface of the cured film are eaten by the solder phase is prolonged, the screen printing characteristics are extremely deteriorated, and the copper alloy particles in the paste are severely settled and separated. The composition of the organic / inorganic component of the film changes. As a result, the solder wettability fluctuates significantly,
Poor practicality as a conductive paste application. A preferable range of the average particle diameter is 7 to 25 μm,
More preferably, it is 9 to 20 μm. At this time, the average particle diameter of the copper alloy powder was measured using a laser diffraction type particle size distribution analyzer (Heros (12L) manufactured by Sympatec GmbH.
A) The median diameter in terms of 50% by volume of the total particle volume determined using & Rodos (12SR)) is defined as the average particle diameter.

The shape of the copper alloy powder used in the present invention can be spherical, polyhedral, scaly, flake, or a mixture thereof. When irregular shaped particles are used, the resin binder is unevenly distributed on the surface of the cured coating film, so that the solder wettability deteriorates, which is not preferable. Preferred particle shapes are spherical, polyhedral, scaly, and flake-like, and more preferably spherical and polyhedral. Regardless of the shape, a known method of mechanically processing powder can be used.

Further, the copper alloy powder used in the present invention may be made of Al, Zn, Sn, Pb, Si, M
n, Bi, Mo, Cr, Ir, Nb, Sb, B, P, M
g, Li, C, Na, Ba, Ti, In, Au, Pd,
Metals such as Pt, Rh, Ru, Zr, Hf, Y, La,
It is permissible to add metalloids and their compounds, and simultaneously with the copper alloy powder used in the present invention, Al, Zn, Sn,
Pb, Si, Mn, Bi, Mo, Cr, Ir, Nb, S
b, B, P, Mg, Li, C, Na, Ba, Ti, I
n, Au, Pd, Pt, Rh, Ru, Zr, Hf, Y,
Powders composed of metals such as La, metalloids and compounds thereof may be mixed.

The resin binder used in the present invention includes:
Known heat-curable resins can be used.
For example, phenolic resin, epoxy resin, melamine resin, urea resin, xylene resin, alkyd resin, unsaturated polyester resin, acrylic resin, polyimide resin,
Furan resins, urethane resins and the like are mentioned, preferably phenol resins, epoxy resins, melamine resins and xylene resins, more preferably phenol resins and melamine resins. Phenol resins include phenol, cresol, xylenol, bisphenol A, p
-A generally known product obtained by adding and condensing formaldehyde, furfural or the like to an alkylphenol or various modified phenols can be used, and a resol type phenol resin is particularly preferable. As the melamine resin, an alkyl etherified melamine resin is preferable. Among the above resin binders, one kind or a combination of two or more kinds is possible, and the combination can be appropriately made according to a base material to which the conductive paste is applied. The amount of the resin binder is preferably 1 to 30 parts by weight. If it is less than 1, the adhesiveness to the substrate is significantly deteriorated, and the conductivity of the coating film due to oxidative deterioration and the printability are insufficient.
If it exceeds 30, the conductivity is reduced due to insufficient contact between the copper alloy powders, and the copper alloy powder is hardly exposed on the surface of the coating film, so that the solder wettability deteriorates and the practicality is poor. Become. The preferred range of the amount of the resin binder is 3 to 18 parts by weight, and more preferably 5 to 13 parts by weight.

Further, as for the resin binder used in the present invention, it is preferable to use a thermoplastic resin together with the above-mentioned thermosetting resin in some cases. On this occasion,
By combining the resin binder, characteristics such as printability and adhesion can be improved. As a method of curing the solderable conductive paste of the present invention, a known method such as a box-type hot blast stove, a continuous hot blast stove, a muffle-type heating furnace, a near-infrared furnace, and a far-infrared furnace can be used. The atmosphere at this time is preferably an atmosphere having a low or no oxygen concentration, an inert gas atmosphere, or a reducing atmosphere, but may be air. Further, a preferable curing temperature is 100 to 210 ° C, more preferably 130 to 180 ° C.
° C. A suitable curing time depends on the temperature, but is preferably in the range of 1 to 300 minutes.

In the present invention, an organic solvent can be used for the solderable conductive paste.
As the solvent, any known and commonly used solvent may be used. For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol mono n-hexyl ether, ethylene glycol monoallyl ether, ethylene glycol dodecyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monoisopropyl Ether, ethylene glycol monophenyl ether, ethylene glycol isoamyl ether, ethylene glycol benzyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether and its acetate, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, diethylene glycol dodecyl ether, diethylene glycol monohexyl ether and its acetate, diethylene glycol methyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol monomethyl ether,
Dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol dodecyl ether, triethylene glycol mono n-butyl ether, triethylene glycol dimethyl ether tripropylene glycol monomethyl ether and its acetate, α-terpineol, β-terpineol, n- Propanol, isopropanol, n-
Butanol, isobutanol, sec-butanol,
tert-butanol, 2-ethylbutanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, methyl amyl alcohol, 3-pentanol, n-hexanol, 3,5,5-trimethylhexanol, n -Heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-octanol, nonanol, n-decanol, undecanol, n-dodecanol, cyclohexanol, 2-methylcyclohexanol, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl Alcohols such as alcohols, aromatics such as toluene and xylene, ketones such as methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, and acetate acetate Esters such as ethyl acetate, isopropyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, methoxybutyl acetate, cyclohexyl acetate, benzyl acetate, ethyl propionate, butyl propionate, isoamyl propionate, dimethylacetamide, dimethylformamide, N -Methylpyrrolidone,
γ-lactone and the like. Of these solvents,
A single resin or a combination of two or more resins can be used, and the combination can be appropriately determined in accordance with the resin binder or paste to be used. Further, the amount of the solvent can be appropriately contained in accordance with the viscosity and thixotropic property of the paste used. In general, in a conductive paste, it is known that a solvent having a high polarity and a solvent having a low polarity are combined to control the thixotropy of the paste and to adjust the leveling property of the paste during printing and application.
These combinations are also possible for the solderable conductive paste in the present invention. For example, dipropylene glycol monomethyl ether and 3,5,5-
Examples include a combination of trimethylhexanol and a combination of diethylene glycol monoethyl ether and cyclohexanol.

In the conductive paste according to the present invention,
It is essential to contain 0.001 to 10 parts by weight of higher fatty acid and / or higher fatty acid ester as a solderability improver. The higher fatty acid and / or higher fatty acid ester used here is a saturated fatty acid and unsaturated fatty acid having about 6 to 30 carbon atoms, or a saturated fatty acid ester and unsaturated fatty acid ester, and any commonly known fatty acid can be used. is there. As higher fatty acids, for example, caproic acid, enanthic acid, caprylic acid, pelargonic acid, isoperargonic acid, capric acid, caproleic acid,
Undecanoic acid, 2-undecenoic acid, 10-undecenoic acid, 10-undecenoic acid, lauric acid, lindelic acid, tridecanoic acid, 2-tridecenoic acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, isopalmitic acid, palmitolein Acids, hiragonic acid, hydnocarpinic acid, margaric acid, ω-heptadecenoic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, isostearic acid, elaidic acid, petroselinic acid, moloctic acid, eleostearic acid, talilic acid, vaccenic acid , Riminoleic acid, vernolic acid, sterculinic acid, nonadecanoic acid, eicosanoic acid, eicosenoic acid, gadrenic acid, arachidonic acid, heneicosanoic acid, docosanoic acid, erucic acid, brassic acid, setrenic acid, clupanodonic acid, tricosanoic acid, 22-to Archwire acid, lignoceric acid, Serakoren acid, herring acid, pentacosanoic acid, cerotic acid, montanic acid and melissic acid. Examples of the higher fatty acid ester include methyl caproate, ethyl caproate, butyl caproate, isobutyl caproate, isopropyl caproate, amyl caproate, isoamyl caproate, vinyl caproate, methyl enanthate, ethyl enanthate, and capryl. Methyl acrylate, ethyl caprylate, butyl caprylate, isobutyl caprylate,
Isopropyl caprylate, amyl caprylate, isoamyl caprylate, vinyl caprylate, methyl pelargonate, ethyl pelargonate, methyl caprate, ethyl caprate, butyl caprate, isobutyl caprate,
Isopropyl caprate, Amyl caprate, Isoamyl caprate, Vinyl caprate, Methyl caproleate, Ethyl caproleate, Methyl undecanoate, Ethyl undecanoate, Methyl 10-undecenoate, Ethyl 10-Undecenoate, Methyl laurate, Lauric acid Ethyl, butyl laurate, isobutyl laurate, isopropyl laurate, amyl laurate, isoamyl laurate, vinyl laurate, benzyl laurate, methyl tridecanoate, ethyl tridecanoate, methyl myristate, ethyl myristate, butyl myristate, Isobutyl myristate, isopropyl myristate, vinyl myristate, methyl myristoleate, ethyl myristoleate, methyl pentadecanoate, ethyl pentadecanoate, palmitic Methyl, ethyl palmitate, butyl palmitate, isobutyl palmitate, isopropyl palmitate, vinyl palmitate, methyl isopalmitate, ethyl isopalmitate, ethyl palmitoleic acid, methyl margarine acid, ethyl margarine acid,
Methyl stearate, ethyl stearate, butyl stearate, vinyl stearate, phenyl stearate, dodecyl stearate, glycidyl stearate,
Hydroxypropyl stearate, ethyl oleate,
Butyl oleate, oleyl oleate, methyl linoleate, ethyl linoleate, isopropyl linoleate, methyl linolenate, ethyl isostearate, methyl elaidate, methyl nonadecanoate, ethyl nonadecanoate,
Methyl eicosanoate, ethyl eicosanoate, ethyl eicosenoate, methyl arachidonic acid, ethyl arachidonic acid,
Ethyl heneicosanoate, methyl docosanoate, methyl erucinate, ethyl erucinate, methyl lignocerate,
Ethyl lignocerate, methyl melysinate and the like.

These higher fatty acids and / or higher fatty acid esters can be used alone or in combination of two or more. In addition, the higher fatty acid referred to herein exhibits a function as a thixotropic agent for the paste, in addition to the effect of improving the solderability. Therefore, the type and amount of each of these higher fatty acids and / or higher fatty acid esters are determined according to the average particle diameter of the copper alloy powder, the type of resin or solvent used as a binder, or the type or configuration of the substrate to which the paste is applied. Any combination and adjustment can be made as appropriate. For example, by increasing the average particle diameter of the copper alloy powder, for example, the resistance to solder erosion can be dramatically improved. However, on the other hand, the sedimentation of the alloy powder in the paste is greatly increased, whereby separation of the copper alloy powder and the organic binder in the paste occurs in a short time, and in addition to causing troubles in printing and coating, the paste This causes a change in solder wettability. However, in the case of the present invention, as a solderability improver to be contained, the higher fatty acid is contained more than the higher fatty acid ester or only the higher fatty acid is contained, so that the thixotropy of the paste is increased and the sedimentation of the particles is increased. Can be suppressed, and practicality can be maintained as a conductive paste having improved solder wettability and solder erosion resistance. In addition, by containing a higher fatty acid ester in a higher amount than a higher fatty acid or by containing only a higher fatty acid ester, the solder wettability and the resistance to solder erosion can be improved.
Since the fluidity of the strike is increased, the printability is improved, and the adhesive strength of the cured paste film is further improved. As another example, when a solderable paste is used as a component external electrode forming application, it is necessary to impart an appropriate thixotropy and leveling property to the paste. By adjusting the blending ratio of fatty acid and higher fatty acid ester (1: 9 to 5: 5 (weight ratio)), it has excellent solder wettability and high solder erosion resistance, and has stable electrode shape and dimensions. It is only possible to form electrodes with accuracy. As described above, by controlling the blending of the higher fatty acid and / or higher fatty acid ester contained in the paste, a paste having excellent solderability and high practicality can be provided.

The content of these solderability improving agents is effective in the range of 0.001 to 10 parts by weight.
If it is less than 0.001, the effect of solderability, that is, the effect of solder wettability will not be exhibited, and if it is more than 10, the absolute amount of the copper alloy powder in the paste will be small, and the conductivity will be deteriorated. And the adhesive strength with the adhesive becomes low. A preferable content is 0.03 to 7 parts by weight, more preferably 0.09 to 3 parts by weight. In addition, a coupling agent, a metal chelating agent, and the like can be added to the solderable conductive paste of the present invention as needed. Suitable coupling agents include vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxymethyldiethoxysilane, N
-Β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane,
Silane coupling agents such as phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, isopropyltriisostearoyl titanate, isopropyltri (N-aminoethyl-aminoethyl) titanate, isopropyltris (dioctylpyrophosphate) titanate, Tetraisopropyl titanate, tetrabutyl titanate, isopropyl trioctanoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl dimethacryl isostearyl titanate, isopropyl tricumyl phenyl titanate, isopropyl isostearyl diacryl titanate, etc. Titanium-based coupling agents Suitable metal chelating agents include ethanolamine, diethanolamine, alkanolamines such as triethanolamine, ethylenediamine, triethylenediamine, o-aminophenol,
Examples include amine compounds such as toluenetetramine and 8-hydroxyquinoline, and acetylacetone and its derivatives. These additives can be used alone or in combination of two or more. In particular, by using a titanium-based coupling agent, the dispersibility of the copper alloy powder in the paste is increased, and the metal particles on the surface of the cured film can be uniformly exposed, which is effective in improving the solderability. The amount added is preferably such that the conductivity, solderability and adhesive strength of the coating film are not impaired, and 0.001 to 3 parts by weight is appropriate.

The substrate to which the solderable conductive paste of the present invention is applied or printed is a glass epoxy resin substrate, a paper phenol resin substrate, a paper epoxy resin substrate, a polyimide resin substrate, a polyester resin substrate, or a BT substrate. Rigid substrates and flexible substrates such as resin resin substrates, polyphenylene sulfide resin substrates, polyphenylene ether resin substrates, polyether ketone resin substrates, and polyetherimide resin substrates, ceramic substrates such as alumina substrates and aluminum nitride substrates, and aluminum and stainless steel substrates Any generally known substrate such as a metal substrate can be used. In addition, as other base materials, chip resistor electrodes, ceramic capacitor external electrodes, tantalum capacitor internal and external electrodes, aluminum electrolytic capacitor housings, hybrid ICs, foot parts for through holes, ITO glass electrodes, etc. The paste can be printed and applied. The coating film printed and applied to these substrates can be used as a cured coating film alone that imparts good conductivity and mechanical strength without soldering. Further, by applying soldering on this coating film, it can be effectively utilized as having better conductivity and mechanical strength. In addition, the conductive coating film in the present invention means that the cured coating film is 1 × 1
It means that it exhibits a volume resistivity of 0 ⁻³ Ω · cm or less.

The solderable conductive paste of the present invention is applied to the above-mentioned base material by a screen printing method, an intaglio printing method, a bar coating method, a dipping method, a transfer method, a brush coating method, a dispenser method, a spray method or the like. Can be printed and applied. At this time, it is desirable to appropriately adjust the viscosity of the paste depending on each printing and coating method. The method for soldering the solderable conductive paste of the present invention includes a flat dip method, a wave soldering method, a flow soldering method, a two-stage wave soldering method, a multi-stage flow soldering method, a cascade method, and the like. Immersion soldering method, iron soldering method, reflow method, VPS method, ultrasonic soldering method, laser soldering method and the like. Among these, the flow soldering method and the reflow method are particularly preferable in terms of workability and process cost.

Examples of the solder material used in the soldering of the present invention include typical Sb-Pb eutectic solders and Ag, Sb, Cu, Bi, In,
One containing elements such as Ge, Si, and Al, or Sn-
Ag-based, Sn-Au-based, Sn-Sb-based, Pb-Ag-based,
Generally known solder materials such as Pb-In, In-Al, and In-Ge can be used. The forms of these solder materials include bar solder, block solder,
It can be used as a solder cream or a thread solder, and it is possible to perform soldering by appropriately combining a soldering method with the above method depending on each mode.

When the solderable conductive paste of the present invention is subjected to a soldering process, a flux generally used may be used. Suitable fluxes include inactive rosin-based flux, weakly active rosin-based flux, active rosin-based flux,
Commercially available fluxes such as organic acid-based fluxes and inorganic acid-based fluxes can be used, and these can be applied to the soldering surface by spraying or dipping them on the cured paste film. is there. Furthermore, if necessary, the flux-cured cured coating film can be subjected to a preheating treatment using a box-type hot-air stove, a continuous hot-air stove, a far-infrared furnace, or the like. These flux-treated cured coating films can be soldered by the above-mentioned soldering method and solder material.

Next, a method for producing the solderable conductive paste of the present invention will be described, but it is not particularly limited to the following production method. 1. Copper alloy powder production process The copper alloy powder used in the present invention is produced by an atomizing method. A gas atomization method and a water atomization method are desirable, and particularly, an inert gas atomization method containing nitrogen, helium, or the like is preferable. At this time, the oxygen contained in the gas is 2
% Or less, more preferably 0.1% or less.

For example, a mixture or alloy of copper and silver is melted in an inert gas such as nitrogen gas in a graphite crucible using a high-frequency induction heating device or the like. After melting, the molten metal is introduced from the crucible tip into the spray tank with an inert gas atmosphere, and then compressed inert gas is adiabatically expanded from the multiple gas ejection holes provided near the crucible tip. It is possible to produce a copper alloy powder by injecting the high-speed air flow from the crucible just toward the metal melt that has begun to fall into the spray tank and atomizing it. The pressure of the helium gas before expansion used at this time is preferably 10 kg / cm ² or more, more preferably 20 kg / cm ² or more.

[0027] If necessary, the copper alloy powder may be classified using a classifier or an airflow classifier so that the average particle size of the obtained copper alloy powder falls within a suitable range. , Crush the powder using a jet mill, wet mill, hammer mill, etc.,
It is also possible to change the shape. 2. Surface Treatment Step The higher fatty acid and / or higher fatty acid ester as a solderability improver can be surface-treated on the copper alloy powder before the kneading step, or can be added simultaneously with the resin binder or the like in the kneading step.

Prior to the kneading step, it is possible, but not essential, to surface-treat these higher fatty acids and / or higher fatty acid esters on the copper alloy powder. Also,
The use of a solvent for the surface treatment is an effective means for uniformly coating these solderability improvers on the copper alloy powder, but is not always essential. In this case, it is desirable to distill off the solvent or filter after the treatment. When no solvent is used, the mixing and dispersing of the solderability improver can be performed using a mixer or the like. The mixer at this time is not particularly limited, and examples thereof include a ribbon mixer, a V-type mixer, a rotary mixer, a Henschel mixer, a flash mixer, a Nauta mixer, and a tumbler. Further, a method of dispersing and coating a solderability improving agent on the powder surface using a rotary ball mill, a vibration ball mill, a planetary ball mill, or the like is also effective. Solderability improver in the present invention, as a commercially available embodiment, liquid, solid, powder, granulated, flake, crystalline and other properties, in the sense of increasing the homogeneity of the surface treatment, It is desirable to use a liquid having a fine particle form or a liquid. It is also effective to pulverize these additives in advance in a mortar or the like. 3. Paste kneading process Additives such as copper alloy powder, resin binder, solderability improver, solvent and coupling agent, for example, by planetary mixer, Banbury mixer, Henschel mixer, helical rotor, three roll, batch type kneader etc. It is possible to prepare the conductive paste of the present invention by kneading. In this case, in order to obtain a homogeneous conductive paste, it is possible to go through a kneading process of two or more steps, for example, kneading with a three-roll mill and then re-kneading with a planetary mixer.

The kneading conditions depend on the kneader, but it is desirable to knead and disperse the paste while applying a relatively large share. It is also an effective means to perform vacuuming during kneading. The kneading temperature is preferably room temperature or a temperature at which the curing of the resin binder is not accelerated. In some cases, it is also possible to provide a water-cooled jacket in the kneading machine and perform kneading while cooling.

The solderable conductive paste of the present invention can be manufactured by the above-described method.
Next, the present invention will be described in detail based on Examples and Comparative Examples, but the present invention is not limited to only these Examples.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the examples, a method for evaluating a solderable conductive paste of the present invention will be described. (1) Solder wettability In order to quantitatively evaluate the solder wettability, the solder ball wettability was measured. First, a solderable conductive paste is screen-printed on a paper epoxy substrate (CEM-3, manufactured by Matsushita Electric Works, Ltd.) on which no copper foil is laminated, in a 2 cm square solid form at 150 ° C., 30 ° C. And heat-cured in a batch-type hot-air drying furnace. Next, about 2 cc of a weakly active rosin-based flux (manufactured by Nippon Alpha Metals: RM-615) was dropped onto the cured coating film, and Sn-Pb eutectic solder balls (Nihon Handa Co., Ltd.) were further dropped thereon.
(Sn / Pb = 63/37, Φ = 2 mm), reflowed in an infrared furnace with a peak temperature of 260 ° C. and a residence time of 4 minutes, and soldered. Measure the spread diameter of the solder after soldering, and use the following formula to calculate the spread rate (%)
And solder wettability was evaluated. As a criterion for evaluation, a material having a spread of 175% or more was regarded as having excellent solder wettability.

[0032] However, d1 is the diameter of the solder ball before soldering (mm) d2 is the spread diameter of the solder after soldering (mm) As a reference example, on a printed circuit board copper foil performed under the same conditions of soldering Table 1 shows the results of the solder ball spreading test. (2) Solder erosion resistance To quantitatively evaluate the solder erosion resistance, the following method was used. First, a solderable conductive paste was placed on a glass epoxy board (FR-4, manufactured by Matsushita Electric Works, Ltd., FR-4) on which no copper foil was laminated. A cured coating film was formed by screen printing, and was cured by heating in a batch-type hot-air drying furnace at 150 ° C. for 30 minutes. Next, this cured coating film was coated with a weakly active rosin-based flux (JS-64MS, manufactured by Yamaei Chemical Co., Ltd.).
C), dipped and applied in a batch hot air drying oven
Preheating was performed at 1 ° C. for 1 minute. This was dipped in a Sn-Pb eutectic solder bath (260 ° C.) for 10 seconds to perform soldering, and the dewetting state of the soldering surface was examined according to the following criteria to evaluate the resistance to solder erosion. And

Evaluation criteria: ： １: No dewetting occurred in any one Δ: Dewetting occurred in 10 to 10 ×: Dewetting occurred in 11 to 100 (3) Conductivity Conductivity As an evaluation of, the volume specific resistivity of a coating film of a solderable conductive paste which was not cured with a solder and was heat-cured was measured using a digital multimeter (model 7561 manufactured by Yokogawa Electric Corporation) with four terminals. It was measured by the method. The formula for calculating the volume resistivity is shown below.

Volume resistivity (Ω · cm) = (R × t × W) / L where R: resistance between electrodes (Ω), t: thickness of coating film (cm), W: coating film thickness Width (cm), L: length (cm) between electrodes. (4) Oxidation resistance In order to quantitatively evaluate the oxidation resistance of the paste, the following method was used. First, a solderable conductive paste was applied to a glass epoxy substrate (FR-4, manufactured by Matsushita Electric Works, Ltd.) on which no copper foil was laminated in the same manner as used for the evaluation of the resistance to solder erosion. In the size of 2mm □,
100 cross-cut cured coating films were formed by screen printing and heat-cured at 150 ° C. for 30 minutes in a batch-type hot-air drying furnace. Next, the substrate was further exposed to the cured coating film in the air at 210 ° C. for 15 minutes using a batch-type hot-air drying oven and then taken out to room temperature, and then weakly active rosin-based flux (Yamaei Chemical Co., Ltd.) Co., Ltd .: JS-64M
SC), and dipped in a batch hot air drying oven.
Preheating was performed at 0 ° C. for 1 minute. This is called Sn-Pb
Oxidation resistance was evaluated by dipping in a eutectic solder bath (230 ° C.) for 10 seconds and soldering, and examining the state of solder wetting on the soldered surface according to the following criteria.

Evaluation criteria: ： １: No solder wetting failure of any one Δ: 10 to 10 solder wetting failures X: 11 to 100 solder wetting failures (5) Migration resistance Migration resistance As a test, the following method was used. First, on a glass epoxy substrate (FR-4, manufactured by Matsushita Electric Works, Ltd.) on which no copper foil is laminated, printed and cured with a gap of 1 mm, between two coated solderable conductive paste coated electrodes. A DC voltage of 50 V is applied to the film, and then about 0.2 cc of pure water is dropped between gaps of the coating film.
During this time, the time (sec) until the leakage current exceeded 400 μA and short-circuited was measured. In addition, as a criterion for evaluation, a sample having this time exceeding 150 seconds was determined to have excellent migration resistance. (6) Adhesive strength The following method was used to evaluate the adhesive strength. First, a conductive paste that can be soldered is applied to a paper phenol board (available from Matsushita Electric Works, FR
-1) On the top, 10 electrodes having a size of 2 mm square are formed by screen printing and curing, and Sn-
A Pb eutectic solder was pre-coated, and then a 0.8 mmφ solder plating wire was soldered by iron. This is 2
A tensile test was performed at a speed of 0 mm / sec, and the strength at break was determined as an average value of 10 pieces. As a standard of strength at this time, 4 kgf or more was regarded as excellent. (7) Sedimentation resistance As an evaluation of sedimentation resistance, about 10 cc of a solderable conductive paste was poured into a measuring cylinder, and the time from the start of standing at a room temperature of 25 ° C. to the separation of the paste was defined as Evaluation was made according to the following criteria.

[0036]

[0037]

Example 1 Copper particles (purity 99% by weight or more) 37.1k
g and 1.9 kg of silver particles (purity: 99% by weight or more) were placed in a graphite crucible, and were melted and heated to 1600 ° C. by a high-frequency induction heating device. The atmosphere was performed in nitrogen of 99% by volume or more. Next, after introducing the molten metal from the tip of the crucible into a spray tank in a helium gas atmosphere, a helium gas (purity 99) was introduced from a gas nozzle provided near the tip of the crucible.
Atomization was performed by ejecting a pressure of 35 kg / cm ² G) by volume% or more to produce a copper alloy powder. The obtained powder was a spherical powder having an average particle size of 8.0 μm. Also,
The average silver concentration ratio between the powder surface and the powder was 4.6.

To 100 g of the obtained copper alloy powder, 0.5 g of stearic acid was previously subjected to a surface treatment with a ball mill, and then 8.1 g of a resol type phenol resin and 0.07 g of isopropyl triisostearoyl titanate.
g, triethanolamine 0.47 g, and butyl carbitol 3.2 g as a solvent were added and kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0039]

Example 2 For 100 g of the copper alloy powder produced in Example 1, 8.1 g of resole type phenol resin, 0.35 g of stearic acid, 0.07 g of isopropyl triisostearoyl titanate and 0.47 g of triethanolamine
g, and 3.2 g of butyl carbitol as a solvent were added and kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0040]

Example 3 Copper particles (purity 99% by weight or more) 28.2k
g and 5.6 kg of silver particles (purity: 99% by weight or more) were placed in a graphite crucible, melted and heated to 1700 ° C. by a high-frequency induction heating device. The atmosphere was performed in nitrogen of 99% by volume or more. Next, after introducing the molten metal from the tip of the crucible into a spray tank in a nitrogen gas atmosphere, nitrogen gas (purity of 99% by volume or more, pressure of 35 kg / cm ² G) is supplied from a gas nozzle provided near the tip of the crucible. Was spouted and atomized to produce a copper alloy powder. The obtained powder was a spherical powder having an average particle diameter of 19.3 μm. The average silver concentration ratio between the powder surface and the surface was 2.7.

With respect to 100 g of the obtained copper alloy powder, 7.6 g of resol type phenol resin, 0.3 g of n-butyl etherified melamine resin, 1.7 g of lauric acid, 0.4 g of methyl stearate, and 0.3 g of triethanolamine were used. 08
g, butyl cellosolve (1.0 g) and dipropylene glycol monomethyl ether (2.4 g) were added as a solvent and kneaded with a three-roll mill to prepare a paste. Solder wettability, solder erosion resistance, conductivity of the obtained paste,
Table 1 shows the results of oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance.

[0042]

EXAMPLE 4 7.8 g of resol type phenol resin, 0.4 g of n-butyl etherified melamine resin and 0.4 g of stearic acid were added to 100 g of the copper alloy powder produced in Example 3.
05 g, triethanolamine 0.08 g, and butyl carbitol 2.4 g as a solvent were added and kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.
Shown in

[0043]

Example 5 The copper alloy powder prepared in Example 3 was removed as much as possible with a particle size of 8 μm or less using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. to obtain an average particle size of 33.9 μm. A copper alloy powder was obtained. To 100 g of the obtained copper alloy powder, a resole type phenol resin 8.5 was used.
g, Cresol novolak type phenolic resin 0.9
g, 9.1 g of palmitic acid, 0.05 g of isopropyl triisostearoyl titanate, and 4.1 g of ethylene glycol monophenyl ether as a solvent were kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0044]

Example 6 The copper alloy powder prepared in Example 1 was removed as much as possible with a particle size of 10 μm or more using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. to obtain an average particle size of 5.4 μm. A copper alloy powder was obtained. To 100 g of the obtained copper alloy powder, 0.1 g of oleic acid and 1.8 g of ethyl myristate were previously subjected to a surface treatment, then 6.8 g of a resol-type phenol resin, 0.05 g of isopropyl triisostearoyl titanate, and ethylene as a solvent were used. 4.1 g of glycol monophenyl ether was added and kneaded with a three-roll mill to prepare a paste. Solder wettability, solder erosion resistance, conductivity of the obtained paste,
Table 1 shows the results of oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance.

[0045]

EXAMPLE 7 8.6 g of a resol-type phenol resin, 0.50 g of methyl stearate, and 0.36 of triethanolamine were added to 100 g of the copper alloy powder produced in Example 1.
g, and 2.9 g of dipropylene glycol monoethyl ether as a solvent were added and kneaded with a three-roll mill to prepare a paste. Solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance of the obtained paste,
Table 1 shows the results of the adhesive strength and the sedimentation resistance.

[0046]

Comparative Example 1 The copper alloy powder prepared in Example 1 was removed as much as possible with a powder having a mean particle size of 3.9 μm using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. A copper alloy powder was obtained. To 100 g of the obtained copper alloy powder, 1.9 g of methyl myristate was previously subjected to a surface treatment, and then a resol-type phenol resin was added.
3 g, 0.07 g of triethanolamine, 0.05 g of isopropyl triisostearoyl titanate, and 3.9 g of butyl carbitol acetate as a solvent were added and kneaded with a three-roll mill to prepare a paste. Solder wettability, solder erosion resistance, conductivity of the obtained paste,
Table 1 shows the results of oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance.

[0047]

Comparative Example 2 The copper alloy powder prepared in Example 3 was removed as much as possible with a mean particle size of 45.3 μm using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. A copper alloy powder was obtained. 6. With respect to 100 g of the obtained copper alloy powder, resol type phenol resin 7.
9 g, stearic acid 8.6 g, methyl linoleate 1.1
g, isopropyl triisostearoyl titanate.
03 g, 3.6 g of ethyl cellosolve as a solvent were added,
The mixture was kneaded with three rolls to produce a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0048]

Comparative Example 3 Copper particles (purity 99% by weight or more) 12.6k
g and 24.0 kg of silver particles (purity of 99% by weight or more) were placed in a graphite crucible, melted and heated to 1750 ° C. by a high-frequency induction heating device. The atmosphere was performed in nitrogen of 99% by volume or more. Next, after introducing the molten metal from the tip of the crucible into a spray tank in a nitrogen gas atmosphere, nitrogen gas (purity 99% by volume) was introduced from a gas nozzle provided near the tip of the crucible.
As described above, atomization was performed by ejecting a pressure of 35 kg / cm ² G) to produce a copper alloy powder. The obtained powder was a spherical powder having an average particle diameter of 16.8 μm. The average silver concentration ratio between the powder surface and the powder was 1.2.

To 100 g of the obtained copper alloy powder, 1.5 g of lauric acid and 0.6 g of methyl myristate were subjected to a surface treatment in advance, and then a resol type phenol resin was used.
8 g, n-butyl etherified melamine resin 0.2 g, isopropyl triisostearoyl titanate 0.07
g, triethanolamine 0.47 g, and butyl cellosolve 3.2 g as a solvent were added and kneaded with a three-roll mill to prepare a paste. Solder wettability of the obtained paste,
Table 1 shows the results of solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance.

[0050]

Comparative Example 4 To 100 g of the copper alloy powder prepared in Example 1, 7.1 g of resol type phenol resin, 0.3 g of cresol novolac type phenol resin, 0.08 g of isopropyl triisostearoyl titanate, and dipropylene as a solvent Glycol monomethyl ether 3.7
g was added and kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0051]

Comparative Example 5 To 100 g of the copper alloy powder prepared in Example 3, 8.2 g of a resol type phenol resin, 0.06 g of triethanolamine, and 3.8 g of benzyl alcohol as a solvent were added and kneaded with a three-roll mill. Was performed to produce a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0052]

Comparative Example 6 For 100 g of the copper alloy powder prepared in Example 3, 7.8 g of a resol-type phenol resin, 12.6 g of stearic acid, 0.04 g of triethanolamine, and 3.8 g of dipropylene glycol monomethyl ether as a solvent. Was added and kneaded with a three-roll mill to prepare a paste. Table 1 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0053]

Comparative Example 7 7.9 g of a resol-type phenol resin, 0.15 g of an isobutyl etherified melamine resin, and 0.1 g of isopropyl triisostearoyl titanate were added to 100 g of commercially available copper powder (purity: 99% by weight or more, average particle diameter: 10 μm). 07 g, 0.12 g of triethanolamine, and 3.9 g of butyl carbitol acetate as a solvent were added and kneaded with a three-roll mill to prepare a paste.
Solder wettability, solder erosion resistance of the obtained paste,
Conductivity, oxidation resistance, migration resistance, adhesive strength,
Table 2 shows the results of the sedimentation resistance.

[0054]

Comparative Example 8 To 100 g of the commercially available copper powder used in Comparative Example 7, 1.5 g of stearic acid was previously subjected to a surface treatment, then 8.1 g of a resol-type phenol resin, 0.09 g of triethanolamine, and disolvent as a solvent. 3.7 g of propylene glycol monoethyl ether was added and kneaded with a three-roll mill to prepare a paste. Table 2 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0055]

Comparative Example 9 The commercially available copper powder used in Comparative Example 7 was removed as much as possible with a powder having a mean particle diameter of 5.1 μm using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. A copper powder was obtained. 100 g of the obtained copper powder
With respect to 0.05 g of docosanoic acid and methyl linoleate.
5 g was previously surface-treated, and then 5.7 g of a resol-type phenolic resin and ethyl etherified melamine resin.
0 g, γ-aminopropyltriethoxysilane 0.1
g and 3.2 g of carbitol as a solvent were added and kneaded with a three-roll mill to prepare a paste. Table 2 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0056]

Comparative Example 10 For 100 g of commercially available silver powder (purity: 99% by weight or more, average particle diameter: 1 μm), 8.7 g of a resol-type phenol resin, 0.12 g of isopropyl triisostearoyl titanate, and butyl carbitol acetate 3 as a solvent Then, the paste was kneaded with three rolls to prepare a paste. Table 2 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0057]

Comparative Example 11 Commercially available silver powder 100 used in Comparative Example 10
g, 3.0 g of ethyl palmitate was subjected to a surface treatment in advance, and then 8.1 g of a resol type phenol resin,
3.4 g of butyl acetate was added as a solvent and kneaded with a three-roll mill to prepare a paste. Solder wettability, solder erosion resistance, conductivity, oxidation resistance of the obtained paste,
Table 2 shows the results of migration resistance, adhesive strength, and sedimentation resistance.

[0058]

Comparative Example 12 7.8 g of resol type phenol resin and 0.08 g of isopropyl tri (N-aminoethyl-aminoethyl) titanate were added to 100 g of commercially available 5 wt% silver-plated copper powder (average particle size: 6.2 μm). Then, 3.6 g of ethyl cellosolve was added as a solvent, and the mixture was kneaded with a three-roll mill to prepare a paste. Table 2 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0059]

Comparative Example 13 For 100 g of the commercially available silver-plated copper powder used in Comparative Example 12, 0.05 g of stearic acid, 1.95 g of methyl stearate, 8.0 g of a resole type phenol resin, and 3.8 g of butyl cellosolve as a solvent. Was added and kneaded with a three-roll mill to prepare a paste.
Solder wettability, solder erosion resistance of the obtained paste,
Conductivity, oxidation resistance, migration resistance, adhesive strength,
Table 2 shows the results of the sedimentation resistance.

[0060]

Comparative Example 14 The commercially available silver-plated copper powder used in Comparative Example 12 was removed as much as possible with a particle size of 5 μm or less using a gas flow classifier TC-15N manufactured by Nisshin Engineering Co., Ltd. .1 μm of silver-plated copper powder was obtained. To 100 g of the obtained silver-plated copper powder, 2.5 g of stearic acid and 0.2 g of methyl eicosanoate were previously subjected to a surface treatment, and then a resole-type phenol resin 8.1.
g, γ-aminopropyltriethoxysilane 0.1 g,
4.0 g of butyl cellosolve was added as a solvent, and the mixture was kneaded with a three-roll mill to prepare a paste. Table 2 shows the results of the solder wettability, solder erosion resistance, conductivity, oxidation resistance, migration resistance, adhesive strength, and sedimentation resistance of the obtained paste.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

As described above, the solderable conductive paste of the present invention can improve and improve the solderability, which has been a fatal problem in the prior art, to be comparable to that of copper foil. In addition, it has basic characteristics as a solderable conductive paste, that is, excellent oxidation resistance, migration resistance, adhesion and sedimentation resistance, and is very useful in industry.

Claims (5)

[Claims] [Claim 1] The general formula Ag _x Cu _y (where 0.00
1 ≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1
(Atomic ratio)), and 100 parts by weight of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particle, and a conductive paste containing at least one or more resin binders and solvents. Higher fatty acids or higher fatty acid esters as solderability improvers 0.001
A solderable conductive paste containing from 10 to 10 parts by weight. 2. A compound of the general formula Ag _x Cu _y (where 0.00
1 ≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1
(Atomic ratio)), and 100 parts by weight of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particle, and a conductive paste containing at least one or more resin binders and solvents. Higher fatty acids and higher fatty acid esters as solderability improvers 0.001 to 1
A solderable conductive paste containing 0 parts by weight. 3. A compound of the general formula Ag _x Cu _y (where 0.00
1 ≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1
(Atomic ratio)), and 100 parts by weight of a copper alloy powder having a region where the silver concentration on the particle surface is higher than the average silver concentration of the particle, and a conductive paste containing at least one or more resin binders and solvents. A solderable conductive paste, comprising 0.001 to 10 parts by weight of a higher fatty acid ester as a solderability improver. 4. The copper alloy powder has an average particle size of 5 to 35 μm.
The solderable conductive paste according to claim 1, wherein: 5. A solderable conductive coating film obtained by applying or printing the conductive paste according to claim 1 on a base material and then curing.