JPH06136299A - Conductive paste enabling strong soldering - Google Patents

Abstract

PURPOSE:To provide a conductive paste comprising copper-silver alloy powder having a specific composition and containing the silver in a high concentration on the surfaces of the particles, an organic binder such as a phenolic resin, and an additive such as triethanolamine, and good in the soldering property and in the adhesion. CONSTITUTION:100 pts.wt. of copper alloy powder represented by formula: AgxCu1-x (0.001<=x<=0.4, atomic ratio), and containing the silver on the surfaces of the particles in a concentration >=2.1 times than the average concentration of the silver and having a silver concentration range increasing toward the surfaces of the particles, 1-60 pts.wt. of silver alloy powder of formula: AgyCu1-y (0.4<=y<=0.999, atomic ratio), 1-50 pts.wt. of at least one kind of phenolic resin as an organic binder, and 0.001-30 pts.wt. of triethanolamine as an additive are compounded with each other and kneaded to provide the objective conductive paste capable of increasing a solder strength, having excellent adhesion strength free from the trouble of soldering failure, and capable of applied to electronic parts in a wide field.

Description

Detailed Description of the Invention

[0001]

The present invention has a good solderability,
In particular, the present invention relates to a conductive paste that can be soldered by reflow and a molded product using the paste. Capacitor external electrodes, aluminum electrolytic capacitor housing fixed to printed circuit board, solar cell conductive circuit, ITO glass electrode, IO glass electrode, Nesa glass electrode, printed circuit soldering conductive part, thick film conductor circuit, jumper circuit, hybrid It can be applied to IC circuits.

[0002]

2. Description of the Related Art Silver, copper, silver palladium, gold, platinum, nickel and carbon pastes have been conventionally known as conductive pastes using a resin as a binder. , Those using silver-plated copper and silver-copper mechanical alloying powder are well known. These known materials are used by curing the coating film by heat curing, electric wire curing, near or far infrared curing, and soldering.

[0003]

The problems of the known solderable conductive paste are as follows. In the case of using copper powder, the surface of the particles has a high oxidizing property, and uneven soldering occurs during soldering. With silver powder, conductivity is obtained, but solder erosion easily occurs and adhesive strength with solder cannot be obtained. Further, when used as a conductor, there is a problem of silver migration. In the case of using silver-plated copper powder, even a small amount of silver-plated powder still has a problem of silver migration. Further, when the silver-copper mechanical alloying powder is used, a large amount of silver which improves the solderability of copper is required, and therefore the migration property is deteriorated.

Known soldering methods include a dipping method and a reflow method, but the above problems still exist even if these methods are used. In particular, in the reflow type soldering, the flux is not applied in most cases in the case where the flux is applied to the cured film and then the soldering is performed, and the solderability becomes more difficult with the known conductive paste.

[0005]

As a result of earnest studies, the inventors of the present invention have found that the general formula AgxCu1-x (however, 0.000
1 ≦ x ≦ 0.4, atomic ratio), the silver concentration on the grain surface is higher than 2.1 times the average silver concentration, and the copper alloy powder 100 has a region in which the silver concentration increases toward the surface. With respect to parts by weight, the general formula AgyCu1-y (however, 0.4
<Y ≦ 0.999) silver alloy powder 0.1 to 60 parts by weight,
A paste containing 1 to 50 parts by weight of at least one kind of phenolic resin, 0.001 to 30 parts by weight of triethanolamine, and 0.001 to 30 parts by weight of rosin is conductive and solderability, particularly reflow soldering. I found that it was good.

The copper alloy powder used in the present invention has a silver concentration of 2.1 times or more and has a region in which the silver concentration increases from the inside toward the surface, and the general formula AgyCu1-y.
(However, 0.4 <y ≦ 0.999, atomic ratio) The silver alloy powder is preferably produced by the method disclosed in USP 5091114 already filed by the present inventors.

If the amount x of silver of the copper alloy powder that can be used in the present invention is less than 0.001, sufficient solderability cannot be obtained, and if it exceeds 0.4, solder erosion tends to occur. Poor adhesion. The surface concentration of silver is 2.1 times or more the average silver concentration, but is preferably 2.1 times or more and 25 times or less, more preferably 3 times or more and 15 times or less. The surface silver concentration refers to the XPS (X-ray photoelectron spectroscopy analyzer: XSAM800 K, which has already been disclosed.
(Manufactured by RATOS). A carbon double-sided adhesive tape having conductivity was adhered to the sample stand, and the sample powder having such a composition was gently attached so as to completely cover the double-sided tape so as not to deform it. The measurement was performed under the following conditions.

Measurement conditions: 10 ⁻⁸ torr argon atmosphere Magnesium Kα line (voltage 12 kV, current 10 mA)
And the photoelectron take-off angle is 90 degrees with respect to the sample surface.
I went again. Etching conditions: Argon gas was used at an accelerating voltage of 3 keV, an incident angle of 45 ° with respect to the sample surface of an argon ion beam, and a chamber pressure of 10 ⁻⁷ torr for 10 minutes. To measure the silver concentration, repeat the measurement and etching five times.
The average value of the measured values was set as the surface silver concentration. The average silver concentration is a value measured by dissolving in concentrated nitric acid and using ICP (high frequency inductively coupled plasma emission spectrometer Seiko Denshi).

In the present invention, the general formula AgyCu1-y (where 0.4 <y≤0.
(999, atomic ratio) 0.1 to 60 parts by weight of the silver alloy powder is mixed, but by adding the silver alloy powder,
Solderability is considerably improved. That is, in the cured film, the copper alloy powder, the silver alloy powder is dispersed,
Solder. At this time, the copper alloy powder on the surface of the cured film,
The silver alloy powder ratio g is important. That is, the silver alloy powder has a high bondability with the solder, and the diffusion of the solder into the solder and the diffusion of the solder into the silver alloy powder occur from the surface. With a silver alloy powder having such a composition on all surfaces, solder erosion is likely to occur, and the silver alloy powder is melted in the solder phase and extracted, so that sufficient adhesive strength cannot be obtained. However, as in the present invention, silver alloy powder of 0.1 to 6 is added to 100 parts by weight of solderable copper alloy powder.
When 0 parts by weight are mixed, both the silver alloy powder part that positively binds to the solder and the copper alloy powder part that binds the solder to a certain extent are present, resulting in higher solderability, excellent solder corrosion resistance, and high solder erosion resistance. It can have adhesive strength.

When the silver alloy powder exceeds 60 parts by weight with respect to 100 parts by weight of the copper alloy powder, solder erosion easily occurs, and the silver alloy powder on the surface is eaten by the solder phase.
If it is less than 0.1 part by weight, the adhesive strength is not sufficient.
The amount of silver alloy powder is 1 with respect to 100 parts by weight of copper alloy powder.
-40 parts by weight is more preferred. If necessary for the copper alloy powder used in the present invention, the metal composition may be Ti, Zn, S.
n, Pt, Au, Pd, Pb, Mn, Mg, Li, B,
P, C, Si, In, Al, Sb, Cr, Ge, Co,
You may add the compound which consists of elements of Zr, W, Ta, Tl, Bi, Ni, and Fe.

The average particle size of the copper alloy powder used in the present invention is 0.1 to 100 μm, and if it is less than 0.1 μm, the solderability is poor due to the oxidation of the powder. Also, 1
When it exceeds 00 μm, the thickness of the coating film becomes too thick and the conductivity deteriorates. Preferably 0.1 to 50 μm,
Furthermore, 0.3 to 20 μm is preferable. The average particle size used here means the volume-averaged average particle size. The measurement was performed using a laser diffraction type particle size measuring device. As the particle shape, powder having a known shape such as spherical shape, scale shape, or a mixture thereof can be used.

In the case of scale-like powder, powder having an aspect ratio (longest diameter of disc / thickness) of 2 or more is preferable. The aspect ratio is preferably 2 or more and 500 or less. The silver alloy powder has an average particle diameter of 0.1 to 10 like the copper alloy powder.
0 μm is preferable. The powder form is preferably spherical, scaly and a mixture thereof. As the phenol resin used in the present invention, known phenol resins can be used, and examples thereof include novolac type phenol resin, resol type phenol resin, xylene resin modified resol type resin, and rosin modified phenol resin. Of these, resol type and modified resol type resins are preferable. The amount of phenol resin is 1 to 50 parts by weight, preferably 1 to 30 parts by weight. If it is less than 1, the adhesiveness is insufficient,
If it exceeds 50, the solderability is poor. Further, it is preferable to mix and use an epoxy resin in order to improve the adhesiveness, depending on the application. For example, the mixing ratio of the epoxy resin is 0.5 to 100 parts by weight of the phenol resin.
50 parts by weight, preferably 1 to 30 parts by weight can be mixed. If it exceeds 50 parts by weight, the solderability will deteriorate. Known epoxy resins can be used,
For example, bis A type epoxy resin (liquid or solid), brominated epoxy resin, bis F type epoxy resin, cycloaliphatic epoxy resin, triglycidyl isocyanurate type epoxy,
A glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic epoxy resin, etc. can be used.

A solvent can be used for the strong solderable conductive paste of the present invention. This gives the paste an appropriate viscosity and thixotropy, and a known solvent can be used. Reactive diluents can also be used for the epoxy resin mixture. For example, ethyl cellosolve, methyl cellosolve, butyl cellosolve,
Known solvents such as hexyl cellosolve and their acetates, methyl carbitol, butyl carbitol and their acetates, butyl acetate, toluene and methyl acetate may be used.

It is also possible to use a mixture of phenolic OH-modified epoxy resin, acrylic resin, urethane resin, polyester resin and amino resin. A known method may be used as the curing method. In particular, as the atmosphere, it is possible to cure in air, nitrogen or a reducing atmosphere. The curing temperature is 100 ° C to 180 ° C, preferably 130 ° C to 180 ° C. It can be cured by heating, far infrared rays, near infrared rays, electron beams and the like.

The strong solderable conductive paste of the present invention contains 0.001 to 30 parts by weight of triethanolamine per 100 parts by weight of copper alloy powder.
If it exceeds 0 parts by weight, the adhesiveness will be poor. Also, 0.
If it is less than 001 parts by weight, the environment resistance is poor. It is preferably 0.01 to 10 parts by weight, and further 0.1 to 7 parts by weight.
Parts are preferred.

The strong solderable conductive paste of the present invention further contains 0.001 to 30 parts by weight of rosin with respect to 100 parts by weight of copper alloy powder. The rosin is partially hydrogenated rosin, Modified rosins such as fully hydrogenated rosin, esterified rosin, maleated rosin, disproportionated rosin, and polymerized rosin can be mentioned. If it exceeds 30 parts, the sagging of the paste is likely to occur and the adhesiveness becomes insufficient. If the amount is less than 0.001 part, the solderability during reflow becomes poor. It is preferably 0.5 to 20 parts, and more preferably 0.6 to 10 parts. The present invention enables not only dip soldering to the solder bath but also reflow solderability. The reflow soldering can be performed using a known reflow furnace. For example, infrared heating, hot air circulation method, latent heat of vaporization method, hot plate, heating tool, light beam,
Laser and air heater methods can be used. The heating temperature is 10 ° C. to 20 ° C., which is the melting point of the solder paste used.
It is preferable to set the maximum temperature at a higher temperature. The soldering atmosphere may be air, nitrogen, or a reducing gas atmosphere. As the solder to be soldered, known solder can be used.

If desired, a thixotropic agent, a defoaming agent, a copper oxide removing agent, and a coupling agent may be added to the strong solderable paste of the present invention. As the copper oxide removing agent, higher fatty acids and their copper salts (linoleic acid,
Stearic acid, linolenic acid, oleic acid), phenols and phenol compounds (eg hydroquinone, catechol, pyrocatechol, pyrogallol, etc.), hydrogenated castor oil as a thixotropic agent, silane coupling agent, titanium cup as a coupling agent. A ring agent can also be added. Among them, titanium coupling agent,
Those containing higher fatty acids and their copper salts are preferred. The amount of these additives is preferably 0.01 to 50 parts by weight with respect to 100 parts by weight of the copper alloy powder.
0.1 to 30 parts by weight is preferable.

An organic base material is one of the base materials used by applying or printing the strong solderable conductive paste of the present invention. Examples of the material include polyphenylene sulfide resin, paper phenol resin substrate, glass epoxy resin substrate, polyphenylene ether resin, polyether ketone resin, polyester resin, polystyrene resin, polyimide resin, phenol resin, and epoxy resin. The shape of these base materials is the substrate, capacitor housing,
Examples include different types of substrates and particles. The coating method is not particularly specified and may be a known method. Examples of those using these base materials include, for example, fixing of a casing of an aluminum electrolytic capacitor or joining of electrodes, a conductive part for soldering of a printed circuit, a thick film conductor circuit of a printed circuit, a jumper circuit part of a printed circuit board. It can also be used for flexible circuit boards and printed circuits.

Further, as the ceramic substrate, it is used as a conductive circuit or contact which is applied or printed on an alumina substrate, a small alumina substrate, a glass substrate, a carbonized borosilicate substrate, or an external electrode of a tantalum capacitor. be able to. Further, as the conductive base material, not only the conductivity imparting material for the organic base material but also a conductive glass electrode or a metal base material can be used. For example, circuits or contacts on ITO or IO glass electrodes, circuits or contacts of Nesa glass electrodes, conductive contacts between glasses inside a liquid crystal panel, adhesion of lead wires of CdS portion of photoconductive element, circuit repair, It can be used for bonding lead wires of potentiometers and as electrode parts for solar cells. The metal base material can be used for a printed circuit board copper foil portion, a copper or aluminum electrode joint portion of an aluminum electrolytic capacitor, a solar cell electrode contact portion, a circuit portion, and an enamel substrate.

The present invention relates to a conductive paste composed of a copper alloy powder and a silver alloy powder which are excellent in strong solderability, and particularly excellent in solderability in reflow, and will be described below with reference to examples. The adhesive strength was measured by soldering together tin-plated copper wires 0.8 mmφ and measuring the peel strength when pulled vertically. 5 kg or more was practically excellent.

[0021]

【Example】

[0022]

Example 1 Copper particles (average particle size 2 mm, purity 99.9)
% Or more) 228.6 g and silver particles (average particle size 3 mm, purity 99.9% or more) 43.2 g are mixed and put in a graphite crucible, and the mixture is placed in a nitrogen atmosphere using a high frequency induction heating device in a nitrogen atmosphere.
It melt | dissolved by heating to 00 degreeC. After melting, it was jetted into the nitrogen atmosphere from the tip of the crucible. At the same time as the jet, nitrogen gas (purity 9
(9.99% or more) (30 kg / cm ² G) was jetted to the melt and atomized. The obtained powder was a spherical powder having an average particle diameter of 12 μm. When the silver concentration on the surface of the obtained powder was measured, it was 0.6, 0.5 from the surface.
4, 0.45, 0.3, 0.26, the surface silver concentration is 0.57, the average silver concentration x is 0.1, and the surface silver concentration is 5.7 of the average silver concentration. It was double.

Similarly, 63.5 g of copper particles and 972 g of silver particles were mixed, heated and dissolved in a graphite crucible up to 1700 ° C., and the melt was atomized in a nitrogen atmosphere at a pressure of 30 kg / cm ² G. . The obtained silver alloy powder was spherical with an average particle diameter of 10 μm. The average silver concentration y is 0.
9, the copper concentration was 0.1. Among the obtained copper alloy powder, 10 g or less of powder (average 5 micron) 10 g, and in the obtained silver alloy powder, 10 g or less of powder (average 5 μm) 2 g, 0.6 g of resol type phenol resin, triethanolamine 0.01 g, rosin 0.03 g, hexyl cellosolve 0.3 g, titanium coupling agent 0.0
01 g and a thixotropic agent 0.0001 g were mixed to prepare a paste.

[0024]

Example 2 The paste obtained in Example 1 was applied to an aluminum electrolytic capacitor housing made of polyphenylene sulfide resin and heat-cured at 170 ° C. for 20 minutes. Apply the cream solder paste to the cured film and apply 150
C., 2 minutes, and soldering was performed in a reflow furnace set at 225.degree. C. for 20 seconds. The solderability was 100%. Further, in the same manner, it was applied onto a glass epoxy resin substrate and heat-cured at 170 ° C. for 15 minutes. After curing, the cream solder was applied and soldered in a reflow oven in the same manner. The solderability was 100%.
The adhesive strength is 6k when the capacitor case is pushed.
It was as good as g.

[0025]

EXAMPLE The paste obtained in Example 1 was applied on the IO conductive film of a solar cell panel with a width of 100 μm and a length of 30 mm. After coating, it was cured by heating at 170 ° C. for 20 minutes. After curing, a cream solder paste was applied. After coating, soldering was performed in a reflow furnace at 150 ° C. for 2 minutes and 230 ° C. for 20 seconds. The solderability was good. Also IT
The adhesiveness with O was 6 kg or more, which was good. The electrical conductivity was 10 ⁻⁴ Ω · cm before soldering, which was good.

[0026]

Example 4 The paste obtained in Example 1 was applied to a polyetherketone resin substrate having a thickness of 1 mm and a width of 100 μm and a thickness of 30 m.
Lines of m length were printed by screen printing. 170
C., and cured by heating for 20 minutes. A cream solder paste was printed on the cured film and soldered at 230 ° C. in a reflow oven. The solderability was 100%. The conductivity before soldering was 10 ⁻⁴ Ω · cm. A pattern was further printed on this substrate and used as a conductive circuit.

[0027]

Example 5 The paste obtained in Example 1 was printed on a circuit board of alumina. Cured at 170 ° C. using far infrared radiation. By printing solder paste on the cured film,
Soldering was performed in a 230 ° C. reflow furnace. The conductivity before soldering is 10 ⁻⁴ Ω · cm, and the solderability is 100.
%Met. The adhesive strength was 7 kg, which was excellent.

[0028]

Example 6 The paste obtained in Example 1 was prepared by etching copper foil of a paper phenol substrate to 100 μm.
Screen printing was performed as a jumper circuit between m conductors (interval 1 mm). It was heat-cured at 170 ° C. using near infrared rays. The conductivity was 10 ⁻⁴ Ω · cm. Furthermore, print solder paste on a part of the jumper wire, 230 ℃
Soldered in a reflow oven. 100% solderability
Met. The adhesive strength was as high as 8 kg.

[0029]

Example 7 A circuit was screen printed with the paste obtained in Example 1 on a copper foil laminated polyphenylene ether resin substrate. It was cured by heating at 170 ° C. for 20 minutes. The conductivity was 10 ⁻⁴ Ω · cm. Further, the solder paste was printed on the terminals of the circuit and soldered in a 230 ° C. reflow oven. The solderability was 100%. The adhesive strength was as high as 7 kg.

[0030]

Example 8 The paste obtained in Example 1 was applied on a part made of a polystyrene resin casing. 160 ℃,
Heat cured for 30 minutes. Furthermore, after applying the solder paste, soldering was performed in a reflow furnace at 150 ° C. for 2 minutes and 230 ° C. for 20 seconds. The solderability was 100%.
The adhesive strength was 6 kg.

[0031]

Example 9 The circuit obtained by screen-printing the paste obtained in Example 1 on a polyimide resin substrate. It was heat-cured in a far infrared furnace set at 165 ° C. Conductivity is 10 ^-4
It was Ω · cm. Furthermore, the solder bath was subjected to dipping at 230 ° C. for 5 seconds. The solderability was 100%. Also,
The adhesive strength was 8 kg.

[0032]

Example 10 252.7 g of copper particles and 2.16 g of silver particles
Was placed in a graphite crucible and melted by heating to 1700 ° C. in a nitrogen atmosphere using a high frequency induction heating device. After melting, the melt was ejected from the tip of the crucible into a nitrogen atmosphere. Simultaneously with the jetting, nitrogen gas (purity 99.99% or more, pressure 40 kg /
cm ² G) was jetted toward the melt and atomized. The obtained powder had an average particle size of 11 μm. When the silver concentration on the surface was measured, it was 0.1, 0.06, 0.0 from the surface.
4, 0.02, 0.01, and the surface silver concentration is 0.0
It was 8. The average silver concentration x was 0.005, and the surface silver concentration was 16 times the average silver concentration.

Similarly, 63.5 g of copper particles and 10 silver particles
8 g was thoroughly mixed and dissolved in a graphite crucible by heating to 1750 ° C. The melt was atomized with 40 kg / cm ² G of nitrogen gas. The obtained silver alloy powder has an average particle size of 10
It was a spherical powder of μm. The average silver concentration y is 0.
5, the silver concentration was 0.5. Among the obtained copper alloy powder, 10 g or less of powder (average 5 micron) 10 g, and in the obtained silver alloy powder, 5 μm or less of powder (average 2 micron)
5 g, resol type phenol resin 2 g, novolac type phenol resin 0.1 g, bis A type epoxy resin H. 1
g, bis F type epoxy resin 0.05 g, rosin 0.2
g, triethanolamine 0.2 g, thixotropic agent 0.00
1 g, butyl cellosolve 2 g, and defoaming agent 0.001 g were sufficiently mixed to obtain a paste.

[0034]

[Embodiment 11] Using a paste obtained in Embodiment 10 on a small aluminum substrate on which a circuit has already been formed,
A mm square pad was printed and cured at 170 ° C. for 20 minutes. In addition, print the solder paste on the pad,
Soldering was performed in a reflow furnace set at 0 ° C. The solderability was 100%. This pad was used as a contact for the conductive circuit. The adhesive strength was 7 kg.

[0035]

Example 12 The paste obtained in Example 10 was used to print as an electrode contact on a Nesa glass used in a liquid crystal display part. After printing, it was cured at 170 ° C. for 15 minutes using an infrared oven. Further, cream solder was printed on the cured film and then soldered in a reflow oven set at 230 ° C. The conductivity in the thickness direction of the film was sufficient, and the solderability was 100%. Adhesive strength is 8k
It was g.

[0036]

[Example 13] Using the paste obtained in Example 10, a carbon paste was applied on the entire surface of the external electrode of a tantalum capacitor which had been already applied and cured by dipping. After coating, it was cured by heating at 160 ° C. for 30 minutes. After curing, further apply solder paste on the entire surface, 240 ℃
Soldered in a reflow oven set to.

The conductivity was measured with a silver electrode, and good conductivity of the order of 10 ^-5 Ω · cm was obtained. The solderability was 100%. The adhesive strength was 7 kg.

[0038]

Example 14 The paste obtained in Example 10 was used to apply to the CdS part of the photoconductive element. 170 ° C, 15
Heat cured for a minute. Further, a solder paste was applied and soldered in a reflow oven set at 230 ° C. for 15 seconds. The conductivity and adhesion were good. The soldered portion was used as a lead wire takeout portion. The adhesive strength was 6 kg.

[0039]

Example 15 The paste obtained in Example 10 was used to apply to the lead wire attachment portion of the potentiometer.
It was cured by heating at 170 ° C. for 20 minutes. Further, a solder paste was applied and soldered in a reflow oven set at 230 ° C. for 20 seconds. When a lead wire was attached, the adhesive strength was 9 kg and the solder wettability was good.

[0040]

Example 16 The paste obtained in Example 10 was used to print on the aluminum extraction electrode portion of an aluminum electrolytic capacitor. It was cured by heating at 160 ° C. for 30 minutes. further,
Print the solder paste and attach it to the copper contact on one side 2
Soldering was performed in a Liuro furnace set at 30 ° C. for 20 seconds.
The adhesive strength was 7 kg and the conductivity was good.

[0041]

Example 17 Using the paste obtained in Example 10, a circuit was screen-printed on an enamel substrate.
It was cured by heating at 180 ° C. for 10 minutes. Furthermore, after printing the solder paste, soldering was performed in a reflow oven set at 230 ° C. for 15 seconds. The solderability was 100%. Adhesion to the substrate of 7 kg was sufficient.

[0042]

Example 18 228.6 g of copper particles and 43.2 g of silver particles
Mixed in a graphite crucible and placed in a nitrogen atmosphere at 1750
It was melted by heating to ℃ using high frequency induction heating. After thawing
The melt was jetted from the tip of the crucible in a nitrogen atmosphere (purity of 99.9% or more). Simultaneously with the ejection, nitrogen gas (20 kg /
(cm ² G, purity 99.99% or more) was jetted to the melt and atomized. The obtained powder has an average particle diameter of 12μ.
It was a spherical powder of m. When the silver concentration on the surface was measured, from the surface, 0.7, 0.6, 0.55, 0.45,
The surface silver concentration was 0.35, the surface silver concentration was 0.65, the average silver concentration x was 0.1, and the surface silver concentration was 6.5 times the average silver concentration.

190.5 g of copper particles and 756 g of silver particles were mixed and similarly heated and melted in a graphite crucible to 1750 ° C. The melt was atomized with 40 kg / cm ² G of nitrogen gas. The obtained silver alloy powder has an average particle diameter of 10 μm.
m was spherical. The average silver concentration y was 0.7, and the average copper concentration was 0.3. 10 in the obtained copper alloy powder
Powder of 10 μm or less (average particle size 5 μm), 0.1 g of powder of 5 μm or less (average particle size 2 μm) in the obtained silver alloy powder, 1.0 g of xylene resin-modified resole type phenol resin, Nopolak type phenol resin 1 0.0 g, rosin-modified phenol resin 0.5 g, resol type phenol resin 1 g, hydrogenated rosin 0.2 g, maleated rosin 0.
1 g, completely hydrogenated rosin 0.4 g, disproportionated rosin 0.5
g, polymerized rosin 0.03 g, triethanolamine 0.
001 g, a thixotropic agent 0.001 g, a titanium coupling agent 0.001 g, hexyl cellosolve 1 g, butyl cowbitol acetate 1 g, an antifoaming agent, and 0.001 g were sufficiently mixed to obtain a paste.

[0044]

Example 19 Ten of the copper alloy powder obtained in Example 18 was used.
Powder of 10 μm or less (average particle diameter 4 μm) was scalded for 10 minutes using a vibrating ball mill in a stainless steel container using 50 cc of solvent zaphtha, surfactant, 0.1 g of 2 stainless steel balls of 2 mmφ. When the obtained powder was filtered and dried, the average particle diameter was 25 μm,
A scale powder having a thickness of 1 μm (aspect ratio 25) was obtained.
The silver concentration on the surface of the scale powder is 0.5, 0.48, 0.3,
At 0.3 and 0.2, the surface silver concentration was 0.4, and the average silver concentration was 4.9 times. 10 g of the obtained copper alloy scale powder
Using the same composition as in Example 18 (copper alloy scale powder 10
A paste of 4 parts by weight of silver alloy powder to 0 parts by weight) was prepared.

[0045]

Example 20 The paste obtained in Example 18 was printed on an etched copper foil portion of a polyester flexible printed circuit board and heat-cured at 170 ° C. for 20 minutes. Further, a solder paste was printed on the ground take-out portion and soldered in a reflow furnace at 230 ° C. for 20 seconds. The electroconductivity and the adhesive property of 8 kg were good. Also,
Adhesiveness was good even after weaving 180 degrees.

[0046]

Example 21 The paste obtained in Example 18 was used to apply to a casing of an electronic component made of glass. 170
It was heat-cured in a far-infrared furnace set at ℃. Solder paste was applied to the surface of the cured film and soldered in a 230 ° C. reflow furnace. The lead tip was taken out from the soldered part. The solderability was 6 kg, and the adhesion was sufficient.

[0047]

Example 22 The paste obtained in Example 18 was printed as a jumper wire on an insulating film (epoxy resin) already formed on a glass epoxy printed board. After printing, it was heat-cured in a far infrared furnace at 170 ° C. The solder paste was printed on the cured film. When soldering was performed in a reflow oven at 230 ° C, the solderability to the circuit connecting portion of the jumper wire was sufficient. Also, 9 kg of adhesiveness was sufficient.

[0048]

[Comparative example]

[0049]

Comparative Example 1 10 g of commercially available copper powder (purity 99.9% or more, average particle size 2 μm), 1 g of resol type phenol resin,
Epoxy resin 0.3 g, partially hydrogenated rosin 0.1 g, triethanolamine 0.01 g, phenol 0.001
g, 0.001 g of stearic acid, 1 g of butyl carbitol acetate, and 0.001 g of thixotropic agent were sufficiently mixed to obtain a paste. The obtained paste was screen-printed as a circuit on a glass epoxy resin substrate. After printing 1
It was heat-cured at 70 ° C. for 20 minutes. Conductivity is 10 ^-3 Ω · c
It was bad with m. In addition, print the solder paste 23
When soldered in a 0 ° C. reflow furnace, the solderability was only 50%.

[0050]

Comparative Example 2 10 g of commercially available silver powder (purity 99.9% or more, average particle diameter 1 μm), resol type phenol resin 1 g,
Ethyl carbitol 1g, triethanolamine 0.0
1 g and 0.01 g of completely hydrogenated rosin were mixed and pasted. The paste was applied to the copper foil portion of the printed board. Further, a solder paste was printed on the cured film and soldered in a 230 ° C. reflow oven. Although solder was attached, the solder was significantly eaten away and the adhesive strength was not 1 kg.

[0051]

Comparative Example 3 101.6 g of copper particles and 259.2 g of silver particles
In a graphite crucible and put in a nitrogen atmosphere (purity 99.99%
In the above), it was melted up to 1750 ° C. by using high frequency induction heating. The melt is jetted into a nitrogen atmosphere (purity 99.99% or more), and at the same time, nitrogen gas (purity 99.99% or more, pressure 40 kg / cm ² G) is jetted to the melt,
It was atomized. The obtained powder was a spherical powder having an average particle diameter of 12 μm. The silver concentration on the surface is 0.8,
It was 0.7, 0.6, 0.54 and 0.3, and the surface silver concentration was 0.75. The average silver concentration x is 0.6.
The surface silver concentration was only 1.25 times the average silver concentration.

Powder 1 having a particle size of 10 μm or less among the obtained powders 1
0 g (average 5 μm), 1 g of resole type phenol resin,
Triethanolamine 0.2 g, maleated rosin 0.
A paste was prepared by thoroughly mixing 01 g and 1 g of butyl acetate. The resulting paste was printed on a paper phenolic resin printed circuit board. It was heat-cured at 170 ° C. for 10 minutes. At this time, when a migration test (water-drop test) (10 DCV, 1 mm interval) was performed, remarkable migration occurred. Further, when a solder paste was printed and soldering was performed by reflow, the adhesive strength was reduced to 0.3 kg due to solder erosion.

[0053]

Comparative Example 4 10 g of a powder (average particle diameter 2 μm) of 5 μm or less in the spherical powder (average silver concentration x = 0.1) of the copper alloy powder produced in Example 1, the silver alloy produced in Example 1 Spherical powder (average silver concentration y = 0.9), powder of 5 μm or less (average particle diameter 2 μm) 20 g Resol-type phenol resin 7 g, triethanolamine 0.1 g, fully hydrogenated rosin 0.01 g, linoleic acid 0. 01 g, epoxy resin 0.
1 g and 2 g of ethyl cellosolve were thoroughly mixed to obtain a paste.

Print the paste on the ITO transparent electrode and
It was heat-cured at 70 ° C. for 20 minutes. When a solder paste was printed on the obtained cured film and soldering was performed by reflow at 230 ° C. for 20 seconds, solder erosion occurred and the adhesive strength was almost 0.2 kg.

[0055]

Comparative Example 5 10 g of powder (average 2 μm) of 5 μm or less in the copper alloy spherical powder (average silver concentration x = 0.1) produced in Example 1, 1 g of resol type phenol resin, 5 g of triethanolamine, rosin 0.01 g, butyl cellosolve 2 g, and a thixotropic agent 0.0001 g were mixed to prepare a paste. The obtained paste was screen-printed on a glass epoxy resin substrate. It was heat-cured at 170 ° C. for 15 minutes. The conductivity was poor at 10 ^-2 Ω · cm. Furthermore, the solder paste was screen-printed and soldered in a reflow oven at 230 ° C. for 20 seconds. Solderability was poor at a few percent.

[0056]

[Comparative Example 6] 10 g of powder (average 2 μm) having a particle size of 5 μm or less in the spherical powder (average silver concentration x = 0.1) produced in Example 1
m), 1 g of a resol type phenol resin, 0.1 g of triethanolamine, 7 g of completely hydrogenated rosin, 2 g of ethyl cellosolve acetate, 0.001 g of pyrogallol, and 0.001 g of a silane coupling agent to prepare a paste. The resulting paste was screen printed on a paper phenolic resin substrate. It was cured by heating at 160 ° C. for 30 minutes. After curing, the solder paste was printed using screen printing and soldered in a reflow oven at 230 ° C. for 20 seconds. As for solderability, the solder was granulated and hardly attached. Moreover, the adhesiveness with the substrate was poor.

[0057]

COMPARATIVE EXAMPLE 7 10 g of a powder having an average particle size of 10 μm or less (average particle diameter 4 μm) in the spherical powder (average silver concentration x = 0.1) produced in Example 1, 1 g of resol type phenol resin, 0.00008 g of triethanolamine. , Hydrogenated rosin 0.00
005 g and butyl cellosolve 1 g were sufficiently mixed to obtain a paste. The resulting paste was screen printed on a paper phenolic resin substrate. further,. It was heat-cured at 70 ° C. for 30 minutes. Apply solder paste, 230 ℃,
Soldered by reflow for 20 seconds, the solderability is 30
It was bad with%.

[0058]

The present invention provides the general formula AgxCul-x.
(0.001 ≦ x ≦ 0.4, atomic ratio), the silver concentration on the surface is higher than 2.1 times the average silver concentration, and the copper has a region where the silver concentration increases from the inside toward the surface. Solid soldering using 0.1 to 60 parts by weight of silver alloy powder represented by the general formula AgyCul-y (where 0.4 <y ≦ 0.999, atomic ratio) to 100 parts by weight of alloy powder. , Especially reflow solderable conductive paste, the solderability is good because silver is concentrated on the surface, and the problem of solder erosion due to the decrease in silver concentration from the surface toward the inside It has the advantage of not happening. Furthermore, since the silver alloy powder is mixed, a base for diffusion of the solder into the hardened film is created, so that the soldering strength can be further enhanced. Further, the adhesiveness to the substrate to be adhered is improved by holding the mixture binder of the phenol resin and the epoxy resin having such a composition.

Claims (8)

[Claims] 1. A general formula AgxCu1-x (provided that 0.
001 ≦ x ≦ 0.4, atomic ratio), the silver concentration on the grain surface is higher than 2.1 times the average silver concentration, and the copper alloy powder has a region where the silver concentration increases toward the grain surface. 1
0.1 to 60 parts by weight of silver alloy powder of the general formula AgyCu1-x (where 0.4 <y ≦ 0.999, atomic ratio), and at least one or more phenolic resins as organic binder A solderable conductive paste comprising 1 to 50 parts by weight and 0.001 to 30 parts by weight of triethanolamine as an additive. 2. The conductive paste according to claim 1, further comprising 0.001 to 3 parts of rosin per 100 parts by weight of copper alloy powder.
Solderable conductive paste with 0 parts added. 3. The organic binder according to claim 1, which is 0.1 to 5 relative to 100 parts by weight of the phenol resin.
Solderable conductive paste containing 0 parts by weight of epoxy resin 4. The reflow solderable paste according to claim 1. 5. A molded body obtained by curing the paste according to any one of claims 1 to 4 on an organic base material. 6. A molded body obtained by curing the paste according to claim 1 on a ceramic substrate. 7. The organic substrate according to claim 5, wherein the polyphenylene sulfide resin, paper phenol resin substrate, glass epoxy substrate, polyphenylene ether resin, polyimide resin, polyester resin, polyetherketone resin, phenol resin, epoxy resin, polystyrene resin. A molded product comprising one or more selected from the above. 8. A molded body obtained by curing the paste according to claim 1 on ITO, IO conductive glass, or a metal substrate.