JP3222950B2 - Strong solderable conductive paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has good solderability,
In particular, the present invention relates to a conductive paste that can be soldered by reflow and a molded body using the paste. Capacitor external electrode, fixing aluminum electrolytic capacitor housing to printed circuit board, conductive circuit for solar cell, ITO glass electrode, IO glass electrode, Nesa glass electrode, soldering conductive part of printed circuit, thick film conductor circuit, jumper circuit, hybrid Applicable to IC circuits.

[0002]

2. Description of the Related Art Conventionally, silver, copper, silver palladium, gold, platinum, nickel, and carbon paste have been 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 a coating film by heat curing, electric wire curing, or near or far infrared curing and soldering.

[0003]

Problems to be solved by the known solderable conductive paste are as follows. In the case of using copper powder, the oxidizing property of the particle surface is high, and in the case of soldering, unevenness occurs. In the case of using silver powder, conductivity can be obtained, but solder erosion is likely to occur, and adhesive strength with solder cannot be obtained. When used as a conductor, there is a problem of silver migration. In the case of using silver-plated copper powder, a small amount of silver plating powder still has a problem of silver migration. Also, when silver-copper mechanical alloying powder is used, a large amount of silver is required to improve the solderability of copper, and therefore, the migration property is deteriorated.

[0004] Known soldering methods include a dip method and a reflow method, but the above-mentioned problems still exist even when these methods are used. In particular, in most cases, the flux is not applied in the reflow type soldering than in the case of applying the flux to the cured film and then soldering, and the solderability is further difficult with the known conductive paste.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the general formula AgxCu1-x (but 0.00x
1 ≦ x ≦ 0.4, atomic ratio), and a copper alloy powder 100 having a region where the silver concentration on the particle surface is higher than 2.1 times the average silver concentration and the silver concentration increases toward the surface. With respect to parts by weight, the general formula AgyCu1-y (however, 0.4
<Y ≦ 0.999) 0.1 to 60 parts by weight of a silver alloy powder,
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 more conductive and solderable, especially reflow soldering. Was found to be good.

A copper alloy powder used in the present invention having a silver concentration of 2.1 times or more on the surface and having a region where the silver concentration increases from the inside toward the surface, and a general formula AgyCu1-y
(However, the silver alloy powder represented by 0.4 <y ≦ 0.999, atomic ratio) is preferably produced by the method disclosed in US Pat. No. 5,091,114, which has already been filed by the present inventors.

If the silver content x 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 is likely to occur, Poor adhesion. Further, the silver concentration of the surface concentration is 2.1 times or more of the average silver concentration, preferably 2.1 times or more and 25 times or less, more preferably 3 times or more and 15 times or less. The silver concentration on the surface refers to the already disclosed XPS (X-ray photoelectron spectrometer: XSAM800K).
RATOS). A conductive carbon double-sided adhesive tape was attached to the sample table, and the sample powder having such a composition was gently adhered so as to completely cover the double-sided tape so as not to be deformed. The measurement was performed under the following conditions.

Measurement conditions: 10 ^-8 torr Argon atmosphere Kα line of magnesium (voltage 12 kV, current 10 mA)
And the take-off angle of photoelectrons is 90
I went there. Etching conditions: Argon gas was applied at an acceleration voltage of 3 keV, an incident angle of an argon ion beam to the sample surface of 45 degrees, and a room pressure of 10 ^-7 torr for 10 minutes. The measurement of the silver concentration was repeated five times in the measurement and etching.
The average value of the measured values was defined as the silver concentration on the surface. The average silver concentration is measured by dissolving in concentrated nitric acid and using an ICP (high frequency inductively coupled plasma emission spectrometer manufactured by Seiko Denshi).

According to the present invention, the formula AgyCu1-y (where 0.4 <y ≦ 0.
999, atomic ratio), and 0.1 to 60 parts by weight of a silver alloy powder represented by the following formula:
The solderability is considerably better. That is, in the cured film, in the state where the copper alloy powder and the silver alloy powder are dispersed,
Perform soldering. At this time, the copper alloy powder on the cured film surface,
The silver alloy powder ratio g is important. That is, the silver alloy powder has a high bonding property with the solder, and diffusion into the solder and diffusion of the solder into the silver alloy powder occur from the surface. With silver alloy powder having a composition whose surface is all such, solder erosion is likely to occur, and the silver alloy powder dissolves in the solder phase and is extracted, so that sufficient adhesive strength cannot be obtained. However, as in the present invention, the silver alloy powder is 0.1 to 6 parts per 100 parts by weight of the solderable copper alloy powder.
When 0 parts by weight are mixed, both the silver alloy powder portion that positively binds to the solder and the copper alloy powder portion that binds the solder to some extent provide higher solderability, higher solder erosion resistance, and higher 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 tends to occur, and the silver alloy powder on the surface is eroded by the solder phase.
If the amount is less than 0.1 part by weight, the adhesive strength is not sufficient.
The amount of silver alloy powder is 1 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, Ti, Zn, S
n, Pt, Au, Pd, Pb, Mn, Mg, Li, B,
P, C, Si, In, Al, Sb, Cr, Ge, Co,
A compound composed of the elements Zr, W, Ta, Tl, Bi, Ni, and Fe may be added.

The average particle size of the copper alloy powder used in the present invention is 0.1 to 100 μm. If the average particle size is less than 0.1 μm, the solderability is inferior due to oxidation of the powder. Also, 1
If it exceeds 00 μm, the thickness of the coating film becomes too large, and the conductivity becomes poor. Preferably 0.1 to 50 μm,
Further, the thickness is preferably 0.3 to 20 μm. The average particle diameter used here means a volume-integrated average particle diameter. The measurement was performed using a laser diffraction type particle size measuring device. As the particle shape, a powder having a known shape such as a sphere, a scale, and a mixture thereof can be used.

In the case of scaly powder, a powder having an aspect ratio (the longest diameter / thickness of a disc) of 2 or more is preferable. The aspect ratio is preferably 2 or more and 500 or less. The average particle diameter of the silver alloy powder is 0.1 to 10 as in the case of the copper alloy powder.
0 μm is preferred. The powder shape is preferably spherical, scaly, or a mixture thereof. As the phenol resin used in the present invention, a known phenol resin can be used, and examples thereof include a novolak phenol resin, a resol phenol resin, a xylene resin-modified resol resin, and a rosin-modified phenol resin. Among them, resol type and modified resol type resins are preferred. The amount of the 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 will be poor. Further, it is preferable to mix and use an epoxy resin in order to particularly improve the adhesiveness according to the use. 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 the amount exceeds 50 parts by weight, the solderability deteriorates. Known epoxy resins can be used,
For example, bis A type epoxy resin (liquid, solid), brominated epoxy resin, bis F type epoxy resin, cycloaliphatic epoxy resin, triglycidyl isocyanurate type epoxy,
Glycidyl ester type epoxy resin, glycidylamine type epoxy resin, heterocyclic epoxy resin and the like can be used.

The strong solderable conductive paste of the present invention can use a solvent. This gives the paste an appropriate viscosity and thixotropy, and known solvents can be used. For those mixed with an epoxy resin, a reactive diluent can also be used. For example, ethyl cellosolve, methyl cellosolve, butyl cellosolve,
A known solvent such as hexyl cellosolve and their acetates, methyl carbitol, butyl carbitol and their acetates, butyl acetate, toluene, and methyl acetate may be used.

A phenolic OH-modified epoxy resin, an acrylic resin, a urethane resin, a polyester resin, and an amino resin can be mixed and used. As a method for curing, a known method may be used. In particular, the curing can be performed in air, nitrogen, or a reducing atmosphere. The curing temperature is from 100C to 180C, preferably from 130C to 180C. 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 with respect to 100 parts by weight of the copper alloy powder.
If it exceeds 0 parts by weight, the adhesiveness is poor. Also, 0.
If the amount is less than 001 parts by weight, the environmental resistance is poor. Preferably, it is 0.01 to 10 parts by weight, and further 0.1 to 7 parts by weight.
Parts are preferred.

The solid 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 the copper alloy powder. Modified rosins such as fully hydrogenated rosin, esterified rosin, maleated rosin, disproportionated rosin, and polymerized rosin are exemplified. If the amount exceeds 30 parts, dripping of the paste tends to occur, and the adhesiveness becomes insufficient. If the amount is less than 0.001 part, the reflow solderability will be poor. Preferably, it is 0.5 to 20 parts, more preferably 0.6 to 10 parts. The present invention not only allows soldering in a solder bath by dip, but also enables reflow solderability. Soldering by reflow can be performed using a known reflow furnace. For example, infrared heating, hot air circulation system, vaporization latent heat system, hot plate, heating tool, light beam,
Laser, air heater system, etc. can be used. As the heating temperature, the melting point of the used solder paste is 10 ° C to 20 ° C.
It is preferable to set the maximum temperature higher by ° C. The soldering atmosphere may be air, nitrogen, or a reducing gas atmosphere. Known solder can be used as the solder to be soldered.

If necessary, a thixotropic agent, an antifoaming agent, a copper oxide removing agent, and a coupling agent can be added to the strong solderable paste of the present invention. Copper oxide removers include higher fatty acids and their copper salts (linoleic acid,
Stearic acid, linolenic acid, oleic acid), phenol and phenol compounds (eg, hydroquinone, catechol, pyrocatechol, pyrogallol, etc.), hydrogenated castor oil as a thixotropic agent, silane coupling agent as a coupling agent, titanium cup A ring agent can be added. Among them, titanium coupling agent,
Those containing higher fatty acids and their copper salts are preferred. These additives are preferably used in an amount of 0.01 to 50 parts by weight based on 100 parts by weight of the copper alloy powder.
0.1 to 30 parts by weight is preferred.

One of the substrates used by applying or printing the strong solderable conductive paste of the present invention is an organic substrate. 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 substrates is substrate, capacitor housing,
Examples include particles between different kinds of substrates and particles. The application method is not particularly specified, and may be a known method. Examples of the use of these base materials include, for example, fixing the housing of an aluminum electrolytic capacitor or joining electrodes, conducting parts for soldering printed circuits, thick-film conductor circuits for printed circuits, and jumper circuit parts for printed circuit boards. It can also be used for flexible printed circuit boards.

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

The present invention relates to a conductive paste made of a copper alloy powder and a silver alloy powder which is excellent in strong solderability and particularly excellent in reflow solderability, and will be described below with reference to examples. For the measurement of the adhesive strength, a tin-plated copper wire 0.8 mmφ was soldered together, and the peeling strength when pulled vertically was measured. 5 kg or more was practically excellent.

[0021]

【Example】

[0022]

Example 1 Copper particles (average particle diameter 2 mm, purity 99.9)
%, 228.6 g) and 43.2 g of silver particles (average particle diameter: 3 mm, purity: 99.9% or more) were mixed and placed in a graphite crucible, and mixed in a nitrogen atmosphere using a high frequency induction heating apparatus in a nitrogen atmosphere.
The mixture was dissolved by heating to 00 ° C. After dissolution, it was spouted from the crucible tip into a nitrogen atmosphere. The nitrogen gas (purity 9)
(9.99% or more) (30 kg / cm ² G) was ejected 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 was 0.57, the average silver concentration x was 0.1, and the surface silver concentration was 5.7 of the average silver concentration. It was twice.

Similarly, 63.5 g of copper particles and 972 g of silver particles were mixed, heated and melted in a graphite crucible 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 had a spherical shape with an average particle size of 10 μm. The average silver concentration y is 0.
9. Copper concentration was 0.1. 10 g of powder having a size of 10 μm or less (average 5 μm) in the obtained copper alloy powder, 2 g of powder having a size of 10 μm or less (average 5 μm) in the obtained silver alloy powder, 0.6 g of resole type phenol resin, triethanolamine 0.01 g, rosin 0.03 g, hexyl cellosolve 0.3 g, titanium coupling agent 0.0
01g and 0.0001g of thixotropic agent were mixed to form 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 cured by heating at 170 ° C. for 20 minutes. Apply cream solder paste to the cured film,
Further, soldering was performed in a reflow furnace set at 225 ° C. for 20 seconds. The solderability was 100%. Similarly, it was applied on a glass epoxy resin substrate and cured by heating at 170 ° C. for 15 minutes. After curing, the cream solder was applied and soldered in a reflow furnace in the same manner. The solderability was 100%.
Adhesion strength is 6k after pushing the condenser housing
g.

[0025]

Example 3 The paste obtained in Example 1 was applied on an IO conductive film of a solar cell panel in a width of 100 μm and a length of 30 mm. After the application, it was cured by heating at 170 ° C. for 20 minutes. After curing, a cream solder paste was applied. After the application, soldering was performed in a reflow furnace at 150 ° C. for 2 minutes and 230 ° C. for 20 seconds. Solderability was good. Also, IT
Adhesion with O was as good as 6 kg or more. The conductivity was as good as 10-4 Ω · cm before soldering.

[0026]

Example 4 The paste obtained in Example 1 was applied on a polyetherketone resin substrate 1 mm thick to a width of 100 μm and a thickness of 30 m.
m-length lines were printed by screen printing. 170
The composition was cured by heating at 200C 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. The substrate was further printed with a pattern and used as a conductive circuit.

[0027]

Example 5 A circuit was printed on the alumina substrate using the paste obtained in Example 1. Cured at 170 ° C. using far infrared. Further print the 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 as excellent as 7 kg.

[0028]

Example 6 The paste obtained in Example 1 was prepared by etching a copper foil of a paper phenol substrate by 100 μm.
Screen printing was performed as a jumper circuit between m conductors (interval 1 mm). The composition was cured by heating at 170 ° C. using near infrared rays. The conductivity was 10 ⁻⁴ Ω · cm. Furthermore, print a solder paste on a part of the jumper wire,
Soldering was performed in a reflow furnace. 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 polyphenylene ether resin substrate on which a copper foil was laminated. The composition was cured by heating at 170 ° C. for 20 minutes. The conductivity was 10 ⁻⁴ Ω · cm. Further, a solder paste was printed on the terminals of the circuit, and soldered in a 230 ° C. reflow furnace. 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 housing. 160 ° C,
Heat cured for 30 minutes. Further, after applying the solder paste, soldering was performed in a reflow furnace at 150 ° C. for 2 minutes and at 230 ° C. for 20 seconds. The solderability was 100%.
Further, the adhesive strength was 6 kg.

[0031]

Example 9 A circuit was screen-printed from the paste obtained in Example 1 on a polyimide resin substrate. The composition was heated and cured in a far-infrared oven set at 165 ° C. Conductivity is 10 ^-4
Ω · cm. Further, dip was performed in a solder bath at 230 ° C. for 5 seconds. The solderability was 100%. Also,
The adhesive strength was 8 kg.

[0032]

Example 10 Copper particles 252.7 g, silver particles 2.16 g
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 dissolution, the melt was jetted from the crucible tip into a nitrogen atmosphere. Simultaneously with the ejection, nitrogen gas (purity 99.99% or more, pressure 40 kg /
cm ² G) toward the melt and atomized. The obtained powder had an average particle size of 11 μm. The silver concentration on the surface was measured to be 0.1, 0.06, 0.0
4, 0.02 and 0.01, and the silver concentration on the surface is 0.0
It was 8. The average silver concentration x was 0.005, and the silver concentration on the surface was 16 times the average silver concentration.

Similarly, 63.5 g of copper particles and 10 particles of silver particles
8 g was sufficiently mixed and dissolved by heating to 1750 ° C. in a graphite crucible. The melt was atomized with 40 kg / cm ² G nitrogen gas. The average particle diameter of the obtained silver alloy powder is 10
It was a spherical powder of μm. Further, the average silver concentration y is 0.1.
5. Silver concentration was 0.5. 10 g of powder of 10 μm or less in the obtained copper alloy powder (average 5 μm), powder of 5 μm or less in the obtained silver alloy powder (average 2 μm)
5 g, resol type phenol resin 2 g, novolak type phenol resin 0.1 g, bis A type epoxy resin 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 defoamer 0.001 g were sufficiently mixed to obtain a paste.

[0034]

Example 11 The paste obtained in Example 10 was used to coat a small aluminum substrate on which a circuit had already been formed.
A mm-square pad was printed and cured at 170 ° C. for 20 minutes. Further, the solder paste is printed on the pad, and 23
Soldering was performed in a reflow furnace set at 0 ° C. The solderability was 100%. This pad was used as a contact of a conductive circuit. The adhesive strength was 7 kg.

[0035]

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

[0036]

Example 13 Using the paste obtained in Example 10, a carbon paste was applied to the entire surface of the external electrode of the tantalum capacitor, which had already been applied and cured, using a dip. After the application, it was cured by heating at 160 ° C. for 30 minutes. After curing, further apply solder paste on the entire surface,
Soldering was performed in a reflow furnace set to.

When the conductivity was further measured by attaching a silver electrode, a good conductivity of the order of 10 ⁻⁵ Ω · cm was obtained. The solderability was 100%. Further, the adhesive strength was 7 kg.

[0038]

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

[0039]

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

[0040]

Example 16 Using the paste obtained in Example 10, printing was performed on an aluminum extraction electrode portion of an aluminum electrolytic capacitor. The composition was cured by heating at 160 ° C. for 30 minutes. further,
Print solder paste and paste it on one copper contact 2
The soldering was performed in a reflow 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 formed on an enamel substrate by screen printing.
The composition was cured by heating at 180 ° C. for 10 minutes. Further, after printing the solder paste, it was soldered in a reflow furnace set at 230 ° C. for 15 seconds. The solderability was 100%. 7 kg was sufficient for the adhesion to the substrate.

[0042]

Example 18 228.6 g of copper particles and 43.2 g of silver particles
And placed in a graphite crucible and placed in a nitrogen atmosphere at 1750
It melted by heating using high frequency induction heating to ℃. After melting,
The melt was spouted from the crucible tip in a nitrogen atmosphere (purity of 99.9% or more). Nitrogen gas (20kg /
cm ² G, purity 99.99% or more) to the melt and atomized. The resulting powder has an average particle size of 12μ.
m spherical powder. When the silver concentration on the surface was measured, it was found that 0.7, 0.6, 0.55, 0.45,
0.39, 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 dissolved in a graphite crucible by heating to 1750 ° C. in the same manner. The melt was atomized with 40 kg / cm ² G nitrogen gas. The obtained silver alloy powder has an average particle diameter of 10 μm.
m. The average silver concentration y was 0.7 and the average copper concentration was 0.3. Among the obtained copper alloy powder, 10
10 g of powder having an average particle diameter of 5 μm or less (average particle diameter of 5 μm), 0.1 g of powder having an average particle diameter of 5 μm or less (average particle diameter of 2 μm), 1.0 g of a xylene resin-modified resole type phenol resin, and a nopolak type phenol resin 1 0.0 g, rosin-modified phenol resin 0.5 g, resole-type phenol resin 1 g, hydrogenated rosin 0.2 g, maleated rosin 0.0 g
1 g, fully hydrogenated rosin 0.4 g, disproportionated rosin 0.5
g, polymerized rosin 0.03 g, triethanolamine 0.1 g.
001 g, 0.001 g of a thixotropic agent, 0.001 g of a titanium coupling agent, 1 g of hexyl cellosolve, 1 g of butyl carbitol acetate, 0.001 g of an antifoaming agent, and a paste were sufficiently mixed to form a paste.

[0044]

Example 19 10% of the copper alloy powder obtained in Example 18
10 g of powder having an average particle diameter of 4 μm or less (average particle diameter: 4 μm) was scalyed for 10 minutes using a vibrating ball mill in a stainless steel container using 50 cc of solvent saphtha, 0.1 g of a surfactant and 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 silver concentration on the surface was 0.4, which was 4.9 times the average silver concentration. 10 g of the obtained copper alloy scale powder
And the same composition as in Example 18 (copper alloy flake powder 10)
A paste was prepared by mixing 4 parts by weight of silver alloy powder with respect to 0 parts by weight.

[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 cured by heating 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. Both the conductivity and the adhesion of 8 kg were good. Also,
Adhesion was good even when woven 180 degrees.

[0046]

Example 21 The paste obtained in Example 18 was applied to a case of an electronic component made of glass. 170
The composition was heated and cured in a far-infrared oven set at a temperature of ℃ C. A solder paste was applied to the surface of the cured film and soldered in a reflow furnace at 230 ° C. The lead was taken out from the soldered part. The solderability of 6 kg was sufficient for both the adhesion and the adhesion.

[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 circuit board. After printing, it was cured by heating in a far infrared oven at 170 ° C. The solder paste was printed on the cured film. When soldered in a reflow furnace at 230 ° C., the solderability of the jumper wire to the circuit connection was sufficient. Further, 9 kg was sufficient for the adhesiveness.

[0048]

[Comparative example]

[0049]

Comparative Example 1 Commercially available copper powder (purity 99.9% or more, average particle diameter 2 μm) 10 g, resol type phenol resin 1 g,
0.3 g of epoxy resin, 0.1 g of partially hydrogenated rosin, 0.01 g of triethanolamine, 0.001 of phenol
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
The composition was cured by heating at 70 ° C. for 20 minutes. Conductivity is 10 ^-3 Ω · c
m was bad. Furthermore, solder paste is printed and 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 size 1 μm), 1 g of resole type phenol resin,
1 g of ethyl carbitol, 0.0 of triethanolamine
1 g and 0.01 g of completely hydrogenated rosin were mixed and pasted. A paste was applied to the printed circuit board copper foil portion. Further, a solder paste was printed on the cured film and soldered in a 230 ° C. reflow furnace. Although the solder was attached, the solder erosion was remarkable and the adhesive strength was 1 kg.

[0051]

Comparative Example 3 101.6 g of copper particles and 259.2 g of silver particles
Into a graphite crucible and placed in a nitrogen atmosphere (purity 99.99%
) To 1750 ° C using high frequency induction heating. The melt is jetted into a nitrogen atmosphere (purity 99.99% or more), and simultaneously with the jet, nitrogen gas (purity 99.99% or more, pressure 40 kg / cm ² G) is jetted to the melt.
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,
0.7, 0.6, 0.54, and 0.3, and the silver concentration on the surface was 0.75. The average silver concentration x is 0.6
The silver concentration on the surface was only 1.25 times the average silver concentration.

Among the obtained powders, powder 1 having a size of 10 μm or less
0 g (average 5 μm), resol type phenol resin 1 g,
0.2 g of triethanolamine, maleated rosin 0.
01 g and butyl acetate 1 g were sufficiently mixed to obtain a paste. The obtained paste was printed on a paper phenolic resin printed circuit board. It was cured by heating at 170 ° C. for 10 minutes. At this time, when a migration test (water-drop test) (10 DCV, 1 mm interval) was performed, significant migration occurred. When the solder paste was printed and soldered by reflow, the adhesive strength was reduced to 0.3 kg due to solder erosion.

[0053]

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

Printing the paste on the ITO transparent electrode,
The composition was cured by heating at 70 ° C. for 20 minutes. A solder paste was printed on the obtained cured film, and soldering was performed by reflow at 230 ° C. for 20 seconds. As a result, solder erosion occurred, and the bonding strength was almost 0.2 kg.

[0055]

Comparative Example 5 Among the copper alloy spherical powder (average silver concentration x = 0.1) produced in Example 1, 10 g of powder having a size of 5 μm or less (average 2 μm), 1 g of resole type phenol resin, 5 g of triethanolamine, rosin A paste was prepared by mixing 0.01 g, 2 g of butyl cellosolve, and 0.0001 g of a thixotropic agent. The obtained paste was screen-printed on a glass epoxy resin substrate. The composition was cured by heating at 170 ° C. for 15 minutes. The conductivity was as low as 10 ⁻² Ω · cm. Further, the solder paste was screen-printed and soldered in a reflow furnace at 230 ° C. for 20 seconds. Solderability was as poor as several percent.

[0056]

Comparative Example 6 Of the spherical powder (average silver concentration x = 0.1) produced in Example 1, 10 g of powder having a size of 5 μm or less (average 2 μm)
m), 1 g of resole 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 were sufficiently mixed to form a paste. The obtained paste was screen-printed on a paper phenolic resin substrate. The composition 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. Solderability was hardly adhered due to the granularity of the solder. In addition, the adhesion to the substrate was poor.

[0057]

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

[0058]

The present invention relates to a compound of the general formula AgxCul-x
(0.001 ≦ x ≦ 0.4, atomic ratio) Copper having a region where the silver concentration on the surface is higher than 2.1 times the average silver concentration and the silver concentration increases from the inside toward the surface. Strong 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) with respect to 100 parts by weight of alloy powder Regarding the conductive paste, especially reflow solderable conductive paste, the silver is concentrated on the surface, so the solderability is good, and the silver concentration decreases from the surface to the inside, the problem of solder erosion It has the advantage of not happening. Further, since the silver alloy powder is mixed, a solder diffusion site is formed in the cured film, so that the soldering strength can be further increased. Further, by having a mixture binder of a phenolic resin and an epoxy resin having such a composition, the adhesiveness to the substrate to be adhered is improved.

────────────────────────────────────────────────── ─── Continuing on the front page (51) Int.Cl. ⁷ identification code FI H05K 1/09 H05K 1/09 A (58) Investigated field (Int.Cl. ⁷ , DB name) C09D 5/24

Claims (8)

(57) [Claims] 1. A compound of the general formula AgxCu1-x (where 0.1.
001 ≦ x ≦ 0.4, atomic ratio), a copper alloy powder having a region where the silver concentration on the particle surface is higher than 2.1 times the average silver concentration and the silver concentration increases toward the particle surface 1
0.1 to 60 parts by weight of a silver alloy powder having the general formula AgyCu1- y (where 0.4 <y ≦ 0.999, atomic ratio) with respect to 00 parts by weight, and at least one or more phenol resins as an organic binder A solderable conductive paste containing 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 rosin 0.001 to 3 with respect to 100 parts by weight of copper alloy powder.
A solderable conductive paste obtained by adding 0 parts. 3. The organic binder according to claim 1, wherein the organic binder is 0.1 to 5 parts by weight based on 100 parts by weight of the phenol resin.
A solderable conductive paste containing 0 parts by weight of an epoxy resin. 4. The reflow solderable paste according to claim 1, wherein the paste is a reflow solderable paste. 5. A molded article obtained by curing the paste according to claim 1 on an organic substrate. 6. A molded product obtained by curing the paste on any one of claims 1 to 4 on a ceramic substrate. 7. The organic substrate according to claim 5, wherein the organic substrate is a polyphenylene sulfide resin, a paper phenol resin substrate, a glass epoxy substrate, a polyphenylene ether resin, a polyimide resin, a polyester resin, a polyether ketone resin, a phenol resin, an epoxy resin, or a polystyrene resin. A molded article characterized in that it is at least one member selected from the group consisting of: 8. A molded product obtained by curing the paste according to claim 1 on an ITO or IO conductive glass or metal substrate.