JPH06139813A - Paste for outer conductor of low-temperature baked multilayer circuit substrate - Google Patents

Abstract

PURPOSE:To manufacture paste for outer conductors of a low-temperature baked multilayer circuit substrate, which has migration resistance, high adhesiveness, oxidation resistance and besides excellent electric connecting to inner conductors, by specifying the concentration of silver in the surface of each of particles in the paste and the average diameter of the particles respectively. CONSTITUTION:Paste for outer conductors of a low-temperature baked multilayer circuit substrate is represented by a general formula of AgxCu1-x(0.01<=X<=0.4 in atomic ratio), and it has the concentration of silver in the surface of its particle set higher than 2.1 times the average concentration of silver in the whole of each of the particles. This paste is manufactured through the process of mutually compounding 0.1 to 30 pts.wt. of glass frit, in which particles each have an average diameter of 0.1 to 10mum and also not less than 90% of them each have a diameter of not larger than 15mum, against 100 pts.wt. of copper alloy powder in which particles each having a region where the concentration of silver is gradually increased toward the surface of the particle each have an average diameter of 0.1 to 20mum and also not less than 90% of them each have a diameter of not larger than 25mum, the copper alloy powder and an organic vehicle respectively. The paste can thus have excellent adhesiveness to the substrate, solderability, migration resistance and oxidation resistance respectively.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The outer conductor paste for a low temperature fired multilayer circuit board of the present invention can be used as an outer conductor of a low temperature fired multilayer circuit board exhibiting excellent characteristics in high density and high speed signal transmission. It can also be used as a hybrid IC circuit.

[0002]

2. Description of the Related Art In recent years, in the field of electronic materials, with increasing integration and densification, multi-layer technology for hybrid IC substrates has been advanced. Among them, low-temperature firing green sheet multi-layering is being promoted. As a multi-layer method, a noble metal powder such as silver, silver-palladium, silver-platinum, or gold is used as a conductor on a green sheet (substrate before firing) that is prepared by drilling or punching holes for via holes or through holes in advance. Used as a multi-layer circuit board by printing the paste, and if necessary, a dielectric and a resistance paste, making the printed green sheet into a multilayer, and simultaneously firing at a low temperature of 550 to 1060 ° C. in an oxygen-containing atmosphere or in air. ing. Naturally, as a result obtained in this way, a paste of silver, silver-palladium, copper, silver-platinum, or gold has been used as the outer conductor (outer layer conductor) of the low temperature firing multilayer circuit board. A method is also known in which an inner conductor made of the noble metal is formed in air or in an oxygen-containing atmosphere, and then a copper paste as an outer conductor is fired in an inert atmosphere (for example, in a nitrogen atmosphere).

After the outer conductor is produced, printing and firing of a crossover glass, an overglass, an external resistor and the like are repeated as needed to form a circuit as a low temperature firing multilayer circuit board.

[0004]

The known silver, silver-palladium, silver-platinum, gold, and copper used as the outer conductor of a low-temperature fired multilayer circuit board have the following problems. . That is, in the case of silver, when it is used as an internal conductor, since it is laminated, the migration property between the internal conductors does not matter so much, but when the external conductor is silver, the precious metal internal conductor ( That is,
Bonding with silver, silver-palladium, silver-platinum, gold) during firing is good because it is easy to form a solid solution with the inner conductor, but silver between outer conductors between high-density patterns such as multilayer circuit boards Migration is a problem.

In the case of silver-varadium, it is still good to bond it with the internal conductor using a noble metal system at the time of firing, but as an external conductor used as a fine line, the impedance is too high and it is not suitable for practical circuits. . The silver-platinum outer conductor has good bonding with the precious metal-based inner conductor during firing, and has good reliability and solder erosion during fine line circuit soldering, but has a problem in migration property.

[0006] With gold, similarly, bonding with the precious metal internal conductor at the time of firing is good, but it costs too much. When copper is used as the outer conductor, the impedance in the fine line is low and the electrical characteristics are excellent, but after forming the precious metal-based inner conductor by firing in air or an oxygen-containing atmosphere, it is placed in an inert atmosphere. Since it is produced by firing at 100 ° C., the amount of oxygen added for completely firing the organic vehicle must be controlled quite strictly, and firing in a nitrogen atmosphere of 10 ppm or less has been generally used. Therefore, the organic vehicle is left unburned, and defective soldering easily occurs. Further, when the outer conductor is copper, it is alloyed with the inner conductor at the time of firing and bonding with the precious metal-based inner conductor (via-hole conductor and through-hole conductor) at the time of firing of the copper powder or in the minute oxidation state in the preserved state. Is likely to be insufficient, and electrical defects are likely to occur at the joint surface.

[0007]

The present invention is directed to the general formula Ag _x C
u _1-x (where 0.01 ≦ x ≦ 0.4, atomic ratio), and the silver concentration on the surface of the grain is 2.
Copper alloy powder 10 having an average particle size of 0.1 to 20 μm and a ratio of powder having a particle size of 20 μm or less is 90% or more, which has a region higher than 1 time and has a silver concentration increasing toward the particle surface.
Low temperature firing characterized by containing 0.1 to 30 parts by weight of a glass frit having an average particle size of 0.1 to 10 μm and 90% or more of powder having an average particle size of 10 to 10 μm, and an organic vehicle, relative to 0 parts by weight. Multilayer circuit board external conductor paste, and the paste of the composition, silver, silver-palladium,
A general formula Ag _x Cu formed by printing and sintering on an outer layer of a low temperature fired multilayer circuit board having an inner layer inner conductor (including a via hole conductor and a through hole conductor) which is at least one selected from silver-platinum and gold. _1-x (where 0.01 ≦ x ≦ 0.4,
The present invention relates to a low temperature fired multilayer circuit board composed of an outer conductor expressed by atomic ratio).

As a method for producing the copper alloy powder that can be used in the present invention, the atomizing method already applied for by the present inventor is preferable (USP 5091114). According to the disclosure, in an inert gas atmosphere, copper and silver having such a composition at a high temperature of several thousand and several hundred degrees are melted, the melt is atomized using a high-speed inert gas, and rapidly solidified to obtain a fine powder. Is a method of manufacturing.

When the amount of silver x is less than 0.01, sufficient oxidation resistance is poor when firing as an outer conductor, and sufficient bonding with the inner conductor cannot be obtained. If it exceeds 0.4, migration of silver between the outer conductors is likely to occur. It is preferably 0.01 to 0.35, and more preferably 0.01 to 0.35.
0.25 is preferable. Further, the silver concentration on the surface of the copper alloy powder that can be used in the present invention is higher than the average silver concentration and has a region where the silver concentration increases toward the particle surface, but the silver concentration on the surface is average. The silver concentration is 2.1 times or more. If it is less than 2.1 times, not only the oxidation resistance of the conductor during firing is insufficient, but also the bonding with the internal conductor is insufficient. It is preferably 2.1 times or more and 40 times or less. Further, it is preferably 3 times or more and 30 times or less.

The external conductor paste of the present invention is to obtain sufficient electrical conduction by alloy bonding with the internal conductor during firing. That is, silver and the noble metal component of the inner conductor form a solid solution at all rates, and since the silver concentration on the surface of the copper alloy powder used in the present invention is high, silver, silver-palladium, silver-of the already formed inner conductor is formed. The noble metal inner conductor containing platinum or gold and the outer conductor paste having such a composition are easily alloyed, so that sufficient electrical connection can be obtained. Also, as an outer conductor after sintering, one of the advantages is that the average silver concentration is low and there is no problem of migration between conductors.

In the case of a copper outer conductor, if the copper particles are slightly oxidized during firing, the already formed inner conductor is joined to the inner conductor composed of silver, platinum, palladium, gold components, etc. by an alloy. Is not performed sufficiently, causing contact failure. The copper alloy powder used in the present invention has an average particle size of 0.1.
The particle size is up to 20 μm, but if it is less than 0.1 μm, the amount of oxygen contained in the particles is high and a conduction failure during firing is likely to occur. Two
When it exceeds 0 μm, clogging at the time of fine line formation is likely to occur, which is preferable. Preferably 0.2 to 15 μ
It is the average particle diameter of m. Further, the presence of particles of 25 μm or less is present because of fine line printability such as the outer conductor of the low temperature fired multilayer circuit board and sufficient alloying with the inner conductor.
% Or more is required. Further, it is preferably 95% or more.

The average particle diameter used in the present invention means a volume cumulative average particle diameter. The measurement was performed by using a laser diffraction type average particle size measuring device (SALD1100 manufactured by Shimadzu) by completely dispersing the copper alloy particles in ethylene glycol as a solvent. The presence of powder having a particle size of 25 μm or more was similarly determined from the particle size distribution using a laser diffraction type average particle size measuring device.

The low temperature fired multilayer circuit board outer conductor paste of the present invention comprises glass frit and copper alloy powder 100.
It is contained in an amount of 0.1 to 30 parts by weight with respect to parts by weight, but the role of the glass frit is to give a strong adhesive force to the multilayer circuit board. The average particle size of the glass frit is 0.1 to 10 μm. The measurement was carried out in the same manner as the copper alloy powder, and a laser diffraction particle size distribution measuring device (S
ALD1100) was used for volume integration. When the average particle size is less than 0.1 μm, it is difficult to disperse in the paste, and when it exceeds 10 μm, insufficient sintering occurs, printability is poor, and sedimentation easily occurs. Preferably, the average particle size is 0.2 to 7 μm. Also, 15μ
Those having a ratio of m or less of 90% or more can be used. 9
If it is less than 0%, alloying with the internal conductor is hindered. It is preferably 99% or more.

If the glass frit is less than 0.1 parts by weight, the adhesive strength is not sufficient, and if it exceeds 30 parts by weight, the sintering of the copper alloy powder is insufficient. Preferably, it is 0.2 to 20 parts by weight. The components of the glass frit, PbO, is intended to _{SiO 2, B 2 O 3,} ZnO, 1 or more kinds selected from principal component, a glass frit is used, for example, PbO-SiO
_{2 -B 2 O 3, PbO-} SiO 2 -ZnO, PbO-S
_{iO 2 -Bn 2 O 3 -ZnO,} PbO-SiO 2 -Ca
_{O, PbO-SiO 2 -BaO,} PbO-SiO 2 -M
_{gO, PbO-SiO 2 -MnO,} PbO-B 2 O 3,
_{PbO-B 2 O 3 -ZnO,} PbO-B 2 O 3 -CaO
_{-ZnO, PbO-B 2 O 3} -SiO 2 -CaO, Pb
_{O-B 2 O 3 -SiO 2} -MgO, PbO-SiO 2 -
_{Al 2 O 3, PbO-SiO} 2 -B 2 O 3 -Al
_{2 O 3, PbO-B 2} O 3 -Al 2 O 3, PbO-Si
_{O 2 -Al 2 O 3 -CaO,} PbO-SiO 2 -Al 2
_{O 3 -MgO, PbO-B 2} O 3 -Al 2 O 3 -Ca
It is preferable to use an amorphous or crystalline glass frit such as O, SiO ₂ —B ₂ O ₃ system. Above all,
Glass frits containing PbO are preferred. The role of the glass frit is to enhance the adhesion between the low temperature fired multilayer circuit board and the outer conductor of such composition, and it is preferable that the glass frit is bonded to the multilayer circuit board during firing, and the softening point of the glass frit is It is preferably 650 ° C. or lower and 200 ° C. or higher, and more preferably 550 ° C. or lower and 200 ° C. or higher. Also, the difference in coefficient of thermal expansion is 50% that of a multilayer substrate.
It is preferably less than.

To the external conductor paste for a low temperature fired multilayer circuit board of the present invention, cuprous oxide powder may be further added in order to enhance the adhesive strength. It is preferable to use a cuprous oxide powder having an average particle size of 0.1 to 20 μm. If it is less than 0.1 μm, the dispersibility in the paste is poor. If it exceeds 20 μm, sintering of the copper alloy powder is hindered. It is preferably 0.1 to 10 μm. The cuprous oxide powder has a ratio of powder of 25 μm or less of 90.
% Or more is preferable. If it is less than 90%, not only the screen printability but also the sintering of the copper alloy powder is hindered. It is preferably at least 95%. The amount of cuprous oxide added may be 0.1 to 20 parts by weight based on 100 parts by weight of the copper alloy powder. When it is less than 0.1, sufficient adhesive strength cannot be obtained, and when it exceeds 20 parts by weight, sintering of the copper alloy powder is hindered. Preferably, 0.1 to 13 parts by weight,
0.1 to 7 parts by weight is more preferable. Also in the case of cuprous oxide powder, the average particle size and particle size distribution were measured by volume integration in the same manner as in the measurement method of copper alloy powder. 25μ
The ratio of m or less was obtained from the particle size distribution.

In addition, cupric oxide, bismuth oxide, lead oxide, magnesium oxide, zinc oxide, boron oxide, silica, cadmium oxide, in order to further improve the adhesiveness to the low temperature firing multilayer circuit board and the solder wettability. It is also possible to add 0.1 to 20 parts by weight of fine powder (preferably, an average particle diameter of 0.01 to 10 μm) to 100 parts by weight of the copper alloy powder.

The low-temperature fired multilayer circuit board outer conductor paste of the present invention contains an organic vehicle, and the organic vehicle may be any known organic vehicle without particular limitation. The role of the organic vehicle is to provide the paste with an appropriate viscosity and thixotropy, for example, a known organic binder such as ethyl cellulose, methyl cellulose, acrylic resin, butyral resin, etc. It is something to give. As the solvent, a known solvent can be used.

If necessary, a thixotropic agent such as a coupling agent (titanium coupling agent or silane coupling agent), hydrogenated castor oil, colloidal silica or oxidized polyethylene, or a higher fatty acid (eg stearic acid, linolenic acid). , Linoleic acid, palmitic acid, etc.) and their copper salts can also be added. The amount of the organic vehicle used is 1 to 300 with respect to 100 parts by weight of the copper alloy powder.
Parts by weight are preferred. The additive is copper alloy powder 1
0.001 to 30 parts by weight is preferable with respect to 00 parts by weight.

By printing the external conductor paste of the present invention,
When firing, it is preferable to fire in an inert atmosphere, but as the inert atmosphere, nitrogen, argon, hydrogen, or helium atmosphere is preferable. In particular, the nitrogen atmosphere is preferable from the economical viewpoint. When firing in an inert atmosphere, it is preferable to fire at a low temperature of about 550 to 1050 ° C. to form a sintered body. At this time, it is more preferable to dope oxygen to 500 to 600 ° C. in order to sufficiently burn off the organic vehicle. For example, 1-1000
It is preferably doped with ppm. As the firing furnace, a resistance heating furnace or a known firing furnace such as a near infrared furnace may be used, but a belt conveyor type furnace is preferable. The firing time is not particularly specified, but is 3 minutes to 120 at the maximum firing temperature.
Minutes are preferred.

In the outer conductor of the present invention formed as a sintered body by firing at the above temperature, it is particularly preferable that the silver concentration on the conductor surface is higher than the average silver concentration. The silver concentration on the surface of the outer conductor is preferably at least twice the average silver concentration, and further 3
It is preferably double or more. That is, since the temperature is for sintering, the sintering starts from the contact point between the particles rather than the melting of the particles. At this time, the surface of the obtained outer conductor also has a conductor surface having a high silver concentration. However, the firing temperature is 1
If the temperature exceeds 100 ° C., the outer conductor is melted and fluidized so that the shape of the conductor is broken and the silver concentration is averaged. Further, if the oxygen doping amount enters excessively, the copper concentration on the conductor surface will rather increase.

The low temperature firing multilayer circuit board outer conductor of the present invention is
Due to the high silver concentration on the surface, external resistors and glass pace
Coating the outer conductor with an insulating paste.
Even when heat-treated, it has resistance to oxidation, electrical, solder wetting
There are advantages such as less deterioration of sex. Can be used in the present invention
Green sheet for low temperature firing multi-layer substrate
Known materials can be used for the
In particular, alumina (Al ₂O₃), Forsterai
(2MgO ・ SiO₂), Mullite (3AI₂O₃・
2 SiO₂), Cordierite (2MgO.2Al)₂O₃
・ 5 SiO₂), CaZrO₃With B as the main component
₂O₃, SiO₂With the addition of the glass component of
Spojumen (Li₂O ・ Al₂O₃・ 4SiO₂)system
Or BaO / SnO₂, TiO₂, B₂O₃Consisting of B
aSn (BO₃)₂System, BaTi (BO₃)₂System, Al
₂O₃, CaO, SiO₂, MgO, B₂O₃From etc.
System, BaO, Al₂O₃, SiO₂From additives
Glass systems are preferred.

For example, PbO-SiO₂-B₂O₃−
CaO glass + Al₂O₃, CaO-Al₂O₃-S
iO₃-B₂O₃System glass + Al₂O₃, BaO-Al
₂O ₃-SiO₃-B₂O₃Glass, SiO₂-B₂
O₃System glass + Al₂O₃+ CaZrO₃, SiO₂−
B₂O₃System glass + Al₂O₃, SiO₂-B₂O₃system
Glass + Al₂O₃+ 2MgO-SiO₂, 2MgO-
2 Al₂O₃-5 SiO₂System, ZnO-MgO-Al₂
O₃-SiO₂System, BaSnB₂O₆-BaTiB₂O
₃System, Al₂O₃-CaO-SiO₂-MgO-B₂O
₃System, BaO-SiO₂-Al₂O₃-CaO-B₂O
₃System, etc. The thickness of the green sheet
5 μm to 2000 μm can be used
However, it is not specified.

The silver concentration on the surface of the copper alloy powder used in the present invention and the silver concentration on the surface of the outer conductor obtained by the outer conductor paste for a low temperature firing multilayer circuit board of the present invention are measured by XPS (X-ray photoelectron Spectroscopic analyzer: XSAM800 manufactured by KRATOS) was used. Measurement conditions: Carbon double-sided tape was attached to the sample table, copper alloy powder or external conductor chips (barred without overcoating) were attached to cover the entire surface, and vacuum deaeration was sufficiently performed, followed by argon atmosphere < 10 ⁻⁸ torr MgKα ray Sample current 10 mA 12 kV Measurement was performed at an extraction angle of 90 degrees. Etching conditions: Argon gas 3 keV 10 ⁻⁷ t
orr 5 minutes Measurement and etching are alternately repeated 5 times under the above conditions, and the average value of the first 2 measured values is the silver concentration on the surface x = Ag /
(Ag + Cu), copper concentration 1-x = Cu / (Ag + Cu)
And The average silver concentration of the copper alloy powder and the outer conductor was measured by dissolving the sample in concentrated nitric acid solution and then dissolving the sample in concentrated nitric acid using ICP (high frequency inductively coupled plasma emission spectrometer). It was measured.

In the migration test, an outer conductor width of 80 μm and an interval of 100 μm were prepared and the temperature was 60 ° C. and 90%.
The migration time was measured when 50 DCV was applied to the conductor spacing in relative humidity. A time of 5 hours or more was evaluated as good and a time of less than 5 hours was evaluated as bad. Further, the electrical connection on the connection surface between the inner conductor and the outer conductor was judged by measuring the impedance between the conductor of the second layer and the outer conductor connected by the via hole.

Solder wettability of outer conductor (solderability)
Was dipped in a 230 ° C. tin / lead eutectic solder bath for 10 seconds to make the wet area 95% or more good. Anything less than that was considered defective. The impedance of the outer conductor was measured using the 4-terminal method. Examples will be shown below.

[0026]

【Example】

[0027]

[Powder Preparation Example 1] 571.5 g of copper particles and 108 g of silver particles
Thoroughly mixed in a graphite crucible in a nitrogen atmosphere at 1700
It melted by heating to ℃. The melt was jetted from the tip of the crucible into a nitrogen atmosphere, and simultaneously with the jetting, 50 kg / cm ² of nitrogen gas was jetted to the melt to atomize. The obtained powder had an average particle size of 12 μm. The silver concentration on the surface of the copper alloy powder was 0.5, 0.4, 0.3, 0.2, and 0.14, and the silver concentration on the surface was 0.45. The average silver concentration x was 0.1, and the surface silver concentration was 4.5 times the average silver concentration.

An example of producing a copper alloy powder produced in the same manner is shown below.

[0029]

[Table 1]

[0030]

Example 1 Among the copper alloy powders obtained in Powder Preparation Example 1,
A powder having a size of 10 μm or less was classified. The obtained powder is an average particle
The child diameter was 4.5 μm. 10g of the powder and PbO-B
₂O ₃-ZnO-SiO₂Glass frit (average particle size
5 μm, 10 μm or less 99% or more) 0.2 g, ethyl acetate
Lulose 0.05g, acrylic resin 0.5g, terpeno
1 g, butyl carbitol 2 g, butyl carbitol
Luacetate 2g, cuprous oxide powder (average particle size 2μ
m) 0.1 g, silicone oil 0.001 g, titanium oxide
Mixing 0.0001g of pulling agent to make paste
It was

Further, mullite contains B ₂ O ₃ , CaO and Mg.
The silver paste, the dielectric, and the ruthenium-based resistance paste are printed as a circuit on the green sheet formed by adding O, and 1
It was laminated in 0 layer and further baked in air at 800 ° C. for 60 minutes. A paste having the above composition was printed as an outer conductor on the obtained multilayer circuit board. After printing, it was baked at 700 ° C. in a nitrogen atmosphere for 10 minutes. At this time, oxygen was doped at 400 ppm up to 500 ° C.

When the silver concentration on the surface of the obtained conductor was measured, the silver concentration was 0.6, 0.5, 0.45 from the surface.
0.4 and 0.3, the surface silver concentration was 0.55, which was 2.75 times the average silver concentration. Regarding the conductivity of the conductor, it was found that the outer conductor and the inner conductor in the surface layer were joined well, and there was almost no increase in the resistance value at the joint surface between the inside and the outside.

Further, as a printed resistor, a lanthanum boride type resistor was printed between the conductors and fired at 900 ° C. in a nitrogen atmosphere. No increase in resistance was observed due to the conductor electrode. Further, even when overcoat glass was printed and treated in a nitrogen atmosphere at 550 ° C., discoloration of the conductor surface was not observed. The migration test was successful. The impedance of the outer conductor was also good.

[0034]

[Example 2] 5 of the copper alloy powders obtained in Powder Preparation Example 1
The powder having a particle size of μm or less was classified. The obtained powder has an average particle size.
It was 2 μm. 10 g of the obtained classified powder, PbO-B
₂O ₃-ZnO glass frit (average particle size 0.3μ
m, 15 μm or less and 99% or more) 0.3 g, cuprous oxide powder
Powder (average particle size 0.2 μm) 0.1 g, ethyl cellulose
Soluble 0.02g, acrylic resin 0.04g, butyl rib
0.6 g tall acetate, cuprous oxide powder (average particles
Diameter 0.2 μm, 10 μm or less 99% or more) 0.1 g,
0.001g of precipitation inhibitor was mixed thoroughly to form a paste
It was

Separately, forsterite is added to B ₂ O ₃ and Si.
A paste containing 5% of silver-palladium is printed on a green sheet having a via hole formed by adding O ₂ , a ruthenium-based resistor is further printed, a dielectric glass paste is further printed, and a silver is also used for a via hole. -Palladium conductor paste was printed, six green sheets prepared in the same manner were laminated, and cofired in air at 700 ° C.

Circuit printing was performed using the paste having the above composition as an outer conductor of a multilayer circuit board in which a silver-palladium conductor was already formed in a via hole for connection with the outer conductor. After printing, baking was performed in a nitrogen atmosphere at 750 ° C. for 10 minutes. Up to 550 ° C., 500 ppm of oxygen was doped. The silver concentration on the surface of the obtained outer conductor was 0.9, 0.8,
0.7, 0.5, 0.4 and the surface silver concentration is 0.8
5, which was 3.4 times the average silver concentration.

The outer conductor and the inner conductor thus obtained were joined well, and the conductivity was not found to increase in resistance at the joint surface. Moreover, the result of the migration test was good. Further, a lanthanum boride-based resistor paste and a dielectric glass paste were coated and fired in a nitrogen atmosphere. The change in resistance value at the junction between the resistor and the outer conductor was good at 0.1% or less.

[0038]

[Example 3] 2 of the copper alloy powders obtained in Powder Preparation Example 3
The powder having a particle size of μm or less was classified. The obtained classified powder had an average particle diameter of 0.8 μm (20 μm or less and 99% or more).
Classifying powder _{10g, PbO-SiO 2 -MgO-} B 2 O 3
-ZnO glass frit (average particle size 1 μm, 15 μm
Below 99%) 0.02 g, butyl cellosolve 0.2
g, butyl carbitol acetate 0.1 g, silicone oil 0.001 g, thixotropic agent 0.0001 g, cuprous oxide powder (average particle size 0.2 μm, 25% or less 99% or more) 0.8 g, cadmium oxide 0.1 g , Bismuth oxide 0.1 g (average particle size 0.5 μm, 25 μm or less 99%
that's all). Palmitic acid 0.1g, stearic acid 0.1g
Were mixed into a paste.

Separately, B ₂ O ₃ was added to alumina and cordierite.
Is added. A circuit was formed by using a silver-platinum paste on the green sheet in which the via hole was formed. further,
After printing the ruthenium-based resistor paste and the dielectric paste and the silver-platinum paste in the via holes, eight green sheets were laminated in the same manner and co-fired in the air at 800 ° C.

After forming a via-hole conductor for connection with an external conductor on the obtained multilayer circuit board, circuit printing was performed using the external conductor paste having the above composition. further,
Firing was performed in a nitrogen atmosphere at 700 ° C. for 10 minutes. At this time, 5
300 ppm oxygen was doped up to 00 ° C. When the silver concentration on the surface of the obtained outer conductor was measured, the silver concentration was 0.88, 0.8, 0.7, 0.6, 0.5 from the surface, and the silver concentration on the surface was 0. It was 84. The average silver concentration is 0.25, and the surface silver concentration is 3.3 of the average silver concentration.
It was double.

The outer conductor and the inner conductor were joined well, and no increase in resistance was observed at the joint surface. Also,
The result of the migration test was good. Further, an insulating glass paste was printed on the outer conductor and fired in a nitrogen atmosphere at 550 ° C. At this time, oxygen up to 500 ℃ 10
Doped with 0 ppm. No discoloration or the like due to the glass coating of the obtained outer conductor circuit was observed.

[0042]

[Example 4] 3 of the copper alloy powders obtained in Powder Preparation Example 4
The powder having a particle size of μm or less was classified. The obtained powder is 1.2 on average.
was μm. Classified powder 10g, PbO-SiO ₂ -Ca
O-ZnO-B ₂ O ₃ glass frit (average particle diameter 0.
5 μm, 15 μm or less 99% or more) 1 g, copper oxide 0.1
g, bismuth oxide 0.002 g, cuprous oxide (average particle size 0.2 μm, 15 μm or less 99% or more) 0.025
g, ethyl cellulose 0.2 g, acrylic resin 0.2
g, butyral resin 0.1 g, stearic acid 0.000
1 g, a thixotropic agent 0.0002 g, butyl carbitol acetate 0.5 g, and α-terpenol 0.5 g were sufficiently mixed to obtain a paste.

Separately, β-spongemen and BaO-Al
Gold paste was printed as a conductor circuit on a green sheet of ₂ O ₃ —SiO ₂ glass in which a via hole was already formed. Further, after printing via holes and ruthenium-based resistor paste, six green sheets produced in the same manner were laminated and cofired in air at 750 ° C.

After forming a via-hole conductor for joining an outer conductor and an inner conductor on the obtained multilayer circuit board, a circuit printing was performed using the paste having the above composition as the outer conductor. Further, it was baked at 700 ° C. in a nitrogen atmosphere for 10 minutes. At this time, 100 ppm of oxygen was doped up to 550 ° C. No increase in resistance was observed at the joint surface between the inner conductor and the outer conductor. The migration test was good.

The silver concentration on the surface of the outer conductor is 0.
3, 0.25, 0.24, 0.2, 0.15, the surface silver concentration was 0.275, and the average silver concentration was 5.
It was 5 times.

[0046]

[Comparative example]

[0047]

Comparative Example 1 63.5 g of copper particles and 108 g of silver particles were mixed and put in a graphite crucible ,. It was heated to 700 ° C. and melted in a nitrogen atmosphere. The melt was jetted into the nitrogen atmosphere from the tip of the crucible, and at the same time, 40 kg / cm ² G of nitrogen gas was jetted to the melt to atomize. The obtained powder had an average particle size of 13 μm. The average silver concentration x was 0.5 and the average copper concentration was 0.5. Of the obtained copper alloy powder, a powder having a particle size of 10 μm or less was classified. The average particle size of the powder after classification was 5 μm. Copper alloy powder 10g after _{classification, PbO-B 2 O 3 -SiO} 2 ( average particle diameter 1
μm) Glass frit 0.2 g, cuprous oxide powder (average particle size 0.5 μm, 10 μm or less 99% or more) 0.01
g, ethyl cellulose 0.3 g, terpenol 0.6
g, butyl carbitol acetate 0.3 g, and an anti-settling agent 0.001 g were sufficiently mixed to obtain a paste.

A silver-platinum (3 wt%) paste was printed onto an already via-hole formed green sheet of alumina and BaO-B ₂ O ₃ -SiO ₂ glass. Furthermore, after printing in the via hole, a known ruthenium-based resistor was printed, and also a dielectric was printed. Then, six green sheets printed in the same manner were laminated and thermocompression bonded by a hot press. Calcination was performed at 700 ° C. in air for 10 minutes. The copper alloy paste prepared as described above was printed as a circuit as an external conductor of a low-temperature fired multilayer circuit board in which a silver-platinum paste was similarly prepared in a via hole for connection with an external conductor. After firing in a nitrogen atmosphere at 900 ° C. for 10 minutes (3000 ppm of oxygen was doped to 500 ° C.), a known lanthanide-type resistor was printed, and then firing was performed at 900 ° C. for 10 minutes.

When a migration test was conducted on the outer conductor produced by firing, the migration was remarkable. Further, the silver concentration on the surface of the outer conductor is 0.
It was 1, 0.2, 0.3, 0.4 and 0.5, and the surface silver concentration was 0.15, which was 0.3 times lower than the average silver concentration.

[0050]

Comparative Example 2 Commercially available copper particles (average particle diameter 2 μm) 10
g, PbO—CaO—SiO ₂ —B ₂ O ₃ (average particle size 1 μm) 1 g, acrylic resin 0.1 g, terpenol 0.1 g, butyl cellosolve 0.3 g, butyl carbitol acetate 0.5 g, cupric oxide 0 0.2 g and 0.0002 g of titanium coupling agent were mixed sufficiently to form a paste.

The paste prepared on the low temperature fired multilayer circuit board prepared in Comparative Example 1 was printed as an external conductor. After printing, baking was performed in a nitrogen atmosphere at 600 ° C. for 10 minutes (50
Oxygen 100 ppm doped to 0 ° C). The connection between the outer conductor and the inner conductor was not so good, and the resistance value increased. Furthermore, lanthanum boride type resistor is printed,
Firing was performed at 900 ° C. for 10 minutes in a nitrogen atmosphere. The matching with the resistor was poor and the noise was high. Also, the solderability of the external conductor was poor.

[0052]

Comparative Example 3 254 g of copper particles and 108 g of silver particles were mixed and put into a graphite crucible, which was heated and melted to 1700 ° C. in a nitrogen atmosphere. The melt was jetted from the crucible tip into a nitrogen atmosphere, and at the same time as the jetting, 5 kg / cm ² G of nitrogen gas was jetted to the melt to atomize. The obtained copper alloy powder had an average particle diameter of 35 μm.

The average silver composition x of the copper alloy powder was 0.2, and the average copper composition was 0.8. The silver concentration on the surface was 0.8, 0.76, 0.7, 0.6, 0.5 from the surface, and the silver concentration on the surface was 0.78. The silver concentration on the surface was 3.9 times the average silver concentration. 10 g of the obtained copper alloy powder
(Average particle size 35 μm, 25 μm or less 30%), PbO
-B ₂ O ₃ -SiO ₂ (average particle size 1 μm) 0.3 g,
0.2 g of terpenol, 0.2 g of butyl cellosolve, 0.5 g of cuprous oxide (average particle size 1 μm, 10 μm or less 99% or more), and 0.003 g of titanium coupling agent were sufficiently mixed to obtain a paste.

Alumina and BaO--Al ₂ O ₃ --SiO ₂
Gold paste is printed on a green sheet having a via hole formed of glass, the gold paste is also printed on the inside of the via hole, a known ruthenium-based resistor is also printed, and six green sheets produced in the same manner are laminated. After thermocompression bonding with a hot press, it was baked in air at 700 ° C. for 60 minutes. Similarly, a gold conductor was prepared in the via hole for connection with the external conductor, and then the paste was used to perform circuit printing on the obtained low-temperature fired multilayer circuit board. 60 after printing
It was baked in a nitrogen atmosphere at 0 ° C. for 10 minutes (up to 500 ° C., 300 ppm oxygen was doped).

The average particle diameter was large, sufficient sinterability was not obtained, and the outer conductor had high resistance. Also, the connection with the internal conductor was poor, and the resistance value increased remarkably. Also, the solder wettability was poor.

[0056]

[Comparative Example 4] 1 of the copper alloy powders prepared in Powder Preparation Example 5
Powder of 0 μm or less (average silver concentration 0.12, average particle size 4.5 μm, 25 μm or less 99% or more) 10 g, PbO
-B ₂ O ₃ -SiO ₂ glass frit (average particle size 10
μm, 15 μm or less 60%) 1 g, cuprous oxide powder (average particle size 0.5 μm, 25 μm or less 99% or more) 0.00
1 g, ethyl cellulose 0.3 g, and terpenol 3 g were mixed into a paste. The paste prepared as an outer conductor of the same low temperature fired multilayer circuit board as in Comparative Example 3 was printed. Further, it was baked at 600 ° C. for 10 minutes in a nitrogen atmosphere (300 ppm of oxygen was doped up to 500 ° C.). Sufficient sinterability was not obtained, and the resistance value of the outer conductor was high. Further, the resistance value at the joint surface with the internal conductor was very high. However, the migration was good. Also,
Solder wettability was poor.

[0057]

Comparative Example 5 The copper alloy powder obtained in Powder Preparation Example 1
It was classified by μm. The obtained powder after classification had an average particle diameter of 4.5 μm (25 μm or less and 99% or more). 10 g of powder after classification, PbO—SiO ₂ —ZnO (average particle size 30 μm, 15% or less 10%) glass frit 0.
3 g, ethyl cellulose 0.5 g, and terpenol 1 g were sufficiently mixed to obtain a paste.

Silver-palladium paste was printed on a green sheet having via holes formed of forsterite and B ₂ O ₃ . After printing the silver-palladium paste on the via holes as well, six green sheets produced in the same manner were laminated and thermocompression bonded with a hot breath. Further, it was heated and baked at 800 ° C. for 60 minutes. A silver-palladium conductor was similarly formed in the via hole for an external conductor of the obtained multilayer circuit board, and then the paste was printed as an external conductor. After printing, firing was performed in a nitrogen atmosphere at 700 ° C. for 10 minutes. (Oxygen 900ppm dope up to 500 ° C). In the obtained copper alloy conductor, the glass frit was deposited in the conductor film and the resistance was high. The silver concentration on the surface of the outer conductor was 0.15, 0.18, 0.2, 0.2 and 0.2, and the silver concentration on the surface was 0.165, which was lower than the average silver concentration.

[0059]

Comparative Example 6 The copper alloy powder obtained in Powder Preparation Example 1
It was classified by μm. The obtained classified powder had an average of 4.5 μm. Classification after powder _{10g, PbO-SiO 2 -B 2} O
₃ (average particle diameter 1 μm) 5 g of glass frit, 0.3 g of ethyl cellulose, 1 g of terpenol, and 0.002 g of titanium coupling agent were sufficiently mixed to obtain a paste.

Silver paste was printed on both the circuit and the via hole on a green sheet made of BaO--Al ₂ O ₃ --SiO ₂ glass in which the via hole was previously formed. further,
A ruthenium-based resistor paste was printed, six green sheets prepared in the same manner were thermocompression bonded, and fired in air at 700 ° C. for 1 hour. Further, after similarly forming a silver conductor in a via hole for connection with an external conductor, the copper alloy paste was printed. After printing, it was heated and baked in a nitrogen atmosphere at 600 ° C for 10 minutes (oxygen 400p up to 500 ° C).
pm doped). After firing, glass was deposited on the surface of the outer conductor, and sufficient conductivity was not obtained at the joint surface with the inner conductor.

[0061]

[Comparative Example 7] The copper alloy powder obtained in Powder Preparation Example 1 was replaced with 10
It was classified by μm. The obtained classified powder has an average particle diameter of 4.5μ.
It was m. Powder after classification (average particle size 4.5 μm, 2
5 μm or less 99%) 10 g, ethyl cellulose 0.3
g, terpenol 0.4 g, and butyl carbitol acetate 0.3 g were sufficiently mixed to prepare a paste.

Screen printing was performed as an outer conductor of the multilayer circuit board prepared in Comparative Example 6. After printing, it was heated and baked in a nitrogen atmosphere at 600 ° C for 10 minutes (oxygen 4
00 ppm dope). The calcined copper alloy conductor lacked adhesive strength to the multilayer substrate and was easily peeled off from the substrate.

[0063]

Comparative Example 8 Of the copper alloy powders obtained in Powder Preparation Example 1, 1
10 g of powder of 0 μm or less (99% or more of powder having an average particle size of 4.5 μm and 25 μm or less), PbO—B ₂ O ₃ —Si
O ₂ glass frit (average particle size 1 μm, 15 μm or less 99% or more) 4 g, cuprous oxide (average particle size 18 μm,
25 μm or less 70%) 3 g, ethyl cellulose 0.7
g, butyl carbitol acetate 2 g, and an anti-settling agent 0.001 g were sufficiently mixed to obtain a paste. The obtained paste was screen-printed as an outer conductor of the same multilayer circuit board as in Comparative Example 7. After printing, it was baked at 800 ° C. for 30 minutes. (Oxygen 100 ppm doping up to 500 ° C.). The sintered copper alloy conductor was insufficiently sintered, and sufficient conductivity was not obtained at the joint surface with the internal conductor.

[0064]

According to the present invention, the general formula Ag _x Cu _1-x (0.
01 ≦ x ≦ 0.4, atomic ratio), the average particle diameter is 0, which has a region in which the silver concentration on the grain surface is higher than 2.1 times the average silver concentration and the silver concentration increases toward the grain surface. 1 ~
1 with an average particle size of 0.1 to 10 μm with respect to 100 parts by weight of a copper alloy powder of 20 μm and 20 μm or less of 90% or more
Glass frit 0.2 to 30 with 5 μm or less of 90% or more
It is intended to provide a paste for an external conductor of a low-temperature fired multilayer circuit board consisting of parts by weight and an organic vehicle, but not only has excellent adhesion to the board, solder wettability, migration resistance, and oxidation resistance, Silver, silver palladium,
It is intended to provide an internal conductor made of gold, silver-platinum, an external conductor having excellent electrical bonding property because it is easily alloyed during firing, and a low temperature firing multilayer circuit board.

Claims (5)

[Claims] 1. The general formula Ag _x Cu _1-x (provided that 0.0
1 ≦ x ≦ 0.4, atomic ratio), and the average particle has a silver concentration higher than 2.1 times the average silver concentration and has a region where the silver concentration increases toward the particle surface. 9 powders having a diameter of 0.1 to 20 μm and 25 μm or less
0% or more, with respect to 100 parts by weight of the copper alloy powder, the average particle size is 0.1 to 10 μm and 15 μm.
Glass frit in which 90% or more of m or less powder is 0.1
To 30 parts by weight of organic vehicle, low temperature firing multilayer circuit board outer conductor paste 2. The paste according to claim 1, which has an average particle size of 0.1 to 20 μm and 90% of powder having a particle size of 25 μm or less.
A low-temperature fired multilayer circuit board outer conductor paste obtained by adding 0.1 to 20 parts by weight of the above cuprous oxide powder to 100 parts by weight of a copper alloy powder. 3. The glass frit according to claim 1 or 2, wherein the glass frit is composed mainly of at least one oxide component selected from PbO, SiO ₂ B ₂ O ₃ and ZnO. Low temperature firing multilayer circuit board outer conductor paste. 4. The low-temperature fired multilayer circuit board outer conductor paste according to claim 1, wherein the inner layer conductor circuit or via-hole conductor or through-hole conductor is at least silver, silver-palladium, silver-platinum, A general formula Ag _x Cu _{1-x formed} by printing on an outer layer of a low temperature firing multilayer circuit board characterized by being one or more selected from gold and sintering.
(However, 0.01 ≦ x ≦ 0.4, atomic ratio) A low temperature fired multilayer circuit board having an outer conductor. 5. A low temperature fired multilayer circuit board, wherein the silver concentration on the surface of the outer conductor according to claim 4 is higher than twice the average silver concentration.