JPH1125754A - Manufacture of copper-metallized composition and glass-ceramic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a copper-metallized composition which is superior in adhesion to a substrate and of a glass-ceramic substrate by suppressing the occurrence of a warpage of the substrate in the case of simultaneous firing with the glass-ceramic substrate. SOLUTION: In this method, the manufacture of a glass-ceramic substrate is conducted such that copper powder and a metallized paste, which includes glass powder and a vehicle, are printed on the surface of a green sheet, including a raw-material powder composed of a glass-ceramic composition, and that the sheet is fired in a nitrogen atmosphere at a temperature of 800 to 1100 deg.C. In this case, copper powder, which has oxide films on surfaces, an oxygen content in the copper powder of 0.3 to 5.0 pts.wt. relative to 100 pts.wt. of its copper component, and whose average particle diameter is 2 to 6 μm, is used as the copper powder in the metallized paste.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper metallized composition which can be co-fired with glass ceramics, and a method for producing a glass ceramic substrate using the same.

[0002]

2. Description of the Related Art A ceramic material such as alumina has conventionally been used as a substrate for mounting a semiconductor element or the like, but recently, it has a low dielectric constant and a low sintering temperature as compared with alumina. Conductor of resistance, eg Cu, A
Glass ceramics have attracted attention as a substrate material that can be applied particularly to the demand for high integration of circuits, because it is excellent in that it can form wirings of u and Ag. In recent years, glass-ceramic materials have attracted attention as a substrate material used in the field of communications, in particular, because they can form low-resistance wiring, and among them, wiring using Cu has been particularly advanced.

As a method of manufacturing a glass ceramic substrate using copper as a metallized wiring layer, a metallized paste containing copper powder is printed on a green sheet made of a glass ceramic raw material and an organic binder to form a conductor pattern. Alternatively, a through hole is formed by punching a sheet, a copper metallizing paste is filled in the through hole, and a copper metallizing paste is printed at a predetermined position on the sheet. Then, a plurality of green sheets formed by printing or filling these metallized pastes are formed, and these sheets are positioned and laminated under pressure.
Thereafter, the laminate is heated to remove the binder, and the conductor paste and the glass ceramic are simultaneously fired to produce the laminate.

[0004] Further, as a copper metallized composition which can be co-fired with glass ceramics, JP-A-63-1
No. 74203 proposes a composition in which amorphous SiO ₂ is added in a proportion of 0.5 to 10 parts by weight with respect to copper powder, and JP-A-1-202096 proposes a composition in which MgO is added in a proportion of 1 to 2% by weight. I have.

In Japanese Patent Application Laid-Open No. Hei 5-243700, glass powder that melts at a temperature of
It has been proposed to mix with copper powder at a rate of 4% by volume.

Japanese Patent Publication No. 60-50755 discloses a copper powder in a copper metallized composition by printing a conductor pattern with a copper metallized composition on a fired ceramic substrate and then performing a heat treatment at a temperature of 150 to 200 ° C. It has been proposed that by oxidizing a part of the film and then baking it in a non-oxidizing atmosphere, the adhesive strength of the copper conductor film can be increased without impairing solderability and conductivity.

[0007] Accordingly, an object of the present invention is to provide a copper metallized composition which suppresses the occurrence of warpage even during simultaneous firing with a glass ceramic substrate and has excellent adhesion to the substrate. It is another object of the present invention to provide a method for manufacturing a glass ceramic substrate which includes a copper wiring layer formed with high adhesion and can suppress the occurrence of warpage of the substrate.

[0008]

However, a copper metallized composition containing a ceramic powder such as amorphous silica or MgO as described in the above-mentioned JP-A-63-174203 and JP-A-1-201996. When a product is printed on a glass ceramic green sheet and fired simultaneously, there is a problem that voids increase in the obtained copper wiring layer, and the adhesive strength between the glass ceramic and the copper wiring layer is reduced.

Further, in the method of adding a glass powder that melts at a temperature of 700 ° C. or more to the copper metallized composition proposed in Japanese Patent Application Laid-Open No. 5-243700, the glass floats on the surface of the copper wiring layer during the firing process. Since it remains on the wiring layer, there is a problem that the plating is chipped in the plating step.

In order to solve the above problems, the present inventors have disclosed in Japanese Patent Application No. 8-107136 an inorganic substance which delays the sintering of copper and a metal compound which can reduce the viscosity of the glass component in the glass ceramic porcelain. A copper metallized composition with the addition of was proposed. However, in such a copper metallized composition that adds an inorganic substance that delays sintering of copper,
It was not practically sufficient, for example, warping or undulation of the insulating substrate after firing.

For example, when the above-mentioned copper metallized composition is applied only to one side of a glass ceramic having dimensions of 50 mm in length, 20 mm in width, and 1 mm in thickness, the deformation of the substrate exceeds 0.2 mm. Was.

In the method of oxidizing copper powder proposed in Japanese Patent Publication No. 50755/1985, when a copper metallizing composition is printed on a glass ceramic green sheet and heat-treated, the area near the surface in the thickness direction of the conductor pattern is reduced. Although the copper powder is oxidized, there is a problem that the degree of oxidation of the copper powder in the thickness direction is lower in the thickness direction, so that the degree of oxidation of the copper powder is different in the thickness direction. In addition, this method heat-treats the copper metallized composition printed on the green sheet in an air atmosphere to oxidize the copper, so that there is a problem that the green sheet is hardened by solvent removal or is broken or deformed.

[0013]

Means for Solving the Problems As a result of repeated studies on the above-mentioned problems, the present inventors have found that a copper metallized composition comprising a copper powder, a glass powder and a vehicle has a predetermined surface as copper powder. By using a copper powder coated with an oxide film with an oxygen content of 3, it is possible to fire simultaneously with a glass ceramic substrate, maintain a high adhesive strength with the glass ceramic substrate, and reduce the warpage of the fired substrate. And have led to the present invention.

That is, the copper metallized composition of the present invention is a copper metallized composition comprising a copper powder, a glass powder and a vehicle, having an oxide film on the surface of the copper powder and containing The amount is 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the copper component, and the average particle size is 2 to 6 μm.
The oxide film is formed by an oxidation process.

Further, in the method of manufacturing a glass ceramic substrate according to the present invention, the surface of a green sheet containing a raw material powder made of a glass ceramic composition is formed of a copper powder, a glass powder and a vehicle, and the surface of the copper powder is oxidized. A metallized paste having a film and having an oxygen content of 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the copper component and an average particle size of 2 to 6 μm based on 100 parts by weight of the copper powder, It is characterized by firing at a temperature of 800 to 1100 ° C. in an atmosphere.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The copper metallized composition of the present invention comprises:
It comprises a copper powder, a glass powder and a vehicle, and has an oxide film on the surface of the copper powder. This oxide film is formed by heat-treating the copper powder in an oxidizing atmosphere at 100 to 300 ° C., or by oxidizing the surface by acid treatment. The oxide film of the copper powder has an oxygen content of 0.3 to 0.3 when the copper component amount is 100 parts by weight.
It is formed in an amount of 5.0 parts by weight. Generally, since copper powder has high reactivity with oxygen, an oxide film is unavoidably formed on the surface of the powder, but the amount is at most about 0.2 parts by weight. For example, the feature is that the content of this oxide film is increased to the above content by an oxidation treatment.

Usually, the firing temperature of the glass ceramic substrate and the copper metallized composition co-fired therewith is 80.
Although it is about 0 to 1100 ° C., the firing shrinkage starting temperature during firing is about 200 ° C. lower for the copper metallized composition than for the glass ceramic substrate. Stress is generated, and as a result, the substrate is warped or deformed.

On the other hand, according to the present invention, by forming an oxide film in the above range on the surface of the copper powder in the copper metallized composition, the shrinkage starting temperature of the copper metallized is reduced to the shrinkage starting temperature of the glass ceramic substrate. As a result, after firing, warping or deformation of the substrate due to a difference in firing shrinkage start temperature can be suppressed.

The reason for this is as follows. The sintering of copper powder in the copper metallized composition proceeds from the contact point between the copper particles and proceeds. For example, when fired in a reducing atmosphere such as a nitrogen / hydrogen mixed gas, copper oxide is reduced to copper, and at the same time, volume shrinkage occurs.

Therefore, if an oxide film, that is, a film made of copper oxide, is formed on the surface of the copper powder in the copper metallized composition, the oxide film of the copper powder is reduced and oxidized under the above-mentioned reducing atmosphere. As a result of the contraction of the volume of the film portion, the contact points with the adjacent copper powder are separated, and the sintering does not proceed temporarily. As a result, the copper metallized composition containing copper powder having an oxide film can delay the firing shrinkage onset temperature more than the copper metallized composition containing copper powder without an oxide film.

The same effect can be obtained by adding the surface-oxidized copper powder as a part of the copper powder contained in the copper metallized composition.

Accordingly, the reason why the oxygen content in the copper powder is limited to the above range is that if the oxygen content is less than 0.3 parts by weight, the effect of delaying the firing shrinkage starting temperature is insufficient, and the warpage of the substrate is reduced. And deformation cannot be reduced to 5.0
When the amount exceeds the weight part, voids increase in the copper wiring layer after firing, the adhesive strength between the glass ceramic substrate and the copper wiring layer decreases, the warpage of the substrate increases, and the solder wettability also decreases. is there. The oxygen content is particularly preferably 0.5 to 3.0 parts by weight based on 100 parts by weight of the copper component.

The copper powder in the copper metallized composition is
Average particle size is 2 to 6 μm, preferably average particle size is 2 to 5 μm
m spherical powder is used. In addition, in BET specific surface area, it is 0.1.
It is preferably from 5 to 5.0 m ² / g, particularly preferably from 0.7 to 4.0 m ² / g. This is because if the average particle size is smaller than 2 μm, the effect of suppressing warpage is not sufficient, and if the average particle size is larger than 6 μm, voids increase in the copper wiring layer. In particular, the average particle size is desirably 3 to 5 μm.

As the glass powder in the copper metallized composition, those having a glass melting temperature of 600 to 900 ° C. are desirable. For example, in addition to zinc borosilicate glass and lead borosilicate glass, _2- Al ₂ O
Such as _{3 -BaO-CaO-B 2 O} 3 based glass is used. This glass powder is based on 100 parts by weight of copper powder.
It is appropriate to mix in a ratio of 0.1 to 5.0 parts by weight. In this case, in the present invention, the use of the copper powder having the oxide film forms gaps in the particle size between the powders, so that the floating of the glass can be prevented even when the melting temperature of the glass is high.

Further, as a binder contained as a vehicle, it is desirable to use a methacrylic acid resin having excellent thermal decomposability in a nitrogen atmosphere, specifically, polybutyl isomethacrylate, polybutyl n-butyl methacrylate, and the like. As the solvent in the vehicle, butyl carbitol acetate, dibutyl phthalate, α-terpineol and the like are suitable, and the binder is the copper powder 100.
The appropriate amount is 2 to 6 parts by weight with respect to parts by weight.
0 to 50 parts by weight is suitable.

According to the present invention, a filler component such as alumina, silica, mullite or zirconia is added to a copper metallized composition in an amount of 0 to 100 parts by weight of copper powder in order to adjust the firing shrinkage initiation temperature. It is also possible to add at a ratio of not more than 0.5 part by weight, particularly 0.05 to 0.3 part by weight. When the filler amount exceeds 0.5 parts by weight,
Voids are likely to occur.

Next, the composition constituting the glass-ceramic substrate is composed of a glass component and a ceramic filler component, and a known glass can be used as the glass component. In particular, a crystalline glass that crystallizes during firing is desirable. The strength of the substrate can be improved by the precipitation of a crystal phase from the crystalline glass, and as a result, the adhesive strength of the copper wiring layer can also be improved.

As the ceramic filler component, calcium zirconate, calcium titanate, strontium titanate, barium titanate, alumina, mullite, forsterite, zirconia, spinel and the like can be used.

As the glass component, known glasses such as zinc borosilicate glass and lead borosilicate glass can be used. In particular, SiO ₂ , Al ₂ O ₃ , alkaline earth metal oxide and B Glass containing ₂ O ₃ is desirable in view of cofiring with copper in a nitrogen atmosphere at 800 to 1100 ° C. The glass component and the filler component preferably have a volume ratio of 30:70 to 70:30.

Next, a method of manufacturing a glass ceramic substrate will be described. First, an acrylic resin such as isobutyl methacrylate having excellent thermal decomposability under a nitrogen atmosphere is added to a raw material powder comprising the glass component and a filler component. A slurry prepared by adding an organic binder to the raw material powder in a solid content of 8 to 20 parts by weight, a plasticizer such as a phthalate ester, and a solvent such as toluene, is subjected to a doctor blade method, a rolling method, and extrusion molding. The green sheet is formed by a well-known sheet forming method such as a method.

A paste made of the copper metallized composition containing the above-described copper powder, glass powder and vehicle is printed in a circuit pattern at a predetermined position on the surface of the obtained green sheet by a screen printing method or a gravure printing method. Alternatively, a through hole is formed at a predetermined position of the green sheet, and the hole is filled with the paste, and then a circuit pattern is printed on the sheet surface. Then, green sheets filled or printed with a plurality of pastes are prepared as described above, and a plurality of the green sheets are aligned under pressure and laminated.

Thereafter, the above-mentioned laminated body is, for example, 300 to 5
The binder, plasticizer, and solvent in the green sheet and the copper paste are thermally decomposed and removed by heat treatment in a nitrogen atmosphere containing steam at 00 ° C. Then, the temperature is increased to 700 to 800 ° C. to remove the green sheet and the copper paste. Remove residual carbon.

At this time, if the processing temperature is lower than 700 ° C., the remaining carbon cannot be removed efficiently, and carbon remains in the fired glass ceramic substrate. If the processing temperature is higher than 800 ° C., the densification of the glass ceramic substrate due to shrinkage of firing occurs. The decomposition proceeds rapidly, and undecomposed carbon remains inside the substrate, resulting in poor color tone and poor insulation of the substrate.

Thereafter, 800 to 11 in a dry nitrogen atmosphere.
The glass ceramic substrate having the copper wiring layer of the present invention can be formed by simultaneously firing the glass ceramic substrate and the copper metallized composition at a temperature of 00C, more preferably 900 to 1050C.

[0035]

EXAMPLES Hereinafter, the copper metallized composition of the present invention and a glass ceramic substrate using the same will be described in detail with reference to examples. As crystalline glass powder, SiO ₂ : 44 parts by weight, Al ₂ O ₃ : 28 parts by weight, M
gO: 11 parts by weight, ZnO: 8 parts by weight, B ₂ O _3: 9 parts by weight SiO _2: 53 parts by weight, Al ₂ O _3: 15 parts by weight, M
gO: 1 part by weight CaO: 22 parts by weight, B ₂ O _3: 9 parts by weight SiO _2: 45 parts by weight, Al ₂ O _3: 18 parts by weight, M
gO: 13 parts by weight BaO: 2 parts by weight, B ₂ O _3: 20 parts by weight, Na ₂ O: one of the three types of 2 parts by weight crystallizable glass powder: 60 parts by weight, as a ceramic filler, (A) Calcium zirconate: 20 parts by weight, strontium titanate: 16
Parts by weight, 4 parts by weight of alumina, and 40 parts by weight of (b) alumina, and 100 parts by weight of a glass ceramic raw material powder, 14 parts by weight of an isobutyl methacrylate resin as an organic binder as a solid content, and a plasticizer And 7 parts by weight of dibutyl phthalate were added, and the mixture was mixed by a ball mill using toluene as a solvent for 40 hours to prepare a slurry. Then, the obtained slurry was formed into a green sheet having a thickness of 0.3 mm by a doctor blade method.

Next, copper powder having various oxygen contents shown in Table 1 and having an average particle size of 1 to 8 μm was prepared by treating a commercially available copper powder in the air at 150 ° C. for 1 to 12 hours. SiO ₂ 57%, Al ₂ O ₃ 17%, Ba
2 parts by weight of glass powder (glass melting temperature: 780 ° C.) composed of 8% of O, 8% of CaO, 6% of MgO, and 4% of B ₂ O ₃ , 0.05 part by weight of alumina, and a binder composed of isobutyl polybutyl methacrylate as a vehicle. Parts by weight,
Solvent consisting of a mixed solution (50:50 by weight) of butyl carbitol acetate and dibutyl phthalate
A conductor paste is prepared by adding in parts by weight.

The oxygen content in the copper powder was measured by reducing the copper oxide powder with hydrogen and obtaining the weight of the generated water.

Then, a molded product was produced by pressing and laminating the green sheet on which the copper paste was printed as the uppermost layer. Thereafter, in order to decompose and remove organic components (binders, plasticizers, etc.) in the molded body, a heat treatment at 750 ° C. × 1 h was performed in a nitrogen atmosphere containing steam to reduce the amount of residual carbon in the molded body to 200 ppm or less. After, 900 ℃
By firing for × 1 h, a glass ceramic substrate of copper wiring was obtained.

With respect to the produced glass ceramic substrate,
The relative warpage, adhesion strength and solder wettability after firing were evaluated by the following methods. The method for measuring the warpage is to print a conductor pattern having a shape after firing of 20 mm x 50 mm on a green sheet, and then laminate and press-bond this green sheet as the uppermost layer with three green sheets on which no conductor pattern is printed, A glass ceramic substrate having a thickness of 1 mm was prepared by firing under the above-described conditions, and the prepared substrate was placed on a flat place with the concave surface facing upward. The maximum value (mm) of the lift at both ends of the substrate was shown in Table 1.

As a method for measuring the adhesive strength of copper metallization, a conductor pattern having a shape after firing of 2 mm × 2 mm (2 mm square) is prepared, and this is used as the uppermost layer, and a green sheet without a conductor pattern is formed. The three sheets were laminated and pressed, baked in the same manner as described above, Ni-Au plating was applied to a thickness of 3 μm, and then a lead made of a Cu wire (0.8 mm in diameter) Sn-plated in a 2 mm square pattern was used. The solder was bonded in parallel with the copper metallized surface, and then the lead wire was bent in a direction perpendicular to the copper metallized surface, and a peel test was performed under the conditions of 10 mm / min.

Regarding the solder wettability, the plating (Ni plating: 2.
Visual observation of the solder wetted portion (5 μm, Au plating: 0.1 μm) indicates that a part where the solder is not partially applied is defective, and a part where the solder is entirely applied is good. Indicated.

[0042]

[Table 1]

As is clear from Table 1, in Sample No. 1 in which the oxygen content of the copper powder contained in the copper metallized composition was less than 0.3 part by weight, the adhesive strength and the solder wettability were good, but the relative warpage was high. Is big. Further, Sample No. 9 in which the amount of oxygen in the copper powder contained in the copper metallized composition exceeds 5.0 parts by weight has poor adhesion strength, poor solder wettability, and large relative warpage.

In sample No. 10 in which the particle size of the copper powder was less than 2 μm, the relative warpage was small and the solder wettability was good, but the bonding strength was low and the wiring layer was partially peeled off after firing, so that the lead was successfully formed. Since joining was not possible, the joining strength could not be measured.

Further, in Sample No. 14 in which the particle size of the copper powder exceeds 6 μm, although the relative warpage is small, the solder wettability is poor and the bonding strength is low.

In contrast to these comparative examples, all of the samples of the present invention have a relative warpage of 0.2 mm or less, an adhesive strength to the substrate of 3.0 kg / 2 mm □ or more, and a solder wettability. Good results were obtained. In particular, when a copper powder having an oxygen content of 0.5 to 3% by weight and an average particle diameter of 2 to 5 μm is used, excellent properties such as a relative warpage of 0.16 mm or less and an adhesive strength of 5.0 kg / 2 mm or more are obtained. showed that.

[0047]

As described in detail above, according to the present invention, in a copper metallized composition co-fired with a glass ceramic substrate, a predetermined amount of an oxide film is formed on the surface of copper powder to thereby reduce the copper metallization. The shrinkage start temperature can be made close to the shrinkage start temperature of the glass ceramic substrate, and at the same time as increasing the bonding strength of the copper metallized substrate,
Warpage of a glass ceramic substrate having a copper wiring layer can be suppressed to a small value.

Claims (3)

[Claims] 1. A copper metallized composition comprising a copper powder, a glass powder and a vehicle, wherein the copper powder has an oxide film on its surface, and has an oxygen content of 100 parts by weight of a copper component. 0.3 to 5.0 parts by weight, and an average particle size of 2 to 6 μm. 2. The copper metallized composition according to claim 1, wherein said oxide film is formed by an oxidation treatment. 3. A metallized paste containing a copper powder, a glass powder and a vehicle is printed on the surface of a green sheet containing a raw material powder made of a glass ceramic composition, and fired at a temperature of 800 to 1100 ° C. in a nitrogen atmosphere. In the method for manufacturing a glass ceramic substrate, the copper powder in the metallized paste has an oxide film on a surface, and the oxygen content in the copper powder is 0.3 to 5.0 with respect to 100 parts by weight of a copper component. Parts by weight and having an average particle size of 2
A method of manufacturing a glass ceramic substrate, wherein