JP3152854B2 - Multilayer wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board using a copper paste which can be co-fired with a glass ceramic material.

[0002]

2. Description of the Related Art A ceramic material such as alumina is conventionally used as a substrate for mounting a semiconductor element or the like. However, recently, the dielectric constant is lower and the firing temperature is lower than that of alumina. Low resistance conductor, eg C
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 wiring can be formed by u, Au, and Ag. In recent years, this glass ceramic has been attracting attention as a substrate material used in the communication field, particularly since it can form low-resistance wiring.

Conventionally, a glass ceramic substrate is manufactured as follows. That is, first, a green sheet made of a glass ceramic material and an organic binder is punched to form a through hole, and the through hole is filled with a conductive paste. Next, a conductor pattern is formed by printing a conductor paste at a predetermined position on this sheet, and after aligning these green sheets and pressing and laminating, the laminate is heated to remove binder and fire, A glass ceramic multilayer wiring board is obtained.

Conventionally, a copper paste which can be co-fired with a glass ceramic material is disclosed in
No. 4,203, JP-A-1-202096,
A copper paste using amorphous silica or a ceramic powder such as MgO as an additive is disclosed.

[0005] However, when ceramic powder is added to the copper paste, the surface state of the copper metallized copper after sintering becomes rough, causing problems in plating and solder wettability.

In order to solve this problem, Japanese Patent Laid-Open Publication No.
No. 43700 discloses a copper paste obtained by mixing glass powder that melts at a temperature of 700 ° C. or more with copper powder at a ratio of 5 to 24% by volume.

[0007]

However, in the copper paste disclosed in Japanese Patent Application Laid-Open No. 5-243700, even when the mixing ratio of the glass powder to the copper powder is 5 vol%, which is the smallest, Remains on the copper metallized surface after firing, causing a problem in plating treatment and solder wettability.

[0008] Further, in a high frequency range (1 to 3) such as a communication field.
(GHz), the resistance of the wiring conductor is particularly problematic, so it is necessary to reduce additives such as inorganic substances other than copper as much as possible.

Further, when the glass powder to be added to the copper paste has a very high sintering end temperature by itself than the glass powder of the insulating layer contained in the green sheet, even if the glass powder to be added to the copper paste is However, even when the melting start temperature (sintering start temperature) is 700 ° C. or more, there is a problem that conduction resistance increases due to poor sintering of copper particles.

Further, when the glass powder to be added to the copper paste is crystalline, depending on its softening behavior, crystallization during sintering hinders sintering of the copper particles and reduces the conduction resistance. There was a problem of increasing.

[0011]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that copper powder 10
Non-crystalline SiO ₂ —Al ₂ O ₃ —
B ₂ O ₃ to -RO based glass powder 1 to 4.5 parts by volume containing copper _{paste, SiO 2 -Al 2 O 3 -B} 2 O 3 -M
By printing on a green sheet composed of gO-ZnO-based crystalline glass powder, alumina powder and organic components, laminating and firing a plurality of the green sheets, the plating processability, the solder wettability are excellent, and the adhesive strength is high. In addition, the present inventors have found that an increase in conduction resistance can be prevented, and the present invention has been accomplished.

[0012] The multilayer wiring board of the present invention comprises SiO ₂ -Al ₂
At least the surface of the insulating layer made of O ₃ —B ₂ O ₃ —MgO—ZnO-based crystalline glass and alumina is made of amorphous SiO ₂ —Al ₂ O ₃ —B ₂ O with respect to 100 parts by volume of copper. ₃ −
RO (RO: alkaline earth metal oxide) glass
A copper metallization containing 4.5 parts by volume is formed, and a plating film is formed on the surface of the copper metallization.

In the present invention, by using a material composed of crystalline glass and alumina as the material of the glass-ceramic insulating layer, the crystalline glass is crystallized at the time of firing, whereby the transverse rupture strength of the insulating layer can be increased. In addition, the adhesive strength of copper metallized to be baked on a glass ceramic material can be improved.

The insulating layer made of glass ceramic has S
A green sheet containing a glass ceramic material made of iO ₂ —Al ₂ O ₃ —B ₂ O ₃ —MgO—ZnO-based crystalline glass and alumina is used. As a binder for the green sheet, an acrylic resin having excellent thermal decomposition properties under a nitrogen atmosphere, specifically, isobutyl methacrylate or the like is used.

These binders are added in a proportion of 8 to 20 parts by weight based on 100 parts by weight of the above-mentioned glass ceramic powder in solid content. Further, dibutyl phthalate or the like can be used as a plasticizer, and toluene or the like can be used as a solvent.

The copper powder used in the copper paste of the present invention has an average particle size of 3 to 8 μm (specific surface area by BET method is 0.1 to 0.6 m ² / g), preferably 4 to 7 μm. (Specific surface area is 0.2 to 0.3 m ² / g). The copper powder having such a low specific surface area can suppress rapid sintering at a low temperature of 400 to 650 ° C., although depending on the firing atmosphere, so that the glass ceramic substrate can be prepared without adding the glass powder to the copper paste. Warpage can be controlled. However, when no glass powder is added,
The initial bond strength of the copper metallization after firing is high, but after Ni plating or Au plating, the bond strength decreases with the plating thickness. It is considered that the state of copper metallization peeling at this time is such that the interface metallization between the copper metallization and the glass ceramic porcelain often peels, and the bonding strength at the interface is low.

In the present invention, glass powder is added to the copper paste in order to improve the adhesive strength at the interface between the copper metallization and the glass ceramic porcelain. The glass powder to be added is non-crystalline for the above reason, and its firing shrinkage behavior is the same as that of the crystalline glass used for the glass ceramic insulating layer. Specifically, firing shrinkage of the glass powder alone is started. The temperature and the sintering end temperature used in the range of ± 30 ° C. are used. Thus, the glass powder used for the copper paste of the present invention is made of SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —MgO-Z used for the glass ceramic insulating layer.
SiO showing the same firing shrinkage behavior as nO-based crystalline glass
_{2 -Al 2 O 3 -B 2 O} 3 -RO (RO: alkaline earth metal oxide) based a glass.

Amorphous SiO ₂ —Al ₂ O ₃ —B ₂ O
Examples of the alkaline earth metal oxide used in the _3- RO glass powder include MgO, CaO, SrO, and BaO. Examples of the non-crystalline glass include SiO ₂
50-65 wt%, Al ₂ O ₃ 15~20 wt%, B ₂
O ₃ 2 to 5% by weight, alkaline earth metal oxide 20 to 25
% By weight is desirable from the viewpoint of softening behavior.

Amorphous SiO ₂ —Al ₂ O ₃ —B ₂ O
_The reason that the _3- RO glass powder was contained in an amount of 1 to 4.5 parts by volume with respect to 100 parts by volume of the copper powder was that of amorphous SiO _2.
If the amount of the -Al ₂ O ₃ -B ₂ O ₃ -RO glass powder is less than 1 part by volume, the adhesion strength of the copper metallized metal after the Ni plating treatment is significantly reduced,
On the other hand, if the content exceeds 4.5 parts by volume, the added glass is localized on the surface of the copper metallized film after firing, so that a portion where the Ni plating film is not formed is generated. The glass addition amount is desirably 2 to 3.5 parts by volume based on 100 parts by volume of the copper powder. In addition, it is necessary to uniformly disperse such a small amount of glass powder around the copper powder in the copper paste. For this reason, the particle size of the glass powder to be added is desirably 2 μm or less, preferably 1.5 μm or less.

As the binder in the vehicle used for the copper paste, a methacrylic acid resin excellent in thermal decomposability in a nitrogen atmosphere, specifically, isobutyl methacrylate, normal butyl methacrylate, or the like is used. As a solvent for the vehicle, butyl carbitol acetate, dibutyl phthalate, α-terpineol, or the like is used.

According to the method of manufacturing a multilayer wiring board of the present invention, an amorphous SiO ₂ —Al ₂
A copper paste containing 1 to 4.5 parts by volume of an O ₃ —B ₂ O ₃ —RO glass powder was prepared by using SiO ₂ —Al ₂ O ₃ —B ₂ O
This is a method of printing on a green sheet composed of _3- MgO-ZnO-based crystalline glass powder, alumina powder and an organic component, laminating a plurality of the green sheets, and firing in a nitrogen atmosphere.

That is, SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —
The above-mentioned copper paste of the present invention is printed at a predetermined position on the surface of a green sheet obtained by mixing a binder, a plasticizer, and a solvent with a glass ceramic raw material containing MgO-ZnO-based crystalline glass and alumina, and the conductor is formed. After forming the pattern, the plurality of green sheets are aligned and pressure-laminated.

This laminate is heat-treated in a nitrogen atmosphere containing water vapor at 300 to 500 ° C. to decompose and remove the binder, plasticizer and solvent in the green sheet and the copper paste.

Thereafter, the temperature is increased to 700 to 800 ° C. to remove the residual carbon in the sheet and the copper paste. If the temperature at this time is lower than 700 ° C., the remaining carbon cannot be efficiently removed, and the carbon remains in the fired substrate.
If the temperature is higher than 0 ° C., densification of the substrate due to firing shrinkage proceeds excessively, and undecomposed carbon remains inside the substrate, resulting in poor color tone and poor insulation of the substrate.

Then, 900 to 10 in a dry nitrogen atmosphere.
By firing at a temperature of 50 ° C., a glass ceramic multilayer wiring board can be formed.

[0026]

[Action] _{SiO 2 -Al 2 O 3 -B 2} O 3 -MgO-Z
As a copper paste for co-firing with a glass ceramic material composed of nO-based crystalline glass and alumina, 1 to 4.5 parts by volume of amorphous S per 100 parts by volume of copper powder
By using a copper paste containing iO ₂ —Al ₂ O ₃ —B ₂ O ₃ —RO-based glass powder, plating property,
It has excellent solder wettability, high adhesive strength, and can prevent an increase in conduction resistance.

[0027]

Examples: SiO ₂ : 44% by weight, Al ₂ O ₃ : 28% by weight, MgO: 11% by weight, ZnO: 8% by weight, B ₂ O
₃ : Glass ceramic raw material powder composed of 75% by weight of crystalline glass powder having a composition of 9% by weight and 25% by weight of alumina powder (sintering start temperature: 750 ° C., sintering end temperature:
(900 ° C.), an isobutyl methacrylate resin as an organic binder was added in an amount of 12 wt% in solids, and a dibutyl phthalate as a plasticizer was added in an amount of 8 wt%. The mixture was mixed by a ball mill using toluene as a solvent for 40 hours to prepare a slurry. .

The obtained slurry was formed into a green sheet having a thickness of 0.2 mm by a doctor blade method. 10 sheets of this green sheet were printed with 100 parts by volume of copper powder having an average particle size of 5 μm and a specific surface area of 0.2 m ² / g by the BET method, and the copper paste having the glass addition amount shown in Table 1 was printed. A press-laminated molded article was produced. The composition of the glass is added, SiO _2: 57 wt%, Al ₂ O _3: 17 wt%, (MgO + CaO + SrO + BaO): 22 wt%, B ₂ O _3: 4 weight%, and the sintering initiation temperature of the glass powder alone Is 750 ° C. which is the same as the crystalline glass used for the glass ceramic material, and the sintering end temperature is 890 ° C. Isobutyl methacrylate was used as a binder for the copper paste, and a mixed solution of butyl carbitol acetate and dibutyl phthalate was used as a solvent. The amount of the binder in the copper paste was 3 parts by weight based on 100 parts by weight of the copper powder.

In order to decompose and remove organic components (binders, plasticizers, etc.) in the compact, heat treatment is performed at 730 ° C. for 3 hours in a nitrogen atmosphere containing water vapor to reduce the residual carbon content in the compact to 200 ppm or less. After that, the atmosphere was switched to dry nitrogen, and firing was performed at 1000 ° C. for 1 hour to obtain a glass ceramic substrate having copper wiring.

Then, the adhesive strength, plating property, and conduction resistance of the copper metallization were measured. Here, the measurement of the adhesion strength of the copper metallization was performed by preparing a pattern having a shape after firing of 2 mmφ, and measuring the 2 mm diameter after firing and after plating with Ni—Au.
The lead wire is joined to the φ pattern by soldering, and the pulling speed is 20 mm / min in the direction perpendicular to the copper metallized surface.
Was performed under the following conditions.

Regarding the solder wettability, the plating (Ni plating: 2.
(5 μm, Au plating: 0.1 μm) was visually evaluated for the solder wetted portion.

The plating processability was evaluated by SEM observation of the surface of the plated film after 2.5 μm of electroless Ni plating.

Regarding the conduction resistance, the shape after firing was 10
The measurement was performed on a line pattern having a width of 0 μm and a thickness of 15 μm. Table 1 shows the results.

[0034]

[Table 1]

As shown in Table 1, in the copper paste of the present invention,
It can be seen that the plating property and the solder wettability are excellent, the adhesive strength is high, and the conduction resistance is 2.0 mΩ / □ or less.

The sample No. 7 in Table 1 was made of SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —MgO—Z as a glass powder.
This is a case where nO-based crystalline glass is used.

[0037]

As described in detail above, according to the present invention, SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —MgO—ZnO
As a copper paste for co-firing with a glass-ceramic material comprising a base crystalline glass and alumina, copper powder 10
1 to 4.5 parts by volume of amorphous SiO per 0 parts by volume
By using a copper paste containing _2- Al ₂ O ₃ —B ₂ O ₃ —RO glass powder, it is excellent in plating property and solder wettability, has high adhesive strength, and prevents an increase in conduction resistance. Can be.

In addition, since the firing shrinkage behavior of the glass in the copper paste is matched with that of the glass ceramic material and the amount of glass added is reduced, it is possible to form a copper metallized film having high adhesive strength even after Ni-Au plating. The bonding reliability of the mounted components can be improved.

Continuation of the front page (56) References JP-A-6-97667 (JP, A) JP-A-6-139813 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 1 / 09 H05K 3/46

Claims (1)

(57) [Claims] 1. A _{SiO 2 -Al 2 O 3 -B 2} O 3 -MgO-Z
On at least the surface of the insulating layer made of nO-based crystalline glass and alumina, a non-crystalline S
_{iO 2 -Al 2 O 3 -B 2} O 3 -RO (RO: alkaline earth metal oxide) based glass to form a copper metallizations containing 1 to 4.5 parts by volume, and plated on the surface of the copper metallization A multilayer wiring board comprising a film formed.