JP2002015620A - Conductor composition and wiring board using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring substrate of high adhesive strength wherein the wettability between a wiring layer and glass ceramics is improved without increasing the conductor resistance of the wiring layer even if a copper wiring layer and an insulating substrate made of glass ceramics are simultaneously fired. SOLUTION: In the wiring board 1 formed with the surface and/or the inside of an insulating substrate 2 made of glass ceramics coated by a metallized wiring layer 3 mainly made of Cu. The metallized layer is formed by coating and firing a conductor composition containing 1 to 10 parts by weight of Ni by NiO conversion and 0.1 to 3 parts by weight of CuO to 100 parts by weight of Cu, wherein an Ni diffusion layer is formed in a region of 2 to 20 μm directly beneath the metallized wiring layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring formed by forming a metallized wiring layer containing Cu as a main component formed by firing simultaneously with a single-plate or laminated wiring substrate made of glass ceramic. It relates to a substrate.

[0002]

2. Description of the Related Art In recent years, in a wiring board, compatibility, high density, and high speed of a high-frequency circuit have been demanded, and a dielectric constant lower than that of an alumina-based ceramic material has been obtained. Possible low-temperature fired wiring boards are receiving more attention. This low-temperature fired wiring board is formed on an insulating substrate made of glass ceramic by co-firing with the substrate,
A wiring board provided with a metallized wiring layer mainly composed of a low-resistance metal such as gold or silver is known. Such a wiring board, after printing a conductive paste containing the low-resistance metal powder on a sheet-shaped molded body made of a glass ceramic composition,
It is manufactured by simultaneous firing at 800 to 1000 ° C.

Further, the low-temperature fired wiring board has a low resistance of a wiring layer and a low dielectric constant and a low dielectric loss of an insulating substrate. Applications to various fields such as personal handy phone systems and high-frequency multilayer wiring boards used for various satellite communications are being promoted.

As a low-resistance wiring layer used for a low-temperature fired wiring board, the use of a gold-based material is limited due to the problem of high cost and the use of a silver-based material due to problems such as migration. Although the baking process needs to be performed in a nitrogen atmosphere, the copper-based material is a material for forming the wiring layer because it can sufficiently meet the demands for higher density of the wiring board and higher frequency of the circuit in the wiring board. Has become mainstream.

As a specific method of forming a metallized wiring layer containing Cu as a main component on the surface and / or inside of an insulating substrate made of glass ceramics, a slurry prepared by adding a solvent to a glass ceramic raw material powder and an organic binder is used. Is formed into a sheet shape by a doctor blade method or the like, a through hole is punched into the obtained green sheet, and a via paste is formed by filling the through hole with a conductive paste containing Cu as a main component. A conductor paste containing Cu as a main component is printed and formed into a wiring pattern by screen printing or the like, and a plurality of green sheets on which a wiring pattern and a via-hole conductor are formed are laminated under pressure and fired at 800 to 1000 ° C. It is produced by this.

[0006] The conductor paste containing Cu as a main component is formed of an alloy or a mixture with Ni or the like as appropriate depending on the application. (JP-A-11-66952,
JP-A-6-10811, JP-A-10-308120
No., JP-A-10-64332).

[0007]

However, when Ni is added to a conductor containing Cu as a main component as described above, Cu and Ni are alloyed during the sintering process, so that the conductor resistance is increased or the added Ni is added. However, there is a problem in that electrical characteristics are deteriorated due to excessive diffusion of porcelain into the porcelain and an increase in the dielectric constant of the porcelain.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a method for simultaneously firing a copper wiring layer containing Ni and an insulating substrate made of glass ceramic.
An object of the present invention is to provide a wiring board having high adhesive strength by increasing the wettability between the wiring layer and the glass ceramic without increasing the conductor resistance of the wiring layer and without deteriorating the electrical characteristics of the glass ceramic.

[0009]

Means for Solving the Problems As a result of repeated studies on the above problems, the present inventors have found that a metallized wiring layer mainly composed of Cu formed on an insulating substrate made of glass ceramics has Ni metal or oxide (Ni, N
By containing a predetermined amount of CuO together with iO), the alloying of Cu and Ni in the metallized wiring layer is inhibited, and the diffusion into the porcelain is suppressed without increasing the conductor resistance of the wiring layer, and It has been found that it is possible to prevent the deterioration of the electrical properties of ceramics, to improve the wettability between the wiring layer and the glass ceramics, and to increase the bonding strength.

That is, the conductor composition of the present invention is a conductor composition that can be co-fired with a glass ceramic, wherein the conductor composition is composed of 1 to 10 parts by weight of Ni and 1 to 10 parts by weight of NiO per 100 parts by weight of Cu. In an amount of 0.1 to 3 parts by weight.

Further, the wiring board of the present invention is characterized in that the insulating substrate made of glass ceramic has Cu
In a wiring board having a metallized wiring layer mainly composed of: a metallized wiring layer, Ni is 1 to 10 parts by weight in terms of NiO, and CuO is 0 in terms of oxide based on 100 parts by weight of Cu. 0.1 to 3 parts by weight, characterized in that a Ni diffusion layer is formed in a region of 2 to 20 μm immediately below the metallized wiring layer.

According to the present invention, by adding Ni to the metallized wiring layer containing Cu as a main component, the wettability of Cu to glass ceramics is improved and the bonding strength is improved. Further, by adding CuO, CuO binds to Ni, and this concentrates immediately below the metallized wiring layer to form a so-called diffusion layer. This suppresses the alloying of Ni and Cu, prevents an increase in conductor resistance, further prevents excessive diffusion of Ni into porcelain, suppresses an increase in the dielectric constant and dielectric loss of glass ceramics, and degrades electrical characteristics. Can be prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the wiring board of the present invention will be described below with reference to the drawings. The description will be made using a multilayer wiring board including a plurality of glass ceramic insulating layers.

According to the wiring board 1 of the present invention, the insulating substrate 2
Is composed of a laminated body in which a plurality of glass ceramic insulating layers 2a to 2d are stacked, and a metallized wiring mainly composed of Cu having a thickness of about 5 to 25 μm is provided between the insulating layers 2a to 2d and on the surface of the insulating substrate 2. Layer 3 is applied. In the insulating substrate 2, a via-hole conductor 4 having a diameter of about 80 to 200 μm formed so as to penetrate the insulating layers 2 a to 2 d in the thickness direction is formed.
Is electrically connected to

The insulating substrate 2 is made of glass ceramics made of glass containing at least SiO ₂ or a composite material of glass containing SiO ₂ and a filler. Specifically, the glass component used is an amorphous glass composed of a plurality of metal oxides containing at least SiO ₂ or, after firing, cordierite, mullite, anorthite, cellian, spinel, garnitite, willemite, dolomite. , And crystallized glass that precipitates crystals of lithium silicate or a substituted derivative thereof. Crystallized glass is desirable for improving the strength.

As a component constituting the glass, SiO _{2 is used.}
Other than these, alkali metal oxides such as Li ₂ O, K ₂ O, and Na ₂ O; alkaline earth metal oxides such as CaO and MgO;
Examples thereof include borosilicate glass containing Al ₂ O ₃ , P ₂ O ₅ , ZnO, B ₂ O ₃ , and PbO. Further, by adding a filler component to the glass, the strength can be improved and the firing temperature can be controlled. Specific filler components include quartz, cristobalite, quartz, corundum (α-alumina), mullite, cordierite,
Forsterite and the like can be exemplified. It is appropriate that the glass component and the filler component comprise 30 to 70% by volume of the glass component and 70 to 30% by volume of the filler component.

The metallized wiring layer 3 is mainly composed of Cu. According to the present invention, Ni is 1 to 10 parts by weight and CuO is 0.1 to 3 parts by weight with respect to 100 parts by weight of Cu. It is obtained by firing a conductor composition contained in parts by weight.

In this conductor composition, when the ratio of Ni is less than 1 part by weight, the diffusion amount of Ni from the metallized wiring layer to the glass ceramic substrate is reduced, and the metallized wiring layer and the glass ceramic substrate This is because the adhesive strength is weak, and conversely, if it exceeds 10 parts by weight, alloying of Cu and Ni proceeds and the conductor resistance increases. The amount of Ni is particularly preferably 3 to 7 parts by weight.

If the amount of CuO is less than 0.1 parts by weight, the amount of NiO added during metallization is less than 0.1 parts by weight.
Is excessively diffused into the porcelain, and as a result, the dielectric constant and dielectric loss of the glass ceramic deteriorate, and the electrical characteristics deteriorate. Further, the alloying of Cu and Ni progresses and the conductor resistance increases. If it exceeds 3 parts by weight, Cu
This is because the sintering of the metallized wiring layer and the glass ceramic substrate are reduced, and the conductor resistance is increased. The amount of CuO is particularly preferably 0.5 to 1.5 parts by weight.

When a metallized wiring layer is formed using the above conductor composition, a Ni diffusion layer is formed immediately below the fired metallized wiring layer. Ni is present in the metallized metal layer 3 in the form of metal Ni or oxide (NiO).

The thickness of the Ni diffusion layer immediately below the metallized wiring layer is suitably 2 to 20 μm, particularly 5 to 10 μm. This diffusion layer is a large factor for enhancing the adhesion of the metallized wiring layer to the insulating substrate. If the thickness of the diffusion layer is smaller than 2 μm, the adhesion of the metallized wiring layer to the insulating substrate is reduced. This is because if it is thicker than 20 μm, the electrical characteristics of the insulating substrate will be deteriorated.

The metallized wiring layer 3 on the surface of the multilayer wiring board is used as a pad for mounting various electronic components 5 such as an IC chip, or as a conductive film for shielding, and for connecting to an external circuit. It is also used as an electrode pad, and various electronic components 5 are joined to the wiring layer 3 via solder, a conductive adhesive, or the like. It is desirable that the via-hole conductor 4 is filled with a conductor having the same components as those of the metallized wiring layer 3 described above. Although not shown, a thick-film resistor film such as tantalum silicide or molybdenum silicide, a wiring protection film, or the like may be further formed on the surface of the wiring substrate as necessary.

In the present invention, the surface of the metallized wiring layer on the surface is formed of Ni or Au on the surface to improve solder wettability.
A plating layer made of such a metal may be appropriately formed.

Next, a method for manufacturing the wiring board of the present invention will be described. First, a glass component as described above, or a glass component and a filler are mixed to prepare a glass-ceramic composition, an organic binder is added to the mixture, and then a doctor blade method, a rolling method, a pressing method, and the like. To form a green sheet.

Next, a conductor paste is printed on the surface of the green sheet. The Cu component as a main component in the conductive paste used is desirably a spherical Cu powder having an average particle size of 0.5 to 10 μm, preferably 3 to 5 μm. This is because the sintering behavior of the metallized wiring layer is approximated to the sintering behavior of the glass ceramic substrate, and the printing accuracy is improved.

According to the present invention, in the conductor paste,
As described above, Ni is replaced by Ni with respect to 100 parts by weight of Cu.
1 to 10 parts by weight, particularly 3 to 7 parts by weight in terms of O, and further C
0.1 to 3 parts by weight, especially 0.5 to 1.5 parts by weight of uO is blended. It is desirable to add Ni, NiO, and CuO as powders having an average particle diameter of 0.1 to 2 μm. The conductive paste is formed by homogeneously mixing an organic binder such as an acrylic resin and an organic solvent such as α-terpineol, dibutyl phthalate, and butyl carbitol, in addition to the inorganic components. The organic binder is 1 to 10 parts by weight based on 100 parts by weight of the inorganic component,
The organic solvent component is desirably mixed at a ratio of 5 to 30 parts by weight.

Next, a wiring pattern is printed on the glass ceramic green sheet by using the above-mentioned conductor paste by a screen printing method or the like. To form a via-hole conductor, a green sheet having a diameter of 50 to 200 mm is formed by laser, micro drill, punching or the like.
A through hole of μm is formed, and the inside thereof is filled with the above-mentioned conductor paste. Then, the green sheets on which the wiring patterns and the via hole conductors are formed are laminated and pressed to form a laminate.

Thereafter, the laminate is subjected to heat treatment in a nitrogen atmosphere at 400 to 800 ° C. or in a nitrogen atmosphere containing water vapor to decompose and remove organic components in the green sheet and the paste. By co-firing in a medium or in a nitrogen atmosphere containing water vapor, a multilayer wiring board having a metallized wiring layer and a via-hole conductor can be manufactured.

Further, according to the wiring board of the present invention, even if the wiring board structure is a laminated structure, only the internal metallized wiring layer is fired simultaneously with the insulating substrate, and the metallized wiring layer on the surface is already fired. Like the internal wiring layer, a conductive paste made of Cu, Ni, and CuO may be formed on the surface of the wiring board by baking. In that case, the baking treatment can be performed at a temperature of 600 to 1000 ° C. in a nitrogen atmosphere.

[0030]

(Example 1) 74% SiO ₂ by weight ratio, 1
4% Li ₂ O, 4% Al ₂ O ₃ , 2% P ₂ O ₅ , 2% K ₂ O,
40% by volume of glass having a composition of 2% ZnO and 2% Na ₂ O (with a deformation point of 480 ° C.) is SiO ₂ as a filler component.
(Quartz) 30% by volume and forsterite 30% by volume mixed in a green sheet for an insulating substrate with a molecular weight of 3
A slurry was prepared by adding and mixing a × 10 ⁵ acrylic binder, a plasticizer, a dispersant, and a solvent, and the slurry was formed into a green sheet having an average thickness of 200 μm by a doctor blade method.

Next, Cu powder 100 having an average particle size of 4 μm
Ni powder having an average particle size of 1 μm, NiO
Powder and CuO powder having an average particle size of 1 μm were weighed in NiO conversion and CuO conversion at the ratios shown in Table 1, respectively. 2 parts by weight of an acrylic resin as an organic binder and α as an organic solvent were added to 100 parts by weight of these inorganic components. -15 parts by weight of terpineol was added and kneaded to prepare a conductor paste.

The conductive paste thus obtained was used as a sample for evaluating the adhesive strength on the glass ceramic green sheet, and the shape after firing was 2 mm square and about 15 μm thick.
Then, screen printing was performed to form a copper wiring pattern having a thickness of m, and four green sheets were laminated under the screen by pressure. At the same time, the sample after firing has a width of 100 as a sample for evaluating conductor resistance.
A wiring pattern having a thickness of 50 μm, a length of 50 mm and a thickness of 15 μm was formed, and four green sheets were laminated under the wiring pattern under pressure.

Next, in order to decompose and remove organic components such as an organic binder, the laminated body on which the unfired wiring pattern is formed is placed in a steam-containing nitrogen atmosphere for 700 minutes.
After degreasing by holding at a temperature of 3 ° C. for 3 hours, the temperature was raised to 950 ° C. in a nitrogen atmosphere and held for 1 hour to prepare a wiring board.

In the obtained wiring board, a 2 mm square copper wiring layer is plated with Ni having a thickness of 1 μm, followed by Au plating having a thickness of 0.1 μm, and then tin plating having a diameter of 0.8 mm. Soldering a copper wire on the plating coating layer in parallel with the substrate, bending the tinned copper wire in a direction perpendicular to the substrate,
The tin-plated conductive wire was pulled vertically at a pulling speed of 10 mm / min, and the maximum load when the copper wiring layer was broken was evaluated as the adhesive strength of the copper wiring layer. In addition, when the maximum load exceeded 2 kg / 2 mm square, the quality was judged as good.

Next, regarding the evaluation of the conductor resistance of the copper wiring layer, the resistance of the copper wiring layer having a width of 100 μm and a length of 50 mm was measured with a digital multimeter, and the actual width and length of the copper wiring layer were measured optically. After the measurement with a microscope, the cross section was measured with a metal microscope, and the resistivity was calculated from the obtained result.
The pass / fail judgment was made when the resistivity was 6 μΩ · cm or less.

Further, the thickness of the Ni diffusion layer immediately below the metallized wiring layer was measured. The measurement was performed under the conditions of an acceleration voltage of 15 KV and a probe current of 2 × 10 ⁻⁷ A using EPMA (WDS) in a 2 mm square pattern for strength evaluation.
The area where the count number of Ni was 100 or more was defined as a diffusion layer and measured.

[0037]

[Table 1]

As is clear from Table 1, the sample No. 1,
When the content of Ni is less than 1 part by weight as in the case of Sample No. 2, the wettability between Cu in the metallized wiring layer and the glass ceramic substrate is reduced, the adhesive strength is reduced, and Sample No. Ni as in 8
When the content exceeds 10 parts by weight, alloying of Cu and Ni progressed and the conductor resistance increased. In addition, the sample No. In the case where the content of CuO is less than 0.1 part by weight as in Example 9, Cu and Ni
Alloying progressed, the conductor resistance increased, and the electrical properties of the glass ceramics also deteriorated. Sample No. When the content of CuO exceeds 3 parts by weight as in 13, the sintering of Cu was inhibited, the adhesive strength was reduced, and the conductor resistance was also increased.

However, in the case of the sample No. 3-7, 1
In each of Nos. 0 to 12 and 14, good adhesive strength of 2 kg / 2 mm or more was exhibited, and low conductor resistivity of 6 μΩ · cm or less was maintained.

In the above embodiment, the substrate structure is described as a laminated body. However, the above-mentioned metallized paste containing Cu as a main component is used on a single glass ceramic sheet.
A wiring board in which a predetermined wiring pattern is formed and the green sheet and the predetermined wiring pattern are integrally fired may be used.

[0041]

As described in detail above, the wiring board of the present invention improves the wettability with the glass ceramic substrate and improves the adhesive strength by including CuO together with Ni in the copper metallized wiring layer. In addition, it is possible to suppress excessive diffusion of Ni into the porcelain, and to obtain a wiring board having excellent electric characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 2 Insulating board 3 Metallized wiring layer 4 Via-hole conductor 5 Electronic component

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H01B 1/00 H01B 1/00 L 1/22 1/22 A F term (reference) 4E351 AA07 BB01 BB24 BB31 BB36 CC12 CC22 DD04 DD19 DD21 EE02 EE03 GG02 GG06 GG15 5E343 AA02 AA23 BB14 BB16 BB24 BB44 BB53 BB72 DD01 ER35 GG02 GG13 GG18 5G301 DA06 DA33 DD01

Claims (2)

[Claims] 1. A conductor composition which can be co-fired with a glass ceramic, wherein said conductor composition is composed of 1 to 10 parts by weight of Ni and 0.1 to 3 parts by weight of CuO based on 100 parts by weight of Cu. The conductor composition characterized by containing in the following ratio. 2. A wiring substrate comprising a metallized wiring layer containing Cu as a main component formed on a surface and / or inside of an insulating substrate made of glass ceramic, wherein the conductor composition according to claim 1 is applied. Obtained by firing,
In a region of 2 to 20 μm just below the metallized wiring layer, N
A wiring substrate formed by forming a diffusion layer of i.