JPH06334351A - Conductor paste and ceramic multilayer interconnection board using same - Google Patents

Abstract

PURPOSE:To provide the title paste for via-conductor capable of directly connecting to an Au conductor on the surface of a low temperature baking ceramic multilayer interconnection substrate as well as satisfactorily connecting to an inner layer wiring. CONSTITUTION:A laminated low temperature baking ceramic green sheet is baked at 850 deg.C using a low temperature baking conductor paste comprising 100wt.% of metallic component composed of 80-99wt.% of Ag and total 1-20wt.% of exceeding at least one kind out of Pd, Au, Pt blended with 0.3-7wt.% of crystallized glass and 8-50wt.% of organic vehicle for via and inner wiring. Accordingly, the ceramic green sheet can be used for via conductor as an outermost layer to be directly connected to the Au conductor on the surface thereby enabling a wiring pattern to be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor paste used for a low-temperature-fired ceramic multilayer wiring board and a low-temperature-fired multilayer wiring board using the same, and particularly for a via conductor of a multilayer wiring board when a gold conductor is provided on the surface. The present invention relates to a paste and a conductor paste for inner layer wiring.

[0002]

2. Description of the Related Art As a wiring board used in electronic equipment, a ceramic multilayer wiring board has come to be used due to demands for higher speed and higher density. Vias are formed in such a multilayer wiring board in order to establish conduction between layers.

The vias are generally formed by laminating and firing ceramic green sheets each having a through hole at each required location and filled with a conductive material.

Alumina is mainly used for the ceramic multilayer wiring board. Since this alumina substrate has a high firing temperature, a wiring material having a high melting point such as Mo or W is also used as a wiring material. However, in recent years,
Due to the demand for higher density and the like, a substrate which has low conductivity resistance such as Cu, Ag and Au and can be fired at a low temperature has been developed (for example, Japanese Patent Laid-Open No. 62-113758) and its use is expanding.

As the conductor of this low temperature fired ceramic substrate, Cu, Ag-based conductor, Au or the like is used. Of which Ag
The conductor can be used for internal wiring and vias, but when it is used as a surface conductor, it easily causes diffusion and short circuit due to migration. Therefore, as the surface conductor, Cu, Ag, Pd are used.
, Ag · Pt, Au, etc. are used. Cu, Ag / Pd, Ag /
Of the conductors such as Pt and Au, especially when using Au conductors such as gold wiring and gold bands for wire bonding on the surface, first connect the outermost layer via and the conductor such as AgPd on the substrate surface,
Then, the method of connecting the conductor such as Ag / Pd and the Au conductor was adopted.

[0006]

As described above, in the low temperature fired substrate using Ag as the wiring material inside, the surface is not
Since it was necessary to connect other metals such as Cu, Ag / Pd, and Au, it was difficult to obtain a highly reliable connection. Especially when using a Ag conductor inside and forming a gold conductor on the surface,
Instead of connecting Au directly on the via, Ag on the substrate surface
・ A method of connecting Au via a conductor such as a Pd alloy is used.This method has a limit to the precision miniaturization of the wiring pattern, and the Au conductor is directly formed on the via of the Ag conductor for miniaturization. Then, the voids may be generated in the via due to the diffusion of Ag.

As described above, in a portion where different kinds of metals come into contact with each other, a connection failure may occur due to a difference in diffusion rate of metal atoms.

[0008]

The present invention does not have such a problem, and as a conductor paste for forming a via conductor which can be directly connected to an Au conductor on the surface, an alloy containing Ag as a main component, a crystallized glass and an organic vehicle. And a conductor paste comprising

That is, the conductor paste of the present invention is Ag
80 to 99% by weight and the sum of at least one of Pd, Au and Pt
It is a conductor paste for a low temperature fired ceramic multilayer wiring board, which comprises 100 parts by weight of a metal component consisting of 1 to 20% by weight, 0.3 to 7 parts by weight of crystallized glass and 8 to 50 parts by weight of an organic vehicle.

A more preferable composition of the above-mentioned conductor paste is selected according to its purpose.

In the following description, terms such as outermost layer via, inner layer via, and internal wiring are conceptually shown in the schematic view (cross-sectional view) of FIG.

That is, the outermost layer 1 is the outermost layer on both the front and back surfaces of the multilayer substrate, and the surface conductor 2 is formed on the surface thereof. The outermost layer via 3 is a via provided in the outermost layer that connects the surface conductor and the inner conductor, that is, the internal wiring 4 or the inner layer via 5. The inner layers sandwiched between the outermost layers are all inner layers, and the wiring provided on the inner layer surface is the inner wiring 4
The inner layer vias 5 are vias provided in the inner layer connecting these internal wirings between layers.

The conductor paste for the outermost layer via connecting the Au conductor on the surface and the conductor inside is preferably Ag of 80 or less.
~ 95% by weight of the total of at least one of Pd, Au and Pt
A paste prepared by mixing 0.3 to 3 parts by weight of crystallized glass and 8 to 25 parts by weight of an organic vehicle with 100 parts by weight of a metal component of 5 to 20% by weight is used.

The wiring paste for the inside of the multilayer substrate is preferably 100 parts by weight of a metal component containing 95 to 99% by weight of Ag and 1 to 5% by weight of one or more of Pd, Au and Pt in total. , Crystallized glass 2-7 parts by weight and organic vehicle 15-50
A conductor paste containing parts by weight is used.

Further, the vias for the inner layers connecting these internal wirings preferably contain 95 to 99% by weight of Ag and P
1 to 5% by weight of the total of at least one of d, Au, and Pt
A conductive paste prepared by mixing 0.3 to 3 parts by weight of crystallized glass and 8 to 25 parts by weight of an organic vehicle with 100 parts by weight of the metal component is used.

The details of the present invention will be described below. The via conductor that contacts Au on the surface is made of Pd, Au, and Pt in addition to Ag.
It is preferable to contain one or more kinds in an amount of 5% by weight or more. If the composition is less than this, poor conduction may occur at the portion in contact with Au. If it is more than 20% by weight, the connection with the inner conductor will be poor.

That is, the internal conductor is required to have a low sheet resistance, and the addition of the dissimilar metal for improving the connection with the via conductor increases the sheet resistance, so that the internal wiring and the interlayer wiring between the layers are not provided. As the inner layer via conductor to be connected, the ratio of metal components other than Ag is 5% by weight or less, preferably 1 to 5% by weight. If less than this,
If the connection with the via conductor for the surface is bad and there are many,
High sheet resistance.

Therefore, in order to make a good connection with this inner layer conductor, the total amount of Pd, Au and Pt of the via conductor of the outermost layer is
20% or less is preferable. Further, it is desirable that the metal composition of the inner layer via conductor that connects the internal wiring between the layers be close to that of the internal wiring.

Commercially available metal powders are used for the conductor paste of the present invention, and the preferable particle size is 0.5 to 2 μm for Ag powder and 0.2 to 1 μm for Pd powder.
m, Pt powder 0.1-1.5 μm, Au powder 0.2-1.5 μm
Is.

The shape of the powder is preferably as close to spherical as possible. If it is spherical, the oil absorption of the powder is small, so it is easy to form a paste, and the solid content and viscosity are easy to adjust.

The glass of the conductor paste component is preferably one that crystallizes by firing at 850 ° C. This is because there is no softening due to re-baking and the adhesiveness with the substrate is excellent. Further, when glass that crystallizes is used, it hardly adheres to a setter such as alumina during firing, contamination of the setter is prevented, and the setter can be reused.

The amount of crystallized glass blended in the via conductor paste is 0.3 to 3 parts by weight based on 100 parts by weight of the metal component. If it is less than 0.3 parts by weight, alumina or the like may adhere to the setter used during firing, and the adhesion between the internal via conductor and the substrate may be poor, resulting in voids. If the amount is more than 3 parts by weight, cracks may occur around the via conductor.

However, the amount of crystallized glass added to the internal wiring paste should be larger than that of the via conductor.
That is, when the amount of the metal component is 2 parts by weight or less relative to 100 parts by weight, the substrate may warp. On the contrary, if the amount is large, the sheet resistance becomes high. Therefore, 2 to 7 parts by weight is preferable.

The organic vehicle is optional as long as it can be made into a paste and has viscosity characteristics such that it can be filled.
For example, a solution obtained by dissolving 10 to 20% by weight of ethyl cellulose, a methacrylate resin or the like in a high boiling point solvent such as terbineol, butyl carbitol or dibutyl phthalate can be used.

If the amount of the organic vehicle is 8 parts by weight or more, it can be made into a paste. However, when the content is 25% or more, voids may occur when the composition is filled and dried, so that the content of the via paste is preferably 8 to 25 parts by weight.

However, since the paste for the internal wiring is not limited to that for vias, the organic vehicle may be of any amount as long as it has a screen-printable paste viscosity, and has an appropriate film thickness after printing. Therefore, the blending amount can be in the range of 15 to 50 parts by weight.

If desired, a dispersant, a viscosity modifier, etc. can be added to the conductor paste of the present invention.

[0028]

[Function] As the conductor paste of the present invention, as the metal component of the outermost via conductor paste for connecting the Au conductor on the surface and the inner conductor, Ag is 80 to 95% by weight and at least one of Pd, Au and Pt is selected. By using the metal components whose total amount is 5 to 20% by weight, when the via conductor and the surface Au conductor are in contact, Pd, Au, and Pt in the via conductor are The moving speed and the moving speed in the alloyed part in contact with Au can be slowed down, the generation of the cavity around the via conductor can be suppressed, and the connection between the via and the surface Au can be ensured. You can

Further, the connection failure with the internal conductor which occurs when such outermost layer via conductor is adopted can be eliminated by selecting the conductor paste for the internal wiring and the internal layer via conductor.

[0030]

EXAMPLES The raw materials for the conductor paste and the preparation of the paste in the following examples and comparative examples are as follows.

(Metal powder) Ag powder: A powder made by Mitsui Mining & Smelting Co., Ltd., having a particle size of about 1 μm and having a nearly spherical shape. Pd powder: made by Sumitomo Metal Mining Co., Ltd., approximately spherical with a particle size of about 0.5 μm. Pt powder: made by Tanaka Kikinzoku Kogyo Co., Ltd., with a particle size of about 1 μm. Au powder: made by Tanaka Kikinzoku International, particle size of about 1μ
m.

(Crystalline glass) SiO2: 33%, Al2O3: 18
%, B2O3: 2%, ZnO: 17%, CaO: 17%, TiO2: 13%.

(Organic Vehicle) The organic vehicle mixed in the paste used for the outermost via conductor and the inner via conductor is 15 parts by weight of 100 parts by weight of a metal component prepared by dissolving ethyl cellulose in 15% dibutyl phthalate. Compounded. In the conductor paste for internal wiring, 35 parts by weight of ethyl cellulose as an organic vehicle dissolved in 15% terbineol was mixed with 100 parts by weight of the metal component.

(Preparation of Paste) A predetermined amount of metal powder, crystallized glass, and organic vehicle were mixed and then passed through a three-roll mill.

(Green Sheet) A ceramic green sheet is a mixture of 50 parts by weight of alumina powder and 50 parts by weight of zinc borosilicate glass, 10 parts by weight of an acrylic resin as an organic binder, and a slurry to form a doctor blade. By the method, it was formed into a sheet with a thickness of about 0.2 mm.

(Multilayer Substrate) 0.15 mm via holes for vias are made in each green sheet at each predetermined position by NC punching, and the through holes of each green sheet are filled with a predetermined via paste by printing. Further, a predetermined internal wiring pattern was printed on it.

After stacking each green sheet and thermocompression bonding, 4
It was debindered at 00 ° C and calcined at 859 ° C.

A commercially available product is provided on a predetermined portion of the surface of the obtained multilayer substrate.
Au conductor paste (Nuchem Cat's Au paste)
Was printed and baked at 850 ° C.

(Evaluation Method) Various measurements in the following Examples and Comparative Examples were carried out by the following methods.

Continuity: A substrate having a pattern as shown in FIG. 2 was prepared, and the continuity between A and B and between C and D was examined with a tester. There were 96 connecting portions on each of the front and back sides of one substrate, 50 substrates were prepared for each example, and the conduction at 9600 places in total was examined.

Adhesion to setter: The alumina setter was observed with a magnifying glass.

Crack: After embedding the substrate in epoxy resin, polishing and observing with a microscope.

Sheet resistance: 0.2 mm × 20 mm wiring was formed inside, and a sample drawn out on the surface with a via conductor was used.
It was measured by the terminal method.

Examples 1 to 7 and Comparative Examples 1 to 3 In the multilayer substrate shown in FIG. 2, the paste of Example 11 described below was used as the internal wiring conductor, and the conductor paste of Example 21 described below was used as the via for the inner layer. The composition of the outer layer via conductor paste is made into each composition shown in Table 1, and a multi-layer substrate is prepared.
The continuity was measured. The results are shown in Table 1.

[0045]

[Table 1]

Regarding the poor conduction in Comparative Examples 1 and 2, as a result of observing the cross section, a cavity was formed near the interface between the surface conductor and the via conductor. Further, in Comparative Example 3, the connection with the surface conductor was good, but a void was observed in a part of the connection portion with the internal wiring conductor.

In the pastes of Examples 8 and 9 and Comparative Examples 4 and 5, the glass compounding amount was changed as shown in Table 2, and the conductivity of the obtained multilayer substrate was measured. The results are shown in Table 2. From this result, the amount of glass added to the paste for vial is 0.3 to 100 parts by weight of the metal component.
It turns out that 3 parts by weight is enough.

[0048]

[Table 2]

Examples 10 to 16 and Comparative Example 6 In the multilayer substrate of Example 6, a multilayer substrate was prepared with the metal component composition of the internal wiring conductors as shown in Table 2, and the sheet resistance and conduction of the internal wirings were measured. . The results are shown in Table 3. In Comparative Example 6, there is a defect at the connection between the via and the internal wiring. On the other hand, in the embodiment, no connection failure has occurred.

[0050]

[Table 3]

Examples 17 to 19 and Comparative Examples 7 and 8 In the multilayer substrates of Example 6, the glass compounding amount of the internal wiring conductor paste was changed as shown in Table 4, and the obtained multilayer substrate was subjected to internal wiring sheets. The resistance was measured. The results are shown in Table 4.

[0052]

[Table 4]

When the glass content was less than 2 parts by weight, the warpage of the substrate was large. Further, when it was more than 7 parts by weight, the sheet resistance was large.

Examples 20 to 25 In the multilayer substrate of Example 6, the via conductor paste for the inner layer having the composition shown in Table 5 was used to measure conduction.
The results are shown in Table 5.

[0055]

[Table 5]

No conduction failure was observed, and good results were obtained by making the composition close to that of the internal wiring conductor.

[0057]

INDUSTRIAL APPLICABILITY The conductor paste of the present invention can be used as a via conductor of the outermost layer of a ceramic multilayer substrate and can be directly connected to an Au conductor on the surface, and the connection is highly reliable.
The wiring pattern can be miniaturized. Further, by selecting the paste composition, it is possible to obtain good mutual connection for the internal wiring and the internal via conductor.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a ceramic multilayer wiring board of the present invention.

FIG. 2 is a cross-sectional view of a continuity evaluation substrate in an example of the present invention.

[Explanation of symbols]

 1 Outermost layer 2 Surface conductor 3 Outermost layer via 4 Internal wiring 5 Inner layer via A, B, C, D terminals

Claims (5)

[Claims] 1. A metal component comprising 80 to 99% by weight of Ag and a total of 1 to 20% by weight of at least one of Pd, Au and Pt.
A conductor paste for a low temperature fired ceramic multilayer wiring board, which comprises 0 parts by weight, 0.3 to 7 parts by weight of crystallized glass, and 8 to 50 parts by weight of an organic vehicle. 2. A metal component comprising 80 to 95% by weight of Ag and 5 to 20% by weight of at least one of Pd, Au and Pt in total.
A conductor paste for the outermost layer via that is connected to the surface Au conductor of the low temperature fired ceramic multilayer wiring board, which is composed of 0 part by weight, 0.3 to 3 parts by weight of crystallized glass, and 8 to 25 parts by weight of organic vehicle. 3. A metal component comprising 95 to 99% by weight of Ag and a total of 1 to 5% by weight of at least one of Pd, Au and Pt.
0 parts by weight, crystallized glass 2-7 parts by weight and organic vehicle 1
Conductor paste for internal wiring of low temperature fired ceramic multilayer wiring board consisting of 5 to 50 parts by weight. 4. A metal component comprising 95 to 99% by weight of Ag and a total of 1 to 5% by weight of at least one of Pd, Au and Pt.
Conductor paste for inner layer vias of low-temperature fired ceramic multilayer wiring boards consisting of 0 part by weight, 0.3 to 3 parts by weight of crystallized glass and 8 to 25 parts by weight of organic vehicle. 5. A ceramic multilayer wiring board having an Au conductor on the surface thereof, comprising a metal component of 80 to 95 wt% Ag and a total of 5 to 20 wt% of at least one of Pd, Au and Pt.
00 parts by weight, 0.3 to 3 parts by weight of crystallized glass, and 8 to 25 parts by weight of organic vehicle are used as the outermost via, and the total of at least one of Ag 95 to 99% by weight, Pd, Au, and Pt. Conductive paste consisting of 100 parts by weight of a metal component consisting of 1 to 5% by weight, 2 to 7 parts by weight of crystallized glass and 15 to 50 parts by weight of an organic vehicle is used for the internal wiring, and 95 to 99% by weight of Ag, Pd and Au are used. , A conductor paste consisting of 100 parts by weight of a metal component consisting of at least one or more of Pt and a total of 1 to 5% by weight, 0.3 to 3 parts by weight of crystallized glass, and 8 to 25 parts by weight of an organic vehicle was used for the inner layer via. A low temperature fired ceramic multilayer wiring board characterized by the above.