JP2002299822A - Low-temperature baked ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-temperature baked circuit board that can suppress the protrusion of via-hole conductors from its surface even when two kinds of dielectric layers having different sintering starting temperatures are integrally baked. SOLUTION: This low-temperature baked circuit board is composed of two different kinds of first and second dielectric layers 1a, 1b, and 2a-2c, and first and second via-hole conductors 31 and 32 formed through the dielectric layers 1a, 1b, and 2a-2b in the thickness direction and containing Ag as the chief ingredient. The second dielectric layers 2a-2c have higher sintering starting temperatures than the first dielectric layers 1a and 1b have. In addition, the first via-hole conductors 31 contain MoO3 in amounts of 2-5 pts.wt. in the Ag- based material and the second via-hole conductors 32 contain Ru2 O in amounts of 2-5 pts.wt. in the Ag-based material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature fired ceramic circuit board in which internal wiring conductors and via-hole conductors formed for connection between layers are arranged between a plurality of stacked dielectric layers.

[0002]

2. Description of the Related Art Conventionally, a firing temperature of 800 to 1050 has been used.
A circuit board using a material that can be fired at a relatively low temperature of ° C. has been widely proposed.

[0003] The circuit board includes a substrate on which a plurality of dielectric layers are laminated, an internal wiring conductor disposed between the dielectric layers of the laminated body, a surface wiring conductor disposed on the surface of the laminated body, and each dielectric layer. It is composed of via-hole conductors that connect between predetermined internal wiring conductors in the layer thickness direction and between the predetermined internal wiring conductor and the surface wiring conductor.

[0004] Various electronic components such as an IC chip are mounted on the surface wiring conductor arranged on the surface of the laminate.

In order to increase the conductivity of the above-mentioned internal wiring conductors to increase the circuit speed, the internal wiring conductors, via-hole conductors and surface wiring conductors may be composed of Ag alone or Ag-Pd, Ag-Pt, or the like. Ag-based material composed of the above Ag alloy is used. In addition, the dielectric layer may be formed at a low temperature (800 to 105) based on the melting point of Ag of the Ag-based conductor described above.
(0 ° C.). For example, a material composed of a glass component and a ceramic component.

[0006]

By the way, as electronic devices have become smaller and more sophisticated, there has been a growing demand for efficiently incorporating elements such as capacitors and filters in a circuit board and improving the characteristics of the built-in elements. I have.

However, when two types of dielectric layers such as glass-ceramic materials having different sintering start temperatures are laminated and fired integrally, a difference occurs in the shrinkage behavior, so that the surface of the via-hole conductor on the substrate surface is reduced. As a result, the wiring conductor on the board surface cannot be formed,
In addition, there has been a problem that the electronic component element cannot be mounted.

[0008] This is because when dielectric layers having different sintering start temperatures are laminated and sintered, the stress due to the difference in contraction of the dielectric layers is concentrated in the laminating direction, and the via-hole conductor on the substrate surface and the dielectric around the via-hole conductor. The body layer will protrude.

Even if the via-hole conductor is not exposed on the surface of the substrate, the stress protrudes to push up the substrate surface immediately above the via-hole conductor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object the purpose of forming via holes from the substrate surface even when two types of dielectric layers having different sintering start temperatures are integrally fired. An object of the present invention is to provide a circuit board capable of suppressing protrusions of a conductor.

[0011]

SUMMARY OF THE INVENTION According to the present invention, two kinds of first and second dielectric layers having different sintering start temperatures are laminated, and an inner layer is provided between the first and second dielectric layers. A low-temperature fired ceramic circuit board comprising a wiring conductor, a first via-hole conductor in a first dielectric layer, and a second via-hole conductor in a second dielectric layer. The second dielectric layer has a higher sintering start temperature than the first dielectric layer, and the first via-hole conductor contains MoO ₃ in an Ag-based conductor material, and the second via-hole conductor is a low-temperature fired ceramic circuit board, characterized by containing Ru ₂ O.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit board according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a circuit board according to the present invention.

In FIG. 1, reference numeral 10 denotes a circuit board,
Is a substrate (hereinafter, referred to as a laminate), 3 is an internal wiring conductor formed in the laminate 1, 4 is a surface wiring conductor formed on the surface of the laminate 1, and 31 and 32 are formed in the laminate 1. Via-hole conductors 5 and 5 are IC chip components mounted on the surface of the multilayer body 1, and 6 is another electronic component.

The laminate 1 includes first dielectric layers 1a and 1b made of a glass-ceramic material and first dielectric layers 1a and 1b.
The second dielectric layers 2a to 2c made of glass-ceramic materials having different components from the glass-ceramic materials a and 1b and having different sintering start temperatures are laminated.
The sintering start temperature of the first dielectric layers 1a and 1b is, for example, in the range of 800 to 900 ° C., and the sintering start temperature of the second dielectric layers 2a to 2c is equal to the first dielectric layer. 1a, 1
It is higher than b, for example, in the range of 900 to 1000 ° C.
Then, the first dielectric layers 1a and 1b are arranged and stacked outside the second dielectric layers 2a to 2c.

An internal wiring conductor film 3 mainly composed of Ag or the like is formed between each of the dielectric layers 1a, 2a to 2c, and 1b in order to achieve a predetermined circuit network and generate a capacitance component. ing. In the first dielectric layers 1a and 1b, a first via-hole conductor 31 penetrating the thickness direction of each layer is formed, and in the second dielectric layers 2a to 2c, the first via hole conductor 31 penetrates the thickness direction of the layer. A second via-hole conductor 32 is formed.

The first via-hole conductor 31 is made of Ag.
Molybdenum oxide (MoO ₃ ) is made of a material containing 2 to 5 parts by weight of silver with respect to 100 parts by weight, and the second via-hole conductor 32 is made of ruthenium oxide (Ru ₂ O) with 2 to 5 parts by weight of Ag with respect to 100 parts by weight of Ag. It consists of a material containing 5 parts by weight.

First and second dielectric layers 1a, 1b, 2a
2c are made of a glass-ceramic material. The ceramic powder of the glass-ceramic material is cristobalite,
Insulating ceramic materials such as quartz, corundum (α-alumina), mullite, cordierite, BaTiO ₃ , Pb ₄
Magnetic ceramic materials such as dielectric ceramic materials such as Fe ₂ Nb ₂ O ₁₂ and TiO ₂ , Ni—Zn ferrite, and Mn—Zn ferrite are referred to as ceramics in a broad sense. Further, the glass material may be any one that precipitates a crystal phase of a cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, petalite or a substituted derivative thereof or a crystal phase of a spinel structure by firing. For example, glass frit containing B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , ZnO, and alkaline earth oxide can be used. The thickness of the dielectric layers 1a, 1b, 2a to 2c is, for example, 100
About 300 μm.

The internal wiring conductor film 3, the via hole conductor 31,
Reference numeral 32 denotes an Ag-based conductor film (conductor), the thickness of the internal wiring conductor film 3 is about 8 to 15 μm, and the diameter of the via-hole conductors 31 and 32 can be set to an arbitrary value. ３５０350 μm.

The surface wiring conductor film 4 mainly constitutes a circuit wiring conductor on the surface, serves as a connection pad for an electronic component 6 to be joined via solder, and has a thick film resistance film, a thick film capacitor element. Terminal electrode. In particular, the connection with the internal wiring conductor film 3 is made through the first via-hole conductor 31 formed in the first dielectric layers 1a and 1b.

The surface wiring conductor film 4 is made of an IC chip 5 connected by a bonding thin wire or a flip chip.
As a connection pad (wire bonding pad).

A method for manufacturing the above-described circuit board 10 will be described.

First, a green sheet made of a glass-ceramic material for forming the dielectric layers 1a, 2a to 2c and 1b is formed. Specifically, ceramic materials, glass materials,
An organic binder, a slurry obtained by homogeneously kneading an organic solvent, is tape-formed to a predetermined thickness by a doctor blade method,
The sheet is cut into a predetermined size to create a sheet.

The composition ratio of the above-mentioned ceramic material and glass material is such that the ceramic material is 10 to 60 wt%, preferably 30 to 50 wt%, since firing at a relatively low temperature of 850 to 1050 ° C. 90-40w
t%, preferably 70 to 50 wt%.

The organic binder also needs to pay attention to the wettability with solids (ceramic powder, frit of low melting point glass component), and is thermally decomposable so that it can be burned off in a relatively low temperature and short firing step. Excellent ones are preferable, and ethylenically unsaturated compounds having a carboxyl group and an alcoholic hydroxyl group such as acrylic acid or methacrylic acid-based polymers are preferable.

As the solvent, an organic solvent or an aqueous solvent can be used. For example, in the case of an organic solvent,
For example, 2,4-trimethyl-1,3-pentanediol monoisoventate or the like is used. In the case of an aqueous solvent, the solvent must be water-soluble, and the monomer and the binder include a hydrophilic functional group such as carboxyl. A group has been added. The amount of addition is 2 to 300, preferably 5 to 100, when expressed in acid value. If the added amount is small, the solubility in water and the dispersibility of the powder of the fixed component deteriorate, and if the added amount is large, the thermal decomposability deteriorates. In consideration of the above, it is appropriately added within the above range.

Next, the first via-hole conductor 31 is placed at a predetermined position on the green sheet to be the first dielectric layers 1a and 1b.
Is formed by punching.

The second via-hole conductor 32 is provided at a predetermined position on the green sheet to be the second dielectric layers 2a to 2c.
Is formed by punching.

Next, the conductor of the first via-hole conductor 31 is filled in the through hole of the green sheet to be the first dielectric layers 1a and 1b, and a conductor film to be the internal wiring conductor film 3 is printed on the surface thereof. Then, a drying process is performed. The conductor to be the first via-hole conductor film 31 is made of Ag (Ag alone, Ag-Pd).
Alloy) A conductive paste composed of a powder, MoO ₃ powder, an organic binder such as ethyl cellulose, and a solvent was used.
Further, the conductor film to be the internal wiring conductor film 3 is made of an Ag-based (Ag-based).
A conductive paste obtained by homogeneously mixing a simple substance, an Ag-Pd alloy) powder, a borosilicate-based low-melting glass frit, an organic binder such as ethyl cellulose, and a solvent was used.

Also, the conductor of the second via-hole conductor 32 is filled in the through hole of the green sheet to be the second dielectric layers 2a to 2c, and the internal wiring conductor is placed on the green sheet to be the inner side of the substrate 1. A conductor film to be the film 3 is printed and dried. Further, a conductor film to be the surface wiring conductor film 4 is printed on the green sheet on the front surface side of the substrate 1 and dried. The conductor to be the second via-hole conductor film 32 is made of Ag-based (Ag alone, Ag-Pd alloy) powder, Ru
A conductive paste composed of O powder, an organic binder such as ethyl cellulose, and a solvent was used. The above-mentioned conductive paste was used for the conductor film to be the internal wiring conductor film 3.
Further, as the Ag-based conductive paste to be the surface wiring conductor film 4, one obtained by homogeneously mixing Ag-based (Ag alone, Ag alloy such as Ag-Pd) powder, Pt powder, an inorganic binder, an organic binder, and a solvent is used. . Further, in order to improve the adhesion between the substrate 1 and the surface wiring conductive film 4, a V ₂ O ₅ powder may be added 0.2 to 1.0 parts by weight for each metal component.

As described above, the first and second via-hole conductors 31 and 32, the conductor film as the surface wiring conductor film 4, and the first and second conductor films as the internal wiring conductor film 3 are formed. The green sheets to be the dielectric layers 1a, 1b, 2a to 2c are laminated and integrated according to the lamination order.

Next, the unfired laminate is fired in an oxidizing atmosphere or an air atmosphere. The firing process includes a binder removal process and a sintering process. The binder removal process includes a green sheet that becomes the dielectric layers 1a, 1b, 2a to 2c,
A conductor film serving as the internal wiring conductor film 3, a via-hole conductor 31,
32 for burning off organic components contained in the conductor film 32 and the conductor film serving as the surface wiring conductor film 4, for example, 60
It is performed in a temperature range of 0 ° C. or less.

In the sintering process, the glass component of the green sheet of the glass-ceramic material is crystallized and simultaneously dispersed uniformly at the grain boundaries of the ceramic powder to give the laminate 1 a certain strength and to provide the internal wiring conductor film. 3 conductor film, 1st
And a metal powder and an Ag-based powder of a conductive material of the conductor film to be the first via-hole conductors 31 and 32, the conductor film to be the surface wiring conductor film 4, are made to have low resistance, and the dielectric layers 1a, 2
a to 2c and 1b. This is done until a peak temperature of 850-1050 <0> C is reached.

In this step, the laminated body 1 in which the internal wiring conductor film 3, the first and second via-hole conductors 31 and 32 are formed, and the surface wiring conductor film 4 is formed on the surface is achieved. .

Thereafter, if necessary, the surface wiring conductor film 4
The IC chip 5 and various electronic components 6 are mounted by forming a thick-film resistance element and an insulating protection film having a predetermined shape connected to the IC chip 5.

As a result, the circuit board shown in FIG. 1 is achieved.

Thus, according to the low-temperature fired ceramic circuit board 10 of the present invention, two different types of first and second dielectric layers 1a, 1b, 2a to 2c are laminated, and the first and second dielectric layers are laminated. An internal wiring conductor 3 is arranged between the dielectric layers 1a, 1b, 2a to 2c, and the first and second layers mainly composed of an Ag-based material penetrate through the thicknesses of the first and second dielectric layers, respectively. Via-hole conductors 31 and 32 are arranged.

The second dielectric layers 2a to 2c have a higher sintering start temperature than the first dielectric layers 1a and 1b.
And the first via-hole conductor 31 contains 2 to 5 parts by weight of MoO ₃ based on 100 parts by weight of the Ag-based material,
The second via-hole conductor 32 has ₂ to 5 parts by weight of Ru ₂ O based on 100 parts by weight of the Ag-based material. Therefore, the first
In the via hole 31, MoO ₃ exists between the Ag particles, and sintering of Ag is delayed until the first dielectric layers 1a and 1b start sintering, thereby reducing shrinkage stress due to sintering.

In the second via hole 32,
Ru ₂ O is present between the Ag particles, and the second dielectric layers 2 a to 2
The sintering of Ag is delayed until sintering of c is started, and the shrinkage stress due to sintering is reduced.

When the first dielectric layers 1a and 1b start contracting in a temperature range of 800 ° C. or more,
Since MoO ₃ forms a solid solution with the Ag powder and promotes the shrinkage of Ag, the shrinkage stress of the first dielectric layers 1a and 1b can be reduced. Further, in the temperature region of 900 ° C. or more, when the second dielectric layers 2a to 2c start shrinking,
Ru ₂ O forms a solid solution with Ag and promotes Ag shrinkage.
The contraction stress of the second dielectric layers 2a to 2c can be reduced. As a result, a temperature difference of about 100 ° C. occurs in the sintering of the Ag of the via holes 31 and 32.

Here, the first via-hole conductor 31 is made of Ag
MoO for 100 parts by weight of base material _Three2 to 5 parts by weight
The second via-hole conductor 32 is made of an Ag-based material.
Ru for 100 parts by weight_TwoO 2 to 5 parts by weight
ing. First, MoO_ThreeAnd Ru _TwoWith O, solid solution with Ag
To provide a difference of about 100 ° C.
Material. Also, MoO_ThreeOr Ru_TwoThe amount of O added
If less than 2 parts by weight, it dissolves with Ag and promotes Ag shrinkage.
Effect is insufficient. On the other hand, MoO_ThreeOr Ru_Two
When the amount of O added is more than 5 parts by weight, the first and second
Conductor resistance of via-hole conductors 31 and 32 of
I will.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention.

[0042]

[Experimental Example] The present inventor assumed that the first dielectric layers 1a and 1b whose shrinkage start temperature was set at 800 ° C. and the shrinkage start temperature was 90 ° C.
Laminating the second dielectric layers 2a to 2c set at 0 ° C.,
In the integrally sintered multilayer substrate, the first dielectric layer 1a,
1b, the type and amount of oxide of the first via-hole conductor 31 formed in the first via-hole conductor 31 and the second oxide formed in the second dielectric layers 2a to 2c.
Investigations were conducted by changing the type and amount of oxide of the via-hole conductor 32 described above.

As shown in FIG. 1, in the laminated body 1 having a five-layer structure, the first dielectric layers 1a and 1b
The second dielectric layers 2a to 2c were used for three layers near the center of the laminate 1.

[0044]

[Table 1]

The method of measuring the amount of protrusion of the via-hole conductor is as follows. In the region of the first via-hole conductor 31 of the laminated body 1, the difference in height between the portion having the lowest height and the portion having the highest height is determined by the contact film. The thickness was measured with a probe of a thickness gauge, and those having a thickness of less than 20 μm were determined to be good, and those having a thickness of 20 μm or more were determined to be defective.

The conductor resistance was measured by applying a probe to each of the surface wiring conductor films 4 shown in FIG. 1, and those having a resistance of less than 1 mΩ were determined to be good and those having a resistance of 1 mΩ or more were determined to be defective.

As shown in Table 1, the case where the first via-hole conductor 31 contains 2 to 5 parts by weight of MoO ₃ and the second via-hole conductor 32 contains 2 to 5 parts by weight of Ru ₂ O (sample numbers 4 to 5) 7), the protrusion amount of the via hole conductor was less than 20 μm, and the conductor resistance was less than 1 mΩ.

On the other hand, the first and second via-hole conductors 31,
When both of Nos. 32 contained 2 parts by weight of MoO ₃ (Sample No. 1), the protrusion amount of the via-hole conductor was 25 μm. When both the first and second via-hole conductors 31 and 32 contained 2 parts by weight of Ru ₂ O (Sample No. 2), the protrusion amount of the via-hole conductor was 25 μm.

The first via-hole conductor 31 is made of MoO
₃ 1 part by weight, the second via-hole conductor 32 is a Ru ₂ O 1
When it was contained in parts by weight (Sample No. 3), the protrusion amount of the via-hole conductor was 22 μm. Further, the first via-hole conductor 31 includes MoO ₃ by weight, and the second via-hole conductor 3
2 contains 6 parts by weight of Ru ₂ O (Sample No. 8)
The conductor resistance was 1.5 mΩ.

[0050]

As described above, according to the present invention, two different types of first and second dielectric layers are laminated, and the first and second dielectric layers are respectively provided inside the first and second dielectric layers. A low-temperature fired ceramic circuit board having first and second via-hole conductors containing Ag as a main component and penetrating the thickness of the layer, wherein the second dielectric layer is fired as compared with the first dielectric layer. The starting temperature is high, and the first via-hole conductor is MoO ₃ of 2-5.
And the second via-hole conductor is Ru.
Contains ₂ to 5 parts by weight of 2O. Therefore, MoO ₃ , Ru
₂ O delays sintering of the first and second via-hole conductors before the first and second dielectric layers respectively begin to shrink,
In addition to reducing the shrinkage stress, when the first and second dielectric layers respectively start to shrink, they form a solid solution with Ag and promote the shrinkage of Ag, thereby reducing the shrinkage of the first and second dielectric layers. The shrinkage stress can be reduced, and the protrusion of the via-hole conductor from the substrate surface can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circuit board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Circuit board 1 Laminated body 1a, 1b 1st glass-ceramic layer 2a-2c 2nd glass-ceramic layer 3 Internal wiring conductor film 4 Surface wiring conductor film 31 First via-hole conductor 32 Second via-hole conductor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H01L 23/14 C04B 35/00 J H05K 1/09 H01L 23/14 MF term (reference) 4E351 AA07 BB01 BB31 BB49 CC12 CC22 CC31 DD05 DD17 DD20 DD21 DD31 DD32 DD34 DD41 DD47 EE02 GG01 GG03 4G030 AA10 AA16 AA20 AA27 AA29 AA32. CC35 CC39 DD02 DD13 DD34 EE24 EE25 EE27 EE29 FF05 FF18 FF45 GG04 GG06 GG08 GG09 HH11 HH31

Claims (3)

[Claims] 1. A method according to claim 1, wherein two types of first and second dielectric layers having different sintering start temperatures are laminated, and an internal wiring conductor is arranged between the first and second dielectric layers. The first via-hole conductor is provided in one dielectric layer, and the second via-hole conductor is provided in the second dielectric layer.
A low-temperature fired ceramic circuit board, wherein the second dielectric layer has a higher sintering start temperature than the first dielectric layer, and the first via-hole conductor Is Ag
A low-temperature fired ceramic circuit board, wherein the system conductor material contains MoO ₃ and the second via-hole conductor contains Ru ₂ O. 2. The sintering start temperature of the first dielectric layer is 8
2. The low-temperature fired ceramic circuit board according to claim 1, wherein the sintering temperature of the second dielectric layer is in the range of 900 to 1000 [deg.] C. 3. The first via-hole conductor contains 2 to 5 parts by weight of MoO ₃ based on 100% by weight of the Ag-based conductor material, and the second via-hole conductor is made of Ru _2.
3. The low-temperature fired ceramic circuit board according to claim 2, containing 2 to 5 parts by weight of O.