JPS59107596A - Ceramic multilayer wiring circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a ceramic multilayer wiring circuit board, and particularly to a ceramic multilayer circuit board in which a ceramic insulating material and a conductive pattern of copper, silver, gold or an alloy thereof are alternately laminated. This invention relates to a ceramic multilayer circuit board with a high dielectric constant and low conductor resistance.

[Prior art]

Conventionally, alumina porcelain has been used as a ceramic board for use in this type of circuit board due to its ID thermal conductivity, mechanical strength, and insulation properties.

However, high alumina ceramics have a dielectric constant of 9
Because of the large amount of heat generated in the front and back, the signal transmission speed of the Kameko circuit is slow, making it disadvantageous for high-speed transmission of circuit signals. Also,
The firing temperature of high alumina ceramics is 1500-165
(The conductors that can be used to form wiring circuits at the same time as I' and high temperature are limited to high-melting point metal materials such as tungsten or molybdenum. Tungsten and molybdenum are materials that are difficult to sinter. Dust,
Also, the resistance at room temperature is as large as 5.2 or 5.5 μΩ. When forming a high-density circuit, the smaller the wiring width, the greater the resistance per unit length.

This slows down the signal transmission speed due to the voltage drop.

Eliminating the problems caused by such tungsten and molybdenum conductors, wiring ports for silver, copper, gold and their alloys1
A ceramic plate made of a vitreous refractory material and a glass gap between them has been proposed in order to form a ceramic plate at the same time as firing the ceramic (Japanese Patent Application Laid-Open No. 119814/1983).

However, when manufacturing a ceramic multilayer circuit board based on the composition of this ceramic board, it is not possible to sufficiently adjust the coefficient of thermal expansion between the ceramic board and the conductor18, so the ceramic cracks during the cooling process after firing. This may cause problems such as disconnection or short-circuiting of conductors.

[Purpose of the invention]

An object of the present invention is to provide wiring by controlling the coefficient of thermal expansion of the ceramic material in a ceramic multilayer wiring circuit board in which ceramic insulation material and conductor patterns of copper, silver, gold, or their alloys are alternately laminated. It is an object of the present invention to provide a ceramic multilayer wiring circuit board that has improved compatibility with a conductor paste used in the present invention and can prevent ceramic cracks and conductor disconnections or short circuits.

[Summary of the invention]

The present invention relates to a wiring conductor made of a ceramic material containing at least two types of silicon oxide with different crystal forms and glass interposed in the gap, and a wiring conductor made of copper, silver, gold, or an alloy thereof. By combining these, it is possible to control the thermal expansion coefficient of the ceramic material to a value close to that of the wiring conductor.

Silver (1.6 μΩ・C
rri), copper (1,7μΩ・Crrl), gold (2,2μ
Ω・crn) is known. The melting point of each of these materials is
961tll', 1083t:'' and 1063C. In order to use these conductors in ceramic multilayer circuit boards, it is necessary to select a ceramic material that can be sintered at a temperature lower than this melting point. When fired at high temperatures, the conductor formed by the printing method melts and
If the wire is disconnected, there is a risk of a short circuit.

Further, as the ceramic material, a material with a small dielectric constant is required. It is known that the following equation holds true between the dielectric constant εr and the atmospheric signal delay td.

zotr -L td2□ td is the implementation delay, Cr is the dielectric constant of the material, t is the signal transmission distance, and C is the speed of light. Therefore, by selecting a material with a small dielectric constant, the signal transmission speed can be increased.

Here, the present inventors focused on silicon oxide, which has a relatively small dielectric constant among inorganic materials. However, silicon oxide alone cannot be sintered or packed unless the temperature is 1400C or higher, so a low softening point glass is used as the low-temperature sintering material, and silicon oxide is sintered with this glass.

That is, silicon oxide is classified into various compounds consisting of different crystal forms. For example, materials that are stable at room temperature include quartz glass, α-quartz, α-cristobalite, α-tridymite, and the like. At high temperatures, there are also β-quartz, β-cristobalite, β-tridymite, etc. The present invention is characterized by mixing at least two or more of these silicon oxides having different crystal forms.The reason for mixing is to control the coefficient of thermal expansion of the ceramic material. Generally speaking, the coefficient of thermal expansion of a ζ° rack material decreases as its composition becomes more concentrated. In the present invention, the ceramic is made by mixing two or more types of silicon oxide with different crystal forms and sintered with low melting point glass, so if the coefficient of thermal expansion of the ceramic is in the range from the lowest temperature to 400C, IX 1 o-" /
It is possible to arbitrarily control the range from ll;' to 20 X 1 o-'/C. This is due to the fact that the coefficient of thermal expansion differs depending on the crystal form of silicon oxide. For example, the coefficient of thermal expansion of quartz glass is 0.5 x 1 o-'/c,
That of quartz is 12 to 15 x 10-'/l; that of cristobalite is 10 x 1 o-'/l up to 200C.
c, but around 200C, α-cristobalite becomes β
- Adding the abnormal thermal expansion during phase transition to cristobalite, the heat from room temperature to 400C, the Akbari series number is 23
1 o-6/c. Tridymite also has a coefficient of thermal expansion of 23 x 10-6/C when α and β transitions are added. Therefore, the thermal expansion coefficients of these silicon oxides are as shown in Table 1.

Table 1 Therefore, by mixing two or more silicon oxides with different crystal forms, the coefficient of thermal expansion of the ceramic material can be adjusted as desired.

In addition, in order to create a multilayer wiring circuit board, wiring conductors are required between ceramic materials that are insulators, and through-hole conductors are also required to connect the wiring conductors between each ceramic layer. The thermal expansion coefficients of silver, copper, and gold used for conductors are each 1.91X10''''/C, 17,OX i
, 0-'/U and 14.2X10-'/l:''.The coefficient of thermal expansion of ceramics is the thermal expansion of these conductors 1
If the difference from the series number is too large, cracks may occur in the ceramic during the cooling process after firing, or conductor @ lines may be formed, which is inconvenient for multilayer circuit boards. To solve this problem, it is necessary that the coefficient of thermal expansion of the ceramic material can be arbitrarily selected. In the present invention, the thermal J profile coefficient of the ceramic material can be approximated to the thermal expansion coefficient of the conductor.

When the particle size of the raw material is widened to 1.1, the ceramic substrate becomes denser and the surface unevenness becomes smaller. Ideally, particles with a diameter of 10 μm or less are used.

In the present invention, since silicon oxide is sintered at a relatively low temperature, the low softening point glass is chemically stable and has a low dielectric constant. Those that soften at a temperature lower than the melting point of those alloys are preferred. Preferred examples of such glass include barium borosilicate glass, magnesium borosilicate glass, etc., but two or more types of low softening point glasses may be mixed and used. Note that glass containing lead oxide can also be used as the low softening point glass.

There are no particular restrictions on the mixing ratio of silicon oxide and glass. However, if the amount of glass is too small, it will not be possible to bond silicon oxide. Therefore, the amount of silicon in acid ratio is preferably 5 to 95% by weight, ideally 20 to 80%.

Next, a process for producing a ceramic multilayer wiring circuit board, which is the final objective of the present invention, will be explained.

First, two or more types of silicon oxide powder and glass powder are weighed out at a predetermined mixing ratio, and mixed with a binder, a plasticizer, and a solvent to prepare a slurry. The binder used is polyvinyl butyral resin, methacrylic acid resin, etc., the plasticizer used is dioctyl phthalate, and the solvent used is methanol, trichlorethylene, etc. The slurry is spread onto a polyester resin film using a doctor blade method.
It is leaked to OmrncDN. By drying and removing the solvent, a green ceramic sheet with a predetermined thickness is obtained. The green sheet is made by punching, drilling, etc. holes with a predetermined diameter at predetermined positions, and conductor paste of silver, copper, gold, or their alloys is printed on the hole portions to form wiring conductors. Through-hole conductor section for interlayer wiring (
(indicated by 2 in Figure 1). A conductor pattern (indicated by 1 in FIG. 1) of predetermined wiring is printed on the surface of the green sheet.

After laminating a multilayer ceramic material with through-holes and conductor patterns, as shown by 3 in FIG. 1, it is fired. An atmosphere of a mixed gas of nitrogen and hydrogen and water vapor is used to fire the green sheet printed with copper conductors. The firing temperature is preferably in the range of 900 to 1000 r. This varies depending on the type of glass used and the mixing ratio of silicon oxide and glass as raw materials. The temperature may be maintained at the maximum temperature for 10 minutes to 1 hour. Further, when silver or gold is used as the conductor, a nitrogen gas or air atmosphere can be used for firing. This is because the silver or gold is not oxidized. The firing temperature is 8 for silver.
00~9001Z''% 800~100 (I'
is ideal.

Through the steps described above, a ceramic multilayer wiring circuit board having through-hole conductors and conductor wiring between layers is manufactured.

[Embodiments of the invention]

The present invention will be explained in detail below. In each Nanchu, "part" means the weight part, and "%" means weight %.

Table 2 shows the composition and properties of the low softening point glass used as the raw material.

Table 3 shows the mixing ratio of low softening point glass and silicon oxide, which are the basis of the ceramic material, the sintering temperature, and the characteristics of the sintered body. As is clear from Table 4, the dielectric constant of the obtained sintered body is 4.0 to 5.0, which is not much different, but the coefficient of thermal expansion is a
, 2 X 1 o-6/c to 10.3 X 10"
There are up to '/C. It is possible to control the coefficient of thermal expansion by changing the mixing ratio of silicon oxide and glass and the type of silicon oxide.

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■ Dimension Dimension Dimension Dimension Dimension Dimension Example 1 Weigh out 100 parts of ceramic raw materials at the mixing ratio shown in Table 3, put them into a ball mill, and mix for 24 hours.

Furthermore, 6.0 parts of polyvinyl butyral resin, 1 part of phthalate
Shundioctyl 2.4 parts, trichlorethylene 23, o@
Add 9.0 parts of B5 perchlorethylene and 6.0 g of butyl alcohol and mix again in a ball mill for 10 hours.The mixture becomes a slurry.
is continuously molded onto a polyester film using a doctor blade to a thickness of 0.25 m. Maximum temperature 120
Heat at C to volatilize the solvent and form a green sheet.

Cut the green sheet into a predetermined shape. A through hole is made at a predetermined position by a punching method, and a conductor for interlayer connection of wiring is formed in the through hole by a printing method with silver conductive paste. Further, a predetermined pattern of wiring conductors is printed on the surface of the sheet. Six green sheets printed with silver conductors were stacked using guide holes and heated at 120C for 10 minutes.
Glue with Kylcni pressure.

The stacked green sheets are packed in a furnace and fired in an air atmosphere. The sintering temperature is the sintering temperature shown in Table 3, and the sintering temperature is maintained for about 30 minutes.

Through the above steps, a ceramic wiring circuit board having six conductor layers is obtained. Since this circuit board uses silver as a conductor, the resistance of one wiring having a wiring width of 80 μm is 0.4Ω/Crn.

Example 2 Weighed out 100 parts of ceramic raw materials at the mixing ratio shown in Table 3.
Place in a ball mill and mix for 24 hours.

Further, 5.9 parts of methacrylic final resin, 24 parts of dioctyl phthalate, 23.0 parts of trichloroethylene, 9.0 parts of no-cycloethylene, and 6.0 parts of butyl alcohol were added, and the mixture was again mixed in a ball mill for 10 hours.

This turns the mixture into a slurry. The slurry is continuously molded onto a polyester film using a doctor blade to a thickness of 0.25 mm. Seat maximum temperature 12
Heat at 0C to volatilize the solvent and create a green sheet. The green sheet is cut into a predetermined shape, and through holes and guide holes are formed at predetermined positions using a punching method. A copper conductor base is filled into the through holes for interlayer connections, and a wiring pattern is formed on the surface of the green sheet. Six green sheets on which copper conductive paste has been formed are stacked using guide holes and bonded at 120C with a pressure of 15 Kr/aA.

The stacked green sheets are packed in a furnace and fired. The firing atmosphere is a nitrogen atmosphere containing 3 to 7% hydrogen, and a small amount of water vapor is introduced into the gas to promote thermal decomposition of the organic binder. Ceramics are obtained by firing at the sintering temperatures shown in Table 3.

Through the above steps, a printed circuit board with six conductor layers was obtained. This circuit board uses copper for wiring, so the line width is 8.
The wiring resistance of 0 μm is equal to 0.4Ω/crn.

Example 3 A green sheet was produced in the same manner as in Example 1, and all paste was used for the conductor. Firing was carried out in an air atmosphere in the same manner as Ookiren 1.

The wiring resistance of a printed circuit board with six conductor layers is 0.45 Ω/Cm at a line width of 80 μm.

〔Effect of the invention〕

According to the present invention, the dielectric constant is low, and the sintering temperature can be set to be lower than the melting point of silver, copper, gold, or their alloys, so a conductor with low wiring resistance can be used, and the coefficient of thermal expansion is 3 x 1 o-6/c ~ 10 x 10'''6/
Since it can be adjusted within a range of approximately U, it is possible to obtain a ceramic multilayer wiring circuit board that has a high signal transmission speed and is free from cracks, conductor breaks, and short circuits.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a ceramic multilayer wiring circuit board according to the present invention.

Claims (1)

[Claims] (2) A ceramic multilayer wiring circuit board in which ceramic insulating materials and conductive patterns of copper, silver, gold, or alloys thereof are alternately laminated; What is claimed is: 1. A ceramic multilayer wiring circuit board comprising at least two kinds of the above, and glass is interposed between the silicon oxides. 2. The ceramic multilayer wiring circuit board according to claim 1, wherein the silicon oxide is quartz glass, quartz, cristobalite or trisimalite. 3. The ceramic multilayer wiring circuit board according to claim 1, wherein the ceramic material has a dielectric constant of 6 or less.