JPH06116019A - Glass-ceramic substrate fired at low temperature - Google Patents

Abstract

PURPOSE:To provide a glass-ceramic compsn. giving a fired substrate having a low coefft. of thermal expansion and a low dielectric constant by firing at a low temp. of 750-950 deg.C in the air and suitable for a multilayered circuit board using one kind of binder. CONSTITUTION:A glass-ceramic compsn. having a compsn. consisting of, by weight, 15-50% PbO, 2.5-20% BaO, 5-15% Al2O3, 25-45% SiO2, 0.5-10% B2O3, 0-5% CaO, 0-15% ZnO and 0-1% Sb2O3 is provided. This glass-ceramic compsn. deposits fine celsian during firing at a low temp. and gives the objective glass- ceramic substrate fired at a low temp.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a glass-ceramic composition for a circuit board and a board.

[0002]

2. Description of the Related Art A hybrid IC or a multi-layer circuit board for a multi-chip package is manufactured by screen-printing a conductor, a resistor, an insulator paste or the like on the board and simultaneously firing them. For this, a conductor material such as Au, Ag-Pd, or Ag, which has a small specific resistance, can be miniaturized in a wiring pattern, can be fired at a low temperature of 750 to 950 ° C. in an air atmosphere, and has a low firing cost, is used. Generally, an alumina substrate having a high firing temperature is used as a substrate, but in recent years, a glass ceramic capable of being co-fired at 750 to 950 ° C. in an air atmosphere by mixing borosilicate glass with a dispersant powder such as alumina, forsterite or silica. Substrates have been developed.

The substrate is required to have a coefficient of thermal expansion that is as close as possible to that of a silicon chip in order to prevent inferior adhesion to a conductor and warp of the fired substrate. In addition, it is required to have a low dielectric constant for high-speed signal propagation and excellent high-frequency signals.

In the above glass ceramic substrate, glass powder as a binder and the above dispersant powder are mixed in a dispersion medium such as alcohol and dried to prepare a mixed powder, and a vehicle is added to and mixed with this mixed powder. Make a green sheet by the doctor blade method. Therefore, it is necessary to separately prepare a plurality of kinds of powders, it is necessary to manage the binder production conditions such as raw material blending, pulverization, and classification, and the blending conditions of these binders and the production conditions such as classification. Take the trouble.

[0005]

An object of the present invention is to provide a glass-ceramic composition comprising one kind of binder, which is obtained by firing at a low temperature of 750 to 950 ° C. in an air atmosphere to obtain a fired substrate having a low coefficient of thermal expansion and a low dielectric constant. And to provide a low temperature fired substrate thereof.

[0006]

SUMMARY OF THE INVENTION The present inventor
PbO 15-50, BaO 2.5-20, Al ₂ O ₃
5 to 15, SiO ₂ 25 to 45, B ₂ O ₃ 0.
5-10, CaO 0-5, ZnO 0-15, Sb ₂
It has been found that a glass ceramic composition having a composition of O ₃ 0 to 1 and precipitating a celsian (BaO.Al ₂ O ₃ .2SiO ₂ ) phase finely and uniformly during low temperature firing can achieve the object. .

A low temperature fired substrate can also be prepared by using a composition in which fine powder of celsian is mixed with glass frits having a glass matrix component. However, celsian has a stoichiometric composition (41% by weight of BaO, Al ₂ O ₃ 2
7% by weight, SiO ₂ 32% by weight) 1
It cannot be manufactured without melting and heating at a high temperature of 700 ° C. or higher. Further, according to the present invention, the uniformity of dispersion of celsian in the matrix of the baked substrate is poor, and the mechanical properties are poor.

[0008]

The glass-ceramic composition is manufactured by a conventional method. For example, after blending the raw materials, thoroughly crushing and mixing with a ball mill, etc., load them into a platinum crucible etc.
Melt at 0 ° C. for 1 hour or more and then cool. Next, this glass-ceramic composition is pulverized by a pulverizer and the classified particle size is adjusted to prepare a powder of the glass-ceramic composition.

The glass-ceramic composition of the present invention comprises, by weight%, PbO 15-50, BaO 2.5-20, Al.
₂ O ₃ 5-15, SiO ₂ 25-45, B ₂ O ₃
0.5-10, CaO 0-5, ZnO 0-15, S
b ₂ O ₃ must have a composition of 0 to 1.

The smaller the PbO content, the higher the precipitation temperature of the celsian crystals, the smaller the precipitation amount of the celsian crystals, and the higher the PbO content, the higher the thermal expansion coefficient of the glass. That is, when the content of PbO is less than 15% by weight, the amount of precipitation of celsian crystals is insufficient, and when it exceeds 50% by weight, the thermal expansion coefficient becomes too large.
O should be in the range of 15-50% by weight.

When BaO exceeds 20% by weight, the difference in coefficient of thermal expansion between the glass matrix and the celsian phase becomes too large and cracks occur in the fired substrate, and when it is less than 2.5% by weight, the amount of precipitation of the celsian phase is small. BaO must be in the range of 2.5 to 20 wt.

When Al ₂ O ₃ exceeds 15% by weight, the softening temperature of the glass ceramic becomes too high, and 5% by weight
If it is less than the above range, the amount of precipitation of the celsian phase becomes too small. Therefore, Al ₂ O ₃ should be in the range of 5 to 15% by weight.

When SiO ₂ exceeds 45% by weight, the softening temperature of the glass ceramic becomes too high, and 25% by weight
If it is less than this, the amount of precipitation of the celsian phase becomes too small, so that SiO ₂ must be in the range of 25 to 45% by weight.

B ₂ O ₃ lowers the viscosity of the glass ceramic, lowers the coefficient of thermal expansion, and improves the corrosion resistance. However, if it exceeds 10% by weight, the crystal growth of the celsian phase is impaired. If it is less than 0.5% by weight, the precipitation amount of the celsian phase becomes too small, so that B ₂ O ₃ must be in the range of 0.5 to 10% by weight.

CaO has the effect of lowering the viscosity of the glass ceramic, but if it exceeds 5% by weight, the effect of the addition of BaO is reduced and the softening point of the glass ceramic becomes too high. Must.

ZnO improves the chemical durability, but 15
If the content exceeds 100% by weight, the softening point of the glass ceramic decreases and the amount of precipitation of the celsian phase becomes too small.
Must be in the range of ~ 15% by weight.

Sb ₂ O ₃ is blended as a fining agent for glass ceramics, but if it exceeds 1% by weight, the coefficient of thermal expansion of the fired film becomes too large, so that Sb ₂ O ₃ is 0 to 1% by weight.
Must be in the range.

Next, a method of making a substrate from the glass ceramic composition of the present invention will be described. After mixing and kneading the glass ceramic composition and a binder to adjust the viscosity,
The green sheet is formed by a method such as doctor blade. As the binder, any of those generally used can be used, and for example, a mixture of butyral resin, acrylic resin, acetone, toluene, alcohol, phthalic acid-based plasticizer and the like can be used.

Next, several green sheets are laminated and sintered in an air atmosphere. The maximum heating temperature for sintering is 7
The temperature rising time from 50 to 950 ° C. is set to, for example, about 40 minutes, the maximum heating temperature is maintained for about 20 minutes, and then the temperature is cooled to room temperature. This glass-ceramic composition uniformly deposits fine crystals of mainly celsian during sintering, the deposition is completed in about 10 to 20 minutes, and does not depend on the heating rate. According to scanning differential thermal analysis, the celsian phase crystallization start temperature of the glass ceramic composition is about 720 ° C.

[0020]

[Example] A mixture of the raw materials shown in Table 1 was used with a crusher 1
After pulverizing and mixing for ˜2 hours, the mixture was placed in a platinum crucible and melted in an electric furnace at about 1300 to 1400 ° C. for 2 hours. At this time, the molten glass was agitated with a platinum rod to homogenize the glass, and after the glass was clarified, the glass was allowed to flow out onto a stainless steel plate or a carbon plate and 700 to 800 before being cooled.
The sample was inserted into an electric furnace maintained at 0 ° C. and gradually cooled.
Table 1 also shows the results of measuring the transition point and the yield point by cutting out a portion free from defects such as striae and bubbles from this glass.

[0021]

[Table 1]

The above glass was crushed by adding an organic solvent such as ethyl alcohol or isopropanol to 60 to 1
After drying in a drying oven at 20 ° C, classification is performed and the average particle size is 1 to 3 µ
m of a glass-ceramic composition powder was produced.

100 parts by weight of the glass-ceramic composition was mixed with 1 part by weight of butyral resin, 1 part by weight of phthalic acid-based plastic material and 10 parts by weight of a binder prepared by mixing 10 parts by weight of acetone. A green sheet having a thickness of about 100 μm was formed by the doctor blade method.
A plurality of the green sheets were cut and laminated and pressure-bonded, and the temperature was raised to a maximum temperature of 750 to 950 in the air for 40 minutes and kept at the maximum temperature for 20 minutes.

As a result of identifying the precipitated crystal phase of the sample by the X-ray diffraction method, it was found that the celsian phase was precipitated. In addition, in Examples 9 to 14, willemite (Zn ₂ S
A small amount of i0 ₄ ) was also observed. As a result of measuring the thermal expansion coefficient, the thermal expansion coefficient of the fired substrate is lower than the thermal expansion coefficient of 75 × 10 −7 / ° C. of the alumina substrate, and it has excellent characteristics close to the thermal expansion coefficient of 35 × 10 −7 / ° C. of the silicon chip. Had.
Moreover, as a result of measuring the dielectric constant at a measurement frequency of 1 MHz, it was found that the dielectric constant of the fired substrate was lower than the dielectric constant 9-10 of the alumina substrate and had excellent characteristics. Table 2 is a summary of the above results.
Shown in. Further, as a result of polishing and thinning the sample and observing the precipitated crystal phase with a polarizing microscope, a celsian phase having an average particle size of 3 to 10 μm was uniformly precipitated in the matrix in an amount of 40 to 80% by volume.

[0025]

[Table 2]

[0026]

As described in detail above, according to the present invention, a glass-ceramic composition comprising one kind of binder to obtain a fired substrate having a low coefficient of thermal expansion and a low dielectric constant by low temperature firing at 750 to 950 ° C. in an air atmosphere, And a low temperature fired glass ceramic substrate thereof can be provided.

Claims (2)

[Claims] 1. PbO 15-50, BaO in wt%
2.5-20, Al ₂ O ₃ 5-15, SiO ₂ 2
5-45, B ₂ O ₃ 0.5-10, CaO 0-5, Z
A glass-ceramic composition having a composition of nO 0-15 and Sb ₂ O ₃ 0-1. 2. PbO 15-50, BaO in weight%.
2.5-20, Al ₂ O ₃ 5-15, SiO ₂ 2
5-45, B ₂ O ₃ 0.5-10, CaO 0-5, Z
celsian having a composition of nO 0 to 15 and Sb ₂ O ₃ 0 to 1 and an average particle diameter of 3 to 10 μm is 4 in the matrix.
A low-temperature fired glass-ceramic substrate, wherein 0 to 80% by volume is dispersed and precipitated.