JPH07135379A - Composition for low temperature firing glass ceramic board - Google Patents

Abstract

PURPOSE:To provide a composition for low temperature firing glass ceramic board having high breakage resistance in which chipping and cracking are retarded and the periphery of silver wiring is protected against microcrack at the time of simultaneous wiring with silver paste. CONSTITUTION:The inorganic component of the inventive composition is composed of 35-55wt.% of alumina powder and 65-45wt.% of crystallized glass powder, wherein the crystallized glass powder essentially composed of 15-30wt.% of SinO2, 23-35wt.% of ZnO, 10-15wt.% of B2O3 16-24wt.% of Al2O3, 5-15wt.% of CaO, and 0.1-1wt.% of Cu and the main crystal phase to be deposited is gahnite.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a composition for a low temperature fired glass ceramic substrate.

[0002]

2. Description of the Related Art A composition for low temperature firing glass-ceramic substrates, which is a mixture of glass powder and ceramic filler, is used for multi-layer circuit substrates such as hybrid ICs and multi-chip modules. The composition for a low temperature fired glass ceramic substrate is required to be fired at a low temperature of 800 to 1000 ° C. to obtain a substrate having a mechanical strength close to the thermal expansion coefficient of a silicon chip.

Conventionally, a ceramic filler such as alumina, mullite, cordierite, zircon, forsterite, zirconia, and quartz, and a softening point of 500 to 800.
A composition comprising glass powder containing lead oxide, an alkaline earth metal oxide, an alkali metal oxide, zinc oxide and the like, which is based on aluminoborosilicate and has a temperature of about ° C, is used. Particularly in recent years, a composition containing alumina powder and crystallized glass whose main crystal is cordierite, garnite or wilmite has been known (Japanese Patent Laid-Open Nos. 2-35587 and 4-1987).
321258).

However, the folding strength of the substrate obtained by these compositions is only about 150 to 250 MPa, and the folding strength of a usual alumina substrate is 320 to 500 MP.
Weaker than a. In addition, it is easily chipped or cracked, and is often broken during handling. Further, when co-firing with the silver paste, microcracks are generated around the silver wiring of the substrate, and there is a problem that a good wiring is often not obtained.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a low-temperature firing which provides a substrate having high folding strength, less likely to be chipped or cracked, and in which co-firing with a silver paste does not cause microcracks around silver wiring. An object is to provide a composition for a glass ceramic substrate.

[0006]

Means for Solving the Problems The above-mentioned problems are composed of alumina powder having an inorganic component of 35 to 55% by weight and crystallized glass powder of 65 to 45% by weight, and the crystallized glass powder is essentially SiO _2. 15-30 wt%, ZnO 23 to 35 wt%, B ₂ O ₃ 10~15 wt%, Al ₂ O ₃ 16~24
% By weight, CaO 5 to 15% by weight, CuO 0.1 to 1
It is solved by a composition for low temperature fired glass-ceramic substrate, characterized in that the main crystalline phase which is composed of wt% and is precipitated is garnite.

[0007]

The glass powder used in the present invention has a temperature of 830 to 960.
Gernite (ZnO.Al ₂ O ₃ ) crystals are precipitated at ℃.
That is, the substrate is composed of an alumina phase and a glass phase in which garnite is precipitated as a crystal phase in a glass matrix. The coefficient of linear thermal expansion of the alumina phase is about 75 × 10 ^-7 / ° C.
And the coefficient of linear thermal expansion of the glass matrix is about 40.
˜50 × 10 ⁻⁷ / ° C., and the linear thermal expansion coefficient of the Gurnite is about 77 × 10 −7 / ° C. Further, among the alumina phase, the glass matrix and the garnite, the glass matrix has the lowest mechanical strength.

The crystal phase is cordierite (MgO.Al
₂ O ₃ , linear thermal expansion coefficient of about 26 × 10 −7 / ° C., willemite (2ZnO · SiO ₂ , linear thermal expansion coefficient of about 32 × 10 ⁻⁷ /
If the coefficient of linear thermal expansion of the glass matrix is lower than that of the glass matrix, an excessive tensile stress is generated in the glass matrix due to a temperature change caused by cooling after sintering. As a result, it is considered that microcracks are generated in the glass matrix having low mechanical strength. On the other hand, since the coefficient of linear thermal expansion of garnite is higher than that of the glass matrix, it is considered that compressive stress acts on the glass matrix and microcracks do not occur. As a result, a substrate having excellent mechanical strength can be obtained by using garnite as the crystal phase.

The substrate in the present invention is anorthite (CaO.Al ₂ O ₃ , linear thermal expansion coefficient of about 48 × 10 −7 /
(° C.) crystals may also precipitate at the same time, but the amount of precipitation is so small that the maximum peak is slightly recognized in the identification method by X-ray diffraction, and the effect on the mechanical properties of the substrate can be ignored.

The glass powder can be manufactured by a usual method. For example, raw materials such as carbonates and silicates are mixed so as to have the above glass composition, mixed well, filled in a platinum crucible, and melt-stirred at a temperature of about 1400 ° C., followed by a roller quenching method or a water cooling method. To quench and form a glass lump. Glass powder can be obtained by crushing the glass gob with a ball mill or the like. Glass powder having an average particle size of 0.5 to 3 μm, particularly about 1 μm
Are preferred.

Next, the reasons for limiting the composition will be described. SiO
₂ is an essential component for the formation of glass. If it is less than 15% by weight, the mechanical strength of the glass will be poor, and if it exceeds 30% by weight, willemite with a low coefficient of linear thermal expansion will precipitate and the mechanical strength will also be high. Inferior. ZnO is a constituent element of garnite, and if it is less than 23% by weight, the precipitation amount of garnite is small and the mechanical strength of the glass is inferior.
If it exceeds 5% by weight, the garnite is rapidly precipitated before the sintering is sufficiently advanced, and the sintering of the garnite is not sufficiently advanced.

B ₂ O ₃ acts as a solvent, and if it is less than 10% by weight, the softening point of the glass becomes too high, and if the crystallization temperature is 1000 ° C. or less, the sintering of the substrate does not proceed sufficiently. On the other hand, if it exceeds 15% by weight, not only boric acid is eluted from the green sheet or the substrate due to the action of moisture in the atmosphere, but also the glass phase becomes a stable amorphous glass and crystallization is not sufficiently performed. Al ₂ O ₃ is a constituent element of garnite, and if it is less than 16% by weight, garnite does not precipitate or its precipitation amount is small, and further, willemite precipitates, resulting in poor mechanical strength. On the other hand, if it exceeds 24% by weight, the softening point of the glass becomes too high and the crystallization temperature becomes 10
If the temperature is below 00 ° C., the sintering of the substrate will not proceed sufficiently.

CaO acts as a solvent, but on the other hand, it must be 5% by weight or more in order to prevent the B2O3 concentration in the residual glass from increasing and the water resistance from decreasing after crystallization of the glass. If it exceeds 15% by weight, the softening point of the glass becomes too high and the sintering of the substrate does not proceed sufficiently. CuO is 0.1
When added in an amount of not less than wt%, not only the mechanical strength of the glass is improved, but also the generation of microcracks in the peripheral area of the Ag conductor paste is prevented. If it exceeds 1% by weight, the substrate will be foamed to lower the dielectric constant.

If the amount of unavoidable impurities such as alkali metal and iron mixed in from the melting crucible or the mixer is 0.1% by weight or less, the properties of the substrate are not adversely affected.

As a result of various studies as the ceramic filler, alumina was the most excellent in mechanical strength of the substrate. Although general commercial products can be used, alumina having an average particle size of 0.4 to 2 μm is preferable.

The glass powder and the alumina powder are mixed by a usual method such as a ball mill. The mixing ratio is such that the glass powder is 45 to 65% by weight and the alumina powder is the remaining 55%.
It may be about 35% by weight. If the amount of glass powder is less than 45% by weight, the amount of glass is not sufficient to wet the surface of the alumina powder during melting, so that the sintering does not proceed sufficiently and the mechanical strength of the substrate decreases, while 65% by weight is added. If it exceeds, not only the volume ratio of the glass matrix increases too much but the mechanical strength of the substrate decreases, but also the substrate fuses with the setter during firing, and the substrate is damaged when taken out.

The blending ratio is the softening point of the glass powder,
The optimum mixing ratio may be selected depending on the average particle size of the glass powder and the average particle size of the alumina powder. Generally, the lower the softening point of the glass powder is, or the smaller the average particle size of the glass powder is, as compared with the alumina powder, it is preferable to increase the mixing ratio of the alumina powder.

A mixed powder of the above glass powder and alumina powder is kneaded together with a binder, a plasticizer and a solvent to form a slurry, and a green sheet is manufactured by a doctor blade method or the like. The thickness of the green sheet is not particularly limited, but is generally about 30 to 200 μm.

As the binder, for example, polyvinyl butyral, methacrylic polymer, acrylic polymer and the like can be used, and as the solvent, alcohols, ketones, chlorine-based organic solvents and the like can be used.

After cutting the green sheet into an arbitrary shape,
A through hole is filled with a conductor paste or the like, and a plurality of printed wirings are laminated and pressed by a hot press machine or the like to be integrated to form a laminated body. Hot presses generally have a pressure of 50-
It may be carried out at 300 kgf / cm ² and a temperature of 60 to 90 ° C. The laminate is placed on a setter and the temperature is, for example, 450.
After heating at ~ 600 ° C to remove organics, the temperature is 820
A substrate is prepared by baking at ˜1000 ° C.

[0021]

Examples Examples of reagents SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and Zn
Predetermined amounts of O, CaCO ₃ , and CuO were weighed and mixed by a crusher, and the mixture was put into a platinum crucible and melted at 1400 ° C. The above melt was thoroughly mixed with a platinum rod, poured into water and rapidly cooled to obtain a glass gob. The glass gob was crushed with a stamp mill to a particle size of about 200 μm or less, and then crushed with a ball mill to an average particle size of 1 to 2 μm to obtain glass powder. The glass powder and alumina powder having an average particle size of 1.6 μm (trade name Al-45 manufactured by Showa Denko KK
1) and 1) were mixed in a predetermined amount to obtain various compositions for low temperature fired glass ceramic substrate.

[0022] The low-temperature fired glass ceramic substrate for 100 parts by weight of the composition, 9 parts by weight Po polyvinyl butyral, diisobutyl 7 parts by weight of phthalic acid, 1 part by weight of oleic acid, 40 parts by weight of isopropyl alcohol, trichloroethane 2
0 part by weight was added and mixed by a ball mill for 24 hours to obtain a slurry.

After degassing the slurry in a vacuum, the slurry was molded by a doctor blade method to prepare a green sheet having a thickness of 130 μm. Eight sheets of printed circuit board formed by printing a silver paste in which Ag powder is dispersed in a 4 wt% terpineol solution are laminated at a pressure of 150 kgf / cm ² and a temperature of 85.
It was pressure-molded at 0 ° C. to obtain a laminate. The laminated body was placed on an alumina setter and heated at a temperature of 520 ° C. for 3 hours to remove organic substances, and subsequently baked at a temperature of 900 ° C. for 1 hour in the air to obtain a substrate.

The cross section of the substrate was polished and observed with an optical microscope to examine the presence or absence of microcracks around the silver wiring and foaming of the substrate. The results are shown in Tables 1 and 2.

[0025]

[Table 1]

[0026]

[Table 2]

Further, a substrate was prepared in the same manner as above except that the silver paste was not printed. The thickness of the substrate was 1 mm. The substrate is cut into a width of 10 mm and a length of 40 mm, and the fold strength is measured by a three-point bending fold test at room temperature according to JIS R 1601 at a fulcrum distance of 30 mm and a pressing speed of 0.5 mm / min. did. Further, the crystal phase in the glass matrix of the substrate was identified by X-ray diffractometry. The results are also shown in Tables 1 and 2.

Further, instead of the alumina powder, the average particle size is 1 to
2μm mullite _{(3Al 2 O 3 · 2SiO 2} ) powder, except using celsian _{(BaO · Al 2 O 3 ·} 2SiO 2) powder or zircon (ZrO · SiO ₂₎ powder to produce a substrate in the same manner as the The same test as described above was performed. The results are shown in Table 3.

[0029]

[Table 3]

In Example 3, garnite had a crystal phase, and in the other examples, a small amount of anorthite was observed in addition to garnite, but the amount of precipitation was small. Also,
From Example 10 and Comparative Examples 17 to 18, it is understood that alumina powder is the most excellent as the ceramic powder added to the outside of the crystallized glass.

[0031]

Industrial Applicability According to the present invention, a low-temperature fired glass-ceramic substrate is obtained which has a high welding strength, is less likely to be chipped or cracked, and has no microcracks around silver wiring when cofired with a silver paste. A composition could be provided.

Claims (1)

[Claims] 1. An inorganic component is composed of 35 to 55% by weight of alumina powder and 65 to 45% by weight of crystallized glass powder, wherein the crystallized glass powder is essentially 15 to 30% by weight of SiO ₂ , ZnO. 23-35 wt%, B ₂ O ₃ 10~15 wt%, Al ₂ O ₃ 16~24 wt%, CaO 5 to 15
%, CuO 0.1 to 1% by weight, and a composition for a low-temperature fired glass-ceramic substrate, in which a main crystal phase to be precipitated is gannite.