KR100281991B1 - Low Melting Point Glass Composition Using Composite Filler - Google Patents

Abstract

The present invention relates to a low-melting-point adhesive glass composition, and more particularly, to a zinc zirconium silicate composite or magnesium aluminum zirconium silicate, which is a low-expansion ceramic composite as a filler with 60 to 75 wt% of a low melting glass powder of PbO-B ₂ O ₃ system. The composite is composed of 25 to 40% by weight of powder, and relates to a low-melting-point adhesive glass composition that is excellent in mechanical properties such as mechanical strength and chemical resistance and can be usefully used for hermetic adhesion of a package of alumina for IC.

Description

Low Melting Point Glass Composition Using Composite Filler

The present invention relates to a low-melting-point powder-bonded glass composition used for bonding electronic components, and more particularly, to a zinc zirconium silicate composite, which is a low-expansion ceramic composite as a low melting point glass powder and a filler of PbO-B ₂ O ₃ system, or The present invention relates to a low melting adhesive glass composition composed of a magnesium aluminum zirconium silicate composite and used for hermetic bonding of a cap and a base in a package of alumina for semiconductors.

In recent years, semiconductors have become more integrated due to their larger capacities and larger IC chips. However, the area has become smaller. In addition, since the melting field of a semiconductor package using a ceramic substrate made of alumina or the like is applied to a dynamic field unlike a plastic package, an adhesive state capable of achieving high strength in a small area must be maintained.

Therefore, the adhesive composition used for this purpose should have a particularly high adhesive strength while sufficiently satisfying the basic characteristics such as electrical properties, chemical durability, etc. required for the adhesion of the IC package using a ceramic (usually alumina) substrate.

Known adhesives for alumina ceramic packages include beta-eucryptite, cordierite, willemite and zircon in amorphous low melting glass powder of PbO-B ₂ O ₃ Low-expansion ceramic powders, such as (zircon), are added as a filler. Among these, beta-eucryptite, cordierite, and willemite, each of which has a very low coefficient of thermal expansion, can be added as a filler alone to obtain a coefficient of thermal expansion that matches the alumina package while having proper fluidity at the bonding temperature. Due to the difference of low mechanical strength and large coefficient of thermal expansion between low-expansion amorphous glass powder, micro-cracks are caused and high adhesive strength cannot be maintained.

In order to reduce the microcracks formed at the interface between these fillers and the amorphous glass, the particles of the fillers must be small, in which case the fluidity decreases and the acid resistance rapidly decreases due to the increased surface area of the fillers. In order to compensate for this problem, a powder glass composition using two fillers with zircon or tin oxide solid solution added together with the above fillers has been developed, but mechanical strength and acid resistance are still required to be supplemented. Therefore, there is an urgent need for the development of chemically stable new fillers with high mechanical strength and adequate coefficient of thermal expansion.

Therefore, the inventors have developed a zinc zirconium silicate composite (hereinafter referred to as "ZZS composite") and a magnesium aluminum zirconium silicate composite (hereinafter referred to as "MAZS composite") as a new filler. These fillers have been found to be chemically stable and exhibit significantly higher mechanical strength than when each filler is used alone or as a mixture of two or more fillers as a composite. Accordingly, an object of the present invention is to use a low-expansion ceramic composite, such as ZZS composite or MAZS composite as a filler, it is possible to seal the alumina ceramic package at 450 ℃ or less in a short time, while satisfying the electrical and chemical properties, particularly high adhesive strength To provide a low melting adhesive glass composition having a.

Hereinafter, the present invention will be described in detail.

The present invention relates to a glass composition composed of a PbO-B ₂ O ₃ based low melting glass powder and a filler, wherein the low melting point glass powder of a PbO-B ₂ O ₃ based powder and a ZZS composite which is a low expansion ceramic composite as a filler Or a low melting adhesive glass composition composed of 25 to 40% by weight of a MAZS composite.

The present invention will be described in more detail as follows.

In the present invention, the ZZS composite used as a component of the filler is composed of zircon and willle synthesized by heat treatment by mixing oxide powder to have a composition of 15 to 60 wt% of ZnO, 15 to 60 wt% of ZrO ₂ and 25 to 35 wt% of SiO ₂ A low-expansion ceramic composite having a mite crystal phase, which is characterized by high mechanical strength without containing any reaction accelerator. The MAZS composites were zircon synthesized by heat treatment by mixing oxide powders so as to have a composition of MgO 2-10 wt%, Al ₂ O ₃ 5-25 wt%, ZrO ₃ 30-60 wt%, and SiO ₂ 30-45 wt%. It is a low-expansion ceramic composite having a cordierite crystal phase and is characterized by high density and high mechanical strength without containing any reaction accelerator. The two complexes can be synthesized in a short time at a relatively low temperature as compared to the synthesis of zircon, willemite or cordierite as a three-component or four-component system, respectively.

The composition of the low melting glass powder is 75 to 87% by weight of PbO, 6 to 15% by weight of B ₂ O ₃ , 0.5 to 12% by weight of ZnO, 0.5 to 3% by weight of SiO ₂ and 0.5 to 3% by weight of Al ₂ O ₃ . In this case, the transition point of the glass is sufficiently flowed during the heat treatment at low temperature between 290 ~ 310 ℃ and can be airtight adhesion in the amorphous glass state.

However, the coefficient of thermal expansion of this glass is 110-120 × 10 ⁻⁷ / ° C., which is higher than the coefficient of thermal expansion of the alumina package, 65-70 × 10 ⁻⁷ / ° C., so that the glass tends to generate stresses and cracks. Therefore, 25-40 wt% of the ZZS composite or MAZS composite, which is a low-expansion ceramic filler, was added to the low-melting-point glass powder to match the thermal expansion coefficient of the alumina package. If the ZZS composite is less than 25% by weight, the coefficient of thermal expansion does not match the alumina package, and the mechanical strength is low, so that cracks are easily generated after adhesion. When the ZZS composite exceeds 40% by weight, fluidity is lowered, making it difficult to bond at low temperatures. The same applies to the ZZS composite when the MAZS composite is used as the filler.

On the other hand, the reason for limiting the content of SiO ₂ , ZnO, ZrO ₂ used in the synthesis of the ZZS composite as described above is that any component deviates from the composition of the unreacted substance or crystal phase other than zircon or willemite, They do not satisfy the properties of hermetic adhesion because they induce crystallization of the glass upon adhesion and lower fluidity. Even in the case of the MAZS composite, when the content of MgO, Al ₂ O ₃ , SiO ₂ , ZrO ₂ is out of the above range, an unreacted substance is formed, or crystal phases other than cordierite or zircon are formed. It does not satisfies the characteristics of the gas tight adhesion by deriving the fluidity.

As described above, the low-melting-point adhesive glass composition manufactured by the present invention can seal the alumina ceramic package at a temperature of 450 ° C. or less within a short time, and is excellent in chemical durability such as electrical characteristics and acid resistance, and also excellent in adhesive strength, such as semiconductor integrated circuits. It can be usefully used for adhesion.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

[Preparation of Low Melting Glass Powder]

To prepare PbO-B ₂ O ₃ -based amorphous glass powder, lead oxide, boric anhydride, zinc oxide, silica, and alumina are mixed to the composition ratio of the following Table 1, put into a platinum crucible, and heated at 1000 ° C. in an electric furnace for 1 hour. After homogeneous melting, the glass was poured between stainless rollers to form a thin plate, which was ground with an alumina ball mill. The pulverized powder was again passed through a 250 mesh stainless sieve and used for the preparation of the adhesive composition.

TABLE 1

Example 2

[Manufacture of ZZS Composite]

One of the low-expansion ceramic fillers ZZS composite was synthesized as shown in Table 2 below.

TABLE 2

The ZZS composite was synthesized by wet mixing zinc oxide, fine silica powder and zirconia, and then heat-treated at 1400 ° C. for 4 hours in an electric furnace. The synthesized ZZS composite was characterized by crystal X-ray diffraction analysis and observed the microstructure by scanning electron microscopy. In the ZZS complex, the zircon and willemite crystal phases were homogeneously distributed, each having a particle size of 5 μm or less, and no other crystal phases were formed except for the zircon and willemite.

The synthesized ZZS composite was ground with an alumina ball mill, and fine powder passed through a 250 mesh stainless sieve was used for the preparation of the adhesive composition.

Example 3

Preparation of MAZS Complex

The low-expansion ceramic filler MAZS composite was synthesized as shown in Table 3 below.

TABLE 3

The ZZS composite was synthesized by wet mixing magnesia, alumina, fine silica powder and zirconia in a wet state and then heat-treating at 1400 ° C. for 4 hours in an electric furnace. The synthesized ZZS composite was characterized by crystal X-ray diffraction analysis and observed the microstructure by scanning electron microscopy. In the MAZS complex, zircon and cordierite crystal phases were homogeneously distributed, each having a particle size of 5 μm or less, and no other crystal phases were formed except for zircon and willemite. The synthesized ZZS composite was ground with an alumina ball mill, and fine powder passed through a 250 mesh stainless sieve was used for preparing the adhesive composition.

Example 4

[Production of Low Melting Point Glass Composition]

To the low melting glass powder prepared in Example 1 65% by weight of the ZZS composite or MAZS composite of 35% by weight, respectively, prepared in Examples 2 and 3 was added to prepare a low melting glass composition as shown in Table 4 below.

TABLE 4

As shown in Table 4, the low melting point bonding composition embodied in the present invention has a thermal expansion coefficient capable of hermetically bonding the alumina substrate for IC package at low temperature, and satisfies the dielectric constant and chemical resistance as well. In addition, a vehicle (vehicle) is added to the above composition to form a paste having appropriate viscosity, and then printed on the base and cap of the alumina package, followed by heat treatment at 430 ° C. for 10 minutes, and a heat treatment at 435 ° C. for 10 minutes. Airtight bonding was performed. MIL-STD-883B: METHOD 1011.2: the method of the CONDITION C, that is, the bonded package was subjected to thermal shock 15 times between -65 ℃ to 150 ℃ 15 times, and the airtight adhesiveness of the package was investigated, as shown in Table 4 above. No thermal shock defects were found for all samples. The above results indicate that the low melting point adhesive composition using the low-expansion ceramic composite as a filler is suitable for hermetic adhesion of an alumina package.

In addition, in order to examine the effect of the low-expansion ceramic composite filler, as a comparative example, the adhesive composition (Sample No. 6) and 65% by weight of low-expansion glass using 65% by weight of low-expansion glass, 24% by weight of zircon, and 11% by weight of Willemite. Properties of the adhesive composition (Sample No. 7) using 21% by weight of zircon and 14% by weight of cordierite were measured.

Zircon, Willemite, and Cordierite used herein were in accordance with the method of Korean Patent Publication No. 91-1103, respectively. First, when comparing Example 4-1 (Sample No. 1) and Comparative Example 1 (Sample No. 6) having a similar composition, the thermal expansion coefficient value, which is the main characteristic of the low-melting-point adhesive glass composition, is the case of Example 4-1 The value of 1.4 × 10 ⁻⁷ / ° C. was lower than that of 1. This is because the sintering aid added during the zircon firing of Comparative Example 1 remained at the grain boundaries to increase the thermal expansion coefficient of the fired zircon. The bending strength was 630 kg / cm 2 in Comparative Example 1, which was about 15% lower than that of 720 kg / cm 2 of Example 4-1 having similar chemical composition. This is in good agreement with the general characteristics of ceramics that the mechanical strength is excellent when forming composites. In case of chemical resistance (10% H ₂ SO ₄ , 25 ° C., 10 minutes), as shown in Table 4, Comparative Example 1 was 0.75 mg / cm 2, which shows a sharp drop compared to 0.42 mg / cm 3 of Example 4-1. Can be. Even in the case of testing using nitric acid or hydrochloric acid, Example 4-1 showed excellent chemical resistance compared to Comparative Example 1. In addition, in the dielectric constant, Comparative Example 1 and Example 4-1 of the present invention have similar values, but in the case of dielectric loss, Example 4-1 shows 62, which is much better than that of 160 of Comparative Example 1. This is the effect of Fe ₂ O ₃ added as a sintering aid for the synthesis of zircon used for the implementation of Comparative Example 1.

On the other hand, Comparative Example 2 (Sample No. 7) having the same composition as Example 4-5 (Sample No. 5) using the MAZS composite filler was compared, and this result was also compared with the Comparative Example using the ZZS composite as a filler as follows. Similar to the case. The bending strength was 570 kg / cm 2 in Comparative Example 2, which was about 15% lower than that of 650 kg / cm 2 of Example 4-5. In case of chemical resistance (10% H ₂ SO ₄ , 25 ° C., 10 minutes), as shown in Table 4, Comparative Example 2 is 0.61 mg / cm 2, which is lower than 0/45 mg / cm 3 of Example 4-5. Can be. Even in the case of testing using nitric acid or hydrochloric acid, Example 4-5 showed excellent chemical resistance compared to Comparative Example 2. In addition, in the dielectric constant, Comparative Example 2 and Example 4-5 of the present invention have similar values, but in the case of dielectric loss, Example 4-5 shows 64, which is superior to 130 of Comparative Example 2. This is also the effect of Fe ₂ O ₃ added as a sintering aid for the synthesis of zircon used for the implementation of Comparative Example 2.

As described above, the low-temperature adhesive composition using the low-expansion ceramic composite as a filler exhibits properties suitable for hermetic adhesion of the alumina package for IC, and particularly exhibits high reliability mechanically and chemically, and also has excellent electrical properties.

Claims (3)

PbO-B ₂ O ₃ based low-melting the glass composition consisting of a glass powder and the filler, PbO-B ₂ O as the low-melting glass powder, 60 to 75% by weight of filler of _three-based low-expansion ceramic composite zinc zirconium silicate complexes or Low-melting-point adhesive glass composition, characterized in that consisting of 25 to 40% by weight of magnesium aluminum zirconium silicate composite. The method of claim 1, wherein the zinc zirconium silicate composite is composed of ZnO 15 to 60% by weight, ZrO ₂ 15 to 60% by weight and SiO ₂ , 25 to 35% by weight, characterized in that the zircon and willemite as crystal phase Adhesive glass composition. The method of claim 1, wherein the magnesium aluminum zirconium silicate composite is composed of MgO 2 to 10% by weight, Al ₂ O _{3 5 to} 25% by weight, ZrO ₂ 30 to 60% by weight and SiO ₂ 30 to 45% by weight A low melting point adhesive glass composition comprising cordierite as a crystalline phase.