JPH07315867A - Composition for sealing - Google Patents

Abstract

PURPOSE:To obtain a composition for sealing capable of airtightly sealing an aluminum-based semiconductor package at a low temperature and realizing the aluminum-based semiconductor package having a high mechanical strength and thermal shock resistance by blending a low-melting glass powder with a low-expansion refractory filler powder and a ceramic powder so as to manifest a specific thermal expansion coefficient. CONSTITUTION:This composition for sealing comprises (A) a low-melting glass powder, (B) a low-expansion refractory filler powder, having 6-10mum average particle diameter and containing <=5vol.% particles having >=40mum particle diameter (e.g. cordierite) and (C) a ceramic powder having 1.0-1.6mum average particle diameter (e.g. alumina). The amounts of the components are within the following ranges: 50-75vol.% component (A), 20-45vol.% component (B) and 3-27vol.% component (C). The components are blended so as to provide 60X10<-7> to 71X10<-7>/ deg.C thermal expansion coefficient from ambient temperature to 3O0 deg.C The component (A) contains 77-87wt.% Pb0, 5-15wt.% B2O3, 0-10wt.% ZnO, 0-4wt.% SiO2, 0-2wt.% Al2O3, 0-2wt.% Bad, 0-4wt.% SnO1, 0-10wt.% Bi2O3 and 0-4wt.% V2O5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass composition for low temperature sealing, and more particularly to a sealing composition used for sealing an alumina semiconductor package having high strength and excellent heat resistance.

[0002]

2. Description of the Related Art Since a semiconductor is extremely sensitive to moisture and impurities, it is generally housed in a package and hermetically sealed in order to protect it. Therefore, the package is required to have high mechanical strength and thermal shock strength. For sealing a semiconductor package using alumina,
Since the above-mentioned strength is required, a sealing composition in which a low melting point glass powder and a refractory filler powder are mixed is used. In recent years, as semiconductor technology has advanced, semiconductors have become more highly integrated and larger, and the above requirements have become more stringent.
There is a demand for a sealing composition that can realize a package having high mechanical strength and thermal shock strength.

In order to improve the mechanical strength and thermal shock strength of a semiconductor package, it is necessary that the coefficient of thermal expansion of alumina to be adhered is matched and that the mechanical strength of the sealed object is high. is there. For this reason, JP-A-58-2631
No. 82, JP-A-59-102874, etc., it comprises a low-melting glass powder, a low-expansion ceramic, and a ceramic powder which is not low-expanded but is added for the purpose of improving mechanical strength. Sealing compositions have been developed.

[0004]

However, the conventional sealing composition has a problem in that the mechanical strength required for recent packages is
It does not fully satisfy the thermal shock strength. To meet this requirement, it is necessary to adjust the combination of low-melting glass powder, low-expansion refractory filler powder, and ceramic powder, but the fluidity required for sealing cannot be obtained, and air-tight sealing cannot be achieved. However, there is a problem that the sealing temperature rises and the semiconductor chip is damaged.

The present invention has been made in view of the above problems, and an object thereof is to provide a sealing composition which can be hermetically sealed at a low temperature and can realize an alumina semiconductor package having high mechanical strength and thermal shock strength. Especially.

[0006]

The present invention comprises a low melting point glass powder and a low expansion refractory filler powder having an average particle size of 6 to 10 μm and particles having a particle size of 40 μm or more in an amount of 5% by volume or less. Ceramic powder having a particle size of 1.0 to 1.6 μm, low melting glass powder 50 to 75% by volume, low expansion refractory filler powder 20 to 45% by volume, ceramic powder 3 to 27% by volume. And the coefficient of thermal expansion from room temperature to 300 ° C. is 60 × 10 ^{−7 to} 71.
The composition for sealing is in the range of × 10 ^-7 / ° C.

In the present invention, the average particle size of the particles is measured as follows. The specific surface area (surface area per unit weight) of the particles is determined by the air permeation method, and the density of the particles is multiplied to obtain the surface area per unit volume, and the reciprocal thereof is determined to be the average particle diameter.

The reason for the above limitation will be described below.

The low expansion refractory filler powder reduces the coefficient of thermal expansion of the composition for sealing, approaches the coefficient of thermal expansion of the alumina package to be sealed, relaxes the thermal stress due to sealing, and has a thermal shock resistance of the package. It has the effect of improving the sex.
If the average particle size is smaller than 6 μm, the fluidity required for sealing at low temperature cannot be obtained. If it is larger than 10 μm, the mechanical strength becomes weak, and an alumina package having high mechanical strength cannot be obtained. Furthermore, if the particles of 40 μm or more out of the low expansion refractory filler powder exceed 5% by volume, the mechanical strength of the sealing composition becomes weak, and in order to obtain the desired mechanical strength, a larger amount is required. Need to be added. As a result, the fluidity required for sealing cannot be obtained.

The ceramic powder has the effect of improving the mechanical strength of the sealing composition and improving the mechanical strength of the alumina package. If the average particle size of the ceramic powder is less than 1.0 μm, the fluidity required for sealing cannot be obtained at low temperatures. If the average particle size exceeds 1.6 μm, the same problems as those of the low expansion refractory filler powder larger than 10 μm occur.

The sealing composition of the present invention comprises 55 to 75% by volume of low melting point glass powder and 2% of low expansion refractory filler powder.
0 to 45% by volume and ceramic powder in the range of 3 to 27% by volume.

When the content of the low melting point glass powder exceeds 75% by volume, the coefficient of thermal expansion becomes too large to match the coefficient of thermal expansion of the alumina package of the material to be sealed. If the content is less than 55% by volume, the fluidity required for sealing cannot be obtained at low temperature.

The low expansion refractory filler powder content is 45
If it exceeds the capacity%, the fluidity required for sealing cannot be obtained. Two
If it is less than 0% by volume, it is difficult to match the coefficient of thermal expansion of the alumina package.

When the content of the ceramic powder exceeds 27% by volume, the fluidity required for sealing at a low temperature cannot be obtained, or the compatibility with the thermal expansion coefficient of the alumina package which is the material to be sealed. Can't get If it is less than 3% by volume, it is not effective in improving the mechanical strength of the sealing composition.

In the sealing composition of the present invention, the low-melting glass powder, the low-expansion refractory filler powder and the ceramic powder are mixed in a mixing ratio of 55-70% by volume of the low-melting glass powder and low-expansion refractory filler powder. The range of 20 to 35% by volume and the ceramic powder of 9 to 21% by volume are particularly preferable.

The coefficient of thermal expansion of the sealing composition has a great influence on the thermal shock strength of the alumina package. The sealing composition of the present invention has a coefficient of thermal expansion from room temperature to 300 ° C. in the range of 60 × 10 ^{−7 to} 71 × 10 ⁻⁷ / ° C.

When the coefficient of thermal expansion exceeds 71 × 10 ^-7 / ° C., the coefficient of thermal expansion becomes larger than that of the alumina material to be sealed, and when heat is applied rapidly, tensile stress is generated in the sealing composition. However, microcracks are likely to occur. When the coefficient of thermal expansion is smaller than 60 × 10 ⁻⁷ / ° C., there is the same drawback as in the case where the thermal expansion coefficient exceeds 71 × 10 ⁻⁷ / ° C. when the thermal shock of quenching occurs. In either case, the thermal shock strength of the alumina package is deteriorated, which is not preferable.

The coefficient of thermal expansion of the sealing composition is preferably 62 × 10 ^{−7 to} 66 × 10 ⁻⁷ / for the reason described above, in order to match the alumina package which is the object to be sealed.
The range of ° C is more desirable.

The composition of the low melting point glass powder of the present invention is, by weight, PbO: 77-87% by weight, B ₂ O ₃ : 5-15.
Wt%, ZnO: 0 wt%, SiO _2: 0~4 wt%, Al ₂ O _3: 0~2 wt%, BaO: 0 to 2 wt%, SnO _2: 0~4 wt%, Bi ₂ O _3: 0 wt%, V ₂ O _5: is preferably in the range of 0-4 wt%. PbO: 82-86 wt%, B ₂ O _3: 10~1
4 wt%, ZnO: 1 to 3 wt%, SiO _2: 0~2 wt%, Al ₂ O _3: 0~1 wt%, BaO: 0 to 1 wt%, SnO _2: 0~1 wt%, Bi A range of 0 to 3% by weight of ₂ O _{3 and} 0 to 1% by weight of V ₂ O ₅ is particularly preferable.

If PbO is too small, the softening point becomes high and the sealing temperature becomes high. On the other hand, if there is too much, it tends to crystallize when the glass melts and the fluidity at the time of sealing becomes poor,
Sufficient sealing strength cannot be obtained, which is not preferable. B
_{If the amount of 2} O ₃ is too small, the same problems as in the case of too much PbO occur, and if it is too large, the same problems as in the case of too little PbO occur, both of which are not preferred. ZnO is not preferable because too much ZnO causes the same problems as when too much PbO is present.

SiO ₂ , Al ₂ O ₃ , BaO and SnO
By adding _2, it is possible to improve the acid resistance. If it is too large, the sealing temperature becomes high, which is not preferable. Bi
₂ O ₃ and V ₂ O ₅ have the effect of lowering the sealing temperature by adding them. If it is too large, the same problems as in the case of too much PbO occur, which is not preferable.

The low-melting glass powder preferably has an average particle size of about 1 to 6 μm and a maximum particle size of about 100 μm.

The low expansion refractory filler powder of the present invention has a thermal expansion coefficient of 30 × 10 ⁻⁷ from room temperature to 300 ° C.
It is preferably below / ° C. Among them, cordierite,
β-eucryptite, willemite and zircon are
Since it is relatively easy to obtain, it can be preferably used as a low expansion refractory filler powder.

The ceramic powder of the present invention preferably has a Young's modulus of 2.1 × 10 ⁵ kg / cm ² or more and a thermal conductivity of 75 kcal / m · hr · ° C. or more at room temperature. Specific examples of the ceramic powder include alumina, tin oxide, and TiO ₂ —SnO ₂ solid solution. The TiO ₂ —SnO ₂ solid solution has a TiO ₂ content in the range of 5 to 40 mol% in order to maintain insulation and a low dielectric constant, and the TiO ₂ —SnO ₂ solid solution preferably has a rutile structure. .

The low-melting glass powder, low-expansion refractory filler powder and ceramic powder of the present invention are not particularly limited in their production method, and any known method can be used. That is, the low-melting-point glass includes PbO, B ₂ O ₃ , ZnO, and Si.
O ₂ , Al ₂ O ₃ , BaO, SnO ₂ , Bi ₂ O ₃ , V
Raw materials that give ₂ O ₅ are blended so as to satisfy the above ratio, heated and melted, and then poured into a mold to manufacture a glass block. Next, this glass block is crushed using a ball mill or the like to obtain glass powder. The low-expansion refractory filler powder and the ceramic powder are manufactured by mixing raw materials that give each composition in a predetermined ratio, firing and crushing.

The low-melting glass powder, low-expansion refractory filler powder and ceramics powder may be mixed in any manner.
The pulverization and the mixing may be carried out simultaneously, or the powder may be made into powder having a predetermined size and then mixed.

The sealing composition of the present invention produced in this manner is treated in the same manner as in conventional sealing compositions.
It can be used for sealing semiconductor packages. That is, for example, after mixing the sealing composition and the organic binder, the mixture is attached to a portion of the semiconductor package to be sealed, and the sealing composition is heated to melt, and the organic binder is scattered, Seal the package.

[0028]

As described above, the sealing composition of the present invention is
Since the low-expansion refractory filler powder having a specific particle size and the ceramic powder are mixed, they can be sealed at a low temperature, and the sealed semiconductor package can realize a package having high mechanical strength and thermal shock strength. Therefore, the sealing composition of the present invention is particularly suitable for sealing a semiconductor package made of alumina.

[0029]

EXAMPLES PbO, B ₂ O ₃ , ZnO, SiO ₂ , Al
₂ O ₃ , BaO, SnO ₂ , Bi ₂ O ₃ , and V ₂ O ₅ were mixed in the proportions shown in Table 1, put in a platinum crucible, and the mixture was heated to 1000-
After heating and melting in an electric furnace at 1200 ° C. for 1 hour, it was rapidly cooled and molded into a plate shape to obtain a plate-shaped glass block. Next, this glass block was crushed using a ball mill to obtain glass powder having an average particle size of 1 to 6 μm. The compositions, transition points and softening points of these glasses are shown in Table 1, A, B,
It is described in column C. The obtained glass powder, low-expansion refractory filler powder, and ceramic powder were mixed at a predetermined ratio to obtain a sealing composition.

The mixing ratios, types of low expansion refractory filler powder and ceramic powder, average particle size, etc. are shown in the columns of Tables 2, 3 and 4, respectively. The table also shows the results of measuring the thermal expansion coefficient, fluidity, average particle size, particle size distribution, mechanical strength, and thermal shock resistance of the sealing composition. Furthermore, the same measurement was performed for the comparative example, and the results are also shown in the table. The methods for measuring the characteristics and the like in the table are as follows.

(1) Glass transition point and softening point: Glass was used as a powder and each temperature was measured at a temperature rising rate of 10 ° C./min using a differential thermal analyzer.

(2) Coefficient of thermal expansion: An average coefficient of thermal expansion (unit: 10 ^-7 / ° C) from 30 to 300 ° C was measured by a differential expansion meter at a temperature rising rate of 10 ° C / minute.

(3) Fluidity: Each sealing composition was weighed out in a weight corresponding to its specific gravity, pressure-molded into a cylindrical shape having a diameter of 12.5 mm, placed on a plate glass and kept at a predetermined temperature for 10 minutes.
After heat treatment for a minute, its diameter was measured, and if it was 20 mm or more, it was judged as good.

(4) Average particle size: The specific surface area (surface area per unit weight) of the particles was measured with a Blaine air permeation apparatus, and this was multiplied by the density of the particles, and the reciprocal thereof was determined to be the average particle size. .

(5) Particle size distribution: A cumulative value of particle sizes of 40 μm or more was measured by a laser diffraction type particle size distribution measuring device.

(6) Mechanical strength: An alumina package (28-pin type Ni-Fe) was prepared by using each sealing composition.
Alloy) Airtightly sealed and subjected to MIL-883C-2024 torque strength test to measure the minimum value of 20 samples.

(7) Thermal shock resistance: Aluminous packages (28-pin type Ni-Fe) were prepared using each sealing composition.
Alloy) Airtightly adhered to MIL-883B-1011-2-A
The thermal shock test was conducted. When the He leak tester confirms that there are no leaks of 50 samples each, and the above test is performed, and even if one sample with a leak of 5 × 10 ⁻⁸ cc / sec or more is detected by the He leak tester after the test. There was a leak (poor thermal shock resistance).

From the results of Table 2, Table 3 and Table 4, Examples 1 to 1
It can be seen that the sealing composition of No. 8 of the present invention can be sealed at a temperature as low as that of the conventional sealing composition, and the sealed package has good mechanical strength and thermal shock strength.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

The sealing composition of the present invention can be hermetically sealed at a low temperature, and the sealed semiconductor package has mechanical strength,
A package with high thermal shock strength can be realized. Therefore, the sealing composition of the present invention is particularly suitable for sealing a semiconductor package made of alumina.

Front page continuation (72) Inventor Noboru Nakamura 1-50-1 Gyoda, Funabashi, Chiba Iwaki Glass Co., Ltd.

Claims (4)

[Claims] 1. A low melting glass powder and an average particle size of 6 to 10.
Low expansion refractory filler powder having a particle size of 40 μm or more and 5% by volume or less, and an average particle size of 1.0 to 1.
6 μm of ceramic powder, low melting glass powder in the range of 50 to 75% by volume, low expansion refractory filler powder in the range of 20 to 45% by volume, ceramic powder in the range of 3 to 27% by volume, and from room temperature to 300 A sealing composition having a coefficient of thermal expansion up to ℃ in the range of 60 × 10 ^{-7 to} 71 × 10 ^-7 / ° C. 2. The low melting point glass is PbO: 77-87.
% By weight, B ₂ O ₃ : 5 to 15% by weight, ZnO: 0 to 10
% By weight, SiO ₂ : 0 to 4% by weight, Al ₂ O ₃ : 0 to 2
Wt%, BaO: 0 to 2 wt%, SnO _2: 0 to 4 wt%, Bi ₂ O _3: 0~10 wt%, V ₂ O _5: according to claim 1, wherein in the range of 0-4 wt% A composition for sealing. 3. The low expansion refractory filler powder is at least one selected from cordierite, β-eucryptite, willemite and zircon.
A composition for sealing as described above. 4. The sealing composition according to claim 1, 2 or 3, wherein the ceramic powder is at least one selected from alumina, tin oxide and TiO ₂ —SnO ₂ solid solution.