JPH05319863A - Low melting point sealing composition - Google Patents

Abstract

PURPOSE:To give stable crystalline tendency hardly influenced by heat treating condition or heat capacity by using a mixture of a crystalline glass powder and an amorphous glass powder as a glass powder to be mixed with a fire resisting filler powder. CONSTITUTION:In a low melting point sealing composition made by mixing the glass powder with the fire resisting filler, the glass powder consists of 5-80vol.% crystalline glass powder and 20-95vol.% amorphous glass powder. The component of the crystalline glass powder is preferably 65-85% PbO, 1-17% B2O3, 3-25% ZnO, 0-5% SiO2+Al2O3, 0-20% Bi2O3, 0-20% BaO and 0-6% F2. The component of the amorphous glass powder is preferably 65-85% PbO, 1-20% B2O3, 0-10% ZnO, 0-5% SiO2+Al2O3, 0-20% Bi2O3 and 0-6% F2. The composition is capable of being controlled to extremely low heat expansion coefficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low melting point sealing composition, and more particularly to a low melting point sealing composition suitable for sealing electronic parts such as IC and CCD ceramic packages. Is.

[0002]

2. Description of the Related Art Conventionally, when sealing a ceramic package for an IC or a CCD, when heat resistance is required for the sealing portion, a low melting point seal obtained by mixing a crystalline glass powder with a refractory filler powder. Wearing compositions are mainly used.

Further, the low melting point sealing composition for this use includes:
It is required to have a coefficient of thermal expansion close to that of the material forming the package or device, high mechanical strength, and low dielectric constant so as not to impede the signal transmission speed.

The crystalline glass is a glass in which a crystalline substance is precipitated from the inside by being heated. Particularly, the coefficient of thermal expansion and the strength after heating are determined by the degree of crystallinity (crystal amount / crystal amount + residual glass). Quantity).

That is, since the crystalline substance precipitated inside has a smaller coefficient of thermal expansion than the residual glass, it has the effect of reducing the coefficient of thermal expansion of the whole and improving the strength. In addition, crystalline and residual glass have different permittivities, and the permittivity of crystalline glass depends on the degree of crystallinity.

[0006] Therefore, in order to heat the crystalline glass powder to obtain desired characteristics, it is necessary to adjust the specific crystal to have an appropriate degree of crystallinity.

[0007]

However, since the degree of crystallinity of crystalline glass is affected by the heat treatment conditions and the heat capacity, a certain degree of crystallinity is obtained due to variations in the manufacturing process and variations in each glass production unit. There is a problem that it is difficult to get rid of.

That is, since the crystalline material has a lower energy state than that of glass and is stable, when a sufficient amount of heat is applied, the degree of crystallinity increases until almost all the residual glass is consumed.

If the crystal arrival degree becomes too high, the residual glass having the function of connecting the crystals to each other will be reduced too much, resulting in the formation of tunnel-like voids in the glass, resulting in the loss of the airtightness of the package or the sealing. There is a problem that the strength of the part is reduced.

Further, if the degree of crystallinity is unstable, the dielectric constant varies between the produced sealing materials, and when this is used in an IC ceramic package, the inter-lead capacitance varies. .. As a result, I of each product
The signal transmission speed of C varies, and there is a possibility that a product in which the IC does not function as designed may occur.

The thermal expansion coefficient can be reduced by adding a low expansion refractory filler powder to the crystalline glass powder, but a ceramic having a particularly low thermal expansion coefficient, specifically 45 ×. Materials suitable for sealing packages made of ceramics such as aluminum nitride, silicon carbide, and mullite having a coefficient of thermal expansion of 10 ⁻⁷ / ° C. or less are
It doesn't exist yet.

An object of the present invention is to provide a low melting point sealing composition which has a stable crystallinity tendency which is hardly influenced by heat treatment conditions and heat capacity, and which can be used especially for a ceramic package having a low coefficient of thermal expansion. Is to provide.

[0013]

The low melting point sealing composition of the present invention is a low melting point sealing composition obtained by mixing glass powder and refractory filler powder, and the glass powder is crystalline glass powder 5 ~ 80% by volume and 20 amorphous glass powder
.About.95% by volume.

The crystalline glass powder in the present invention is
By weight percentage, PbO 65-85%, B ₂ O ₃ 1-
17%, ZnO 3-25%, SiO ₂ + Al ₂ O ₃
0-5%, Bi ₂ O ₃ 0-20%, BaO 0-20
%, F ₂ 0 to 6%, and the amorphous glass powder is, in weight percentage, PbO 65 to 85%, B ₂ O ₃ 1
~ 20%, ZnO 0-10%, SiO ₂ + Al ₂ O ₃
0-5%, Bi ₂ O ₃ 0-20%, F ₂ 0-6%
It has a composition of.

Further, in the present invention, the refractory filler powder is willemite ceramic powder, tin oxide ceramic powder, zircon ceramic powder, mullite ceramic powder, lead titanate ceramic powder, cordierite powder, quartz glass powder. , Alumina powder, titanium oxide, niobium oxide, zinc stannate, cristobalite, cubic zirconia, or one or more selected from the group.

[0016]

In the present invention, since the amorphous glass powder is used as the glass powder together with the crystalline glass powder,
It shows a stable crystallization tendency that is hardly affected by heat treatment conditions and heat capacity, and can prevent variations in characteristics.

In the present invention, the reason for limiting the mixing ratio of the crystalline glass powder and the amorphous glass powder as described above is as follows.
When the ratio of the amorphous glass powder is less than 20% by volume,
It is difficult to obtain a stable crystallization tendency, and if it exceeds 95% by volume, the crystallinity is too small and the heat resistance is lowered.

The reason for limiting the composition of the crystalline glass powder in the present invention as described above is as follows.

PbO is a modified oxide of glass, and its content is 65 to 85%, preferably 65 to 83%.
Is. When it is less than 65%, the viscosity of the glass becomes high, and the glass does not flow sufficiently at a practical temperature. When it is more than 85%, remarkable crystallinity is exhibited and it becomes unpractical.

B ₂ O ₃ is a glass network structure-forming oxide, and its content is 1 to 17%, preferably 3 to.
14%. If it is less than 1%, remarkable crystallinity is exhibited, and if it is more than 17%, the viscosity of the glass becomes too high.

ZnO is a component that adjusts the amount of crystals deposited on glass to improve water resistance, and its content is 3
-25%, preferably 3-22%. If it is less than 3%, the above effect cannot be obtained, and if it exceeds 25%, remarkable crystallinity is exhibited.

SiO ₂ and Al ₂ O ₃ are components that stabilize the glass and adjust the crystal amount, and the total content is 0 to 5%, preferably 0 to 4%. If it is more than 5%, the viscosity of the glass becomes so high that it does not flow sufficiently at a practical temperature.

Bi ₂ O ₃ is a component that stabilizes the glass without raising the viscosity and adjusts the crystallinity and fluidity, and the content thereof is 0 to 20%, preferably 0 to 16%. ..
If it exceeds 20%, remarkable crystallinity is exhibited, which is not preferable.

BaO is a component that adjusts glass crystals and improves water resistance, and the content thereof is 0 to 20%, preferably 0 to 15%. When the content is more than 20%, remarkable crystallinity is exhibited, which is not preferable.

F ₂ is a component that lowers the viscosity of glass, and the content thereof is 0 to 6%, preferably 0 to 4%. When the content is more than 6%, remarkable crystallinity is exhibited, which is not preferable.

The crystalline glass used in the present invention contains, in addition to the above components, 5% or less of Fe ₂ O ₃ , CuO and V ₂ O.
₅ , Ag ₂ O, SrO, P ₂ O ₅ , Co ₂ O ₃ and 3%
The following Mo ₂ O ₃ , Rb ₂ O, Cs ₂ O, Nb ₂ O ₅ ,
It is possible to contain Ta ₂ O ₅ , ZrO ₂ , Sb ₂ O ₃ and other rare earth oxides.

The reason for limiting the composition of the amorphous glass used in the present invention as described above will be described below.

PbO is a modified oxide of glass, and its content is 65 to 85%, preferably 68 to 83%.
Is. If it is less than 65%, the viscosity of the glass becomes high and it does not flow sufficiently at a practical temperature. If it is more than 85%, it exhibits crystallinity.

B ₂ O ₃ is a glass network structure-forming oxide, and the content thereof is 1 to 20%, preferably 3 to.
15%. When it is less than 1%, it exhibits crystallinity and is 20
If it is more than%, the viscosity of the glass becomes high and the glass does not flow sufficiently at a practical temperature.

ZnO stabilizes the glass and
It is a component that improves water resistance, and its content is 0 to 1.
It is 0%, preferably 0 to 7%. If more than 10%,
Shows crystallinity.

SiO ₂ and Al ₂ O ₃ have the effect of stabilizing the glass, and the total content is 0 to 5%, preferably 0 to 3%. When it is more than 5%, the viscosity of the glass becomes high and the glass does not flow sufficiently at a practical temperature.

Bi ₂ O ₃ is a component that stabilizes the glass without increasing its viscosity, and its content is 0 to 20%, preferably 0 to 17%. When it is more than 20%, it shows crystallinity.

F ₂ is a component that reduces the viscosity of glass, and its content is 0 to 6%, preferably 0 to 2%. When it is more than 6%, it shows crystallinity.

The amorphous glass used in the present invention is
5% or less of FeO, CuO, V ₂ O other than the above components
₅ , Ag ₂ O, SrO, BaO, P ₂ O ₅ , Co ₂ O ₃
Or less than 3% Mo ₂ O ₃ , Rb ₂ O, Cs ₂ O, Nb
₂ O ₅ , Ta ₂ O ₅ , ZrO ₂ , Sb ₂ O ₃ and other rare earth oxides can be contained.

The crystalline glass having the above composition is 85
The amorphous glass has a coefficient of thermal expansion of × 10 ^-7 / ° C or higher, and the amorphous glass has a coefficient of thermal expansion of 95 × 10 ^-7 / ° C or higher.
To use these mixtures for sealing IC ceramic packages made of, for example, alumina having a coefficient of thermal expansion of 70 × 10 ⁻⁷ / ° C. or aluminum nitride having a coefficient of thermal expansion of 45 × 10 ⁻⁷ / ° C. It is necessary to mix the refractory filler powder to lower the coefficient of thermal expansion.

The mixing ratio of the refractory filler powder is 5 to 5
5% by volume is suitable. If it is less than 5% by volume, the effect of lowering the coefficient of thermal expansion is insufficient, and if it is more than 55% by volume, the fluidity of the glass becomes poor and the adhesion to the ceramic becomes poor.

[0037]

EXAMPLES The low melting point sealing composition of the present invention will be described in detail below based on examples.

Table 1 shows the crystalline glass powder used in the present invention.

[0039]

[Table 1]

Crystallographic peaks were observed when each sample in Table 1 was observed using a differential thermal analyzer. From this, it was understood that crystals were precipitated when the desired heat treatment was applied to each sample in Table 2. ..

Table 2 shows the amorphous glass powder used in the present invention.

[0042]

[Table 2]

When each sample in Table 2 was observed with a differential thermal analyzer, no crystal peak was observed and it was understood that the sample was a stable amorphous glass.

The samples in Tables 1 and 2 were prepared as follows.

First, raw materials that emit as little α-ray as possible are blended and mixed so as to have the composition shown in the table, put in a platinum crucible, melted at 1000 ° C. for 1 hour, and molded into a thin plate.
The sample was crushed and passed through a 350-mesh stainless sieve to obtain a sample having an average particle size of 4 μm.

Table 3 shows samples A to C of Table 1 and D of Table 2.
Fig. 3 shows a low melting point sealing composition obtained by mixing each of the samples (1) to (F) and further mixing various types of refractory fillers.

[0047]

[Table 3]

As is clear from Table 3, each of the samples has good heat resistance and a low coefficient of thermal expansion of 75 × 10 ⁻⁷ / ° C. or less. Each of the samples 6 to 10 had a low expansion of 50 to 55 × 10 ⁻⁷ / ° C. and was close to the coefficient of thermal expansion of aluminum nitride.

Each sample has a high bending strength of 650 kg / cm ² or more, a relatively low dielectric constant of 19.6 or less, and shows a stable crystalline state in which no void is observed after 30 minutes of working temperature. It was

The various refractory filler powders shown in Table 3 were prepared as follows.

The willemite ceramic powder comprises zinc white, optical stone powder and aluminum oxide in a weight ratio of ZnO.
70%, SiO ₂ 25%, Al ₂ O ₃ 5% were mixed and mixed, and then the mixture was baked at 1440 ° C. for 15 hours, then pulverized with an alumina ball mill and passed through a 250 mesh stainless sieve. As a result, a powder having an average particle diameter of 5μ was obtained.

The tin oxide solid solution powder comprises SnO _{2 in} a weight ratio.
Tin oxide, titanium oxide, and manganese dioxide were mixed and mixed to have a composition of 93%, TiO ₂ 2%, and MnO ₂ 5%, and after mixing, they were fired at 1400 ° C. for 16 hours, and then pulverized with an alumina ball mill. The material passed through a stainless steel mesh screen was used.

The zircon-based ceramic powder is obtained by decomposing natural zircon sand with soda, dissolving it in hydrochloric acid, and repeating concentration and crystallization to obtain zirconium oxychloride, which is an α-ray emitting substance having extremely small amounts of U and Th,
After neutralization with an alkali, heating is performed to obtain purified ZrO ₂ , to which high-purity silica stone powder and ferric oxide are added in a weight ratio of ZrO ₂ 66
%, SiO ₂ 32%, Fe ₂ O ₃ 2%, and mixed and baked for 16 hours at 1400 ° C., then crushed with an alumina ball mill and passed through a 250 mesh stainless sieve. I used one.

The mullite type ceramic powder is prepared by mixing aluminum oxide and optical stone powder so as to be 3Al ₂ O ₃ .2SiO _2, and after mixing, firing at 1600 ° C. for 10 hours, and then pulverizing with an alumina ball mill to obtain 250 mesh. The one passed through the stainless steel sieve of was used.

The lead titanate-based ceramic powder is PbTi.
It is a solid solution of CaO in O ₃ crystal.
Titanium oxide, calcium carbonate PbO 70%, TiO
₂ Prepared to have a composition of 20% and CaO 10%,
After mixing, the mixture was fired at 1100 ° C. for 5 hours, and then the fired product was pulverized and passed through a 350-mesh stainless sieve to obtain a powder having an average particle size of 4 μm.

The cordierite powder is magnesium oxide, aluminum oxide, optical stone powder of 2MgO.2Al ₂
After blending so as to become O ₃ .5SiO ₂ , and mixing, 1
It was calcined at 400 ° C. for 10 hours, then pulverized with an alumina ball mill, and passed through a 250-mesh stainless sieve.

As the quartz glass powder and the alumina powder, commercially available products were used.

Table 4 shows the sample No. of Table 3. 2 (Invention product)
And, as a refractory filler in 60% by volume of sample A in Table 1,
Using a low melting point sealing composition (comparative product) obtained by mixing 30% by volume of willemite ceramic powder and 10% by volume of mullite ceramic powder, 100 pieces of 28 lead ceramic dual in-line packages (28 lead C-DIP) are used. After making each one, heat treatment under different conditions, measure the torque strength and airtightness of the package, check how many defective products have occurred for each characteristic, show it, and also show the number of each package Was taken out, the electric capacitance between the leads was measured, and the average value was obtained.

The above torque strength and airtightness were determined based on MIL-STD-883C to be good or bad. The torque strength was 114 lb · m or less (METHOD 2024.2), airtightness. He leakage rate is 5 × 10 ^-8 atm · cc / sec or more (ME
THOD 1014.5) was rated as bad.

As is clear from Table 4, when a comparative product containing no amorphous glass powder was heat-treated under various conditions, a defective product was produced in terms of torque strength and airtightness, and the change in inter-lead electrical capacitance was large. On the other hand, the sample No. of Table 3 which is the product of the present invention. No. 2 did not generate defective products in terms of torque strength and airtightness even when heat treatment was performed under various conditions, and the change in inter-lead capacitance was small.

The characteristics shown in Tables 3 and 4 are measured as follows.

Heat resistance was determined by applying a paste made by adding an acrylic resin and terpineol to a low melting point sealing composition, and fixing 42 alloy leads to a 28-lead C-DIP alumina substrate that had been printed and glaze, and then worked at the working temperature. Heated in
The case where the lead and the alumina substrate did not move was regarded as good.

The coefficient of thermal expansion was measured by subjecting the fired product to an extrusion type thermal expansion measuring device.

The bending strength of the fired product is 10 × 10 × 50 m.
It was molded into a square column of m and measured by a well-known three-point load measuring method.

The dielectric constant was measured by an LCR meter by printing electrodes with Ag paste on pellets of the fired product.

Regarding the voids, the same leaded sample as that used in the above heat resistance test was heated for 20 minutes at the working temperature, and then the surface of the crystalline glass was observed with a mineral microscope to confirm the presence or absence of voids.

The working temperature was the temperature at which 90% of the lead in the depth direction was immersed in the glass by heating the same lead-attached sample used in the heat resistance test.

The torque strength of the package is MIL-ST.
Based on D-883C METHOD 2024.2,
Airtightness is MIL-STD-883C METHOD1
It was measured based on 014.5.

The inter-lead electrical capacitance was obtained by measuring the electrical capacitance between the leads at the ends of the 10 packages randomly picked up and all the leads excluding the leads with an LCR meter, and averaging the values. It is what I asked for.

[0070]

As described above, the low melting point sealing composition of the present invention has a stable crystallization tendency that is not easily affected by heat treatment conditions and heat capacity, and can be adjusted to an extremely low coefficient of thermal expansion. Therefore, it is possible to seal a low expansion ceramic package of 45 × 10 ⁻⁷ / ° C. or less.

[Table 4]

Claims (4)

[Claims] 1. A low melting point sealing composition comprising a mixture of glass powder and refractory filler powder, wherein the glass powder comprises 5 to 80% by volume of crystalline glass powder and 20 to 95% by volume of amorphous glass powder. %, And a low melting point sealing composition. 2. The crystalline glass powder comprises, in weight percentage, P
bO 65-85%, B ₂ O ₃ 1-17%, ZnO
3 to 25%, SiO ₂ + Al ₂ O ₃ 0 to 5%, Bi ₂
O ₃ 0 to 20%, BaO 0 to 20%, F ₂ 0 to 6
% Composition, low melting point sealing composition according to claim 1. 3. The amorphous glass powder comprises, in weight percentage, P
bO 65-85%, B ₂ O ₃ 1-20%, ZnO
0-10%, SiO ₂ + Al ₂ O ₃ 0-5%, Bi ₂
The low melting point sealing composition according to claim 1, having a composition of 0 to 20% O _{3 and} 0 to 6% F ₂ . 4. The refractory filler powder is willemite ceramic powder, tin oxide ceramic powder, zircon ceramic powder, mullite ceramic powder, lead titanate ceramic powder, cordierite powder, quartz glass powder, alumina powder, oxidation. The low melting point sealing composition according to claim 1, which is one or more selected from the group consisting of titanium, niobium oxide, zinc stannate, cristobalite, and cubic zirconia.