JP3180299B2 - Low melting point sealing composition - Google Patents

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 components such as ceramic packages for ICs and CCDs. It is.

[0002]

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

[0003] In addition, low melting point sealing compositions for this purpose include:
It is required to have a thermal expansion coefficient close to the thermal expansion coefficient of the material constituting the package or device, to have a high mechanical strength, and to have a low dielectric constant so as not to hinder the signal transmission speed.

[0004] The crystalline glass is a glass in which crystalline material is precipitated from the inside by heating. Particularly, the coefficient of thermal expansion and the strength after heating are determined by the degree of crystallization (crystal amount / crystal amount + residual glass). Amount).

That is, since the crystalline substance precipitated inside has a smaller coefficient of thermal expansion than the residual glass, it has an effect of reducing the overall coefficient of thermal expansion and improving the strength. The crystalline and the residual glass have different dielectric constants, and the dielectric constant of the crystalline glass depends on the degree of crystallization.

Therefore, in order to obtain desired properties by heating the crystalline glass powder, it is necessary to adjust a specific crystal to have an appropriate crystal arrival.

[0007]

However, since the degree of crystallinity of crystalline glass is affected by the heat treatment conditions and heat capacity, a constant degree of crystallinity can be obtained due to variations in the manufacturing process and in units of glass production. There is a problem that it is difficult to be.

That is, since the crystalline state has a lower energy state and is more stable than that of glass, when a sufficient amount of heat is applied, the degree of crystal arrival increases until almost no residual glass is left.

If the degree of reaching the crystal is too high, the residual glass having the function of connecting the crystals is excessively reduced, and tunnel-like voids are generated in the glass, so that the airtightness of the package is lost or the sealing is performed. This causes a problem that the strength of the portion is reduced.

[0010] Further, if the crystal reach is unstable, a variation in the dielectric constant occurs between the produced sealing materials, and when this is used for an IC ceramic package, the electric capacity between the leads varies. . As a result, I
There is a possibility that a variation in the signal transmission speed of C may occur and a product in which the IC does not function as designed may occur.

The addition of a low-expansion refractory filler powder to the crystalline glass powder can reduce the coefficient of thermal expansion. However, ceramics having a low coefficient of thermal expansion, specifically, 45 × Materials suitable for sealing a package made of ceramics such as aluminum nitride, silicon carbide, and mullite having a coefficient of thermal expansion of 10 ⁻⁷ / ° C. or less include:
Does not yet exist.

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

[0013]

The low melting point sealing composition of the present invention is a low melting point sealing composition comprising a mixture of a glass powder and a refractory filler powder. ~ 80% by volume and amorphous glass powder 20
~ 95% by volume.

Further, the crystalline glass powder in the present invention comprises:
In weight _{percent, PbO 65~85%, B 2 O} 3 1~
17%, ZnO 3 to 25%, SiO ₂ + Al ₂ O _{3
0~5%, Bi 2 O 3 0~20} %, BaO 0~20
%, Has a composition of F ₂ Less than six%, amorphous glass powder, in weight _{percent, PbO 65~85%, 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%
Characterized by having the following composition:

Further, in the present invention, the refractory filler powder comprises a willemite ceramic powder, a tin oxide ceramic powder, a zircon ceramic powder, a mullite ceramic powder, a lead titanate ceramic powder, a cordierite powder, a quartz glass powder. , Alumina powder, titanium oxide, niobium oxide, zinc stannate, cristobalite, and cubic zirconia.

[0016]

In the present invention, amorphous glass powder is used together with crystalline glass powder as glass powder.
A stable crystallization tendency that is hardly affected by heat treatment conditions and heat capacity is exhibited, and variations in characteristics can be prevented.

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

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

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

B ₂ O ₃ is a glass network structure forming oxide, and its content is 1 to 17%, preferably 3 to 17%.
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 and improves water resistance.
２５25%, preferably 3-22%. If it is less than 3%, the above effects cannot be obtained, and if it is more than 25%, remarkable crystallinity is exhibited.

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

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

BaO is a component for adjusting the crystal of the glass and improving the water resistance, and its content 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 the glass, and its content is 0 to 6%, preferably 0 to 4%. If the content is more than 6%, remarkable crystallinity is exhibited, which is not preferable.

The crystalline glass used in the present invention may contain, in addition to the above components, 5% or less of Fe ₂ O ₃ , CuO, 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 why the composition of the amorphous glass used in the present invention is limited as described above will be described below.

PbO is a modified oxide of glass, and its content is 65-85%, preferably 68-83%.
It is. If it is less than 65%, the glass becomes too viscous to flow sufficiently at a practical temperature, and if it is more than 85%, it exhibits crystallinity.

B ₂ O ₃ is an oxide for forming a glass network structure, and its content is 1 to 20%, preferably 3 to 20%.
15%. If it is less than 1%, it shows crystallinity and 20
%, The glass becomes too viscous to flow sufficiently at a practical temperature.

ZnO stabilizes the glass,
It is a component for improving water resistance, and its content is from 0 to 1
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 thereof is 0 to 5%, preferably 0 to 3%. If it is more than 5%, the viscosity of the glass becomes so high that the glass does not flow sufficiently at a practical temperature.

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

F ₂ is a component that lowers the viscosity of the glass, and its content is 0 to 6%, preferably 0 to 2%. If 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 3% or less of 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
× has a thermal expansion coefficient of more than 10 ^-7 / ° C., the amorphous glass has a thermal expansion coefficient of more than 95 × 10 ^-7 / ° C.,
These mixtures are used for sealing, for example, IC ceramic packages made of 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 lower the coefficient of thermal expansion by mixing a refractory filler powder.

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 deteriorates, and the adhesion to the ceramic deteriorates.

[0037]

EXAMPLES Hereinafter, the low melting point sealing composition of the present invention will be described in detail with reference to Examples.

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

[0039]

[Table 1]

When each sample in Table 1 was observed using a differential thermal analyzer, a crystal peak was recognized. From this, it was understood that a crystal was deposited when a 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, indicating that the sample was a stable amorphous glass.

Each sample in Tables 1 and 2 was prepared as follows.

First, raw materials having the smallest possible amount of α-ray emission are mixed and mixed so as to have the composition shown in the table, put into a platinum crucible, melted at 1000 ° C. for 1 hour, and formed into a thin plate.
The sample was pulverized 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 in Table 1 and D in Table 2.
1 shows a low melting point sealing composition obtained by mixing each sample of Nos. To F and further mixing various refractory fillers.

[0047]

[Table 3]

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

Each sample has a high transverse rupture 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 a working temperature of 30 minutes. Was.

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

The willemite ceramic powder is composed of zinc oxide, optical stone powder, and aluminum oxide in a weight ratio of ZnO
After mixing and mixing so as to have a composition of 70%, SiO ₂ 25%, and Al ₂ O ₃ 5%, the mixture is baked at 1440 ° C. for 15 hours, then pulverized by an alumina ball mill, and passed through a 250 mesh stainless sieve. In this way, a powder having an average particle size of 5μ was obtained.

The tin oxide solid solution powder was composed of SnO ₂
A mixture of tin oxide, titanium oxide, and manganese dioxide was prepared to have a composition of 93%, 2% TiO ₂ , and 5% MnO ₂ , mixed, fired at 1400 ° C. for 16 hours, and then pulverized with an alumina ball mill to obtain 250%. What passed through the stainless steel mesh sieve was used.

The zircon-based ceramic powder is obtained by temporarily decomposing a natural zircon sand with soda, dissolving it in hydrochloric acid, and repeating concentration crystallization to obtain zirconium oxychloride having a very small amount of U and Th, which are α-ray emitting substances.
After alkali neutralization, heating was performed to obtain purified ZrO ₂ , and high-purity silica powder and ferric oxide were added thereto in a weight ratio of ZrO ₂ 66.
%, SiO ₂ 32%, and Fe ₂ O ₃ 2%. After mixing, the mixture was baked at 1400 ° C. for 16 hours, then pulverized by an alumina ball mill, and passed through a 250 mesh stainless steel sieve. Was used.

The mullite ceramic powder is prepared by mixing aluminum oxide and optical stone powder so as to obtain 3Al ₂ O ₃ .2SiO ₂ , mixing, firing at 1600 ° C. for 10 hours, and then pulverizing with an alumina ball mill to obtain 250 mesh. Passed through a stainless steel sieve.

The lead titanate-based ceramic powder is PbTi
O ₃ crystal is a solid solution of CaO,
Titanium oxide, calcium carbonate 70% PbO, TiO
₂ 20% 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.

Cordierite powder was obtained by mixing magnesium oxide, aluminum oxide and optical stone powder with 2MgO.2Al ₂
After mixing and mixing to obtain O ₃ .5SiO ₂ , 1
It was fired at 400 ° C. for 10 hours, then pulverized by an alumina ball mill, and passed through a 250 mesh stainless sieve.

Commercially available quartz glass powder and alumina powder were used.

Table 4 shows the results of the sample No. in Table 3. 2 (Product of the present invention)
And, as a refractory filler in the sample A 60% by volume of 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 28 lead ceramic dual in-line packages (28 lead C-DIP) each After manufacturing, heat treatment was performed under different conditions, the torque strength and airtightness of the package were measured, and the number of defective products generated for each characteristic was confirmed. Are taken out, the electric capacitance between the leads is measured, and the average value is obtained.

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

As is clear from Table 4, when the comparative product containing no amorphous glass powder was heat-treated under various conditions, a defective product was generated in torque strength and airtightness, and the change in electric capacity between leads was large. On the other hand, in the sample No. of Table 3 which is the product of the present invention. Sample 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 electrical capacity between leads was small.

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

The heat resistance is determined by fixing a paste obtained by adding an acrylic resin and terpineol to a low melting point sealing composition, fixing a 42 alloy lead to a printed and glazed 28-lead alumina substrate for C-DIP, and working temperature. And heat
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 transverse rupture strength of the fired product was 10 × 10 × 50 m
m, and measured by a well-known three-point load measurement method.

The dielectric constant was measured by printing an electrode on a pellet of a fired product with an Ag paste and using an LCR meter.

As for voids, the same lead-attached sample as the one subjected to the above heat resistance test was heated at the working temperature for 20 minutes, 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 a temperature at which 90% of the lead in the depth direction was immersed in the glass by heating the same lead-attached sample as that subjected to the above heat resistance test.

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

The electric capacity between the leads was measured by using an LCR meter to measure the electric capacity between the leads at the end of 10 packages taken out at random and all the leads except for those leads, and the average value was taken. It is what I sought.

[0070]

As described above, the low melting point sealing composition of the present invention has a stable crystallinity that is hardly affected by heat treatment conditions and heat capacity, and can be adjusted to an extremely low coefficient of thermal expansion. For this reason, a low expansion ceramic package of 45 × 10 ⁻⁷ / ° C. or less can be sealed.

[Table 4]

Claims (4)

(57) [Claims] 1. A low melting point sealing composition comprising a mixture of a glass powder and a refractory filler powder, wherein the glass powder comprises 5 to 80% by volume of a crystalline glass powder and 20 to 95% by volume of an amorphous glass powder. % Of the low melting point sealing composition. 2. The method according to claim 1, wherein the crystalline glass powder has a weight percentage of P
_{bO 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 0~6
%. 2. The low melting point sealing composition according to claim 1, which has a composition of 3. An amorphous glass powder comprising, as a percentage by weight, P
_{bO 65~85%, B 2 O 3} 1~20%, ZnO
_{0~10%, SiO 2 + Al 2} O 3 0~5%, Bi 2
O ₃ 0 to 20%, low melting point sealing composition of claim 1, characterized in that it comprises a composition of F ₂ Less than six% 4. The refractory filler powder comprises a willemite ceramic powder, a tin oxide ceramic powder, a zircon ceramic powder, a mullite ceramic powder, a lead titanate ceramic powder, a cordierite powder, a quartz glass powder, an alumina powder, an oxidized powder. The low melting point sealing composition according to claim 1, wherein the composition is at least one selected from the group consisting of titanium, niobium oxide, zinc stannate, cristobalite, and cubic zirconia.