JPH0597470A - Sealing composition having low melting point - Google Patents

Abstract

PURPOSE:To obtain a sealing compsn. having a low m.p., not contg. a poisonous substance such as T1, capable of sealing at a low temp. of <=400 deg.C without applying load and fit to seal an IC package, a quartz oscillator package CONSTITUTION:This sealing compsn. consists of 45-80 vol.% glass powder having a low m.p. and 20-55 vol.% powder of a low expansion or high expansion refractory filler. The glass powder has a compsn. consisting of, by weight, 70.3-92.0% PbO, 1.0-10.0% B2O3 (B2O3/PbO<=0.11), 5.2-20.0% Bi2O3, 0.01-8.0% F2, 0-15.0% ZnO, 0-5.0% V2O5, 0-2.0% SiO2, 0-2.0% Al2O3, 0-2.0% SnO2 and 0-4.0% BaO.

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 packages and crystal oscillator packages.

[0002]

2. Description of the Related Art A sealing composition used for sealing an IC package or a crystal oscillator package can be sealed at a low temperature so as not to adversely affect the IC or the crystal oscillator, and has a thermal expansion coefficient of the package. It is required to be compatible with the material. In addition to these conditions, the sealing material for the IC package has high mechanical strength and good insulation characteristics so that signal current does not leak.
When the C element is irradiated with α rays, a soft error occurs. Therefore, it is necessary to satisfy the condition that the substance that emits α rays is not included as much as possible.

Conventionally, as the various condition is satisfied, PbO-B ₂ O ₃ system, PbO-B ₂ O ₃ -ZnO
System, and the low melting point glass powder, such as _{PbO-B 2 O 3 -Bi 2} O 3 system, various sealing compositions obtained by adding a refractory filler powder to these glass powders are known. However, these conventional sealing compositions are difficult to seal at a temperature of 400 ° C. or lower, and are extremely sensitive to heat, for example, a package equipped with a highly integrated IC or a special crystal oscillator. Can not be used for sealing.

Under these circumstances, the development of a sealing composition which can be sealed at a temperature of 400 ° C. or lower is underway. For example, _{PbO-B 2 O 3 -Tl 2} O -based glass powder, a mixture of low-expansion refractory filler powder sealing composition low expansion of is proposed in Japanese Patent Publication No. 63-8060 to,
Also U.S. Pat. No. 4743302 PbO-V ₂ O ₅
A TeO ₂ -based glass powder and a sealing composition prepared by mixing it with a low expansion refractory filler powder are disclosed.

[0005]

However, since the sealing composition disclosed in Japanese Patent Publication No. 63-8060 contains a large amount of Tl which is a toxic substance, dust scattering is prevented during manufacturing or sealing work. Need special equipment for. The sealing composition disclosed in U.S. Pat. No. 4,743,302 is
Since it has a strong tendency to crystallize, it has poor fluidity, and therefore has a problem that a strong load must be applied during sealing.

An object of the present invention is that it does not contain toxic substances such as Tl and can be sealed at a low temperature of 400 ° C. or lower without applying a load, and is suitable for sealing IC packages, crystal oscillator packages, etc. A low melting point sealing composition is provided.

[0007]

The present inventors have SUMMARY OF THE INVENTION The result of various studies, the _{PbO-B 2 O 3 -Bi 2} O 3 based glass, a B ₂ O ₃ / PbO in a weight ratio 0.11 It has been found that the above object can be achieved by adjusting below and containing Bi ₂ O ₃ of 5.2% or more and F ₂ of 0.01% or more, and it is proposed as the present invention.

That is, the low melting point sealing composition of the present invention has a weight percentage of PbO 70.3 to 92.0% and B ₂ O _{3
1.0~10.0%, Bi 2 O 3 5.2~20.0} %,
_{F 2 0.01~8.0%, ZnO 0~15.0%} , V 2
_{O 5 0~5.0%, SiO 2 0~2.0} %, Al 2 O 3
0-2.0%, SnO ₂ 0-2.0%, BaO 0-
It is characterized in that it is composed of glass powder having a composition of 4.0% and a B ₂ O ₃ / PbO ratio of 0.11 or less.

The low melting point sealing composition of the present invention has a weight percentage of PbO 70.3 to 92.0% and B ₂ O _{3
1.0~10.0%, Bi 2 O 3 5.2~20.0} %,
F ₂ 0.01 to 8.0%, ZnO 0 to 15.0%, V
₂ O ₅ 0-5.0%, SiO ₂ 0-2.0%, Al ₂ O ₃
0-2.0%, SnO ₂ 0-2.0%, BaO 0-
45% to 80% by volume of a glass powder having a composition of 4.0% and a B ₂ O ₃ / PbO ratio of 0.11 or less, and 20 to 55% by volume of a refractory filler powder. To do.

[0010]

The reason why the composition range of the glass powder in the low melting point sealing composition of the present invention is limited as described above will be described below.

The PbO content is 70.3-92.0%,
It is preferably from 70.5 to 83.0%. PbO is 7
If it is less than 0.3%, the viscosity of the glass becomes high and the glass does not flow sufficiently, and if it is more than 92.0%, crystallization occurs at the time of sealing and it does not flow.

The content of B ₂ O ₃ is 1.0 to 10.0%,
It is preferably 2.0 to 9.5%. B ₂ O ₃ is 1.0
If it is less than%, it will not crystallize due to crystallization during sealing, and 1
If it exceeds 0.0%, it becomes difficult to flow at a temperature of 400 ° C. or lower.

Bi ₂ O ₃ has the effect of stabilizing the glass without increasing its viscosity, and its content is 5.2 to 20.0.
%, Preferably 5.2 to 19.0%. Bi ₂ O ₃
Is less than 5.2%, the above effect does not occur and 20.0
If it is more than%, the viscosity of the glass becomes high and the glass does not flow sufficiently at a temperature of 400 ° C. or lower.

In a glass composition system containing a large amount of Bi ₂ O _3, F ₂ has the effect of lowering the glass transition point and preventing devitrification, and the content thereof is 0.01 to 8.0%, preferably. Is 0.1 to 7.0%. If F ₂ is less than 0.01%, the above-mentioned effect cannot be obtained, and devitrification becomes remarkable at the time of sealing, so that it does not flow. On the other hand, if it exceeds 8.0%, the stability of the glass will be impaired, and crystallization will be remarkable, resulting in no flow.

The content of ZnO is 0 to 15.0%, preferably 0 to 13.0%. ZnO has the effect of stabilizing the glass and improving the water resistance, but if its content exceeds 15.0%, the glass crystallizes and does not flow sufficiently.

The content of V ₂ O ₅ is 0 to 5.0%, preferably 0 to 3.0%. V ₂ O ₅ has the effect of lowering the surface tension of glass and improves the fluidity, but if its content is more than 5.0%, the tendency to crystallize becomes remarkable and it does not flow.

The content of SiO ₂ is 0 to 2.0%, preferably 0 to 1.0%. SiO ₂ has the effect of preventing crystallization, but if its content is more than 2.0%, the viscosity of the glass increases and it does not flow sufficiently at a temperature of 400 ° C. or lower.

The content of Al ₂ O ₃ is 0 to 2.0%, preferably 0 to 1.0%. Al ₂ O ₃ has the effect of stabilizing the glass, but if its content is more than 2.0%, the viscosity of the glass becomes high and it does not flow sufficiently at a temperature of 400 ° C. or lower.

The content of SnO ₂ is 0 to 2.0%, preferably 0 to 1.5%. SnO ₂ has the effect of preventing crystallization of glass, but if its content is more than 2.0%, the viscosity of the glass becomes high and it does not flow sufficiently at a temperature of 400 ° C. or lower.

The content of BaO is 0 to 4.0%, preferably 0 to 3.0%. BaO has an effect of preventing crystallization of glass, but if its content is more than 4.0%, the viscosity of glass becomes high and the glass does not flow sufficiently at a temperature of 400 ° C. or lower.

The low melting point sealing composition of the present invention has a weight ratio of B ₂ O ₃ / PbO of 0.11 or less. B ₂ O ₃
When the / PbO ratio is larger than 0.11, the glass transition point and the sealing temperature become high, and sealing at a temperature of 400 ° C. or lower becomes difficult.

The low melting point sealing composition of the present invention contains, in addition to the above components, 5.0% or less of AgO, SrO and P ₂ O.
₅ , Co ₂ O ₃ , 3.0% or less of Mo ₂ O ₃ , Rb ₂
O, Cs ₂ O, Nb ₂ O ₅ , Ta ₂ O ₃ , ZrO ₂ , N
Rare earth oxides such as iO, Cr ₂ O ₃ , La ₂ O ₃ and CeO ₂ can be contained as other components.

The glass powder having the above composition is amorphous, has a good fluidity because it does not tend to precipitate crystals during sealing, and has a low glass transition point of about 240 to 300 ° C. or less and a glass viscosity. Since it is also low, it is a sealing composition suitable for sealing at low temperatures. However, the coefficient of thermal expansion is 110-14
A 0 × 10 ^-7 / ℃, alumina (thermal expansion coefficient of 70 × 1
0 ^-7 / ° C) and aluminum nitride (45 × 10 ^-7 / ° C)
Therefore, it is necessary to lower the coefficient of thermal expansion in order to seal the ceramic package and the crystal unit package made of these materials. On the other hand, in order to seal a metal package made of a material such as Al-Si alloy (coefficient of thermal expansion 160 × 10 ⁻⁷ / ° C.), it is necessary to increase the coefficient of thermal expansion.

The low melting point sealing composition of the present invention can be adjusted to a desired coefficient of thermal expansion by using at least one low expansion or high expansion refractory filler within the above-mentioned range. is there.

As the low-expansion refractory filler, willemite-based, tin oxide-based, zircon-based, lead titanate-based, and mullite-based ceramic powders, β-eucryptite powders, and cordierite powders should be used. In addition to these fillers, quartz glass powder, niobium pentoxide powder and the like can be used.

As the high-expansion refractory filler, it is preferable to use zinc stannate powder, cristobalite powder, cubic zirconia powder, or the like.

Next, the reason for limiting the mixing ratio of the glass powder and the refractory filler powder in the present invention as described above will be described below.

When the glass powder content is less than 45%, that is, when the refractory filler powder content is more than 55%, the fluidity is deteriorated and sealing at a temperature of 400 ° C. or less becomes difficult. On the other hand, when the glass powder content is more than 80%, that is, when the refractory filler powder content is less than 20%, the above effect cannot be obtained.

[0029]

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

(Example 1)

[0031] Table 1, in the _{PbO-B 2 O 3 -Bi 2} O 3 based glass, B ₂ O ₃ / PbO ratio, and Bi ₂ O
₃ , to explain the effect of F ₂ . Sample No. a typical _{PbO-B 2 O 3 -Bi 2} O 3 based glass, Sample No. b is sample No. and 11.0% less content of B ₂ O ₃ of a composition of a an B ₂ O ₃ / PbO ratio is _{PbO-B 2 O 3 -Bi 2} O 3 based glass was 0.05. In addition, sample No. c is sample No. From the composition of a, the B ₂ O ₃ content was reduced by 11.0%, and the B ₂ O ₃ / PbO ratio was reduced to 0.
And the Bi ₂ O ₃ content was 11.3%
The present invention shows a low melting point sealing composition of the present invention in which F ₂ is added to 2.0% and F ₂ is added at 2.0%.

[0032]

[Table 1]

Each sample in Table 1 was prepared as follows.

The raw material powders are blended so as to have the composition shown in the table,
The mixture was mixed, put in a platinum crucible, melted at 900 ° C. for 1 hour, molded into a thin plate, pulverized, and passed through a 350 mesh stainless sieve to obtain a sample having an average particle diameter of 4 μm.

As is clear from Table 1, the sample No. 1 having the B ₂ O ₃ content reduced and the B ₂ O ₃ / PbO ratio set to 0.11 or less. The glass transition point of sample b is 285 ° C. Although it was 25 ° C lower than that of a, the fluidity and stability were poor. On the other hand, the B ₂ O ₃ / PbO ratio is 0.11
And less than 5.2% of Bi ₂ O ₃ and F
No. ₂ containing 0.01% or more of No. 2 C has a glass transition point of 274 ° C, which is 11 ° C higher than that of sample No. b.
Also shows a low value, and the fluidity of sample No. It was superior to a and had good stability.

These facts indicate that PbO-B ₂ O ₃ -Bi
_{In the 2} O ₃ system glass, the B ₂ O ₃ / PbO ratio is 0.1
It is shown that a sealing composition having a low melting point and having good fluidity and stability can be obtained by adjusting the amount to 1 or less and containing Bi ₂ O ₃ and F ₂ in predetermined amounts.

The glass transition point is measured by a differential thermal analyzer (DT
Determined according to A). The fluidity is such that a sample having a weight equivalent to 1 cm ³ is molded into a button having an outer diameter of 17 mm and a height of 5 mm and then heated at 380 ° C. for 10 minutes, and the diameter of the button at this time exceeds 23 mm. Good, 20-23
mm was acceptable, and those less than 20 mm were not acceptable. Regarding the stability, the surface of the sample after the fluidity test was visually observed, and the case where no crystals were observed was good, and the case where it was observed was not good.

(Example 2)

Table 2 shows examples of the present invention made of glass powder.

[0040]

[Table 2]

As is clear from Table 2, the sample No. A ~
E had a glass transition point of 249 to 293 ° C. and a thermal expansion coefficient of 120 to 135 × 10 ⁻⁷ / ° C., and all showed good fluidity.

Each sample in Table 2 was prepared in the same manner as in Example 1.

Tables 3 to 5 show Examples of the present invention prepared by mixing the refractory filler powder with each of the samples of Table 2. Sample Nos. 1 to 5 are used for sealing alumina packages. Sample Nos. 6 to 9 are for aluminum nitride package sealing. 10 to 12 are Al-Si alloy package seals.

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

As is clear from Tables 3 to 5, sample N
o. 1-12 has a bending strength of 590-640 kg / cm
² , the insulation resistance was 13.2 to 14.5 Ω · cm, and the α ray emission amount was 0.11 to 0.19 count / cm ² · hr, which were favorable values. The thermal expansion coefficient is the same as that of Sample No. 1-5
Of 63 to 70 × 10 ⁻⁷ / ° C., sample No. 6-9 is 51-
53 × 10 ⁻⁷ / ° C., sample No. 10-12 is 155-1
66 × 10 ⁻⁷ / ° C., and alumina (70 × 1
0 ^-7 / ° C), aluminum nitride (45 x 10 ^-7 / ° C),
The value approximated to that of Al-Si alloy (160 × 10 ⁻⁷ / ° C.) was shown.

In addition, each sample was added with a vehicle to form a paste as in a conventional method. Sample Nos. 1 to 5 in alumina. Sample Nos. 6 to 9 in aluminum nitride. When 10 to 12 were printed on Al-Si alloys and the sealing temperature was measured, the sample for alumina package sealing was 360 to 390 ° C, the sample for aluminum nitride package sealing was 370 to 400 ° C, and Al- Si
The sample for the alloy package could be sealed at 380-400 ° C without any load.

These facts indicate that the low melting point sealing composition of the present invention satisfies the various conditions required for the IC package sealing composition, and can be sealed at a temperature of 400 ° C. or less without applying a load. It also shows that the desired coefficient of thermal expansion can be adjusted by mixing a suitable refractory filler powder. Although the composition for sealing the IC package has been described in this embodiment, it can be used for sealing other electronic components such as a crystal oscillator package by adjusting the thermal expansion coefficient to an appropriate value. Is.

The coefficient of thermal expansion in each table was measured using a push rod type thermal expansion measuring device. The bending strength was obtained by sintering the sample, molding it into a prism of 10 × 10 × 50 mm, and measuring it with a three-point load. The insulation resistance was measured at 150 ° C. using a mega ohm meter, and the α-ray emission was measured using a ZnS scintillation counter.

The refractory filler powders shown in Tables 3 to 5 were prepared as follows.

The willemite-based ceramic powder is the weight%
Then, the raw material powder was prepared so that the composition of ZnO was 70%, SiO _{2 was} 25%, and Al ₂ O _{3 was} 5%.
Bake at 15 ° C. for 15 hours, then crush this baked product to 25
The one that passed through a 0 mesh stainless steel sieve was used.

The tin oxide ceramic powder is Sn in weight%.
Raw material powders were blended so as to have a composition of O ₂ 93%, TiO ₂ 2%, and MnO ₂ 5%, and after mixing, calcination was performed at 1400 ° C. for 16 hours, and then the calcination product was crushed and 250 mesh stainless sieve. The one that passed through was used.

The zircon ceramic powder was produced as follows. First, natural zircon sand is once decomposed with soda, dissolved in hydrochloric acid, and concentrated crystallization is repeated to obtain zirconium oxychloride having extremely small amounts of U and Th that are α-ray emitting substances. Purified ZrO ₂ was obtained. Furthermore, high-purity silica stone powder and ferric oxide were added to the purified ZrO ₂ in a weight percentage of ZrO ₂ 66%, SiO ₂
Formulated to have a composition of ₂ 32% and Fe ₂ O ₃ 2%,
After mixing, the mixture was fired at 1400 ° C. for 16 hours, and then the fired product was crushed and passed through a 250-mesh stainless sieve.

The lead titanate-based ceramic powder was prepared by mixing the raw material powders so that the composition of PbO was 70%, TiO _{2 was} 20%, and CaO was 10% by weight.
Then, the product was pulverized and passed through a 350-mesh stainless sieve, which was then used.

Mullite powder is 3Al ₂ O ₃ .2SiO
Mix the raw material powder so that it has the composition of ₂ , and after mixing,
Bake at 00 ° C. for 10 hours, then crush this fired product,
It was passed through a 250-mesh stainless sieve.

The β-eucryptite powder is Li ₂ O.
Raw material powders are blended so as to have a composition of Al ₂ O ₃ .2SiO ₂ , and after mixing, they are fired at 1250 ° C. for 5 hours, and then the fired product is crushed and passed through a 250-mesh stainless sieve. did.

Cordierite powder is 2MgO.2A
The raw material powders were blended so as to have a ratio of 1 ₂ O ₃ .5SiO ₂ , and after mixing, they were fired at 1400 ° C. for 10 hours, and then the fired product was crushed and passed through a 250 mesh stainless sieve. did.

[0059] zinc stannate powder to prepare a raw material powder so that the composition of 2ZnO · SnO _2, after dry mixing, 145
Bake at 0 ° C. for 16 hours, then crush this fired product to 2
The one that passed through a 50-mesh stainless sieve was used.

Cristobalite powder was prepared by first spheroidizing silica glass powder having an average particle size of 10 μm at 1480 ° C.
It was calcined for 6 hours to form cristobalite. In order to improve the fluidity of the cristobalite powder, 5% by volume of ZnO fine particles having an average particle diameter of 0.1 μm was further added and dry-mixed, followed by treatment at 1000 ° C. for 1 hour to form a ZnO coating film on the surface.

The cubic zirconia powder was prepared by first adding a low α-ray type zirconia raw material and calcium carbonate to ZrO ₂ 80
A mixture was prepared such that the ratio of mol% and CaO was 20 mol%, and after mixing, the mixture was fired at 1550 ° C. for 16 hours, and then the fired product was crushed and passed through a 350-mesh stainless sieve.

[0062]

As described above, the low melting point sealing composition of the present invention does not contain harmful substances and can be sealed at a low temperature of 400 ° C. or lower without applying a load. Moreover, since a desired coefficient of thermal expansion can be obtained by using the refractory filler, it is suitable for sealing electronic components such as IC packages and crystal oscillator packages.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C03C 8/10 6971-4G 8/14 6971-4G

Claims (2)

[Claims] 1. PbO 70.3-9 in percentage by weight.
_{2.0%, B 2 O 3 1.0~10.0} %, Bi 2 O 3
_{5.2~20.0%, F 2 0.01~8.0%,} ZnO
0 to 15.0%, V ₂ O ₅ 0 to 5.0%, SiO ₂ 0
_{~2.0%, Al 2 O 3 0~2.0} %, SnO 2 0~
2.0%, BaO 0-4.0% composition, and
A low melting point sealing composition comprising a glass powder having a B ₂ O ₃ / PbO ratio of 0.11 or less. 2. PbO 70.3-9 in percentage by weight.
_{2.0%, B 2 O 3 1.0~10.0} %, Bi 2 O 3
_{5.2~20.0%, F 2 0.01~8.0%,} ZnO
0 to 15.0%, V ₂ O ₅ 0 to 5.0%, SiO ₂ 0
_{~2.0%, Al 2 O 3 0~2.0} %, SnO 2 0~
2.0%, BaO 0-4.0% composition, and
Glass powder 4 having a B ₂ O ₃ / PbO ratio of 0.11 or less
A low melting point sealing composition comprising 5 to 80% by volume and a refractory filler powder of 20 to 55% by volume.