JPH06171975A - Low melting point sealing composition - Google Patents

Abstract

PURPOSE:To provide a low m.p. sealing compsn. not contg. harmful substances such as Tl and capable of airtightly sealing a package at a low temp. of 330-350 deg.C without placing load. CONSTITUTION:This low m.p. sealing compsn. is made of glass powder having a compsn. consisting of, by weight, 15-34% TeO2, 15-45% V2O5, 5-35% PbO, 3-40% Ag2O, 0.5-10% Cs2O and 0.5-10% Sb2O5.

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 specifically, to a hermetically sealing ceramic package or metal package having a heat-sensitive element such as a semiconductor integrated circuit or a crystal unit mounted thereon. The present invention relates to a low melting point sealing composition suitable for

[0002]

2. Description of the Related Art Conventionally, a low melting point sealing composition using glass powder has been used for hermetically sealing a highly reliable package on which elements such as a semiconductor integrated circuit and a crystal oscillator are mounted.

As such a low melting point sealing composition, P
to bO-B ₂ O ₃ based glass, a material obtained by adding refractory material powder of a low expansion, such as lead titanate or willemite is widely known. However, since a low melting point sealing composition using this type of glass is difficult to seal at a temperature of 400 ° C. or less, it is extremely sensitive to heat such as highly integrated LSI and special crystal oscillators. When airtight sealing of a package having an element mounted thereon is performed, the characteristics of the element may be deteriorated.

In view of the above circumstances, various low-melting point sealing compositions capable of sealing at lower temperatures have been proposed in recent years. For example, in JP-A-63-315536, P
bO-B ₂ O ₃ -Tl low melting point sealing composition using ₂ O-based glass is shown, also in the Kohyo Sho 63-502583 _{JP, PbO-V 2 O 5 -Bi} 2 O 3 based glass A low melting point sealing composition using is shown.

[0005]

However, the above low melting point sealing composition has a low transition point of the glass used,
Sealing at 400 ° C or lower is possible, but all have problems. That is, the sealing composition disclosed in JP-A-63-315536 can be sealed at 350 ° C., but since it contains a large amount of highly toxic Tl ₂ O, it cannot be sealed during production or sealing. There is a problem in practical use because it requires equipment to prevent dust from scattering during work.

The sealing composition disclosed in Japanese Patent Publication No. 63-502583 can reduce the sealing temperature to about 330 to 370 ° C., but has a strong tendency to crystallize.
When heated, crystals precipitate and the flowability deteriorates. Therefore, in order to perform sealing at a low temperature, a considerable load must be applied with a metal clip or the like during sealing.

The object of the present invention is to contain no harmful substances such as Tl, and without applying a load, at 330 to 350 ° C.
To provide a low melting point sealing composition capable of hermetically sealing a package at low temperature.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted a number of studies in order to achieve the above object, and as a result, TeO ₂ -V
₂ O ₅ -PbO-Ag ₂ O-Cs ₂ O-Sb ₂ O ₅ glass has a very low glass transition point and a low crystallization tendency, and contains each constituent component of the glass of this system in a predetermined ratio. It has been found that it is possible to obtain a low melting point sealing composition having a sealing temperature of 350 ° C. or lower, 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 TeO _{2 of} 15 to 34% and V ₂ O _{5 of} 15 to 4.
5%, PbO 5 to 35%, Ag ₂ O 3 to 40%, C
It is characterized by comprising glass powder having a composition of s ₂ O 0.5 to 10% and Sb ₂ O ₅ 0.5 to 10%.

A low melting point sealing composition according to another aspect of the present invention is characterized by comprising 45 to 90% by volume of the above glass powder and 10 to 55% by volume of a refractory substance powder.

[0011]

The reason for limiting the composition of the glass powder in the low melting point sealing composition of the present invention as described above is as follows.

TeO ₂ is a component forming the skeleton of the glass of the present invention, and its content is 15 to 34%, preferably 20 to 34%. When TeO ₂ is less than 15%, the glass tends to devitrify, and stable glass cannot be obtained. On the other hand, when the content is more than 34%, the coefficient of thermal expansion of the glass becomes remarkably large. Microcracks are likely to occur due to the difference in expansion coefficient.

V ₂ O ₅ is also a component forming the skeleton of the glass of the present invention, and its content is 15 to 45%, preferably 20 to 35%. If the content of V ₂ O ₅ is out of this range, the glass tends to crystallize significantly and good sealing cannot be achieved.

PbO is a component that lowers the melting point of glass, and its content is 5 to 35%, preferably 15 to 25%.
Is. When PbO is less than 5%, the glass is crystallized at the time of sealing and it becomes difficult to flow. On the other hand, when it is more than 35%, the viscosity of the glass becomes high and the glass does not flow sufficiently.

Ag ₂ O is also a component for lowering the melting point of glass, and its content is 3-40%, preferably 4-30%. If the content of Ag ₂ O is less than 3%, the viscosity of the glass becomes high and the glass does not flow sufficiently. On the other hand, when it is more than 40%, the thermal expansion coefficient of the glass becomes too high.

Cs ₂ O is also a component for lowering the melting point of glass, and its content is 0.5 to 10%, preferably 1 to 8%.
Is. When Cs ₂ O is less than 0.5%, the effect is not obtained, and when it is more than 10%, the coefficient of thermal expansion becomes too high and the glass is foamed.

Sb ₂ O ₅ has an effect of suppressing devitrification of glass, and the content thereof is 0.5 to 10%, preferably 1 to
8%. If Sb ₂ O ₅ is less than 0.5%, the effect is not obtained, and if it is more than 10%, the softening point becomes too high, which is not preferable.

In the present invention, in addition to the above components, ZnO, Bi ₂ O ₃ and Cu ₂ may be used as long as the characteristics are not impaired.
O, Nb ₂ O ₅ , Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ , W
It is possible to select one or more of O ₃ , MoO ₃ , SrO, BaO and CeO ₂ and to add up to 10%.

In the present invention, the thermal expansion coefficient can be adjusted and the mechanical strength can be improved by mixing the glass powder with the refractory substance powder.

In this case, 45 to 90% by volume of glass powder
The refractory substance powder is mixed so as to be 10 to 55% by volume. The reason for limiting the mixing ratio of each powder in this way is as follows.

That is, when the refractory powder is less than 10% by volume, the effect of adjusting the thermal expansion coefficient of the low melting point sealing composition and improving the mechanical strength is small,
On the other hand, if it is more than 55% by volume, the fluidity of the low-melting point sealing composition is remarkably lowered, and sealing with high airtightness cannot be performed.

In order to match the coefficient of thermal expansion of the low melting point sealing composition of the present invention with the coefficient of thermal expansion of an alumina package used as an IC package, a refractory substance powder having a particularly low coefficient of thermal expansion is added. There is a need. As the refractory substance powder of this kind, the lead titanate solid solution powders shown in Japanese Patent Application Nos. 61-87542, 1-86958 and 3-197136, which are filed by the present applicant, are useful. Yes, normal zircon powder, tin oxide powder,
It is also possible to use niobium oxide powder, lead titanate powder, β-eucryptite powder, cordierite powder and the like together.

When the low melting point sealing composition of the present invention is used in a metal package having a higher coefficient of thermal expansion than an alumina package, the refractory substance powder added to the glass powder has a particularly high coefficient of thermal expansion. Low is not required. Therefore, in this case, usual alumina powder, zirconia powder, titania powder, spinel powder, zinc stannate powder, etc. can be used.

[0024]

EXAMPLES The low melting point sealing composition of the present invention will be described in detail below with reference to examples.

Table 1 shows the low melting point sealing composition of the present invention comprising glass powder.

[0026]

[Table 1]

The glass powders in Table 1 (Samples A to F) were prepared as follows.

First, so as to have the composition shown in Table 1, tellurium dioxide, vanadium pentoxide, red lead, silver oxide, cesium carbonate,
Antimony pentoxide, bismuth oxide, niobium pentoxide, alumina and cerium oxide were prepared and mixed. Then, this was put in a platinum crucible, melted in an electric furnace at 700 ° C. for 1 hour, formed into a thin plate, and then pulverized with a ball mill to obtain 2
It was passed through a 50-mesh (opening 63 μm) sieve.

As is clear from Table 1, all the glass powders had a very low transition point of 214 to 220 ° C., and no crystals were precipitated, and they had good fluidity.

The fluidity was judged by molding a powder sample having a weight corresponding to the specific gravity of glass into a button having an outer diameter of 20 mm and a height of about 5 mm, and then heating it at 350 ° C. for 10 minutes. A button having a diameter of more than 23 mm was considered good. Regarding the presence or absence of crystal precipitation, the button surface after the fluidity test was observed with a microscope and no crystal was observed at all, which was regarded as good.

Table 2 shows examples (Sample Nos. 1 to 6) of low melting point sealing compositions obtained by mixing the glass powders A, C and E of Table 1 with various refractory substance powders. It is a thing.

[0032]

[Table 2]

As is clear from Table 2, the coefficient of thermal expansion of each sample is 65 to 75 × 10 ⁻⁷ / ° C., which is close to the coefficient of thermal expansion of alumina ceramics (70 × 10 ⁻⁷ / ° C.). showed that.

Each sample was made into a paste by adding a vehicle as usual, and then printed on an alumina ceramic substrate, and the sealing temperature was measured. All were at a low temperature of 330 to 340 ° C. It could be sealed without applying a load.

The refractory substance powders used in Table 2 are produced as follows.

Pb _0.75 Ca _0.25 TiO ₃ is a litharge,
Calcium carbonate and titanium oxide in PbO6 by weight percentage
4%, CaO 5%, and TiO ₂ 31% were mixed, dry-mixed, fired at 1170 ° C. for 5 hours, then pulverized and passed through a 350-mesh sieve (opening 45 μm).

Pb _0.90 Ca _0.10 Fe _0.15 Nb _0.15 Ti
_0.70 O ₃ is litharge, titanium oxide, ferric oxide, niobium pentoxide, calcium carbonate in a weight percentage, and PbO 6
8.2%, CaO 1.9%, Fe ₂ O ₃ 4.1%,
Nb ₂ O ₅ 6.8% and TiO ₂ 19.0% were mixed, dry-mixed, baked at 1250 ° C. for 5 hours, and then pulverized to 350 mesh (opening 45 μm).
Through the sieve.

SnO ₂ is composed of stannic oxide and zinc white as a sintering aid, in terms of weight percentage, SnO ₂ 99%, ZnO _2.
Formulated to 1%, dry-mixed, 16 at 1480 ° C
After firing for an hour, it was crushed and passed through a 350 mesh screen.

Nb ₂ O ₅ is a niobium pentoxide reagent.
After firing at 0 ° C. for 5 hours, it was ground and then passed through a 350 mesh screen.

The transition point and the coefficient of thermal expansion in each table are
It was determined from the thermal expansion curve measured by a dilatometer.

[0041]

INDUSTRIAL APPLICABILITY As described above, the low melting point sealing composition of the present invention can be hermetically sealed at a low temperature of 350 ° C. or lower without containing a harmful substance and without applying a load. Therefore, it is particularly suitable for hermetically sealing a ceramic package or a metal package on which an extremely weak element such as an LSI or a special crystal oscillator is mounted.

Claims (2)

[Claims] 1. TeO ₂ 15-34% by weight,
_{V 2 O 5 15~45%, PbO} 5~35%, Ag 2 O
_{3~40%, Cs 2 O 0.5~10%} , Sb 2 O 5
A low melting point sealing composition comprising glass powder having a composition of 0.5 to 10%. 2. TeO ₂ 15-34% by weight percentage,
_{V 2 O 5 15~45%, PbO} 5~35%, Ag 2 O
_{3~40%, Cs 2 O 0.5~10%} , Sb 2 O 5
A low melting point sealing composition comprising 45 to 90% by volume of glass powder having a composition of 0.5 to 10% and 10 to 55% by volume of refractory material powder.