JP3409804B2 - Low expansion sealing material - 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-expansion sealing material suitable for sealing electronic parts such as semiconductor devices, fluorescent display tubes and silicon diodes.

[0002]

Conventionally, semiconductor devices, fluorescent display tubes, electronic components PbO-B ₂ O ₃ -based as sealing material used for sealing, such as a silicon _{diode, PbO-ZnO-B 2 O} 3
As a refractory powder, lead titanate (P
A sealing material formed by mixing bTiO ₃ ) powder is known. However, conventional sealing materials have a drawback that there is no material having a sufficiently low coefficient of thermal expansion, and thus they cannot be used depending on the application.

Therefore, the inventors of the present invention have found that Japanese Patent Publication No. 2865/1992.
No. 8, JP-A-2-30639 and JP-A-5-1717.
No. 9 proposes a sealing material having a low coefficient of thermal expansion using a lead titanate solid solution as a refractory powder.

[0004]

However, each of the above-mentioned sealing materials has a problem that the heat resistance after sealing is low. For example, when it is used for sealing a fluorescent display tube, it may be reheated to 350 to 450 ° C. in the subsequent exhaust step, but since the above-mentioned sealing material has low heat resistance, the glass is reheated in this exhaust step. There is an inconvenience that the melting occurs and bubbles are generated in the sealed portion, and as a result, the strength of the sealed portion is significantly reduced.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a low-expansion sealing material having a low coefficient of thermal expansion and heat resistance sufficient to withstand reheating at 350 to 450 ° C.

[0006]

The low expansion sealing material of the present invention comprises a glass powder 50-9 having a transition point of 330-430 ° C.
5% by volume and 5-50% by volume of lead titanate solid solution powder, wherein the lead titanate solid solution powder is (a) P
bO 55-73%, CaO 0.5-12%, TiO
₂ 26-35%, (b) PbO 65-75%, TiO
_{2 10~25%, Fe 2 O 3} 1~10%, WO 3 1~1
2%, CaO 0-5%, (c) PbO 60-73
%, TiO _{2 2 to} 23%, Fe ₂ O ₃ , ZnO, Mg
One or more selected from the group consisting of O, MnO, CoO, and NiO, 0.5 to 10%, Nb ₂ O ₅ , Ta ₂ O _5, and Sb ₂
One or more selected from the group of O ₅ 2 to 18%, CaO, S
One or more selected from the group consisting of rO and BaO, and 0 to 7%.

[0007]

The lead titanate solid solution used as the refractory powder in the low expansion sealing material of the present invention has a coefficient of thermal expansion originally lower than that of lead titanate. Such a lead titanate solid solution is basically composed of Pb _1-X Ca _X TiO ₃ [where 0 <X <0.5] (Pb _1-X , Ca _X ) {Ti _1-Y (Fe _2/3 W _1/3 ) _Y } O ₃ [however 0
<X <0.5, 0 <Y <0.5] Pb _1-X (Ca, Sr, Ba) _X Ti _1-Y {Fe _1/2 (Nb, Ta, Sb) _1/2 } _Y O ₃
[However, 0 <X <0.5, 0 <Y <0.7] Pb _1-X (Ca, Sr, Ba) _X Ti _1-Y {Zn, Mg, Mn, Co, Ni) _1/3 (Nb , T
a, Sb) _2/3 } _Y O ₃ [where 0 <X <0.5, 0 <Y <0.
7], a good refractory powder can be obtained even if the composition of the solid solution deviates slightly from the above stoichiometric value. However, if the ratio of each component deviates from the above composition range, the coefficient of thermal expansion increases,
It is not preferable because it is no different from ordinary lead titanate.
The average particle size of the lead titanate solid solution powder is preferably about 10 μm or less in consideration of workability during screen printing.

In the low expansion sealing material of the present invention, the glass used as the glass powder has a transition point of 330 to 43.
It is at 0 ° C. By using such a glass, it becomes possible to obtain a sealing material which has heat resistance to withstand reheating at 350 to 450 ° C. and which can be sealed at a temperature of 650 ° C. or lower. The reason why the glass transition point range is limited as described above is that the heat resistance of the sealing material is lower than 350 ° C when the transition point is lower than 330 ° C, while the glass transition temperature is higher than 430 ° C. Temperature is 650 ℃
This is because the sealing material has no practical value as described above.

As the glass powder to be used, various kinds of glass can be used. For example, in% by weight, PbO 50 to 85 is used.
%, B ₂ O ₃ 5 to 25%, SiO _{2 0 to} 15%, Al ₂
O ₃ 0-15%, ZnO 0-20%, CuO 0-1
0%, Bi ₂ O ₃ 0 to 25%, Fe ₂ O ₃ 0 to 10%,
It can be used PbO-B ₂ O ₃ -based glass consisting BaO 0 to 5% of the composition.

In the present invention, the mixing ratio of the glass powder and the lead titanate solid solution powder is limited to 50 to 95% by volume of the glass powder and 5 to 50% by volume of the lead titanate solid solution powder. When the glass powder is less than 50% (that is, when the lead titanate solid solution powder is more than 50%), a sealing material having good fluidity cannot be obtained, and when the glass powder is more than 95% (that is, titanic acid is used). When the lead solid solution powder is less than 5%), a sealing material having a low coefficient of thermal expansion cannot be obtained.

In the low-expansion sealing material of the present invention, in order to increase the strength of the sealing material, in addition to the lead titanate solid solution powder, a refractory powder such as zircon or tin oxide is added.
It is possible to contain up to 0% by volume.

[0012]

EXAMPLES The low-expansion sealing material of the present invention will be described below based on Examples and Comparative Examples.

(Example) Tables 1 and 2 show lead titanate solid solution powders (Sample Nos. A to p) used in this example.
Is shown.

[0014]

[Table 1]

[0015]

[Table 2]

Each lead titanate solid solution powder was prepared as follows. List litharge, titanium oxide, ferric oxide, tungsten oxide, zinc white, magnesia, manganese dioxide, cobalt oxide, nickel oxide, niobium pentoxide, tantalum pentoxide, antimony pentoxide, calcium carbonate, strontium carbonate, barium carbonate The composition shown in the table was prepared, dry mixed in a ball mill, and then fired under the conditions shown in the table. Then, the fired product was crushed and passed through a 350-mesh sieve to obtain a powder having an average particle size of about 5 μm.

Table 3 shows low melting point glass powders (Sample Nos. A to D) used in this example.

[0018]

[Table 3]

Each glass powder was prepared as follows.
Lead tin oxide, boric acid, silica stone powder, alumina, zinc white, cupric oxide,
Bismuth oxide, ferric oxide, and barium carbonate were blended so as to have the compositions shown in the table, put in a platinum crucible, melted at 1200 ° C. for 3 hours in an electric furnace, and then molded into a thin plate. Further, the obtained molded product is crushed with a ball mill and 2
It was passed through a 00 mesh sieve to obtain a glass powder having an average particle size of about 7 μm. The glass powder thus obtained is
Transition point 342-400 ° C, yield point 362-430
C., 30 to 300.degree. C. thermal expansion coefficient is 81 to 106
It was × 10 ^-7 / ° C.

Tables 4 and 5 show examples of the present invention (sample Nos. 1 to 18) produced by using the lead titanate solid solution powders of Tables 1 and 2 and the glass powders of Table 3. There is.

The synthetic zircon powder and tin oxide in the table were prepared as follows.

Synthetic zircon is obtained by decomposing natural zircon sand with soda, dissolving it in hydrochloric acid, and repeating concentration crystallization to obtain zirconium oxychloride, which is an α-ray emitting substance having extremely small amounts of U and Th, and is then dissolved in an alkali. After the addition, the mixture was heated to obtain purified ZrO ₂ . Then this purified Z
High-purity silica stone powder and ferric oxide are added to rO ₂ in a weight ratio of ZrO ₂
The composition was 66%, SiO ₂ 32%, and Fe ₂ O ₃ 2%. Then, after firing at 1400 ° C. for 16 hours, the fired product was crushed and passed through a 250-mesh stainless sieve.

Tin oxide is stannic oxide and zinc white as a sintering aid, in terms of weight percentage, SnO ₂ 99%, ZnO.
Formulate to 1%, dry mix, and 1 at 1480 ℃
After firing for 6 hours, it was ground and passed through a 350-mesh screen.

[0024]

[Table 4]

[0025]

[Table 5]

For each sample thus prepared,
The sealing temperature, thermal expansion coefficient and heat resistance were evaluated.

The sealing temperature was determined by performing a flow button test. That is, a powder having a weight corresponding to the true specific gravity of each sample was molded into a button having an outer diameter of 20 mm and a height of about 5 mm by using a mold, and then the powder was placed on a glass plate and heated at a rate of 10 ° C./min in an electric furnace. The temperature was raised by, and the mixture was heated at various temperatures for 10 minutes. The temperature when the outer diameter of the softened and fluidized button reached 22 mm was defined as the sealing temperature. The coefficient of thermal expansion is
Each sample was molded into a size of 4φ × 40 mm, and the thermal expansion coefficient at 30 to 250 ° C. was measured by a quartz push rod type thermal dilatometer. The heat resistance is that the sample powder is once softened and fluidized by heating at the sealing temperature and then reheated while gradually raising the temperature in vacuum, and when the temperature rises to 350 ° C, foaming from the surface of the sample occurs. What did not occur is good, 350
Those in which foaming occurred at a temperature of less than 0 ° C were regarded as unacceptable.

As is clear from the table, the sample No. which is an example of the present invention. 1 to 18 have a sealing temperature of 470 to 590.
Thermal expansion coefficient at 41 ° C, 30 to 250 ° C is 41 to 60 ×
It was 10 ⁻⁷ / ° C., and the heat resistance was good.

Comparative Example 1 Lisage and titanium oxide were
The composition was such that PbO was 73.6% and TiO _{2 was} 26.4% by weight, and the mixture was dry-mixed and then fired at 1100 ° C. for 5 hours.

Then, the fired product was pulverized and passed through a 350-mesh sieve to obtain a lead titanate powder having an average particle size of 5 μm.

A sample was obtained by mixing 30% by volume of the lead titanate powder with 70% by volume of the glass powder (Sample No. A) used in the examples.

The sample thus obtained was evaluated for sealing temperature, coefficient of thermal expansion and heat resistance in the same manner as in Example. The sealing temperature was 530 ° C. and the heat resistance was also good. However, the coefficient of thermal expansion was large at 65 × 10 ⁻⁷ / ° C.

(Comparative Example 2) PbO 84.
3%, B ₂ O ₃ 11.9%, ZnO 2.8%, SiO
_{2 A} glass raw material was prepared so as to have a composition of 1.0%, put into a platinum crucible, melted at 1000 ° C. for 3 hours in an electric furnace, and then formed into a thin plate. Further, the obtained molded product was crushed by a ball mill and passed through a 200-mesh sieve to obtain a glass powder having an average particle size of about 7 μm. The transition point and yield point of the glass powder thus obtained, and 30
The coefficient of thermal expansion at ˜250 ° C. was 300 ° C., 325 ° C. and 110 × 10 ⁻⁷ / ° C., respectively.

Next, 65% by volume of the obtained glass powder and the lead titanate powder (Sample No. m) used in the examples,
A sample was obtained by mixing at a ratio of 35% by volume.

The sample thus obtained was evaluated for sealing temperature, thermal expansion coefficient and heat resistance in the same manner as in Example. The sealing temperature was 430 ° C., which was lower than that of Example. I was able to wear it. The coefficient of thermal expansion is 5
The value was 3 × 10 ⁻⁷ / ° C., which was equivalent to that of the example. However, when the heat resistance was evaluated, it was found that the heat resistance was low because foaming occurred by reheating at 340 ° C. or higher.

[0036]

As described above, the low-expansion sealing material of the present invention can be sealed at 650 ° C or lower and can have a low coefficient of thermal expansion. Moreover, it has heat resistance to withstand reheating at 350 to 450 ° C., and is suitable as a sealing material for electronic parts, particularly semiconductor devices, fluorescent display tubes, silicon diodes and the like.

Claims (2)

(57) [Claims] 1. A glass powder having a transition point of 330 to 430.degree. C. of 50 to 95% by volume and a lead titanate solid solution powder of 5 to 50% by volume, wherein the lead titanate solid solution powder is (a) PbO 55-73%, CaO 0.5-12
%, TiO ₂ 26-35%, (b) PbO 65-75%, TiO ₂ 10-25
%, Fe ₂ O ₃ 1-10%, WO ₃ 1-12%, Ca
O 0-5%, (c) PbO 60-73%, TiO ₂ 2-23%,
Fe ₂ O ₃ , ZnO, MgO, MnO, CoO and NiO
One or more selected from the group of 0.5 to 10%, Nb ₂ O ₅ ,
One or more selected from the group of Ta ₂ O ₅ and Sb ₂ O ₅ 2-1
8%, CaO, 1 or more 0-7% selected from the group consisting of SrO and BaO, low expansion sealing material characterized in that it consists of any of the compositions. 2. A glass powder, in% by weight, of PbO 50.
_{~85%, B 2 O 3 5~25} %, SiO 2 0~15%,
Al ₂ O ₃ 0-15%, ZnO 0-20%, CuO
0 to 10%, Bi ₂ O ₃ 0 to 25%, Fe ₂ O ₃ 0-1
0%, low expansion sealing material according to claim 1, characterized in that it consists of BaO 0 to 5% of the composition.