JPH08719B2 - Sealing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is made by mixing a filler having improved properties with glass, and is suitable for sealing electronic parts such as semiconductor devices, fluorescent display tubes, and laser diodes. It relates to the sealing material.

[Prior Art] As a sealing glass having a lower melting point than before, PbO4 is used in a weight percentage.
0~90%, B ₂ O ₃ consisting of 8~15% PbO-B ₂ O ₃ based glass and PbO
PbO-Zn consisting of 70-85%, ZnO 0.5-7%, B ₂ O ₃ 7-15%
O-B ₂ is O ₃ based glass are known, in general the thermal expansion coefficients of these glasses are the 90 × 10 ^-7 / ℃ above, these thermal脹張coefficient 40~80 × 10 ^-7 / ℃ When sealing with the object to be sealed, large stress will be generated in the low melting point glass after sealing, and it will cause cracks and cracks, so a low expansion filler is mixed in the glass and the coefficient of thermal expansion is adjusted to match that of the object to be sealed. The material is mainly used.

There are various types of low expansion fillers, for example, zircon, willemite, cordierite, lead titanate, β-eucryptite, tin oxide and the like, and one or more of them are low melting point glass. To be used. However, the larger the amount of filler added, the greater the effect of lowering the coefficient of thermal expansion. , It is important to select according to the application.

Among the above-mentioned various fillers, lead titanate has a particularly low coefficient of thermal expansion, and it has a large effect of lowering the coefficient of thermal expansion even if the amount added is small, and various sealing materials using it have been proposed conventionally. .

For example, JP-A-49-89713 discloses a sealing material in which glass is mixed with lead titanate powder having a specific surface area diameter of 10 μm or less. JP-A-58-151374 discloses a low-melting glass powder and lead titanate. Powders, zircon powders, and tin substance powders for low melting point and low expansion adhesive compositions are shown, respectively, and JP-A-62-256741.
The publication discloses a sealing material obtained by substituting a part of Pb of lead titanate with Ca.

[Problems to be Solved by the Invention] However, each of the above-mentioned sealing materials has a problem. That is, the sealing material of JP-A-49-8971 has a thermal expansion coefficient of 5
Since it is large at 4.5 × 10 ^-7 / ℃ or more, for example, borosilicate glass (coefficient of thermal expansion 40 to 50 × 10 ^-7 / ℃) and Kovar (coefficient of thermal expansion 45
~ 50 × 10 ^-7 / ℃) is not suitable for use in sealing. In the case of lead titanate, the larger the particle size of the filler, the greater the effect of lowering the coefficient of thermal expansion.
The low melting point, low expansion adhesive composition of No. 1374 uses a lead titanate powder having an average particle size of 15μ or more, so the coefficient of thermal expansion is sufficiently small, but on the other hand, workability in screen printing in paste form The problem arises that is worse. Further, there is a problem that microcracks are likely to occur in the glass around the filler. The sealing material of JP-A-62-256741 has a low coefficient of thermal expansion even when the particle size of the filler is small, and the generation of microcracks is reduced, but a sealing material without the generation of microcracks is obtained. It is not possible.

The object of the present invention is to have a small average particle size, more specifically 15
It is an object of the present invention to provide a sealing material which uses a filler of μ or less and can sufficiently reduce the thermal expansion coefficient with a small addition amount, does not generate microcracks in glass, and can be further sealed at 450 ° C. or lower. .

[Means for Solving the Problem] The present inventors have found that when Fe ₂ O ₃ , WO _{3 and} preferably CaO are dissolved in PbTiO ₃ crystal, the coefficient of thermal expansion becomes lower than that of general PbTiO ₃ . . Sealing material of the present invention when taken on this basis, in _{weight% PbO65~75, TiO 2 10~25, Fe} 2
It is characterized in that lead titanate-based ceramics composed of O ₃ 1 to 10, WO ₃ 1 to 12 and CaO 0 to 5 is mixed with glass as a filler.

The most preferred form of the filler of the present invention is a crystal having a perovskite structure by replacing part of PbTiO ₃ by _{Pb (Fe 2/3 W 1} /3) O 3 and CaTiO _3, the crystal chemical (Pb
_{1 -x, Cax) {Ti 1} -y (Fe 2/3 W 1/3) y} O 3 and it is intended to be expressed, may not necessarily be the stoichiometric ratio, some deviation It does not impair the properties as a filler. However, if the ratio of each component deviates from the above range, the thermal expansion coefficient of the filler becomes equal to or higher than that of ordinary lead titanate, which is not preferable.

The filler of the present invention has a remarkably low coefficient of thermal expansion, and despite a large difference from that of glass, unlike the sealing material obtained by substituting a part of Pb of lead titanate with Ca described above, The reason why microcracks do not occur in glass is not because the filler of the present invention replaces TiO ₂ with Fe ₂ O ₃ and WO ₃ and thus the content of TiO ₂ in the filler becomes smaller than that of the sealing material. It seems that That is, it is presumed that the filler of the present invention becomes an elastically soft material as a result of the decrease in the TiO ₂ content, and the stress around the filler is relaxed, so that microcracks do not occur.

In the present invention, other fillers such as zircon, tin oxide, β-eucryptite, cordierite, willemite, and mullite may be used together for the purpose of improving mechanical strength.

[Examples] The present invention will be described below based on Examples.

Table 1 shows examples of fillers in the present invention (Sample No. 1).
~ 5) and normal PbTiO3 with an average particle size of about 20 μm (Sample No.
6) is shown.

The fillers shown in Table 1 were prepared by mixing litharge, titanium oxide, ferric oxide, tungsten oxide, and calcium carbonate as raw materials so as to have the composition shown in Table 1, dry-mixing, and baking at 1100 ° C for 5 hours. did. The fired product thus obtained was pulverized and then passed through a 350-mesh sieve to have an average particle size of about 5 μm.

Table 2 shows examples of the glass according to the present invention.

The glass shown in Table 2 was prepared by mixing red lead, boric acid, silica powder, alumina, zinc white, and lead fluoride into the composition shown in the table, putting them in a platinum crucible, and melting them in an electric furnace at 800 ° C for 1 hour. After that, it was formed into a thin plate. The obtained molded product was then crushed with a ball mill and passed through a 200 mesh screen.

Table 3 is an example showing a sealing material in which the glass in Table 2 is mixed with the filler in Table 1 and other fillers.

The sealing material in Table 3 was prepared by mixing glass and filler in the proportions shown in Table 3 and kneading it well with a vehicle in which 5% acrylic resin was dissolved in terpineol to form a paste, and then placing it on the screen. Screen-printed on the object to be sealed with a squeegee. All the samples of Nos. 1 to 15 had good screen printing workability. The sealing temperature of all samples was as low as 410-450 ℃. However, regarding the crack generation, in the sealing material of Sample No. 11 using normal lead titanate as a filler, a large number of cracks are generated, but in the sample containing the filler of the present invention, the sealing material is sealed. No cracks were observed on the glass after it was worn.

For comparison, the number of cracks in the sealing material of JP-A No. 62-256741 was examined. As a result, the cracks of Sample Nos. 1 to 5 described in Table 3 of the publication were found. The numbers were 1,3,3,2,3, respectively.

Incidentally, the number of cracks, at various points on the surface after firing of each sealing material, using a microscope of 100 times, the number of cracks in 1mm square is counted, it is expressed by taking the average thereof. .

The zircon used as other fillers in Table 3 is
ZrO _{2 in} which wt% of zirconia, silica glass powder for optical glass, and ferric oxide, in which U and Th are removed and the amount of α-ray emission is extremely reduced, is used
66.9%, SiO ₂ 31.2%, Fe ₂ O ₃ 1.9% were mixed and mixed, and then calcined at 1400 ° C for 16 hours. The calcined product was crushed and passed through a 350 mesh sieve. I was there.

In addition, tin oxide is prepared by mixing tin oxide and zinc white so that SnO ₂ 99.0% and ZnO 1.0% by weight, and calcining at 1450 ° C for 16 hours, crushing this calcined product and sieving with a 350 mesh sieve. The one that was passed was used.

Beta eucryptite is made by mixing and mixing lithium carbonate, alumina, and stone powder for optical glass so as to have a composition of Li ₂ O ・ Al ₂ O ₃・ 2SiO ₂ and calcination at 1250 ° C for 5 hours. The one that passed through a 250-mesh stainless sieve was used.

As the cordierite, one produced by a method of crystallizing glass was used. That is, magnesia, alumina, and stone powder for optical glass were mixed and mixed in a stoichiometric ratio of 2MgO · 2Al ₂ O ₃ · 5SiO ₂ and melted in a platinum crucible at 1580 ℃ for 4 hours to obtain a thin glass plate. After forming into a shape, 150
The powder was crushed so as to pass through a mesh stainless sieve, and further heated at 1000 ° C. for 12 hours to crystallize cordierite.

Willemite is made of zinc flower, 2ZnO stone powder for optical glass.
The mixture was prepared and mixed so as to have a composition of SiO ₂ , and the mixture was baked at 1400 ° C. for 16 hours, pulverized, and passed through a 250 mesh sieve.

Mullite was prepared by mixing and mixing kaolin, alumina, and magnesia so as to have a composition of Al ₂ O ₃ 71.1%, SiO ₂ 27.9%, and MgO 1.0% by weight, and calcinated at 1700 ° C for 16 hours and then pulverized And passed through a 150 mesh screen.

[Effects of the Invention] As described above, the sealing material of the present invention has a large effect of lowering the coefficient of thermal expansion even if the particle size of the filler is made small, so that the addition amount can be made small and the particle size can be made small at the time of screen printing. Is excellent in workability, can be sealed at 450 ° C. or lower, and is unlikely to cause myocracks in the glass, which is particularly suitable for sealing electronic parts.

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Claims (2)

[Claims] 1. A sealing material comprising a mixture of a low melting point glass powder and the low expansion of the filler, the filler in _{weight% PbO65~75, TiO 2 10~25, Fe} 2 O 3 1~10, WO ₃ 1 to 12, C
A sealing material comprising lead titanate-based ceramics composed of aO0-5. 2. The sealing material according to claim 1, wherein the mixture further contains at least one of zircon, tin oxide, β-eucryptite, cordierite, willemite and mullite as another filler. A sealing material comprising a powder.