JP3425749B2 - Sealing material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material, and more specifically, to a hermetic sealing of a package mounted with a heat-sensitive element such as a semiconductor integrated circuit and a quartz oscillator. The present invention relates to a sealing material suitable for wearing. 2. Description of the Related Art A sealing material using low-melting glass is used for hermetic sealing of a highly reliable package on which elements such as a semiconductor integrated circuit and a quartz oscillator are mounted. Conventionally, as a sealing material, PbO-B ₂ O ₃ -based glass powder to which a low-expansion refractory substance powder such as lead titanate, willemite or the like is added is widely known. Since it is difficult to reduce the sealing temperature of the used sealing material to 400 ° C. or lower, the characteristics may be deteriorated depending on the element. [0004] Under these circumstances, development of a sealing material which can be sealed at a lower temperature has been advanced in recent years. For example, Kohyo Sho _{63-502583, PbO-V 2 O 5} -Bi
A sealing material using ₂ O ₃ -based glass is disclosed, and JP-A-63-315536 discloses PbO-Tl ₂ O-B ₂ O.
Sealing materials using ₃ based glass is disclosed. [0005] The above-mentioned Japanese Patent Publication No. Sho 63-50
The sealing material disclosed in No. 2583 can lower the sealing temperature to about 330 ° C. However, in order to seal at such a low temperature, a considerable load must be applied by a metal clip or the like at the time of sealing.
On the other hand, the sealing material of JP-A-63-315536 can also have a sealing temperature of about 330 ° C., but contains a large amount of highly toxic Tl ₂ O. There is a practical problem, such as the need for equipment to prevent the scattering of dust. An object of the present invention is to provide a sealing material which does not contain a toxic substance and which can seal a package at a temperature of 330 ° C. or less without applying a load. The sealing material of the present invention comprises 45 to 90% by volume of a low melting point composition powder and 1 part of a refractory substance powder.
0 to 55% by volume, and the low melting point composition powder is in mol%, _{20 to} 50% of Ag2O, 5 to 30 of AgI.
_{%, P 2 O 5 20~50%} , PbO + ZnO + CuO
It is characterized by comprising 0-15%. In the sealing material of the present invention, the low melting point composition takes any form of an amorphous glass, a crystalline glass, and a crystal. Amorphous glass and crystalline glass have a transition point of 150
It is very low at ~ 230 ° C and flows sufficiently when heated at 300-330 ° C. The crystalline material has a very low melting point,
It remelts by heating at 330 ° C. to become a low viscosity liquid. The crystalline material is obtained by first melting the raw material, then cooling it to precipitate a crystal, and then pulverizing the crystal. The reason why the composition range of the low melting point composition in the sealing material of the present invention is limited as described above will be described below. [0010] Ag ₂ O and AgI are the main components of the low melting point composition, and are very insoluble in water, so that they have the effect of increasing the chemical durability of the composition. When the content of Ag ₂ O is less than 20% or the content of AgI is less than 5%, the viscosity of the low melting point composition increases and the chemical durability decreases. On the other hand, when Ag ₂ O is more than 50% or when AgI
When but more than 30 percent of financial liquefaction difficult ing. P ₂ O ₅ is a main component of the low melting point composition together with Ag ₂ O and AgI. 20% of P ₂ O ₅ components in total
Fewer and melt liquefaction becomes difficult, that a high viscosity of the low melting point composition is more than 50%. PbO, ZnO and CuO are effective in increasing the stability of the low melting point composition, improving the chemical durability, and reducing the coefficient of thermal expansion. These components may turn high viscosity of the low melting point composition and more than 15%. The low melting point composition having the above composition has a very high coefficient of thermal expansion at 30 to 150 ° C. (or 200 ° C.) of 150 to 220 × 10 ⁻⁷ / ° C., and Insufficient mechanical strength. Therefore, it is necessary to adjust the coefficient of thermal expansion so as to be compatible with the package to be sealed or to increase the mechanical strength. The sealing material of the present invention is obtained by mixing a powder of the low melting point composition with a powder of a refractory substance, so that a thermal expansion coefficient suitable for a package to be sealed can be obtained. In addition, it has sufficient mechanical strength. Among the refractory materials, those which mainly lower the coefficient of thermal expansion include NbZr (PO ₄ ) ₃ and Sr _0.5 Z
NaZr ₂ (PO ₄ ) ₃ type solid solution such as r ₂ P ₃ O ₁₂ , lead titanate and its solid solution, willemite, cordierite,
Zircon, tin oxide, β-eucryptite, zirconium phosphate, niobium pentoxide, quartz glass, mullite, aluminum titanate and the like can be used. In addition, alumina, zirconia, titania, zinc stannate,
Magnesia, quartz, spinel, garnite and the like can be used. The refractory material powder as described above is
Two or more kinds may be used as a mixture. Next, the reason why the mixing ratio of the low melting point composition powder and the refractory substance powder in the sealing material of the present invention is limited as described above will be described below. When the low melting point composition powder is more than 90% by volume, that is, when the refractory substance powder is less than 10% by volume, the above effects cannot be obtained. On the other hand, when the low melting point composition powder is less than 45% by volume, that is, when the refractory substance powder is more than 55% by volume, the sealing material does not flow. EXAMPLES The sealing material of the present invention will be described below with reference to examples. Example 1 As a low melting point composition powder, an amorphous glass powder prepared as follows was used. Ag ₂ O 40% in mole%, AgI 20
_{%, P 2 O 5 35%} , such that the CuO 5% of the composition, silver oxide, silver iodide, orthophosphoric acid, copper phosphate mixed,
It was melted at 700 ° C. for 2 hours using a platinum crucible and vitrified. Next, after molding this molten glass, it was pulverized and passed through a 250-mesh sieve to obtain glass powder having an average particle diameter of 7 μm. The obtained glass powder has a transition point of 155 ° C., 30 to
The coefficient of thermal expansion at 150 ° C. was 210 × 10 ⁻⁷ / ° C. As the refractory substance powder, Ca _0.3 P
A lead titanate solid solution powder having a composition of b _0.7 TiO ₃ was used. The lead titanate solid solution powder is Ca _0.3 Pb _0.7
Calcium carbonate, litharge, and titanium oxide were mixed to obtain a TiO ₃ composition, fired at 1200 ° C. for 5 hours, and then pulverized to obtain a powder having an average particle diameter of 5 μm. Next, 55% by volume of glass powder and 45% by volume of lead titanate solid solution powder were mixed to obtain a sample. The sample thus obtained has a sealing temperature of 300 ° C.
The coefficient of thermal expansion at 0 ° C. was 75 × 10 ⁻⁷ / ° C. Using this sample, alumina (thermal expansion coefficient)
When a lid type IC package made of 70 × 10 ⁻⁷ / ° C.) was sealed, a highly airtight sealed product was obtained. The transition point and the coefficient of thermal expansion were determined using a quartz push rod type thermal dilatometer. (Example 2) The amorphous glass powder prepared in Example 1 was used as the low melting point composition powder, and β-eucryptite powder was used as the refractory substance powder. A sample was prepared by mixing at a rate of 42%. The obtained sample had a sealing temperature of 300.degree.
The coefficient of thermal expansion at 0 to 150 ° C. is 110 × 10 ⁻⁷ / ° C.
Met. Using this sample, forsterite (2M
When a package made of gO.SiO ₂ and a coefficient of thermal expansion of 110 × 10 ⁻⁷ / ° C.) was sealed, a highly airtight sealed product was obtained. The β-eucryptite powder is prepared by converting lithium carbonate, alumina and silica to Li ₂ O.Al ₂ O ₃ .2S
After mixing so as to have a composition of iO ₂ and firing at 1400 ° C. for 10 hours, a powder having an average particle diameter of 5 μm was used. As described above, the sealing material of the present invention does not contain any toxic substances and can be used without applying a load.
Since sealing can be performed at an extremely low temperature of 0 to 330 ° C., it is suitable for sealing a package on which a semiconductor integrated circuit or a crystal oscillator which is sensitive to heat is mounted.

Claims (1)

(57) [Claims 1] 45 to 90% by volume of a low melting point composition powder;
10 to 55% by volume of the refractory material powder is mixed, and the low melting point composition powder is 20% to 50% by mole of Ag ₂ O,
_{AgI 5~30%, P 2 O 5} 20~50%, PbO +
A sealing material comprising ZnO + CuO 0 to 15%.