JP3425751B2 - 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%, _{5 to} 50% of Ag2O, 30 to 80 of AgI.
%, Ag ₂ O + AgI ≦ 85%, P ₂ O ₅ + GeO ₂ + WO
Characterized by comprising the ₃ 10-50%. 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 5%, or when the content of AgI is less than 30%, the viscosity of the low melting point composition becomes high and the chemical durability is lowered. On the other hand, when Ag ₂ O is more than 50% or when AgI
If it is more than 80%, it becomes difficult to melt. Also Ag
₂ the total amount of O and AgI is Ru is limited to 85%. P ₂ O ₅ , GeO ₂ and WO ₃ are Ag ₂ O and A
It is the main component of the low melting point composition together with gI. If the total amount of these components is less than 10%, it becomes difficult to melt, and
Viscous than 0% more low melting point composition that a high. By the way, the low melting point composition having the above composition has a very large thermal expansion coefficient at 30 to 150 ° C. (or 200 ° C.) of 150 to 220 × 10 ⁻⁷ / ° C. High 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. Crystals prepared as follows were used as the low melting point composition powder. Ag ₂ O 30% in mole%, AgI 50
%, A composition of 20% GeO ₂ , silver oxide,
Silver iodide and germanium oxide were mixed and melted at 500 ° C. for 1 hour using a platinum crucible. Next, when the melt was poured out onto a mold, it turned into crystals during cooling. Further, this crystal was pulverized and passed through a 250-mesh sieve to obtain a crystal powder having an average particle diameter of 7 μm. This crystalline product had a melting point of 300 ° C. and a coefficient of thermal expansion at 30 to 200 ° C. of 150 × 10 ⁻⁷ / ° C. As the refractory substance powder, a lead titanate powder was used. The lead titanate powder is prepared by mixing litharge and titanium oxide so as to have a composition of PbO.TiO _2.
After firing at 00 ° C. for 5 hours, the powder was pulverized to obtain a powder having an average particle size of 5 μm. Next, 60% by volume of the crystalline powder and 40% by volume of the lead titanate powder were mixed to obtain a sample. By heating the sample thus obtained at 330 ° C. for 10 minutes, the crystal re-melts, wets the sealed object, and then precipitates again during cooling. Was 77 × 10 ⁻⁷ / ° C. When a package made of alumina (coefficient of thermal expansion: 70 × 10 ⁻⁷ / ° C.) was sealed using this sample, 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. As described above, the sealing material of the present invention does not contain any toxic substances, and does not apply any 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;
It is a mixture of 10 to 55 vol% refractory material powder, low melting point composition powder in mol%, Ag ₂ O 5 to 50%, A
gI 30-80%, Ag ₂ O + AgI ≦ 85%, P ₂ O
₅ + sealing material characterized in that it consists of GeO ₂ + WO ₃ 10~50%.