JPH0436096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing antimony trioxide that emits extremely low amounts of α-ray radiation.

[Conventional technology]

BACKGROUND ART In recent years, with the miniaturization of integrated circuits, malfunctions (soft errors) of integrated circuits due to alpha rays emitted from the sealing material of integrated circuits have become a major problem.

There are various ways to encapsulate integrated circuits, including metals, ceramics, and plastics, mainly made of epoxy resin.However, in recent highly integrated circuits, plastics have become mainstream due to cost considerations. be.

When plastics are used to encapsulate integrated circuits,
It is necessary to make this flame retardant, and antimony trioxide is used for this purpose.

Conventionally, as a method for producing the above-mentioned antimony trioxide for flame retardant, a method of volatilizing and oxidizing antimony sulfide or crude antimony has been used. Because the substance is not removed sufficiently,
The α-ray radiation amount was 1 to 0.01 counts/cm ² ·Hr (hereinafter abbreviated as C/cm ² ·Hr).

If the degree of integration (number of memories) of the integrated circuit is 64 kilodynamic rams (hereinafter abbreviated as KDRAM) or less, it can still be used, but if the degree of integration is more than the above, for example 256KDRAM, α
It is said that a radiation dose of about 0.01 to 0.005 C/cm ² ·Hr is required, and conventional products cannot be used as they are in highly integrated systems.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for easily producing antimony trioxide that can be used for highly integrated circuits.

[Means for solving problems]

In order to achieve this objective, the inventor of the present application has conducted intensive research and found that if crude antimony is crushed into 60 mesh or less and then brought into contact with chlorine gas at a predetermined temperature,
Focusing on the fact that antimony chloride can be easily produced with an exothermic reaction, the antimony chloride thus obtained was either directly hydrolyzed with a large amount of water, or
Alternatively, it was discovered that when the above-mentioned antimony chloride is dissolved in a small amount of water and then distilled, and the resulting distilled antimony chloride is hydrolyzed with water, a product with an α-ray emission amount of 0.01 C/cm ² ·Hr or less can be obtained.The present invention has been reached.

That is, the method of the present invention involves pulverizing crude antimony containing an α-ray emitting substance, preferably 60 mesh or less.
After reducing the mesh size to 100 g or less, the sample is kept at 100°C or higher, and an equivalent or more, preferably 1.5 equivalent or more, of chlorine gas is bubbled therethrough at a substantially uniform flow rate for at least 30 minutes, preferably about 1 hour per 100 g of the sample. , the resulting distillate is collected and hydrolyzed by adding a large amount of water, or the distillate is dissolved by adding a small amount of water and distilled at 135-230℃,
It is characterized by adding a large amount of water to the distilled product for hydrolysis.

The antimony trioxide produced by hydrolysis is washed multiple times with hot water at 60°C or higher, separated into solid and liquid, and dried to produce a product.

[Effect]

In the method of the present invention, the raw material is set to 60 meshes or less, preferably 100 meshes or less, in order to improve the reaction efficiency, and if the raw material is coarser than this, the amount of chlorine gas used increases, which is undesirable. .

The reason why the reaction with chlorine gas is carried out at 100°C or higher at a substantially uniform flow rate per 100 g of sample for 30 minutes or more, preferably about 1 hour, and using at least an equivalent amount, preferably at least 1.5 equivalents, is due to the reaction with antimony. The reaction proceeds efficiently to produce antimony chloride with a lower content of alpha-ray emitting substances than the crude metallic antimony raw material, and by hydrolyzing this antimony chloride, antimony trioxide with a low alpha-ray emission amount can be obtained. This is what I did.

In this process, excess chlorine gas is discharged into the atmosphere through an alkaline solution and a washing tower.

Antimony chloride obtained in the first step is 135 to 230
The reason why the distillation is preferably carried out at 200 to 230°C is to prevent low-temperature distillates such as water, hydrochloric acid, and arsenic, and relatively high-temperature distillates such as sulfur and lead from contaminating the antimony chloride. This is for the purpose of Therefore, if the yield is important even if the purity of the product is slightly reduced, the distillation temperature should be 135 to 200℃, and if you want to obtain a product with higher purity, the distillation should be collected in the temperature range of 200 to 230℃. In both cases, the temperature is kept at about 70°C to prevent antimony chloride from solidifying during the distillation and in the receiving vessel.

Incidentally, since the distillate at a temperature of 135°C or lower is water, hydrochloric acid, etc., the distillate is cooled with water until the temperature reaches 135°C, and the obtained hydrochloric acid, etc. are collected separately. The amount of water used when hydrolyzing antimony chloride is 10 by volume in the case of SbC ₃ obtained by oxidizing with chlorine gas.
If it is further distilled, the volume is 20 times or more.
However, sufficient hydrolysis cannot be achieved unless the temperature is 60°C or higher.

Since the purpose of the present invention is to obtain a product with high purity, careful attention must be paid to the water and containers used, especially the water used for hydrolysis and washing.
It is desirable to use one with a resistance of 5MΩ or more.

According to the present invention, although the process is short, it is highly pure and has a low α-ray emission amount, with a scintillation counter value of 0.01 C/cm ² ·Hr or less.

〔Example〕

Examples will be described below.

Example 1 300 g of crude antimony with a particle size of 100 mesh or less (JIS sieve) and 99.80% by weight of Sb was charged into the combustion tube of a horizontal annular furnace, the temperature inside the furnace was maintained at 150°C, and 2 equivalents of chlorine to Sb was charged. Gas (cylinder gas) was introduced at a uniform flow rate for 3 hours. During this time, the temperature outside the furnace at the outlet was 70℃.
The receiving vessel was kept at room temperature and 531 g of antimony chloride was obtained.

During the operation, the reaction gas passed through a 10% by weight aqueous sodium hydroxide solution and then through a washing tower and was discharged into the atmosphere.

Next, 200g of the above antimony chloride was placed in a beaker 5, and 5MΩ ionized water 5 was added thereto, heated on a heater while stirring with a propeller type stirrer, and kept at 95-98°C for 1 hour. Afterwards, suction filtration was carried out, and the obtained cake was similarly divided into 5
The cake was transferred to a beaker, added with the same ionized water 5, and stirred at the above temperature for 30 minutes to perform repulsion washing twice. The cake was vacuum dried at 70 to 100°C for 24 hours, yielding 121 g of antimony trioxide. It was done.

The purity of antimony trioxide was determined by the impurity subtraction method, and it was 99.92% by weight, and the amount of α-ray radiation was 0.005C/
cm ² ·Hr, average particle size (F.SSS) 3.65 μm, and the calculated actual binding yield was about 90%.

Example 2 Take 155 g of antimony trioxide obtained in Example 1 into a beaker, add 16 ml of the ionized water (hereinafter simply referred to as ionized water) used in Example 1 to make an aqueous solution, and add this to a beaker with a condenser. After the beaker residue was washed with a small amount of water and transferred to the flask, a distillation apparatus was set and atmospheric pressure distillation was carried out while heating the flask with a mantle heater and adjusting the temperature.

Water is distilled out at a distillation temperature of 105 to 110℃, and when the temperature rapidly rises to 200℃, replace the receiving container.
Thereafter, distillation was carried out at 200 to 220°C until the flask was dry, and 140 g of antimony chloride was obtained.

During the first half of the distillation operation, the distillate was cooled with water, and during the second half, the distillate was kept warm at 70°C.

The entire amount of antimony chloride thus obtained was hydrolyzed in the same manner as in Example 1, followed by repulp washing and drying to obtain 85 g of antimony trioxide.

As a result of the measurement, the scintillation counter value
Satisfactory results were obtained: 0.003 C/cm ² ·Hr, purity 99.95% by weight, average particle size (F.SSS) 3.95 μm, direct yield 95.1%, and total yield approximately 86%.

〔Effect of the invention〕

According to the method of the present invention, the manufacturing process of antimony oxide can be kept to a minimum and the amount of α-ray radiation of conventional products can be reduced to 1/10 or less.

There are advantages such as the ability to obtain products with good particle size and color tone.

Claims (1)

[Claims] 1. Distillate produced by holding 60 mesh or less of antimony at 100°C or higher and aerating an equivalent or more amount of chlorine gas at a substantially uniform flow rate for at least 30 minutes per 100 g of the sample. It is characterized by the fact that the substance is dissolved as it is or by adding a small amount of water to it, then heated and distilled at 135 to 230℃, and the resulting distillate is hydrolyzed by adding water. A method for producing low antimony trioxide. 2. The method for producing antimony trioxide with a low amount of α-ray radiation according to claim 1, wherein the heating distillation is carried out at 200 to 230°C.