JPS6241715A - Production of lead titanate for low-melting glass - Google Patents

Abstract

PURPOSE:To produce uniform powder of lead titanate capable of being readily sintered, by adding a solution of a lead compound to a solution for forming precipitates, drying and firing the formed precipitates, mixing a titanium compound therewith and calcining the resultant mixture. CONSTITUTION:Metallic lead or lead oxide with about >=99.99% grade is dissolved in nitric acid to give about 5-10mol concentration of free nitric acid. The resultant aqueous solution or an alcoholic solution is then added to a solution for forming precipitates, e.g. ammonia, to form precipitates, which are then dried, fired and pulverized. A titanium compound is then added thereto, and the resultant mixture is thoroughly mixed and calcined to afford lead titanate powder having characteristics of <=0.1CPH/cm<2> radioactive alpha particle counts and capable of being readily sintered. Therefore, the powder can be suitably utilized as a filler for low-melting glass.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the use of lead titanate for easily sinterable low melting glass! !
Regarding the manufacturing method. In particular, the present invention relates to a method for producing lead titanate powder, which is used to reduce malfunctions of semiconductors, and which can be used as a filler for low-melting glass suitable as a sealant for semiconductor devices, for example.

BACKGROUND OF THE INVENTION Lead titanate (PbTiO3) powder has already been widely used as a component of low-melting glass for sealing semiconductor devices, piezoelectric materials, pyroelectric materials, and the like.

Among these uses, low-melting glass for hermetically sealing semiconductor devices is used, for example, as described in JP-A-54-36314, JP-A-54-36316, JP-A-55-100239, etc. , PbO, B203 as the main components, and a small amount of Δβ203, S]02
, Zn○, PbF2, etc., and about 50 to 60% by weight of non-devitrification low melting point glass powder and about 50 to 40% by weight of low expansibility lead titanate powder as a filler. Lead-based low melting point glass is the mainstream.

By the way, in semiconductor devices that use such glass as a sealant, there is a phenomenon in which the semiconductor memory causes a temporary erroneous operation, and the cause of this phenomenon is believed to be due to radioactive α particles generated by the semiconductor device. Therefore, various studies have been made to prevent α particles from entering semiconductor devices and to remove sources of α particles.

For example, in the specification of JP-A-59-169955, Memo IJ states that, in order to reduce the occurrence of errors, a radioactive isotope is used as a non-devitrified, low-melting glass powder. less than 20PPb and the number of counts of radioactive α particles is 0. 1 C P H /cn{or less.

On the other hand, there are two conventional methods for producing lead titanate powder, namely, a method in which a bulk composite of PbTiO3 synthesized by heating a mixed powder of PbO and T102 is mechanically crushed after being allowed to cool. Dry method: A mixed solution of a lead compound and a titanium compound is added to a precipitate forming solution to co-precipitate,
The so-called "co-wetting method", which consists of drying and calcining this coprecipitate, has become known.

Problems to be Solved by the Invention As mentioned above, lead borate-based low melting point glass consisting of non-devitrification low melting point glass powder and low 1P tonicity lead titanate C) powder is used as a sealing agent for semiconductors. Conventionally, in order to prevent the adverse effects of radioactive isotopes, the number of counts of radioactive α particles in non-devitrified, low-melting glass powder was set to 0. 1C
Although it has been proposed to reduce P H /ctd or less, no attention has been paid to lead titanate powder with low TLG tonicity, and as a result, it is impossible to completely prevent memory errors in semiconductor devices. I could not do it.

In addition, even in the production method of low-expansion lead titanate powder,
In the conventional dry method, the curie point of lead titanate powder is relatively high at approximately 500°C, and the crystal lattice has a very large distortion, so sinterability is not sufficient, and in addition, it is difficult to produce a product with a uniform composition. The disadvantage was that it was difficult to

On the other hand, according to the known co-precipitation method, the powder with excellent uniformity can be obtained by a 1/2 inch flow, but it has the disadvantage that secondary particles are easily formed and therefore it is difficult to easily sinter. Furthermore, as a titanium compound, it is desirable to use titanium tetrachloride, which is inexpensive, but when this is used, there is a problem that the chlorine ions in titanium tetrachloride react with lead ions to produce whiteness. There was a problem in that expensive titanium oxynitrate or the like had to be used as the titanium compound.

In view of the current situation, the present invention aims to improve or eliminate the drawbacks of the prior art as described above, and therefore to produce lead titanate for low-melting glass that satisfies the requirements of easy sinterability, uniformity, and low cost. The present invention provides a method for producing lead titanate, which is used to reduce malfunctions in semiconductors, and which can be suitably used, for example, as a filler for low-melting glass, which is a sealant for semiconductor devices.

Means to Solve the Problems Therefore, the first aspect of the present invention is to first add an aqueous or alcoholic solution of a lead compound to a precipitate forming solution to form a precipitate, and then dry bottle and calcinate the precipitate. Then, a titanium compound is mixed with the mixture and calcined, so that the count number of radioactive α particles is 0. I
The present invention relates to a method for producing lead titanate for use in low-melting glass with a CP t(/cnf or less).

In the present invention, the aqueous or alcoholic solutions of lead compounds used include nitric acid, lead acetate,
oxalic acid? (Examples include aqueous or alcoholic solutions of lead formate, trimethyl red hydroxide, etc.)

In particular, in the present invention, the count number of radioactive α particles generated from radioactive isotopes such as U and Th is set to 0, 1 CP.
In order to keep the temperature below H/cl'lI and to prevent memory errors in semiconductor devices, an aqueous solution of a lead compound obtained as follows is suitable.

That is, metallic lead or zinc oxide with a grade of 4 nines or higher,
- Dissolving lead oxide such as lead oxide, eyeball lead oxide, and lead dioxide in nitric acid so that the concentration of free nitric acid is 5 to 1Qmol,
Radioactive isotopes such as IJ and Th are complex ionized (it was found that the adsorption efficiency of LJ, Th, etc. is good in the above free nitric acid concentration range), and then the liquid is purified using an anion exchange resin. An aqueous solution that has been treated to adsorb and remove radioactive isotopes can be suitably used in the present invention.

Other Hoboku 1 raw α particle counts are 0.1 CP H
/ () An oxide obtained by a conventional method as metallic lead collected from an old stratum below M or a thick layer of it,
The salt may be made into an aqueous solution or an alcohol solution.

In the present invention, a precipitate forming liquid is used. Examples of the precipitate forming liquid include ammonia, ammonium oxalate, and alkali.

Next, the titanium compound used in the present invention is purified distilled titanium tetrachloride or its thermal decomposition product.
Titanium dioxide is preferred.

An aqueous or alcoholic solution of titanium chloride, titanium oxynitrate, titanium butoxide, titanium propioxide, etc. is dissolved in nitric acid so that the concentration of free nitric acid becomes 5 to 10 mol, and the solution is purified using an anion exchange resin. After that, it is added to the precipitate forming solution to form a precipitate, and then the precipitate is dried and calcined at about 120 to 900°C,
Furthermore, a titanium compound treated with a ball mill can also be used if necessary.

Next, the method for loading the lead titanate powder of the present invention will be specifically explained.

First, an aqueous or alcoholic solution of a lead compound is added while stirring the precipitate-forming liquid, or vice versa, to form a precipitate.

This precipitate is washed with alcohol or the like if necessary, and then dried and fired at about 120 to 800°C.

Next, a titanium compound was added to the fired product that was ground in a ball mill, and after thorough mixing, the
Calcinate at 0℃. In this way, a uniform and easily sinterable lead titanate powder is obtained.

Note that if the calcination temperature is lower than 400°C, the solid phase reaction of the mixed powder will be insufficient, and if it exceeds 1200°C, the powder will become coarse 7, resulting in poor sinterability. .

Next, in the second tfJ, p of the present invention, a precipitate is generated by adding an aqueous solution or an alcohol solution of a titanium compound to a precipitation/precipitate forming solution, and the precipitate is dried at about 120 to 900°C. Radioactive α characterized by firing, then mixing a lead compound with it and calcining it.
This is a method for producing lead titanate for use in low-melting glass with a particle count of 0.1 CP H/ctd or less.

In the present invention, the aqueous or alcoholic solution of the titanium compound includes titanium tetrachloride, titanium oxy-6-phosphate,
Examples include aqueous or alcoholic solutions of titanium butoxide, titanium probiokind, and the like. In particular, in the present invention, an aqueous solution from which radioactive isotopes such as Th are removed can be suitably used by distilling inexpensive titanium tetrachloride. Further, as in the case of the lead compound solution, a titanium compound solution which has been purified with an anion exchange resin can also be used.

In addition, the lead compound used in the present invention is obtained by adding a solution purified with the anion exchange resin used in the first embodiment to a precipitate forming solution, drying and calcining the produced precipitate, and a radioactive α particle count is 0.1 CP
Examples include metal lead or an oxide of the metal lead having a hydrogen permeability of H/cM or less.

As the precipitate forming liquid used in the present invention, the same one as used in the first embodiment can be used. Furthermore, lead titanate can be manufactured in the same manner as the manufacturing method of the first embodiment.

Effects of the Invention According to the method of the present invention, easily sinterable and uniform lead titanate powder can be obtained. Furthermore, since inexpensive titanium tetrachloride or titanium dioxide obtained by thermal decomposition can be used, the manufacturing cost is also low. In addition, the lead titanate powder that is humiliated has a radioactive alpha particle count a of 0.1 CP)]
/ci or less, so it can be suitably used as a filler for low-melting glass, which is a sealant for semiconductor devices. In addition, it has the advantage that it can be suitably used for equipment, materials, etc. that can cause problems when the number of radioactive α particles is large.

Example Hereinafter, the present invention will be explained in more detail by way of practical examples.

Actual blood example 1 Test: ≦Special grade (pb○99.9% or more) -lead oxide 22
, 31 g was added to 150 mβ of reagent grade nitric acid diluted (1:1) with pure water, and dissolved by heating to form an aqueous solution [
,Ta. This aqueous solution was passed through a tower filled with an anion exchange resin to adsorb and remove Ll, Th, etc., and then added dropwise to 4N ammonia 1β with stirring to form a lead hydroxide precipitate.

This precipitate was washed with pure water, dried at 120°C for 1 hour, calcined at 750°C for 1 hour, and ground in a ball mill.

Next, reagent-grade titanium tetrachloride (purity 9
9. 9 5% or more, specific gravity 1.72-1. 7 6)
7. Chlorinated titanium dioxide powder produced by thermal decomposition reaction of distilled titanium dioxide powder. 68 g was added, mixed in a ball mill, calcined at 850° C. for 2 hours, and further ground in a ball mill to obtain lead titanate (PbTi03) powder.

The count number of radioactive α particles in this powder was measured using an α-ray measuring device and found to be O-074 CPH/am.

When this powder was observed using a scanning electron microscope, it was found to be approximately O. βC has a uniform particle size of 3μ and is determined by X-ray diffraction method.
As a result of plotting the relationship between OS θ and sin θ (where β represents the half width of the diffraction line and θ represents the Black angle), it is almost parallel to the horizontal axis (sin θ axis), and is almost uniform without compositional fluctuations. It was confirmed that it was of the composition.

Example 2 Titanium tetrachloride 1 purified by distillation 8. 9 7 g of water C solution dissolved in pure water, 100 mβ, was added with stirring to 4.
The mixture was dropped into 1 liter of N ammonia water to form a titanium hydroxide precipitate. This precipitate was washed with pure water, dried at 120°C for 1 hour, further calcined at 750°C for 1 hour, and then ground in a ball mill.

Next, the count number of radioactive α particles is 0.0 in the pulverized material.
Using metallic lead of 5 CP H/cnt, 922.31 g of monoxide produced by a conventional method was added, mixed in a ball mill, fired at 850°C for 2 hours, and further crushed in a ball mill to add lead titanate powder. Ta. The radioactivity α of this t-segment flux
The result of measuring the number of particle counts was 0.066CPH/C
It was m. The powder also has a uniform particle size of about 0.3μ,
Furthermore, as a result of plotting the relationship between β cos θ and sin θ by X-ray diffraction, it was confirmed that the composition was uniform.

Comparative Example 1 Commercially available reagent special grade pb○, T i 02 powder was converted into PbT.
The mixture was blended to have a composition of iO3, mixed in a ball mill, calcined at 950°C for 2 hours, and ground again in a ball mill.
I made a powder.

Results of measuring the number of counts of radioactive α particles in this powder 3
．． It was 85 CP H/cffl. Further, as a result of plotting the β cos O-sin θ relationship of this powder by X-ray diffraction, compositional fluctuations were observed.

Claims (9)

[Claims] (1) A precipitate is produced by adding an aqueous or alcoholic solution of a lead compound to a precipitate forming solution, the resulting precipitate is dried and calcined, and then a titanium compound is mixed therein and calcined. The count number of radioactive α particles is 0.1
A method for producing lead titanate for low melting point glass of CPH/cm^2 or less. (2) The aqueous solution of the lead compound is an aqueous solution in which metallic lead or lead oxide with a grade of 4 nines or higher is first dissolved in nitric acid so that the free nitric acid concentration becomes 5 to 10 mol, and then purified with an anion exchange resin. A method for producing lead titanate for low melting point glass according to claim (1). (3) Titanium for low-melting glass according to claim (1), wherein the titanium compound is titanium tetrachloride purified by distillation or titanium dioxide obtained by thermal decomposition of the titanium tetrachloride. Method for producing acid lead. (4) The method for producing lead titanate for low melting point glass according to claim (1), wherein the low melting point glass is a glass for sealing a semiconductor device. (5) Adding an aqueous or alcoholic solution of a titanium compound to a precipitate forming solution to form a precipitate, drying and calcining the resulting precipitate, then mixing a lead compound therein and calcining it. The count number of radioactive α particles is 0.1
A method for producing lead titanate for low melting point glass of CPH/cm^2 or less. (6) The method for producing lead titanate for low-melting point glass according to claim (5), wherein the titanium compound is titanium tetrachloride purified by distillation. (7) An aqueous solution of a lead compound is prepared by first dissolving metallic lead or lead oxide with a grade of 4 nines or higher in nitric acid so that the concentration of free nitric acid becomes 5 to 10 mol, and then purifying the solution with an anion exchange resin, A lead titanate for low melting point glass according to claim (5), which is added to a precipitate forming solution to form a precipitate, and the obtained precipitate is dried and fired. Production method. (8) The lead compound has a radioactive α particle count of 0.1
The method for producing lead titanate for low melting point glass according to claim (5), wherein the lead oxide is lead oxide having a CPH/cm^2 or less. (9) The method for producing lead titanate for low melting point glass as set forth in claim (5), wherein the low melting point glass is a glass for sealing a semiconductor device.