JPH07196338A - Production of filler powder - Google Patents

Abstract

PURPOSE:To provide a production method for filler powder capable of producing the filler at low cost without deteriorating the fluidity of a sealing material. CONSTITUTION:Firstly, crystallizable glass powder is compounded with powder of a fireproof material and mixed. Next, the mixture is baked at a temperature at which the glass powder sufficiently crystallizes while the crystallizable glass and the fireproof material does not fuse with each other, and then the objective filler powder is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a filler powder, and more particularly to a method for producing a filler powder used as a sealing material for sealing electronic parts such as IC packages and display devices. .

[0002]

2. Description of the Related Art Conventionally, filler powder has been used as a sealing material for sealing electronic parts such as IC packages and display devices together with low melting point glass powder for adjusting the thermal expansion coefficient.

A method called a crystallized glass method is generally known as one of the methods for producing the filler powder. The crystallized glass method is a method in which a glass raw material prepared to have a desired chemical composition is first melted, molded and crushed to prepare a crystalline glass powder, and then baked to crystallize them. , Willemite, β-quartz solid solution, cordierite, β-eucryptite, zinc petalite, garnite, etc.

[0004]

However, in the method as described above, the crystalline glass powders are re-pulverized because they are fused with each other and strongly hardened in the firing step of the crystalline glass powder to form a solid crystal mass. There is a drawback that it is necessary and the manufacturing cost is high.

In the re-grinding step, fine powder of crystalline material having a particle size of 0.5 μm or less is generated. If classification is performed to remove this fine powder, the yield of filler powder is lowered and the cost becomes very high. Not preferable. Therefore, it is usually mixed with the low-melting glass powder while containing fine powder. However, when such fine powder is present in the sealing material, the specific surface area of the filler increases (that is, the reaction area with the glass increases, and it easily dissolves in the low-melting glass), so that the fluidity of the sealing material decreases. It has a problem of causing it.

An object of the present invention is to provide a method for producing a filler powder which can be produced at low cost and which does not impair the fluidity of the sealing material.

[0007]

Means for Solving the Problems As a result of various experiments conducted by the present inventors, if it is possible to prevent the crystalline glass powders from contacting each other during firing, it is possible to crystallize them in the powder state. It was found that the re-grinding was possible and the re-grinding became unnecessary, and the present invention was proposed.

That is, in the method for producing a filler powder of the present invention, the refractory substance powder is added to and mixed with the crystalline glass powder, and the crystalline glass powder and the refractory substance powder are not welded and the crystalline glass is not melted. It is characterized by firing at a temperature sufficient for the powder to crystallize.

[0009]

In the method for producing the filler powder of the present invention,
First, the refractory substance powder is added to the crystalline glass powder. The addition amount of the refractory substance powder is 0.1 parts by weight or more, and more preferably 1 to 70 parts by weight based on 100 parts by weight of the crystalline glass powder.
It is desirable that the amount is parts by weight. If the addition amount of the refractory substance powder is less than 0.1 part by weight, the effect of hindering the contact between the crystalline glass powders is almost lost.

The crystalline glass powder to be used is produced by melting a glass raw material prepared so as to have a desired chemical composition, shaping and crushing it, and is a glass used for producing a filler powder. If so, it is possible to use those having various compositions. Examples of such substances include willemite, β-quartz solid solution, cordierite, β-eucryptite, zinc petalite,
A crystalline substance such as garnite can be used. The composition of the crystalline glass may deviate from the theoretical composition values of these crystals to some extent. Further, it is desirable to use crystalline glass powder having a particle diameter of 45 μm or less.

The refractory substance powder is mixed to prevent contact between the crystalline glass powders, has a high melting point equal to or higher than that of a crystalline substance obtained by firing the crystalline glass powders, and has a crystal structure. Use a glass that does not easily react with the glass. Examples of such materials include willemite ceramics, zircon ceramics, tin oxide ceramics, zirconia, alumina, cordierite, titanium oxide, silica, β-quartz solid solution,
β-eucryptite, zinc petalite, and garnite are preferable, and lead titanate-based ceramics, mullite-based ceramics, niobium oxide, cristobalite, and other crystalline powders can also be used. It is desirable to use the refractory material powder having a particle diameter of 45 μm or less.

Subsequently, the crystalline glass powder and the refractory material powder are uniformly mixed. When crushing the crystalline glass powder,
The refractory substance powder may be added and mixed and ground by a ball mill or the like.

Thereafter, these mixed powders are fired at a temperature sufficient for the crystalline glass powder and the refractory material powder not to be fused and for the crystalline glass powder to crystallize. When fired under such conditions, the presence of the refractory substance powder prevents the crystalline glass powders from contacting each other, and the crystalline glass powders are crystallized in the powder state. The mixture of the crystalline powder and the refractory powder thus obtained can be used as it is as a filler powder for a sealing material because the powders are not welded to each other. It should be noted that fine glass powder generated in the crushing step when preparing the crystalline glass powder may be mixed in the mixed powder, but such fine powder is crystalline glass having a large particle size in the process of firing the mixed powder. Since it adheres to the surface of the powder, there is almost no fine powder in the obtained filler powder.

In the method of the present invention, it is practically difficult to separate the obtained filler powder into crystalline substance of crystalline glass powder and refractory substance powder. Therefore, when it is desired to obtain a filler powder made of a single material, it is necessary to use a refractory substance powder having the same crystal phase as the crystalline glass powder.

Next, a sealing material using the filler powder obtained by the method of the present invention will be described.

Such a sealing material comprises a low melting point glass powder and the filler powder produced as described above.
The ratio of the two is preferably in the range of 45:55 to 95: 5 by volume% low melting glass powder: filler powder.

As the low-melting glass powder, it is preferable to use one having a glass transition point of 350 ° C. or lower. As such a powder, PbO-B ₂ O ₃ system, PbO-Bi are used.
₂ O ₃ -Fe ₂ O ₃ system, PbO-Bi ₂ O ₃ -CuO
System, PbO-B ₂ O ₃ -ZnO-based, PbO-B ₂ O ₃ -
It is possible to use amorphous or crystalline glass such as Bi ₂ O ₃ system and PbO—V ₂ O ₅ system.

In addition to the filler powder prepared as described above, the same or different kind of filler powder prepared by a usual method may be added to the sealing material. Examples of such filler powder include willemite ceramics, zircon ceramics, tin oxide ceramics, lead titanate ceramics, zirconia, alumina, cordierite, mullite ceramics, niobium oxide, β-eucryptite, and oxides. Titanium, silica, garnite, quartz glass, cristobalite, etc. can be used.

[0019]

EXAMPLES The present invention will be described below based on examples.

Tables 1 and 2 show examples of the present invention (Samples A to A).
H) and a comparative example (Sample I) are shown.

[0021]

[Table 1]

[0022]

[Table 2]

First, pure silica powder, aluminum oxide, zinc oxide, zirconia, titanium oxide, lithium oxide, magnesium oxide, and aluminum phosphate were mixed and mixed so that the composition shown in the table was obtained, and this mixture was put into a platinum crucible. 1500-
It was melted at 1650 ° C. for 3 hours. Next, the molten glass was shaped into a plate, crushed, and then passed through a 350-mesh stainless sieve to obtain a crystalline glass powder having a particle size of 45 μm or less.

Next, the refractory substance powder was added in the proportion shown in the table, mixed, and then fired under the firing conditions shown in the table.
Sample I was fired without adding refractory powder.

When the fired product thus obtained was used as a filler powder for a sealing material, whether or not crushing or crushing was required was examined, and samples A to C produced by the method of the present invention were examined. It was found that H can be used as it is without crushing or crushing. On the other hand, since the sample I was a hard and hard lump-shaped crystal substance, it could not be crushed, and a filler powder equivalent to that of the sample H could not be obtained unless it was re-ground with a ball mill.

The specific surface areas of the samples A to H before firing (crystalline glass powder) and after firing (filler powder) were measured by a fluid type specific surface area measuring device, and the average particle size was measured by a Microtrac particle size analyzer. As a result, the average particle size (D
_The specific surface area decreased significantly after firing, although there was almost no change in the ( ₅₀ value). On the other hand, with respect to the sample I, the specific surface area and the average particle diameter were measured after re-grinding. As a result, the average particle diameter (D ₅₀ value) was similar to that of the example, but the specific surface area was larger than the value of each example after firing. From these facts, it can be inferred that the filler powder produced by the method of the present invention had a small specific surface area because the fine powder was fused to the surface of the crystalline glass powder during firing.

In order to confirm whether or not the fine powder is welded,
After each of the filler powders of Samples A to H was kneaded and cured with a resin, the cross section of the cured product was polished and observed with an electron microscope. As a result, in each sample, fine powder was adhered to the surface of the filler powder. Was recognized.

In the obtained filler powder, sample A has β
-A mixture of quartz solid solution powder and zircon-based ceramic powder, Sample B is a mixture of β-quartz solid-solution powder and willemite-based ceramic powder, Sample C is a mixture of cordierite powder and zirconia powder, and Sample D is β
A mixture of eucryptite powder and tin oxide ceramic powder, sample E a mixture of zinc petalite powder and cordierite powder, sample F a mixture of garnite powder, zirconia powder and titanium oxide powder, sample G of willemite. The ceramic ceramic powder, the mixture of alumina powder and silica powder, and Sample H and Sample I were all willemite ceramic powders.

Next, a sealing material was prepared using the obtained filler powders of Samples A to I.

Table 3 shows the low-melting glass powder used (Sample a).
~ C) are shown. Tables 4 and 5 show examples of the sealing material produced using the above filler powder (Sample No.
1 to 9) and a comparative example (sample No. 10).

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

[Table 5]

The low melting glass of Table 3 was prepared as follows.

First, to obtain the composition shown in Table 3, Komeitan,
Bismuth oxide, iron oxide, boric acid, zinc oxide, pure silica powder, aluminum oxide, and barium carbonate were mixed and mixed, and this mixture was put into a platinum crucible and melted at 900 ° C. for 1 hour. Next, the molten glass was shaped into a plate, crushed, and then passed through a 350-mesh stainless sieve to obtain a low-melting glass powder having a particle size of 45 μm or less. The samples a to c thus obtained have glass transition points of 290 to 300 ° C. and 3
Thermal expansion coefficient at 0 to 250 ° C. is 108 to 115 × 1
It was 0 ^-7 / ° C.

Subsequently, the low melting glass powder and the filler powder were mixed in the proportions shown in Tables 4 and 5 to prepare a sealing material.

The sealing material thus prepared was evaluated for sealing temperature, coefficient of thermal expansion, transverse rupture strength, insulation resistance and fluidity. Sample Nos. The sealing materials 1 to 9 have a sealing temperature of 390 to 4
Coefficient of thermal expansion at 00 ° C and 30 to 250 ° C is 50 to 7
5 × 10 ^-7 / ° C, flexural strength 550-650 kg / cm
² , insulation resistance at 150 ℃ is 13.2 to 14.2Ω ・ c
m, and the fluidity was good. On the other hand, Sample No. using the filler powder of Sample I. 10 is 30 ~
Coefficient of thermal expansion at 250 ° C is 68 × 10 ^-7 / ° C, bending strength is 600 kg / cm ² , insulation resistance at 150 ° C is 1
Although it was 3.3 Ω · cm and showed the same value as each sample of the example, regarding the sealing temperature and the fluidity, the sample No. using the same kind of filler powder in the same ratio was used. It was worse than 9. It is considered that this is because the fine powder contained in the filler powder of Sample H adversely affected the fluidity.

Regarding the necessity of crushing when producing the filler powder, it is necessary that the average particle size of the fired product is 2 μm or more larger than that of the mixed powder before firing.
If it is less than μm, it is not necessary. Regarding the necessity of crushing, when crushing with one hand using a spoon, it is determined that there is a lump that cannot be crushed and has a particle size of 1 mm or more. The glass transition point and the coefficient of thermal expansion were measured using a push rod type thermal expansion measuring device. The bending strength was measured by molding each sample into a prism of 10 × 10 × 50 mm, firing it, and then measuring it with a three-point load. The insulation resistance was measured using a mega ohm meter. In addition, the fluidity of a cylinder with an outer diameter of 20 mm and a height of 5 mm prepared from each sample is 4
After heating and flowing at 00 ° C for 10 minutes, the flow diameter was 21
Less than mm is not acceptable, 21-22 mm is acceptable, 2
Those exceeding 2 mm were regarded as good.

The crystalline materials used as the refractory material powder and other filler powders were prepared as follows.

The willemite ceramics i is zinc oxide, optical stone powder, and aluminum oxide in a weight ratio of ZnO70.
%, SiO ₂ 25%, Al ₂ O ₃ 5%, and after mixing, fired at 1440 ° C. for 15 hours, crushed, and passed through a 350-mesh stainless sieve to obtain a particle size of 45 μm. The following powders were used.

For the willemite ceramics ii, the crystalline glass powder used in the sample H was previously prepared at 1200 ° C. for 10 hours.
After being fired for an hour, it was crushed and passed through a 350-mesh stainless sieve.

Zircon-based ceramics are obtained by first decomposing natural zircon sand with soda, dissolving it in hydrochloric acid, and repeating concentration crystallization to obtain zirconium oxychloride, which is an α-ray emitting substance having extremely small amounts of U and Th,
Then, after neutralization with alkali, heating was performed to obtain purified ZrO ₂ .
Subsequently, high-purity silica stone powder and ferric oxide were added to Zr in a weight ratio.
The composition of O ₂ 66%, SiO ₂ 32%, and Fe ₂ O ₃ 2% was prepared, mixed, baked at 1400 ° C. for 16 hours, further pulverized, and passed through a 350-mesh stainless sieve. I used the one.

The tin oxide ceramics are SnO in a weight ratio.
₂ 93%, TiO ₂ 2%, MnO ₂ 5% were mixed with tin oxide, titanium oxide and manganese dioxide, and after mixing, fired at 1400 ° C. for 16 hours, then crushed and
The one that had been passed through a 50-mesh stainless sieve was used.

Lead titanate-based ceramics are
Titanium oxide and calcium carbonate are 70% by weight of PbO,
The mixture was prepared so as to have a composition of TiO 20% and CaO 10%, mixed and then fired at 1100 ° C. for 5 hours, and then the fired product was crushed and passed through a 350-mesh stainless sieve.

As zirconia, alumina, cordierite, titanium oxide and silica, commercially available products of 350 mesh pass were used.

[0046]

As described above, according to the method of the present invention, since re-grinding after firing is not necessary, it is possible to manufacture the filler powder at a lower cost than the conventional method. . Further, since the filler powder produced by the method of the present invention has a small specific surface area, it does not impair the fluidity of the sealing material, and is suitable as a method for producing the filler powder for the sealing material.

Claims (1)

[Claims] 1. A temperature sufficient to prevent the crystalline glass powder and the refractory powder from adhering to each other and to crystallize the crystalline glass powder after the refractory powder is added to and mixed with the crystalline glass powder. A method for producing a filler powder, which comprises firing at.