JP2947558B2 - Ceramic insulating material and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ceramic insulating material having characteristics suitable for use in a multilayer ceramic package, an electronic circuit board, and the like, and a method for manufacturing the same.

(Prior Art) In addition to alumina, mullite is known as a ceramic insulating material used for a package material of a semiconductor device or the like or a substrate for an electronic circuit.

Mullite has a relative dielectric constant of 7.0 to 7.5 (1 MHz) and a coefficient of thermal expansion of 3.5 to 4.5 to 10 ^-5 / ° C, and is characteristically superior to alumina. However, it is difficult to obtain a sufficiently dense sintered body at a sintering temperature of 1600 ° C. or less,
Since the firing temperature is high, it is difficult to form a substrate and a circuit pattern by simultaneous firing. This is because when fired at high temperature, the glass component of the substrate penetrates into the metallized layer formed on the substrate, and as a result,
This is because the resistance value of the formed conductor layer becomes large and it becomes difficult to form a suitable conductor layer.

Instead of these, as a material for obtaining a ceramic insulating material having more excellent characteristics as compared with the above-mentioned mullite, there is a conventional example using a system in which silica powder is added to mullite powder as a raw material powder (Japanese Patent Application Laid-Open No. 61-36168). ). In this example, the mullite and the silica raw material powder each have an average particle size of 5
μm and 2μm are used.
There is a problem that the temperature is as high as 1600 ° C. and the relative dielectric constant is 6.2 to 6.4, which is higher than the value 5.3 obtained from the electrical equivalent circuit of the composite.

Further, in addition to the above, as a material which can be fired at 1600 ° C. or less using a raw material powder having an alumina-silica diameter, a ceramic insulating material which has already been fired using a fine raw material powder has been developed by a part of the present inventors ( Japanese Patent Application No. 62-100268
issue). This ceramic insulating material is obtained by using a powder with a higher SiO ₂ content than the stoichiometric composition of mullite and firing it at a temperature of 1600 ° C or less using fine raw material powder of 1μm or less. It has a low relative dielectric constant, a thermal expansion coefficient close to that of silicon, and has sufficient strength as a circuit board material or the like.

(Problems to be Solved by the Invention) In actually commercializing a package for a semiconductor device, a substrate for an electronic circuit, or the like, it is an essential condition that a thin and large-sized substrate can be easily manufactured. The green sheet method is frequently used as a method for easily manufacturing a substrate that satisfies these conditions, and is also frequently used in manufacturing a substrate using alumina, mullite, or the like as a raw material.

By the way, when a fine powder is used as a raw material powder, the fine powder is agglomerated in a solvent and has poor dispersibility. Therefore, in the example shown in Japanese Patent Application No. 62-100268, the raw material powder is calcined once, and the calcined powder is mixed with an organic solvent or the like in a ball mill, pulverized into a slurry, and further formed into a green sheet. ing.

However, even with this method, sufficient dispersibility cannot be obtained. As a result, it has been found that it is difficult to form a green sheet of stable quality, and that the characteristics of the sintered body vary greatly even when firing is performed.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a ceramic insulating material which can easily form a green sheet of stable quality, can be fired at a low temperature, and has good characteristics, and a method for producing the same.

(Means for Solving the Problems) The present inventors have conducted intensive studies to achieve the above object, and as a result, have found a ceramic insulating material having characteristics suitable for a package for a semiconductor device, a substrate for an electronic circuit, and the like, and a method for manufacturing the same. I came to find it.

That is, according to the present invention, in terms of oxide, Al ₂ O ₃ and SiO ₂ are 10% by weight ≦ Al ₂ O ₃ <62% by weight, 90% by weight ≧ SiO ₂ > 38
Alumina-silica-based powder having a chemical composition of substantially 100% by weight in the range of 100% by weight is calcined at 1000 ° C. to 1400 ° C., and the obtained calcined powder is pulverized in a solvent such as methanol to obtain a powder. Adjust to a raw material powder with a surface area of 1-50 m ² / g,
A binder, a plasticizer, and an organic solvent are added to this raw material powder to form a slurry.The slurry is formed into a green sheet, and then fired at a temperature in the range of 1300 ° C. to 1600 ° C. at which a cristobalite phase is not generated. It is characterized by comprising a mullite phase and a silicate glass phase.

In addition, as a method for producing the same, Al ₂ O ₃
And SiO ₂ in an amount of 10% by weight ≦ Al ₂ O ₃ <62% by weight, 90% by weight ≧ S
An alumina-silica-based powder having a chemical composition of substantially 100% by weight in the range of iO ₂ > 38% by weight is calcined at 1000 ° C. to 1400 ° C., and the obtained calcined powder is pulverized in an organic solvent. The specific surface area is adjusted to a raw material powder having a range of 1 to 50 m ² / g, a binder, a plasticizer, and an organic solvent are added to the raw material powder to form a slurry.
By baking at a temperature in the range of 00 ° C. to 1600 ° C. at which a cristobalite phase is not generated, a constituent phase is obtained as a sintered body composed of a mullite phase and a silicate glass phase.

As the alumina-silica-based powder used as a starting material in the present invention, an alumina-silica-based powder obtained by a method such as a metal alkoxide hydrolysis method, a coprecipitation method, and a thermal decomposition method can be used. Since this alumina-silica-based powder is a fine powder, it has poor dispersibility when a slurry is formed, so that it is not possible to make a slurry as it is to produce a green sheet. Therefore, it is important to calcine the alumina-silica-based powder before preparing a powder having an appropriate specific surface area. The specific surface area of the raw material powder is determined by the calcination temperature, calcination time, etc.
By setting the calcination time to 1 to 4 hours, a powder having a required specific surface area can be obtained. For example,
The weight composition ratio of Al ₂ O ₃ and SiO ₂ is 40:60, and the calcination temperature is 1100 ° C.
The specific surface area is 5 to 50 when the calcination time is 1 hour in the range of 1300 ° C.
A calcined powder of m ² / g is obtained.

Then, the calcined powder is further subjected to 5 to 50 in a solvent such as an organic solvent as exemplified below, for example, in methyl alcohol or methyl ethyl ketone using a vibration ball mill.
It is pulverized for a time, dried and granulated to finally produce a raw material powder having a predetermined specific surface area. In fact, the specific surface area of the raw material powder is better to adjust to be in the range of 1 to 50 m ² / g, preferably those specific surface area in the range of 30 to 40 m ² / g. If the specific surface area of the raw material powder exceeds 50 m ² / g, it becomes difficult to obtain a green sheet having a uniform composition, and if the specific surface area is 1 m ² / g or less, the relative density of the sintered body decreases. Is not preferred.

Next, an organic component such as an organic solvent, a binder, a plasticizer, and a dispersant is added to the raw material powder, pulverized, mixed and formed into a slurry, and formed into a green sheet by a doctor blade method or the like.

Examples of organic components that can be used, such as an organic solvent, a binder, a plasticizer, and a dispersant, include the following, but are not limited thereto. The organic components can be used alone or in combination.

Examples of organic solvents: methyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, ethyl alcohol, butyl alcohol,
One type or a mixture of two or more types using isopropanol, methyl acetate, ethyl acetate, toluene, acetone or the like.

Examples of binders: Butyral resins such as polyvinyl butyral, and acrylic resins such as methyl methacrylate.

Examples of plasticizers: di-n-butyl phthalate, dioctyl phthalate,
Polyethylene glycol, benzyl-n-butyl phthalate, butyl phthalyl butyl glycolate.

Examples of dispersants: sorbitan ester type dispersant, polyoxyethylene type dispersant, polycarboxylic acid type dispersant.

The amount of the organic solvent to be added to the raw material powder is 2 to 5 times the volume of the raw material powder, and is adjusted to a slurry viscosity suitable for forming a green sheet.

The amount of the binder, plasticizer and dispersant added to the raw material powder is 30% by volume to 70% by volume of the total amount with the raw material powder.
Is suitable, and may be determined in consideration of workability at the time of press-punching the green sheet, shrinkage at the time of firing, and the like. In addition, the addition amount of these organic components is not basically different from the conventional method for producing a green sheet.

When the green sheet obtained by the above-described method is fired, a sintered body is obtained. The sintering temperature is in the range of 1300 ° C to 1600 ° C, so that a suitable sintered body composed of a mullite phase and a silicate glass phase can be formed. The firing time is optimally 1 to 4 hours. However, even with the same composition, a cristobalite phase may be generated depending on the firing temperature and its profile. If the cristobalite phase is generated, the coefficient of thermal expansion of the sintered body becomes extremely large. Therefore, it is necessary to set the firing temperature so that the cristobalite phase is not generated.

Further, the composition ratio of Al ₂ O ₃ and SiO ₂ can be set by changing the mixing ratio of the starting materials. When the alumina-silica-based powder is obtained by a method for hydrolyzing a metal alkoxide, a coprecipitation method, a thermal decomposition method, or the like, for example, by adjusting the molar ratio of aluminum isopropoxide and methyl silicate as raw materials to an arbitrary ratio, can do.
If, when the composition ratio of Al ₂ O ₃ is 10 wt% or less, since the flexural strength of the sintered body decreases, is not preferable as a package and an electronic circuit board for a semiconductor device, the composition of the Al ₂ O ₃ When the ratio is 62% by weight or more, it is necessary to set the firing temperature to 1600 ° C. or more, which is not preferable because a suitable conductor pattern cannot be formed by simultaneous firing with the substrate. Therefore, the composition ratio of Al ₂ O ₃ needs to be 10% by weight or more and 62% by weight or less.

Hereinafter, a specific example of the method for manufacturing a ceramic insulating material according to the present invention will be described. It is needless to say that the present invention is not limited to these examples.

Example 1 Benzene solution of aluminum isopropoxide (concentration
1mol / l) and benzene solution of methyl silicate (concentration 2mol)
/ l) were mixed such that the weight composition ratio of Al ₂ O ₃ and SiO ₂ was 40:60. 1.5 liter of distilled water and 0.75 liter of methanol adjusted to pH = 10 to 11 with ammonia to the mixed benzene solution 1
Was hydrolyzed with a mixed aqueous solution of the above, and dried to synthesize an alumina-silica powder.

Next, this synthetic powder was calcined at 1200 ° C. for 1 hour to obtain a calcined powder. The specific surface area of the obtained calcined powder was about 20 m ² / g. Some mullite phases were formed in the calcined powder.

Next, this calcined powder was crushed in a solvent using methanol as a solvent for 50 hours using a vibration ball mill, and then dried and mesh-granulated to prepare a raw material powder having a specific surface area of about 30 m ² / g.

Next, methanol was used as an organic solvent, polyvinyl butyral was used as a binder, dibutyl phthalate was used as a plasticizer, and polycarboxylic acid was used as a dispersant. The resulting mixture was mixed with a rotary ball mill for 72 hours to prepare a slurry.
After defoaming the obtained slurry, the slurry was applied to a thickness of 0.4 to 0.8 mm on a carrier film using a doctor blade and dried to prepare a green sheet.

Next, the green sheet was heated in the air to degrease the organic components in the green sheet, and then fired at 1350 ° C. for 4 hours to obtain a sintered body.

<Test Example 1> The density of the green sheet and the sintered body obtained in Example 1 was measured, and the relative density was calculated. Table 1 shows the results.

Here, the relative density is a ratio of the density of each of the green sheet and the sintered body to the density of the green sheet and the sintered body when the porosity is assumed to be 0%.

The relative density of the green sheet is a measure of the workability of the green sheet, and the relative density of the sintered body is a measure of the degree of densification. When the relative density of the green sheet is high, the workability of the green sheet is good, and when the relative density of the sintered body is high, the green sheet is more dense.

Here, the results of using raw material powders whose specific surface area is changed by changing the calcination temperature are shown. Specifically, the specific surface area is 47
Raw material powder adjusted to m ² / g (corresponding to calcination temperature of 1150 ° C), specific surface area 30m ² / g (corresponding to calcination temperature of 1200 ° C)
Raw material powder adjusted to have a specific surface area of 12 m ² / g
(Corresponding to a calcining temperature of 1250 ° C.).

Regardless of the raw material powder having any specific surface area, the relative density of the green sheet shows a high value, and a green sheet with good workability can be obtained. We were able to get a solid body.

As a comparative example of the first embodiment, Al ₂ O ₃ and SiO ₂
Is the same as in Example 1 above, and the calcined powder is directly used as in Example 1 without crushing in a solvent after calcination.
Table 2 shows the characteristics of the sintered body obtained by forming a green sheet by slurrying in the same manner as described above. The firing conditions are the same as in Example 1 (4 hours at 1350 ° C.).

As can be seen from the results of Tables 1 and 2, in the comparative example, a green sheet having a high relative density could be obtained by using a powder having a specific surface area of 1 to 12 m ² / g. However, even when the specific surface area is 30 m ² / g, the density and relative density of the sintered body are inferior to those of Example 1.

FIG. 1 and FIG. 2 are electron micrographs of the grain structure of the sintered body fracture surface in Example 1 shown in Table 1 and Comparative Example shown in Table 2.

The sintered body of Example 1 has a dense structure, whereas the sintered body of the comparative example does not have a dense structure. First
From FIG. 2 and FIG. 2, it can be seen that when the calcined powder is pulverized in a solvent, a dense sintered body having excellent sinterability can be obtained.

For the sintered body of the <Test Example 2> calcined powder obtained by the method of creating a green sheet was triturated in a solvent, Al ₂ O ₃ and SiO ₂
The sintering density, the relative dielectric constant, the coefficient of thermal expansion, and the like of the sintered body were measured in the same manner as in Test Example 1 while changing the composition ratio and firing conditions. Table 3 shows the results. In the table, ◎ indicates the measured value of Example 1 described above.

From Table 3, it can be seen that the firing temperature can be lowered as the composition ratio of Al ₂ O ₃ is smaller, and that the cristobalite phase precipitates when firing at a higher temperature even if the composition ratio is the same in the constituent phases. . When the cristobalite phase precipitates, the relative dielectric constant becomes slightly higher, and the volume change around 200 ° C. becomes extremely large. For this reason, it is not preferable to use a material in which a cristobalite phase is precipitated for a semiconductor package, a substrate for an electronic circuit, or the like.

In the case where the cristobalite phase does not precipitate, the relative dielectric constant is small and the coefficient of thermal expansion is more excellent than that of the conventional ceramic insulating material. Further, these sintered bodies have sufficient strength to be used for a semiconductor package, a substrate for an electronic circuit, or the like. The firing density, the relative dielectric constant, and the coefficient of thermal expansion all tend to increase as the composition ratio of Al ₂ O ₃ increases.

Further, when the composition ratio of Al ₂ O ₃ is 10% by weight or less, the strength of the sintered body is reduced, which is not preferable.
When the composition ratio of Al ₂ O ₃ is 62% by weight or more, the firing temperature is 1600.
C. or more, making it difficult to form a suitable conductor pattern by simultaneous baking of the substrate and the circuit pattern, which is not preferable in the production of semiconductor packages and electronic circuit substrates.

(Effect of the Invention) According to the ceramic insulating material and the method of manufacturing the same according to the present invention, as described above, a powder obtained by calcining an alumina-silica-based powder having a specific composition ratio is pulverized in a solvent. The specific surface area is adjusted to a raw material powder having a range of 1 to 50 m ² / g, and the raw material powder is mixed with a binder, a plasticizer, and an organic solvent to form a slurry, which is formed into a green sheet. As a result, the dispersibility of the raw material powder is improved, the green sheet can be formed well, and it is dense at a firing temperature of 1600 ° C or less, has a small relative dielectric constant, and has a thermal expansion coefficient closer to that of silicon. And a sintered body having a small area and a large area can be obtained.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing a grain structure of a fractured surface of a sintered body produced by the method of the present invention, and FIG. 2 is an electron micrograph showing a grain structure of a fractured surface of a sintered body of a comparative example.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Kuribayashi, inventor 711, Rita Kurita-sha, Nagano, Nagano Prefecture Inside Shinko Electric Industries, Ltd. Shinko Electric Industries Co., Ltd. (72) Inventor Shuzo Kanzaki 8-12-4 Fujiyamadai, Kasugai City, Aichi Prefecture (72) Inventor Shumi 2-1 Mataho-cho, Nishi-ku, Nagoya City, Aichi Prefecture 2-230 72) Inventor Yuki Ohashi 5-6 Shonai-dori, Nishi-ku, Nagoya-shi, Aichi 102 Corp. Shonai 102 (72) Inventor Takaaki Nagaoka 2-1 Mataho-cho, Nishi-ku, Nagoya-shi, Aichi 2-35, Taho housing complex 2-351 (72) Inventor Chiaki 2165 Toda, Atsugi-shi, Kanagawa Pref.Hokkaido Chemical Industry Co., Ltd.Development Research Laboratory Joint Referee Chief Masami Sakai Referee Mitsuo Karato Referee Masahiro Inoue (56) References JP 61-36168 (JP, A) JP Akira 63-265859 (JP, A) PCT National Akira 59-500714 (JP, A) (58 ) investigated the field (Int.Cl. ^6, DB name) C04B 35/00

Claims (2)

(57) [Claims] (1) In terms of oxides, Al ₂ O ₃ and SiO ₂ are substantially 100 wt% within the range of 10 wt% ≦ Al ₂ O ₃ <62 wt%, 90 wt% ≧ SiO ₂ > 38 wt%. Alumina-silica powder having a chemical composition of 1% by weight is calcined at 1000 ° C. to 1400 ° C. The calcined powder is pulverized in an organic solvent to have a specific surface area of 1%.
~ 50m ² / g adjusted to the raw material powder in the range, binder, plasticizer, organic solvent is added to this raw material powder to make a slurry, and this slurry is formed into a green sheet, then 1300 ℃ ~ 1600 ℃ A ceramic insulating material characterized in that the ceramic insulating material is fired at a temperature at which a cristobalite phase is not generated in the range and a constituent phase is composed of a mullite phase and a silicate glass phase. 2. In terms of oxide, Al ₂ O ₃ and SiO ₂ are substantially 100% in the range of 10% by weight ≦ Al ₂ O ₃ <62% by weight, 90% by weight ≧ SiO ₂ > 38% by weight. Alumina-silica powder having a chemical composition of 1% by weight is calcined at 1000 ° C. to 1400 ° C. The calcined powder is pulverized in an organic solvent to have a specific surface area of 1%.
~ 50m ² / g adjusted to the raw material powder in the range, binder, plasticizer, organic solvent is added to this raw material powder to make a slurry, and this slurry is formed into a green sheet, then 1300 ℃ ~ 1600 ℃ A method for producing a ceramic insulating material, characterized in that a constituent phase is obtained as a sintered body composed of a mullite phase and a silicate glass phase by firing at a temperature at which a cristobalite phase is not generated in the range.