JPH07106762A - Manufacture of alumina ceramic substrate - Google Patents

Abstract

PURPOSE:To obtain a compact alumina ceramic substrate having less-rugged surfaces and a high density by adding specific amounts of a solvent and (meth) acrylic resin to a alumina powder and a specific amount of a plasticizer to the (meth)acrylic resin. CONSTITUTION:After forming a green sheet by using slurry prepared by mixing sintering assistant, (meth)acrylic resin, plasticizer, and solvent with alumina powder and printing conductor paste and insulating paste to the surface of the green sheet, an alumina ceramic substrate is obtained by piling up the green sheet upon another and baking the laminated body. At the time of preparing the slurry, the solvent and (meth)acrylic resin are added by 60-100wt.pts. and 5-10wt.pts., respectively, to 100wt.pts. alumina powder. As understood from the figure, the alumina ceramic substrate has a high density when the adding amount of the acrylic resin is within a range from 5 to 10wt.pts., but the density after baking starts to drop when the adding amount exceeds 10wt.pts. and the density drop becomes more conspicuous as the adding amount increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an alumina ceramic substrate, and more particularly to a method for manufacturing an alumina ceramic substrate useful as a substrate for mounting LSI or the like.

[0002]

2. Description of the Related Art Small electronic components in which semiconductor elements (LSI, IC, etc.) are mounted on an alumina ceramics laminated substrate containing alumina as a main component are used in communication devices, computers, etc. Year by year, we are moving toward smaller, thinner and higher performance.

Therefore, the alumina ceramics laminated substrate is also in the direction of further miniaturization in accordance with the miniaturization of these electronic components.

A method of manufacturing a conventional alumina ceramics laminated substrate will be described. First, 10 to 20 parts by weight of a sintering aid and 5 to 5 parts by weight of a resin (binder) such as polyvinyl butyral (PVB) are used with respect to 100 parts by weight of alumina powder.
20 parts by weight, 15 to 40 parts by weight of a solvent such as xylene, dibutyl phthalate (DBP), dioctyl adipate (D
2 to 10 parts by weight of a plasticizer such as OA) and other additives are mixed to form a slurry, and the slurry is used to form a tape by a doctor blade method, and this is dried to produce a green sheet. To do. Next, according to each purpose and use of the green sheet, through holes and the like are formed, and a conductor paste, an insulating paste, a resistance wiring paste, or the like is printed in a predetermined pattern, and then these are laminated, The alumina ceramic laminated substrate is manufactured by firing the obtained laminated body.

[0005]

However, in the manufacturing process of such an alumina ceramics laminated substrate, the density and the density of the manufactured alumina ceramics laminated substrate are varied depending on various characteristics such as the composition of the produced green sheet and its internal structure. The shape, structure, etc. differ greatly.

The reason why the above phenomenon occurs is as follows.
The following can be considered. When the green sheet is laminated and then fired, the sintering is promoted by first performing a degreasing step of decomposing and eliminating the binder and the plasticizer present inside the laminate. Let it be densified. However, since the heat treatment in the degreasing step is performed in a reducing atmosphere in which the oxygen content is not sufficient, the binder and the like are less likely to be oxidatively decomposed as compared with the case of degreasing in an oxidizing atmosphere. for that reason,
The degree of decomposition and disappearance of the binder, etc. greatly depends on the decomposability of the binder, etc. and the structure and amount of voids inside the green sheet. If these conditions are not appropriate, part of the binder, etc. will form in the form of carbon, etc. It remains inside. Since this residue hinders the sintering of the alumina powder in the firing process, the presence of this residue makes it difficult for the sintered body to be densified, has a pore inside, or has unevenness on the surface. Will be manufactured.

By the way, in order to miniaturize the alumina ceramics laminated substrate, the line width of the circuit wiring formed inside the laminated body or on the surface of the laminated body is made small so that many circuit wirings are formed in a small area. There is a need to. However, when such fine wiring is formed on an alumina ceramics laminated substrate having pores remaining inside or irregularities on the surface as described above, when compared to the line width of the wiring, the laminated surface inside the laminated body or the surface of the laminated body However, there is a problem in that it is difficult to miniaturize the wiring because the unevenness of the wiring becomes larger and the problem such as disconnection of the circuit wiring easily occurs.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a high-density alumina ceramics substrate which is densified and has small surface irregularities.

[0009]

In order to achieve the above object, a method of manufacturing an alumina ceramics substrate according to the present invention comprises an alumina powder, a sintering aid, a (meth) acrylic resin,
In a method for manufacturing a ceramic substrate, after mixing a plasticizer and a solvent to form a slurry, a ceramic green sheet having a predetermined size is formed using the slurry, and a conductor paste and an insulating paste are printed, laminated, and fired. , 100 to 100 parts by weight of the alumina powder, 60 to 100 parts by weight of the solvent and 5 to 5 parts of the (meth) acrylic resin.
It is characterized in that 10 parts by weight is added and 30 to 70% by weight of the plasticizer is added to the (meth) acrylic resin.

[0010]

According to the method of manufacturing an alumina ceramics substrate having the above-mentioned structure, alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer and a solvent are mixed to form a slurry, and the slurry is used to perform a predetermined process. In a method of manufacturing a ceramic substrate, in which a ceramic green sheet having a size of 1 is formed, and a conductor paste and an insulating paste are printed, laminated, and fired, 100 parts by weight of the alumina powder is added to
Since 60 to 100 parts by weight of the solvent and 5 to 10 parts by weight of the (meth) acrylic resin are added, and 30 to 70% by weight of the plasticizer is added to the (meth) acrylic resin, a large amount of the above solvent is added. Since the ceramic green sheet produced by the addition of the above has many voids and the amount of the (meth) acrylic resin as a binder itself is small and easily decomposed, the binder and the like are decomposed in the degreasing step and completely removed from the molded body Alumina ceramics substrate which is easily discharged into the alumina ceramics, promotes sintering, reduces internal pores, improves surface smoothness, and has excellent characteristics such as strength. Therefore, even if fine wiring is formed inside or on the surface of the substrate, disconnection does not occur.

Further, the addition of the plasticizer further increases the uniformity of the distribution of the binder and the like inside the alumina green sheet, which causes the binder and the like to remain in the degreasing step and the binder and the like remain. Does not occur, and the sintering proceeds uniformly inside the molded body.

[0012]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the ceramic substrate manufacturing method according to the present invention will be described below.

First, a method of manufacturing a green sheet laminate containing alumina as a main component will be described. First, a mixed powder obtained by adding 10 to 20 parts by weight of a sintering aid such as SiO ₂ or MgO to 100 parts by weight of an alumina powder having an average particle size of 0.8 to 4 μm was crushed by a ball mill, and further, an acrylic resin. Or a binder made of methacrylic resin 5
10 parts by weight, 5 to 10 parts by weight of a plasticizer such as dioctyl phthalate (DOP) and dibutyl maleate (DBM), and 60 to 100 parts by weight of a solvent such as toluene and xylene are added and mixed using a ball mill. Slurry. Next, air bubbles are removed from the slurry, a sheet is formed using a doctor blade method, and dried at 60 to 140 ° C. to produce an alumina green sheet, and the density of the obtained green sheet is measured.

This green sheet is processed into a desired shape with a cutter or a punching die, and if necessary, a through hole is formed into a desired shape with a punching die or the like. Next, a conductor paste is screen-printed on the green sheet which has been processed by the above-mentioned steps to form a wiring pattern having a line width of 50 to 200 μm. After that, a predetermined number of the green sheets on which the wiring patterns have been formed are stacked, and hot pressed under the conditions of a pressing pressure of 10 to 100 kg / cm ² and a pressing temperature of 20 to 120 ° C.

The laminate obtained by the above method is fired at 1600 to 1700 ° C. in a reducing atmosphere using a mixed gas of hydrogen, nitrogen and water vapor.

When the alumina ceramics substrate is manufactured by the above-mentioned method, the relationship between the density of the green sheet and the solvent amount, the relationship between the acrylic resin addition amount and the sintered body density, the addition amount of the plasticizer to the acrylic resin and the green sheet The relationship between variations in density and sintered body density and the relationship between green sheet density and sintered body density were examined. In this case, in all the examples, the binder is acrylic resin, the solvent is toluene or xylene, and the plasticizer is DO.
Other manufacturing conditions, such as a press pressure of 30 to
The same conditions were adopted, such as 100 kg / cm ² , pressing temperature 60 to 120 ° C., firing temperature 1600 ° C., and the obtained results were compared.

As a comparative example, the addition amount of the binder, solvent and plasticizer to 100 parts by weight of the alumina powder was outside the range of the above-mentioned examples, and the other conditions were the same as those of the examples. Manufactured.

FIG. 1 is a graph showing the relationship between the density of the green sheet produced by the above method and the amount of solvent with respect to 100 parts by weight of alumina powder. In this case, 10 parts by weight of acrylic resin was added to 100 parts by weight of alumina powder, and 30% by weight of plasticizer was added to the acrylic resin. If the amount of solvent exceeds 100 parts by weight, it becomes difficult to form a green sheet. From FIG. 1, it can be seen that when the amount of the solvent is 60% by weight or more, the density of the green sheet is greatly reduced. Next, FIG. 2 is a graph showing the relationship between the amount of the acrylic resin and the density of the sintered body after firing with respect to 100 parts by weight of the alumina powder when the green sheet was manufactured by the above method. In this case, the plasticizer is added to the acrylic resin in an amount of 30% by weight, and the density of the green sheet is adjusted to 2.5 by hot pressing. When the amount of acrylic resin was less than 5 parts by weight, it became difficult to form a green sheet. As can be seen from the figure, when the amount of acrylic resin is in the range of 5 to 10 parts by weight, high density alumina ceramics is obtained, but when it exceeds 10 parts by weight, the firing density starts to decrease and the weight increases. The tendency becomes remarkable according to.

From FIG. 2, it is understood that the preferable addition range of the acrylic resin is 5 to 10 parts by weight.

Next, FIG. 3 is a graph showing variations in the density of the green sheet when the amount of the plasticizer with respect to the acrylic resin is changed. In this case, alumina powder 1
The amount of the solvent relative to 00 parts by weight is 30, 50, 80 and 100 parts by weight.

As is clear from FIG. 3, when the amount of the plasticizer with respect to the binder (acrylic resin) is 30% by weight or more, the acrylic resin is softened and the resin is easily mixed uniformly inside the slurry, and the slurry is also easily mixed. The viscosity of the green sheet decreases and the molding becomes easy, and the variation in the density of the green sheet decreases. On the other hand, when the amount of the plasticizer is more than 70% by weight, the green sheet becomes sticky and firmly adheres to the underlying base film at the time of formation, so that it becomes difficult to peel off.

As described above, by setting the amount of the plasticizer to the acrylic resin in the range of 30 to 70% by weight, the acrylic resin is uniformly dispersed in the green sheet, and the decomposition failure due to the non-uniformity of the resin dispersion. Is less likely to occur. Further, since the plasticizer itself is also easily decomposed by heating in the degreasing step, decomposition and disappearance of the binder and the like are significantly promoted in the degreasing step.

Next, FIG. 4 is a graph summarizing the above-mentioned experimental results, showing the relationship between the density of the green sheet and the firing density. As can be seen from this graph, in the method for producing an alumina ceramics according to the example, the density of the green sheet and the firing density are in an inversely proportional relationship, and the firing density increases as the density of the green sheet decreases. There is. This is because the green sheet that has a low density and contains many pores inside is more likely to decompose the acrylic resin or plasticizer contained inside the green sheet in the degreasing process and discharge it to the outside. is there. Therefore, within the addition range of the binder and the like according to the embodiment, the amount of carbon or the like that hinders the sintering is reduced inside the molded body, and the sintering can be progressed more smoothly in the firing step, so that the internal pores are reduced. ,
It is possible to manufacture a sintered body having less unevenness on the surface. The strength of the alumina ceramics substrate obtained in the above example had a value of 3200 kg / cm ² or more, and sufficiently satisfied the strength required for the substrate.

Whether or not the circuit wiring of the alumina ceramics obtained by the method for producing alumina ceramics according to the above-mentioned example was broken was measured by electric resistance and it was 6 × 10 ⁻⁶ Ω · cm or less, It turned out that it wasn't broken.

[0025]

As described in detail above, in the method for producing an alumina ceramic substrate according to the present invention, the slurry is prepared by mixing alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer and a solvent. After forming, a ceramic green sheet having a predetermined size is formed using the slurry, and a conductive paste and an insulating paste are printed, laminated and fired. Since 60 to 100 parts by weight of the solvent and 5 to 10 parts by weight of the (meth) acrylic resin are added, the ceramic green sheet produced by the addition of the large amount of solvent has many voids and is a binder ( Since the amount of (meth) acrylic resin itself is small and it is easily decomposed, the binder decomposes in the degreasing process and is removed from the molded body. Easily be discharged in all, it is possible to accelerate the sintering, small amount of internal pore surface is smooth, it is possible to produce an excellent alumina ceramic substrate on the characteristics such as strength. Therefore, even if fine wiring is formed inside or on the surface of the substrate, disconnection does not occur.

According to the method (2) for manufacturing an alumina ceramic substrate according to the present invention, in the method for manufacturing an alumina ceramic substrate described in (1) above, the amount of the resin is 30 to 70% by weight based on the (meth) acrylic resin. Since a plasticizer is added, the addition of this plasticizer increases the uniformity of the distribution of the binder and the like inside the alumina green sheet, which causes the binder to remain in the degreasing process and the binder remains. It is possible to produce an alumina ceramics substrate which is capable of uniformly advancing sintering inside the molded body, has a small amount of internal pores, has a smooth surface, and has excellent properties such as strength.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of solvent and the green sheet density with respect to 100 parts by weight of alumina powder in the method for manufacturing an alumina ceramics substrate according to an example of the present invention.

FIG. 2 is a graph showing the relationship between the amount of acrylic resin and the firing density with respect to 100 parts by weight of alumina powder in the method for manufacturing an alumina ceramic substrate according to the example.

FIG. 3 is a graph showing the relationship between the amount of plasticizer with respect to the acrylic resin and the variation in green sheet density in the method for manufacturing an alumina ceramic substrate according to the example.

FIG. 4 is a graph showing the relationship between the green sheet density and the firing density in the method for manufacturing an alumina ceramics substrate according to the example.

Claims (1)

[Claims] 1. An alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer and a solvent are mixed to form a slurry, and the slurry is used to form a ceramic green sheet of a predetermined size. In a method for manufacturing a ceramic substrate in which a conductor paste and an insulating paste are printed, laminated and fired, 100 parts by weight of the alumina powder is added to
60 to 100 parts by weight of the solvent and 5 to 10 parts by weight of the (meth) acrylic resin are added, and 30 to 70% by weight of a plasticizer is added to the (meth) acrylic resin. Manufacturing method of ceramics substrate.