JP2845104B2 - Manufacturing method of alumina ceramics substrate - Google Patents

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 an 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 ceramic laminated substrate containing alumina as a main component are used in communication equipment, computers, and the like. Every year, the trend toward miniaturization, thinning, and high performance is increasing.

[0003] Accordingly, the alumina ceramic laminated substrate is also being miniaturized in accordance with the miniaturization of these electronic components.

A method for manufacturing a conventional alumina ceramic 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 added 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
A plasticizer such as OA) is mixed with 2 to 10 parts by weight and other additives to form a slurry, a tape is formed by the doctor blade method using the slurry, and the tape is dried to produce a green sheet. I do. Next, according to the purpose and use of the green sheet, a through hole or the like is formed, and a conductor paste, an insulating paste, or a resistor wiring paste or the like is printed in a predetermined pattern. The alumina ceramic laminated substrate is manufactured by firing the obtained laminate.

[0005]

However, in the manufacturing process of such an alumina ceramic laminated substrate, the density and the density of the manufactured alumina ceramic laminated substrate depend on various characteristics such as the composition and the internal structure of the produced green sheet. Their shapes, structures, and the like differ greatly.

[0006] The reason why the above phenomenon occurs is as follows.
The following can be considered. After sintering the green sheets, when sintering the laminate, sintering is promoted by first performing a degreasing step of decomposing and eliminating a binder or a plasticizer present in the interior of the laminate, followed by sintering. And densify. However, since the heat treatment in the degreasing step is performed in a reducing atmosphere where the oxygen content is not sufficient, the binder and the like are less likely to be oxidized and decomposed than in the case of degreasing in an oxidizing atmosphere. for that reason,
The degree of decomposition and disappearance of the binder etc. largely depends on the decomposability of the binder etc. and the structure and amount of voids inside the green sheet, and if these conditions are not appropriate, a part of the binder etc. will be formed in the form of carbon etc. Remains inside. Since this residue hinders sintering of the alumina powder in the firing step, if this residue is present, the densification of the sintered body does not easily progress, and the sintered body has pores inside or irregularities on the surface. Will be manufactured.

By the way, in order to reduce the size of the alumina ceramic laminated substrate, the lamination surface inside the laminated body and the line width of the circuit wiring formed on the surface of the laminated body are reduced to form many circuit wirings in a small area. There is a need to. However, when such fine wiring is formed on an alumina ceramic laminated substrate having pores remaining on the inside or having irregularities on the surface, the lamination surface or the surface of the lamination inside the laminate is compared with the line width of the wiring. The unevenness of the wiring becomes larger, and a problem such as disconnection of the circuit wiring is apt to occur. Therefore, there is a problem that it is difficult to miniaturize the wiring.

The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a dense, high-density alumina ceramic substrate having small surface irregularities.

[0009]

In order to achieve the above object, a method for producing an alumina ceramics substrate according to the present invention comprises an alumina powder, a sintering aid, a (meth) acrylic resin,
After forming a slurry by mixing a plasticizer and a solvent, a ceramic green sheet of a predetermined size is formed using the slurry, and further a conductive paste and an insulating paste are printed, laminated, and fired. , With respect 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 by adding 10 parts by weight and adding a plasticizer of 30 to 70% by weight based on the (meth) acrylic resin.

[0010]

According to the method of manufacturing an alumina ceramic substrate having the above-described structure, a slurry is formed by mixing alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer, and a solvent, and then using the slurry to form a predetermined slurry. Forming a ceramic green sheet of the dimensions of, and further printing a conductor paste and an insulating paste, lamination, in a method of manufacturing a ceramic substrate to be fired, with respect to 100 parts by weight of the alumina powder,
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. In the ceramic green sheet produced by the addition of, the amount of voids increases, and the amount of the (meth) acrylic resin as a binder itself is small and easily decomposed. This facilitates sintering, reduces internal pores, improves surface smoothness, and produces an alumina ceramics substrate having excellent properties such as strength. Therefore, even if fine wiring is formed inside or on the surface of the substrate, disconnection or the like does not occur.

Also, the addition of the plasticizer further increases the uniformity of distribution of the binder and the like inside the alumina green sheet, thereby causing a place where the binder and the like hardly come off in the degreasing step and the binder and the like remain. No sintering occurs, and sintering proceeds uniformly inside the compact.

[0012]

Examples and Comparative Examples Examples and comparative examples of the method for manufacturing a ceramic substrate according to the present invention will be described below.

First, a method of manufacturing a green sheet laminate mainly containing alumina 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 alumina powder having an average particle diameter of 0.8 to 4 μm is pulverized by a ball mill, and furthermore, an acrylic resin. Or a binder 5 composed of methacrylic resin
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.

The green sheet is processed into a desired shape by a cutter or a punching die, and if necessary, through holes are formed in a desired shape by a punching die or the like. Next, a conductor paste is screen-printed on the green sheet processed by the above-described process to form a wiring pattern having a line width of 50 to 200 μm. Thereafter, a predetermined number of the green sheets on which the wiring patterns have been formed are laminated, 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.

The relationship between the density of the green sheet and the amount of the solvent when the alumina ceramics substrate is manufactured by the above method, the relationship between the amount of the acrylic resin added and the density of the sintered body, the amount of the plasticizer added to the acrylic resin and the green sheet The relationship between the density and the variation of the sintered body density and the relationship between the green sheet density and the sintered body density were examined. In this case, in all of the examples, the binder is an acrylic resin, the solvent is toluene or xylene, and the plasticizer is DO.
Using P, as other manufacturing conditions, for example, a pressing pressure of 30 to
The same conditions such as 100 kg / cm ² , a press temperature of 60 to 120 ° C., and a baking temperature of 1600 ° C. were adopted, and the obtained results were compared.

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

FIG. 1 is a graph showing the relationship between the density of the green sheet produced by the above-described method and the amount of the solvent with respect to 100 parts by weight of the alumina powder. In this case, 10 parts by weight of an acrylic resin is added to 100 parts by weight of alumina powder, and a plasticizer is added at 30% by weight to the acrylic resin. When the amount of the solvent exceeded 100 parts by weight, formation of a green sheet became difficult. FIG. 1 shows 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 a 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 is manufactured by the above method. In this case, a plasticizer is added to the acrylic resin at 30% by weight, and the density of the green sheet is adjusted to 2.5 by hot pressing. When the amount of the acrylic resin was less than 5 parts by weight, it was difficult to form a green sheet. As can be seen from the figure, when the amount of the 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 in accordance with the following.

FIG. 2 shows that the preferable addition range of the acrylic resin is 5 to 10 parts by weight.

Next, FIG. 3 is a graph showing the variation of 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 is 30 parts by weight, 50 parts by weight, 80 parts by weight and 100 parts by weight based on 00 parts by weight.

As is apparent from FIG. 3, when the amount of the plasticizer with respect to the binder (acrylic resin) is set to 30% by weight or more, the acrylic resin is softened, and the resin is easily mixed uniformly inside the slurry. Of the green sheet becomes easy to be molded, and the variation of the density of the green sheet is reduced. On the other hand, when the amount of the plasticizer exceeds 70% by weight, the green sheet becomes sticky and strongly adheres to the base film laid below during the formation, so that the green sheet is hardly peeled off.

As described above, by setting the amount of the plasticizer to 30 to 70% by weight with respect to the acrylic resin, the acrylic resin is uniformly dispersed in the green sheet. Etc. are unlikely to occur. Further, since the plasticizer itself is easily decomposed by heating in the degreasing step, the 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 experimental results, and is a graph 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 alumina ceramics according to the example, the density of the green sheet and the firing density are substantially inversely proportional, and as the density of the green sheet decreases, the firing density increases. I have. This is because the green sheet, which has a low density and contains a lot of pores, tends to decompose the acrylic resin and plasticizer contained in the green sheet during the degreasing process and discharge it to the outside. is there. Therefore, within the range of addition of the binder and the like according to the example, carbon and the like that inhibit sintering in the molded body is reduced, and sintering can be more smoothly progressed in the firing step, so that the number of internal pores is reduced. ,
It is possible to manufacture a sintered body having less irregularities 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, which sufficiently satisfied the strength required for the substrate.

Whether or not the circuit wiring of the alumina ceramics obtained by the method for manufacturing alumina ceramics according to the above embodiment was broken or not was measured by electric resistance measurement, and it was 6 × 10 ⁻⁶ Ω · cm or less. It turned out that there was no disconnection.

[0025]

As described above in detail, in the method for manufacturing an alumina ceramics substrate according to the present invention, a slurry is prepared by mixing alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer and a solvent. After the formation, a ceramic green sheet of a predetermined size is formed by using the slurry, a conductor 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 adding a large amount of the solvent has many voids and is a binder ( Since the amount of the (meth) acrylic resin itself is small and easily decomposed, the binder decomposes in the degreasing step and 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 or the like does not occur.

According to the method for manufacturing an alumina ceramic substrate (2) according to the present invention, in the method for manufacturing an alumina ceramic substrate according to the above (1), 30 to 70% by weight based on the (meth) acrylic resin. Since the plasticizer is added, the addition of the plasticizer increases the uniformity of distribution of the binder and the like inside the alumina green sheet, thereby causing a place where the binder hardly comes off in the degreasing process and the binder remains. No sintering occurs, the sintering can proceed uniformly inside the molded body, and an alumina ceramics substrate having a small amount of internal pores, a smooth surface, and excellent properties such as strength can be produced.

[Brief description of the drawings]

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

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

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

Continuation of the front page (56) References JP-A-3-158233 (JP, A) JP-A-5-167253 (JP, A) JP-A-4-38894 (JP, A) JP-A-3-158233 (JP) JP-A-4-114961 (JP, A) JP-A-4-88699 (JP, A) JP-A-2-123793 (JP, A) JP-A-61-46096 (JP, A) 5-148009 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05K 3/46

Claims (1)

(57) [Claims] After a slurry is formed by mixing alumina powder, a sintering aid, a (meth) acrylic resin, a plasticizer and a solvent, a ceramic green sheet having a predetermined size is formed using the slurry. In a method of manufacturing a ceramic substrate in which a conductor paste and an insulating paste are printed, laminated, and fired, with respect to 100 parts by weight of the alumina powder,
Alumina, wherein 60-100 parts by weight of the solvent and 5-10 parts by weight of the (meth) acrylic resin are added, and 30-70% by weight of a plasticizer is added to the (meth) acrylic resin. Manufacturing method of ceramic substrate.