JPH06143239A - Manufacture of ceramic board - Google Patents

Abstract

PURPOSE:To obtain a ceramic board having a small irregularity in a shrinkage factor by sequentially laminating an adhesive layer containing vitreous component as a main ingredient and a green sheet containing sintering retardant component on both side surfaces of a laminate containing alumina as a main ingredient, and baking it while applying pressure to both side surfaces. CONSTITUTION:At least two of vitreous components such as Al2O3, MgO, SiO2, BaO, etc., are mixed, and a slurry is formed, for example, together with acrylic resin, plasticizer, solvent to form a green sheet. It is laminated on both side surfaces of a green sheet laminate (sample layer) 11 containing alumina as a main ingredient by a hot press to form an adhesive layer 12. Then, a green sheet is formed similarly to the layer 12 by using sintering retardant components such as AlN, Al2O3, SiC, etc. It is hot pressed to both side surfaces of the layer 12 to form restraint layers 13. The obtained laminate is baked while pressurizing in a reduced atmosphere. Thus, a baking shrinkage in a surface direction of the layer 11 can be suppressed.

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 a ceramics substrate, and more particularly to a method for manufacturing a ceramics substrate which is useful as a substrate for mounting an LSI or the like and has a small shrinkage variation.

[0002]

2. Description of the Related Art Small electronic components in which semiconductor elements (LSI, IC, etc.) are mounted on a laminated substrate containing alumina as a main component are
It is used for communication equipment, computers, etc., but these products are becoming smaller, thinner, and higher in performance year by year.

Therefore, the alumina laminated substrate is also in the direction of further miniaturization in accordance with the miniaturization of these products, but in order to further miniaturize, there are the following problems.

First, a conventional method for manufacturing an alumina laminated substrate will be described. First, alumina powder, sintering aid,
A solvent (xylene or the like) and other additives are mixed to form a slurry, and the slurry is used to prepare a green sheet by a doctor blade method. Next, the green sheet is processed into a form according to each purpose and use, laminated, and then the laminated body is fired to manufacture the alumina laminated substrate.

However, the green sheet produced in the manufacturing process of the alumina laminated substrate is not a uniform tape, but has variations in shrinkage in the in-plane direction and the thickness direction.
In addition, by firing the green sheet, about 50%
Volume contraction of. For this reason, when fine wiring is provided, there are cases in which wire bonding cannot be performed or an IC or the like cannot be mounted on the circuit board due to variations in shrinkage of the sintered body after sintering. Further, there are problems such as difficulty in increasing the number of pins and TAB. In addition, there is a problem that the through hole in the substrate and the tungsten wiring are misaligned with each other and the wire is easily broken.

Therefore, a flexible and removable layer containing a non-metallic inorganic powder is laminated on the surface of the green sheet, and the green sheet is fired while applying pressure in the thickness direction of the green sheet, so that the in-plane direction is improved. A method of suppressing shrinkage has been proposed (International Publication Number WO 91/10630).

In the above method, since pressure is applied in the thickness direction during firing, shrinkage in the in-plane direction is suppressed, and shrinkage mainly occurs in the thickness direction. As a result, variations in shrinkage are small, and since the non-metal inorganic powder does not sinter even after firing, it does not adhere to the sintered body and can be easily removed.

[0008]

However, in the above method, the shrinkage-suppressing layer formed on the green sheet,
Since the green sheet is not firmly fixed to the green sheet, the green sheet is easily moved during the firing process, and the in-plane shrinkage of the green sheet cannot be sufficiently suppressed. Therefore, if the pressure is increased in order to suppress the movement of the particles of the green sheet, the binder in the green sheet is not completely removed, resulting in insufficient sintering. On the other hand, when the pressure is low, there is a problem that the green sheet contracts in the in-plane direction as described above, and the variation in the contraction rate in the in-plane direction still remains.

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 manufacturing a ceramic substrate with high dimensional accuracy by further suppressing the shrinkage that occurs during firing of the ceramic substrate.

[0010]

In order to achieve the above object, a method for manufacturing a ceramic substrate according to the present invention is directed to an adhesive layer containing a glass component as a main component on both surfaces of a green sheet laminate containing alumina as a main component. After laminating, a green sheet containing a hardly-sinterable component is laminated on both sides of the green sheet laminate on which the adhesive layer is laminated, and the obtained laminate is fired while applying pressure to both sides. I am trying.

[0011]

According to the method of manufacturing a ceramic substrate according to the present invention, as shown in FIG. 1 (a), glass components are formed on both surfaces of a green sheet laminate containing alumina as a main component (hereinafter referred to as sample layer 11). After laminating an adhesive layer 12 containing as a main component, a green sheet (hereinafter referred to as a constraining layer 13) containing a hardly-sinterable component is laminated on both surfaces of the sample layer 11 on which the adhesive layer 12 is laminated, Since it is fired while applying pressure from the press 14 to both sides of the laminated body,
The adhesive layer 12 is softened to form a glass layer in the vicinity of 1250 ° C., the sample layer 11 and the constraining layer 13 are adhered by the glass layer, and the particles on the surface of the sample layer 11 become hard to move, so that the sample layer 11 Sinter shrinkage in the in-plane direction is suppressed, and variations in shrinkage are reduced.

The state after firing is shown in FIG. 1 (b). The adhesive layer 12 is diffused in the sample layer 11 and the constraining layer 13, and the glass having the composition of the adhesive layer 12 is formed on the sample layer 11. No layer is formed, and the glass layer does not adhere to the wiring formed on the sample layer 11. Restraint layer 13
A small amount of the hardly sinterable component may adhere to the sample layer 11, but since the amount is at most about one layer of the hardly sinterable powder, there is no problem even if it is used as it is. Further, the hardly sinterable powder in the constraining layer 13 is not fixed by the glass component, but is removed after being broken into pieces.

[0013]

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 (sample layer) containing alumina as a main component will be described. The sample layer can be obtained by a usual method for producing an alumina green sheet.

First, with respect to 100 parts by weight of alumina powder,
A mixed powder containing 10 to 20 parts by weight of a sintering aid such as SiO ₂ or MgO is crushed by a ball mill, and further a binder such as PVB 5
˜20 parts by weight, 2 to 10 parts by weight of a plasticizer such as DBP and DOA and 15 to 40 parts by weight of a solvent such as xylene are added and mixed by using a ball mill to form a slurry. Next, air bubbles are removed from the slurry, a sheet is formed using a doctor blade method, and dried at 60 to 120 ° C. to produce an alumina green sheet. The green sheet obtained by the above method 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 processed green sheet to form a wiring pattern. After that, a predetermined number of the green sheets on which the wiring patterns have been formed are stacked, and the press pressure is applied.
5 to 300 kg / cm ² , press time 0.5 to 200 seconds, press temperature
Hot pressing is performed under the condition of 50 to 130 ° C.

Next, a method for producing an adhesive layer containing a glass component as a main component and a method for laminating the adhesive layer on the sample layer will be described.

Examples of the glass component compound include:
Al ₂ O ₃ , MgO, SiO ₂ , CaO, TiO ₂ , BaO, B ₂ O ₃ , La ₂ O
₃ , CeO ₂ , ZrO _{2 and the} like, and the adhesive layer is formed by using a mixture containing at least two kinds of the compounds. The particle size of the glass component compound is preferably about 2 to 5 μm. If the particle size of the compound is less than 2 μm, a large amount of a binder or the like described later is required, which is not preferable. On the other hand, if the particle size exceeds 5 μm, it is difficult to produce a sheet having a uniform thickness, which is not preferable. .

A preferred composition example of the glass component is shown in Table 1 below.

[0019]

[Table 1]

A binder 5 such as acrylic resin, methacrylic resin or PVB is added to 100 parts by weight of the mixture having the above composition.
.About.20 parts by weight, 2 to 10 parts by weight of a plasticizer such as DBP and DOP and 15 to 40 parts by weight of a solvent such as xylene are added and mixed using a ball mill to form a slurry. As the binder used in this case, an acrylic resin or a methacrylic resin is preferable because it is easily decomposed and scattered during firing. next,
As in the case of producing the sample layer, air bubbles are removed from the slurry, a sheet is formed using the doctor blade method, and dried at 60 to 120 ° C. to produce a green sheet. The thickness of the green sheet is preferably 10 to 50 μm. If the thickness of the green sheet is less than 10 μm, it is too thin to serve as an adhesive layer, while if it exceeds 50 μm, it is difficult to decompose and remove organic substances during firing, which is not preferable.

The green sheet thus obtained is laminated on both sides of the sample layer by hot pressing. The conditions for hot pressing are the same as those for forming the sample layer.

The adhesive layer containing the above glass component as a main component,
After adding the same binder, plasticizer and solvent as above to the glass component to form a slurry, the obtained paste-like slurry is used as it is, and alumina is mainly used by a printing method such as screen printing which is usually performed. It can also be formed by printing on both sides of a green sheet as a component.

Next, a method for producing a green sheet (constraint layer) containing a hardly-sinterable component and a method for laminating the constrain layer on a green sheet laminate having an adhesive layer laminated thereon will be described.

As the compound for the hard-to-sinter component, for example, AlN
, Al ₂ O ₃ , SiC, Si ₃ N ₄ , BN, SiO ₂ , MgO and the like. The constraining layer component is formed by using a mixture containing at least one kind of the compound. Further, the particle size of the compound for the hardly-sinterable component is preferably about 2 to 5 μm.
If the particle size of the compound is less than 2 μm, it is not preferable because a large amount of the binder and the like described later is required, while the particle size is 5
When it exceeds μm, it becomes difficult to produce a sheet having a uniform thickness, which is not preferable.

A binder 5 such as acrylic resin, methacrylic resin or PVB is added to 100 parts by weight of the mixture for the hardly sinterable component.
.About.20 parts by weight, 2 to 10 parts by weight of a plasticizer such as DBP and DOP, and 15 to 40 parts by weight of a solvent such as xylene are added and mixed using a ball mill to form a slurry. As the binder used in this case, an acrylic resin or a methacrylic resin is preferable because it is easily decomposed and scattered during firing. Thereafter, as in the case of the sample layer production, air bubbles are removed from the slurry, a sheet is formed using the doctor blade method, and dried at 60 to 120 ° C. to produce a green sheet. The thickness of the green sheet is 50-200 μ
m is preferred. If the thickness of the green sheet is less than 50 μm, the in-plane shrinkage of the sample layer cannot be stopped and in-plane shrinkage occurs, while if the thickness exceeds 200 μm, the decomposition of the binder becomes difficult, It is not preferable because the binder remains.

The constraining layer made of the green sheet containing the hardly-sinterable component thus obtained is further laminated on both sides of the sample layer having the adhesive layer formed on both sides by hot pressing. The conditions for hot pressing are the same as those for forming the sample layer.

A laminated body obtained by the above-mentioned method, in which the adhesive layer is laminated on both surfaces of the sample layer, and the constraining layer is laminated on both surfaces of the adhesive layer, is used with a mixed gas of hydrogen and nitrogen. In the reducing atmosphere described above, firing is performed while applying a pressure of 50 to 300 kg / cm ² in the thickness direction of the laminate. The firing temperature is preferably 1500 to 1600 ° C.

The variation in shrinkage rate of the ceramic substrate manufactured by the method according to the embodiment of the present invention as described above was compared with the variation in shrinkage rate of the ceramic substrate manufactured by another method. As another method, (A) without applying pressure to the sample layer produced by the above production method, firing under the same firing conditions, (B) similar to the pressure applied to the sample layer in the above example While applying pressure, firing under the same conditions, (C) laminating a constraining layer containing a hardly sinterable component to the sample layer, while applying a pressure similar to the pressure applied in the above example, The three methods of firing under the conditions of were adopted.

The results are shown in FIG. In FIG. 2, the vertical axis represents the variation (%) in shrinkage ratio, and the horizontal axes A, B, and C are
The methods (A), (B) and (C) described above are shown respectively, and D shows the method of the above embodiment.

As is apparent from FIG. 2, the ceramic substrate obtained by the method for manufacturing a ceramic substrate of the present invention according to the embodiment has much less variation in shrinkage than the conventional method.

[0031]

As described above in detail, in the method for manufacturing a ceramic substrate according to the present invention, the adhesive layers containing a glass component as a main component are laminated on both surfaces of the green sheet laminate containing an alumina as a main component. After that, a green sheet containing a hardly sinterable component is laminated on both sides of the green sheet laminated body in which the adhesive layer is laminated, and the obtained laminated body is fired while applying pressure to both sides. Since the adhesive layer is softened and the sample layer and the constraining layer are adhered, and the particles in the constraining layer do not move, it is possible to suppress the sintering shrinkage in the in-plane direction of the sample layer and to reduce the variation in shrinkage rate. It can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method for manufacturing a ceramic substrate of the present invention, in which (a) shows a state before firing and (b) shows a state after firing.

FIG. 2 is a graph comparing variations in shrinkage rate of a ceramic substrate obtained by the method for manufacturing a ceramic substrate according to an example of the present invention with other methods.

[Explanation of sign]

 11 sample layer 12 adhesive layer 13 constraining layer

Claims (1)

[Claims] 1. A green sheet laminate containing alumina as a main component, and an adhesive layer containing a glass component as a main component is laminated on both sides of the green sheet laminate, and the green sheet laminate on which the adhesive layer is laminated is hardly sintered. A method for manufacturing a ceramic substrate, comprising laminating green sheets containing a functional component, and firing the resulting laminated body while applying pressure to both sides.