JPH0543710A - Green sheet and production of multilayer ceramic circuit board - Google Patents

Abstract

PURPOSE:To obtain a green sheet for LSI circuit board having good dimensional precision by impregnating a cloth comprising a ceramic and glass fibers with a slurry containing ceramics, glass or their mixture, a resin, a plasticizer and a solvent. CONSTITUTION:While inorganic woven fabric 3 comprising ceramic and glass fibers is impregnated with a slurry 2 comprising ceramics, glass or these mixture, a binder resin, a plasticizer and a solvent such as acetone or 2-butanone filled, in a doctor blade 1, the impregnated fabhric is tape-cast on a carrier tape 4 comprising a polyester film byt he use of the doctor blade to obtain the objective green sheet 5 substantially not shrinking when baked and capable of compensating the dimensional precision. Penetrated holes 6 and conductor wirings are formed in the green sheet 5, and the treated green sheet 5 is laminated and subsequently baked to obtain a multilayer ceramic circuit board 8.

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 green sheet and a multilayer ceramic circuit board, and more particularly to a VL.
The present invention relates to a method of forming a green sheet for mounting an SI at a high density and forming an ultra-low dielectric constant ceramic circuit board suitable for high-speed signal propagation. In recent years, the speed of semiconductor devices used in large-scale general-purpose computers and supercomputers has increased remarkably, and the delay time per gate has become less than 100 ps. Has come to do. As a result, ceramics suitable for high-density and fine multi-layer wiring have come to be applied to the material of the CPU circuit board of the computer. In order to implement a higher-speed computer in the future, it is essential to develop high-density and fine multi-layer wiring and to develop ultra-low dielectric constant ceramics suitable for high-speed signal propagation.

[0002]

2. Description of the Related Art In a conventional multilayer ceramic circuit board, the width of signal wiring is widened to reduce the dielectric constant of the material without changing the impedance that affects the entire transmission system, or the distance between the power supply and ground and the signal wiring is increased. Need to narrow.
However, since the wiring width cannot be increased for the purpose of high-density mounting, it is necessary to reduce the interlayer distance, that is, the thickness of the green sheet, in order to reduce the dielectric constant of the material and increase the signal propagation speed.

[0003]

However, in the above-mentioned conventional multilayer ceramic circuit board, ceramic powder and resin are kneaded in a solvent and fired to form a green sheet. When the thickness is reduced, the thin green sheet is easily deformed, and therefore, when the LSI is mounted on the green sheet, the dimensional accuracy cannot be compensated. Therefore, in a manufacturing process for handling a large green sheet such as a multi-layer substrate for a high speed computer, it is practically difficult to reduce the dielectric constant which requires a green sheet of 200 μm or less.

Further, ceramics shrink and change in size during firing. If these are large, there is a problem that it is difficult to compensate for the highly accurate dimensions required for high-density mounting. Therefore, the present invention makes it possible to make the thickness less likely to be deformed, to compensate for dimensional accuracy when mounting an LSI, to facilitate handling during the process, and to make it difficult to shrink when fired. It is an object of the present invention to provide a method for manufacturing a green sheet and a ceramic circuit board, which can compensate for dimensional accuracy.

[0005]

In order to achieve the above object, the method for producing a green sheet according to the present invention comprises a cloth made of ceramics and glass fibers, a slurry made of ceramics, glass or a mixture thereof and a resin / plasticizer and a solvent. Is impregnated with. In the present invention, the cloth is tape-cast on a carrier film while being impregnated with the binder system, a conductor paste is printed on the tape-cast cloth to form a power supply or ground wiring, and then tape-casting is further performed. In this case, after the carrier film, the carrier film may be peeled off to obtain a green sheet that can be handled during the process,
After the tape casting, the multilayer green sheet may be pressed again together with the carrier film to be laminated, and then the carrier film may be peeled off to obtain a green sheet having excellent flatness.

In the present invention, the ceramics may be hollow ceramics. In this case, since it is possible to introduce air into the green sheet, the dielectric constant can be further lowered, which is preferable. In the present invention, the glass may be composed of a plurality of glasses having different softening points,
In this case, the softening point of the glass can be adjusted appropriately, which is preferable. For example, it is possible to prevent the glass from melting until the resin and the solvent are blown, and it is possible to melt the glass after the blow.

In the present invention, the multi-layer ceramic circuit board may be formed by forming the conductive holes and the conductor wirings in the green sheet, then stacking them and then firing them.

[0008]

In the present invention, as shown in FIG. 1, since the green sheet 5 is formed of the inorganic fiber cloth 3 of ceramics and glass fibers, it is less likely to be deformed even if it is made thinner than the conventional ceramic powder. Can, LS
When I is mounted, the dimensional accuracy can be compensated and the handling during the process can be facilitated.
Moreover, the shrinkage in the surface direction of the green sheet 5 when fired can be reduced from the conventional 20% to 5%, and the dimensional accuracy can be compensated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a method of manufacturing a green sheet according to an embodiment of the present invention. In FIG. 1, 1 is a slurry 2
Is a doctor blade filled with, and 3 is an inorganic fiber cloth formed by plain knitting hollow alumina fibers, borosilicate glass and quartz glass fibers. Further, 4 is a carrier tape made of a polyester film for tape-casting the inorganic fiber cloth 3, and 5 is a green sheet formed by impregnating the inorganic fiber cloth 3 with the slurry 2 and tape-casting on the carrier tape 4.

Next, a method for manufacturing the green sheet will be described with reference to FIG. First, hollow alumina fibers having a diameter of 12 μm and borosilicate glass and quartz glass fibers having a diameter of 12 μm are flat-knitted at a ratio of 1: 1: 1 to form an inorganic fiber cloth 3 having a width of about 500 m. Separately, a hollow fiber and borosilicate glass are kneaded with a binder resin, a solvent such as acetone and 2-butanone, and a plasticizer to prepare a slurry 2. Then
The inorganic fiber cloth 3 is impregnated with the slurry 2 filled in the doctor blade 1 and is tape-cast on the carrier tape 4 made of a polyester film using the doctor blade 1 to form a film having a thickness of 50 μm.
It is possible to obtain a degree of green sheet.

Next, FIG. 2 is a diagram for explaining a method of manufacturing a multilayer ceramic circuit board according to an embodiment of the present invention.
In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, 6 is a conductive hole formed in the green sheet 5, 7 is a copper paste filled in the green sheet 5, and 8 is a green. It is a multilayer ceramic circuit board formed by laminating sheets 5.

Next, a method of manufacturing the multilayer ceramic circuit board will be described with reference to FIG. The green sheet 5 formed as shown in FIG.
After peeling off, it is cut into a predetermined size, and the through holes 6 are formed on the upper and lower sides by a punch. Next, after filling the conductive holes 6 with the copper paste 7, a wiring pattern having a width of 100 μ is screen-printed with the copper paste 7. Then, the laminated body obtained by alternately stacking 30 layers of the green sheets 5 and pressing the same was used in a nitrogen atmosphere 10
The multilayer ceramic circuit board 8 can be obtained by firing at about 00 ° C.

That is, in this embodiment, the inorganic fiber cloth 3 made of ceramics and glass fibers is impregnated with the slurry 2 made of resin, plasticizer and solvent to obtain the green sheet 5.
To form. Since the green sheet 5 is formed of the inorganic fiber cloth 3 of ceramics and glass fibers in this way, it is possible to make it more difficult to deform even if the thickness is made smaller than in the case of forming the green sheet 5 by using the conventional ceramic powder.
The dimensional accuracy can be compensated for when mounted, and handling during the process can be facilitated.
In addition, regarding the thickness of the green sheet 5, the inorganic fiber cloth 3
When the slurry 2 is impregnated in the above, the thickness can be made substantially the same as before the impregnation, and the green sheet 5 having a thickness of about 30 μm can be handled. Further, the shrinkage in the surface direction of the green sheet 5 when fired can be reduced from the conventional 20% to 5%, and the dimensional accuracy can be compensated.

In the above embodiment, the inorganic fiber cloth 3 is 1
The case where the slurry 2 is impregnated from the upper and lower sides of the inorganic fiber cloth 3 by passing it through the individual doctor blade 1 has been described, but the present invention is not limited to this, and as shown in FIG. The doctor blade 1 filled with the slurry 2 so as to be sandwiched is arranged on the two carrier tapes 4, and first, the slurry is applied from the lower side of the inorganic fiber cloth 3 by the doctor blade 1 arranged rearward in the traveling direction of the inorganic fiber cloth 3. 2 is then impregnated with the inorganic fiber cloth 3 by means of a doctor blade 1 arranged in front of the inorganic fiber cloth 3 in the traveling direction.
The slurry 2 may be impregnated from the upper side and finally the slurry 2 may be impregnated from the upper and lower sides.

Next, in the present invention, the green sheet may be manufactured as follows as shown in FIG. Hollow quartz, borosilicate glass, and alumina are mixed so that the dielectric constant of the substrate after firing is 3.0. Then, this is kneaded with a binder resin, a solvent such as acetone and 2-butanone, and a plasticizer to prepare a slurry 2. Next, a doctor blade 1 is used to form a green sheet having a thickness of about 100 μm on a carrier tape 4 made of a polyester film, and naturally dried, and a mesh pattern for a power source or a ground layer is printed on the surface. Next, a green sheet having a thickness of about 100 μm is formed again on the green sheet wound without peeling the carrier tape 4 by using the doctor blade 1 and naturally dried, and then the carrier tape 4 is peeled off. The manufacturing of the multilayer ceramic circuit board is the same as that of the embodiment described with reference to FIG. In the case of this embodiment, since the conductor paste 9 is printed on the doctor blade 1 tape-cast on the carrier tape 4 to form the power supply or the ground wiring, and the tape is further stacked, the thickness of one layer is thin. Since it can have a multi-layer structure, it is possible to obtain a green sheet that can be handled during the process. Further, since the multi-layer green sheet is pressed again together with the carrier tape 4 and laminated, it is possible to obtain substantially the same flatness as the conventional green sheet. In FIG. 4, 10 is a squeegee and 11 is a screen mask.

[0016]

According to the present invention, it is possible to make it difficult to deform even if the thickness is reduced, it is possible to compensate the dimensional accuracy when the LSI is mounted, and it is easy to handle during the process. Moreover, there is an effect that shrinkage is less likely to occur when firing and dimensional accuracy can be compensated.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method of manufacturing a green sheet according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing a multilayer ceramic circuit board according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a method of manufacturing a green sheet applicable to the present invention.

FIG. 4 is a diagram illustrating a green sheet manufacturing method applicable to the present invention.

[Explanation of symbols]

 1 Doctor Blade 2 Slurry 3 Inorganic Fiber Cloth 4 Carrier Tape 5 Green Sheet 6 Conduction Hole 7 Copper Paste 8 Multilayer Ceramic Circuit Board 9 Conductor Paste 10 Squeegee 11 Screen Mask

Claims (8)

[Claims] 1. A method for producing a green sheet, which comprises impregnating a cloth made of ceramics and glass fibers with a slurry made of ceramics, glass or a mixture thereof, and a resin / plasticizer and a solvent. 2. A method for manufacturing a green sheet, wherein the cloth is tape-cast on a carrier film while being impregnated with the slurry. 3. A method for producing a green sheet, which comprises printing a conductor paste on the tape-cast green sheet to form a power supply or ground wiring, and then further tape casting. 4. The method for manufacturing a green sheet according to claim 2, wherein the carrier film is peeled off after the tape casting. 5. The method for producing a green sheet according to claim 2, wherein after the tape casting, the multilayer green sheet is pressed again together with the carrier film to be laminated, and then the carrier film is peeled off. 6. The method of manufacturing a green sheet according to claim 1, wherein the ceramic is a hollow ceramic. 7. The method for producing a green sheet according to claim 1, wherein the glass is a plurality of glasses having different softening points. 8. A method for manufacturing a multilayer ceramic circuit board, comprising: forming a through hole and a conductor wiring in the green sheet according to claim 1;