JP2004136690A - Green sheet manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process which can efficiently produce a green sheet free of longitudinal wrinkles and having a uniform thickness. <P>SOLUTION: The manufacturing process, which is for forming a green sheet 10 with a doctor blade 3a after coating a slurry 4 containing ceramic powders on a carrier film 1 that is conveyed to one direction, is characterized by providing an arcuate supporting surface 8 along the transfer direction of the carrier film 1 in the underside thereof and conveying on the supporting surface 8 the carrier film 1 coated with the slurry 4a. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for manufacturing a green sheet used for a multilayer substrate for electronic components.

Generally, as a green sheet manufacturing apparatus, a doctor blade method as shown in FIG. 2 is employed. In this apparatus, a carrier film 1 is pulled out from a supply roll 1a, is conveyed in one direction over a plurality of horizontally arranged support rollers 2, and has a doctor blade 3a above the carrier film 1; A coater section 3 in which a slurry 4 containing powder is stored is disposed, and the slurry 4 in the coater section 3 is moved from the gap 3b between the doctor blade 3a and the carrier film 1 as the carrier film 1 moves. The slurry 4a in the form of a sheet is formed by applying the slurry, and the slurry 4a is dried by blowing hot air in the drying unit 5 to form the green sheet 10. After that, the green sheet 10 is pulled out together with the carrier film 1 by the pair of drawing rollers 6a and 6b. And is wound on a winding roll 10a.

As such a green sheet manufacturing apparatus using the doctor blade method, for example, in Patent Document 1, by forming a green sheet on a transport film, by providing a flat spacer at the end of the transport film support table, There is a description to prevent the occurrence of film wrinkles. Patent Document 2 discloses a ceramic green sheet manufacturing method in which a ceramic slurry is applied to a carrier film by using a doctor blade method and passed through a drying device to obtain a ceramic green sheet. It is described that the carrier film is dried by a hot air drying device arranged in a subsequent stage, and in the hot air drying device, the carrier film is supported by an endless belt stretched over a pair of rolls arranged thereunder. . Further, Patent Documents 3 to 5 disclose a coating device for a magnetic material or the like using a plurality of stretching rolls arranged in an upwardly convex shape. Patent Document 6 describes that in a method of forming a green sheet on a transport film by a doctor blade method, a conveyor belt is used as a transport unit and a heating unit is provided below the film.
JP-A-3-277504 JP-A-5-004211 JP-A-5-104049 JP-A-5-261326 JP-A-7-000898 JP-A-62-124903

However, in the apparatus shown in FIG. 2, the draw-out rollers 6a and 6b cause vertical wrinkles 1b in the carrier film 1 due to the tension applied in the transport direction indicated by the arrow T as shown in FIG. There is a problem that the thickness is transferred to the green sheet 10 and the thickness dimension in the width direction is disturbed 10b. In particular, in the case of a green sheet used for a multi-layer substrate, a defect in the thickness dimension causes a defect when a circuit pattern is printed and becomes a defect. In this case, there is a problem that a portion that does not adhere to the circuit is generated, resulting in a circuit defect. In addition, recently, in order to increase the working efficiency such as a cutting process of a substrate and a through-hole process required for a multilayer substrate, the green sheet 10 is processed integrally with the carrier film 1. It is required that the thickness of the carrier film 1 be reduced to 100 μm or less so as not to hinder the operation. When the green sheet 10 is manufactured using the thin carrier film 1, the height of the vertical wrinkles 1b becomes more remarkable, and there is a problem that almost all parts of the green sheet 10 are defective in thickness and dimensions.

Further, in the drying section 5 of the above-described apparatus, the sheet-like slurry 4a is dried by blowing hot air from above the slurry, and only the surface of the slurry 4a is dried and contracted and solidified first, and then the lower layer is dried. Therefore, there is a problem that a crack is generated in the green sheet 10 due to a time difference in contraction between the surface and the lower layer.

The object of the present invention is to solve the conventional problems described above and to provide a manufacturing method capable of efficiently manufacturing a green sheet having a uniform thickness without vertical wrinkles.

The green sheet manufacturing method according to the present invention is a green sheet manufacturing method in which a slurry containing ceramic powder is applied on a carrier film conveyed in one direction and a green sheet is formed by a doctor blade. Along the lower side, an arch-shaped support surface is provided, and the carrier film coated with the slurry is conveyed on the support surface.

Further, the method of manufacturing a green sheet according to the present invention is to provide a conveyor belt having an arch-shaped support surface below the carrier film along the transport direction, and transport the carrier film coated with the slurry on the conveyor belt. It is characterized by doing.

As the arch-shaped support surface, the carrier film is provided below the carrier film, and the carrier film is supported in an arch shape along the transport direction to prevent vertical wrinkles of the carrier film due to tension applied in the transport direction. Examples of the support forming the support surface include a large single arch-shaped plate, a large number of support pieces or small-diameter support rollers densely arranged in an arch shape, and the like. The carrier film coated with the slurry may be directly conveyed on the surface of the support, but a conveyor belt is preferably provided between the arch-shaped support and the carrier film coated with the slurry. The conveyor belt itself, which supports and transports the carrier film interposed, is formed as an arch-shaped support surface, which reduces the tension applied to the carrier film and prevents vertical wrinkles It is on that. As the conveyor belt, a belt that is made of a material that does not deform even under the drying conditions of the applied slurry, does not emit unnecessary volatile components, and has a width larger than that of the carrier film is suitable. More preferably, the rigidity of the conveyor belt itself is so high that defects such as irregularities on the surface of the support structure that supports the conveyor belt, which cause vertical wrinkles, are not transmitted to the carrier film.

Further, the method for manufacturing a green sheet according to the present invention is characterized in that a heating means is provided below a support having an arch-shaped support surface, and a coated slurry is heated from the carrier film side. .

The heating means is for heating the applied sheet-shaped slurry from the carrier film side and quickly drying the same to form a flexible green sheet having a desired size and shape without generating defects such as cracks. For example, a heating element that converts electric energy into heat energy, or a heat source in the form of a pipe or a plate using hot water, steam, or another heat medium can be used.

According to the green sheet manufacturing method of the present invention, an arch-shaped support surface is provided below the carrier film in the transport direction, and the carrier film coated with the slurry is transported on the support surface. Therefore, the carrier film to which the slurry is applied is pressed and supported in a state of being stuck to the arch-shaped support surface, so that generation of vertical wrinkles can be prevented.

Further, according to the manufacturing method of the present invention, since the coated sheet-shaped slurry is heated from the carrier film side by providing a heating means below the support having the arch-shaped support surface, the arch-shaped support is provided. The sheet-like slurry applied from the carrier film side can be heated by the heating means provided on the support in a state where the wrinkles of the carrier film are prevented by the surface, and the entire slurry is uniformly and quickly dried without cracking. can do.

According to the green sheet manufacturing method of the present invention, a practically excellent effect that a high-quality green sheet having high thickness dimensional accuracy without vertical wrinkles and having no defects such as cracks can be efficiently manufactured can be obtained. To play.

FIG. 1 is an explanatory view of a green sheet manufacturing apparatus used in the embodiment of the present invention, wherein 1 is a carrier film, 3 is a coater, 4 is a slurry made of ceramic powder or the like, 5 is a drying unit, and 6a , 6b denotes a pull-out roller, 7 denotes a conveyor belt, 8 denotes an arch-shaped support surface, 9 denotes a heating means, and 10 denotes a green sheet, respectively, which are the same as those in FIGS. 2 and 3 described above. Are denoted by the same reference numerals.

As shown in FIG. 1, the carrier film 1 pulled out from the supply roll 1a is made of, for example, PET (polyethylene terephthalate) resin and has a width of 500 mm and a thickness of 75 μm. The conveyor belt 7 transports the carrier film 1 drawn from the supply roll 1a in one direction at a constant speed. As a material of the conveyor belt 7, an organic woven fabric such as polyester is used so as not to damage the green sheet.

In the case of the present embodiment, the support surface 8 supports the slurry 4 a that has just been applied to the carrier film 1 and still has fluidity, and the support plate 8 a that supports the slurry 4 b that has been dried and has lost fluidity. The upper surface is formed in a gentle arch shape with a curvature radius of about 10 to 20 m along the transport direction. The support plate 8a is formed of a stainless steel plate having a curved surface with a smooth finished surface, while the support roller 8b is composed of a plurality of small diameter rollers made of stainless steel, and the carrier film 1 to be supported has vertical wrinkles. The conveyor belt 7 stretched on the support surface 8 is supported by the arched curved surface, and the carrier film 1 is vertically wrinkled by the tension applied in the transport direction. Is prevented from occurring.

The coater unit 3 is provided on the carrier film 1 and includes a doctor blade 3a. The slurry 4 stored inside the coater unit 3 is removed from the gap 3b between the doctor blade 3a and the carrier film 1 as the carrier film 1 moves. It is drawn out to a desired width and thickness and applied.

The drying section 5 is for drying the sheet-like slurry 4a applied on the carrier film 1 from the front side into a green sheet 10, generally by hot air or other appropriate heating. In addition, a heating means 9 comprising a heating element provided below the support plate 8a for heating and drying the slurry 4a also from the carrier film 1 side is provided.

The pair of pull-out rollers 6a and 6b pull out the green sheet 10 from the belt conveyor 7 with the carrier film 1 interposed therebetween, and the drawn-out green sheet 10 is taken up by a take-up roll 10a. I have.

A case where a green sheet having a width of 450 mm and a thickness of 200 μm is manufactured using the above-described green sheet manufacturing apparatus will be described.

First, a slurry 4 containing a ceramic powder, a low melting point glass powder, an organic binder, a plasticizer, a dispersant, and the like, and mixing and preparing them, is stored in the coater section 3, and the slurry 4 is applied to the carrier film 1. Is drawn out from the gap 3b with the doctor blade 3a along with the movement of the doctor blade 3a, and is applied in a sheet shape having a width of 450 mm and a thickness of 200 μm.

Next, while transporting the carrier film 1 on the arch-shaped support surface 8 with the movement of the conveyor belt 7, the drying unit 5 provided with the heating means 9 heats the sheet-like slurry 4 a to heat the inside of the slurry. The volatile component is quickly evaporated and uniformly dried to obtain a green sheet 10.

Next, the green sheet 10 together with the carrier film 1 is pulled out from the belt conveyor 7 by a pair of pull-out rollers 6a and 6b, and is wound on a winding roll 10a.

When a green sheet manufactured using the above-described green sheet manufacturing apparatus was measured and inspected, no trace of vertical wrinkles and no cracks on the surface were observed, and the thickness thereof had a desired high dimensional accuracy within 200 μm ± 10 μm. High quality green sheets were obtained.

FIG. 1 is an explanatory diagram of a green sheet manufacturing apparatus used in the present invention. Explanatory drawing of the conventional green sheet manufacturing apparatus. It is explanatory drawing of the vertical wrinkle produced in the green sheet by the conventional manufacturing method, (A) is a perspective view which shows the external appearance of the green sheet which produced the vertical wrinkle, (B) is XX sectional drawing of (A). Partial enlarged view.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Carrier film 1b Vertical wrinkle 2 Support roller 3 Coater part 4 Slurry 5 Drying part 6a, 6b Extraction roller 7 Belt conveyor 8 Support surface 9 Heating means 10 Green sheet

Claims (3)

In a green sheet manufacturing method in which a slurry containing ceramic powder is applied onto a carrier film conveyed in one direction and a green sheet is formed by a doctor blade, an arch-shaped support is provided below the carrier film in the conveying direction. A method for producing a green sheet, comprising: providing a carrier film coated with a slurry on the supporting surface. The conveyor belt according to claim 1, wherein a conveyor belt having an arch-shaped support surface is provided below the carrier film in the transport direction of the carrier film, and the carrier film coated with the slurry is transported on the conveyor belt. Green sheet manufacturing method. The green sheet according to claim 1 or 2, wherein a heating means is provided below the support having the arch-shaped support surface to heat the applied sheet-shaped slurry from the carrier film side. Production method.

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