JP4049093B2 - Green sheet manufacturing method - Google Patents

Description

  The present invention relates to a method for producing 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 adopted. In this apparatus, a carrier film 1 is pulled out from a supply roll 1a and conveyed in one direction on a plurality of support rollers 2 arranged horizontally. A doctor blade 3a is provided above the carrier film 1, and a ceramics. A coater unit 3 is provided in which slurry 4 containing powder is stored, and the slurry 4 in the coater unit 3 is moved from the gap 3b between the doctor blade 3a and the carrier film 1 as the carrier film 1 moves. By coating, a sheet-like slurry 4a is formed, and this is dried by blowing hot air in the drying unit 5 to form a green sheet 10, and then the green sheet 10 together with the carrier film 1 is pulled out by a pair of drawing rollers 6a and 6b. And is wound around a winding roll 10a.

As a green sheet manufacturing apparatus using such a doctor blade method, for example, Patent Document 1 discloses a method of forming a green sheet on a transport film, and by providing a flat spacer on the end of the transport film support base, There is a description to prevent the occurrence of film wrinkles. Further, Patent Document 2 discloses a ceramic green sheet manufacturing method in which a ceramic slurry is applied on a carrier film using a doctor blade method and passed through a drying device to obtain a ceramic green sheet. It is described that it is dried by a hot air drying device arranged in the subsequent stage, and in the hot air drying device, the carrier film is supported by an endless belt stretched between a pair of rolls arranged below the carrier film. . Patent Documents 3 to 5 describe a coating apparatus such as a magnetic body using a plurality of stretch rolls arranged in a convex shape upward. 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 as a transport means is used and a heating means 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 62-124903 A

  However, in the apparatus of FIG. 2, the vertical roller 1b is generated in the carrier film 1 by the pulling rollers 6a and 6b 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 10b is distorted in the width direction by being transferred to the green sheet 10. In particular, in the case of a green sheet used for a multilayer substrate, a defect in the thickness dimension causes a defect when printing a circuit pattern, and even if the circuit pattern can be printed, the subsequent lamination and firing In addition, there arises a problem that a non-contact portion is generated and a circuit is defective. In recent years, the green sheet 10 has been processed in an integrated state with the carrier film 1 in order to increase the working efficiency of substrate cutting and through-hole processing required for a multilayer substrate. Therefore, it is required to reduce the thickness of the carrier film 1 to 100 μm or less. When the green sheet 10 is manufactured using the thin carrier film 1, the height of the vertical gutter 1b becomes more prominent, and there is a problem that the most part of the green sheet 10 has a thickness dimension defect.

  Further, in the drying unit 5 of the apparatus, hot air is blown onto the sheet-like slurry 4a from above, and only the surface of the slurry 4a is first dried to shrink and solidify, and then the lower layer is dried. Therefore, there is a problem in that the green sheet 10 is cracked due to the time shift of the shrinkage between the surface and the lower layer.

  An object of the present invention is to solve the conventional problems as described above, and to provide a production method capable of efficiently producing a green sheet having no vertical defects and a uniform thickness.

Green sheet manufacturing method according to the present invention, on a carrier film to be transported in one direction, the green sheet manufacturing method of forming a green sheet by the doctor blade by applying a slurry containing a ceramic powder, the lower side of the carrier film the upper surface is provided with a conveyor belt having a support surface arched in the curvature along the conveying direction, the slurry on the support surface with the movement of the conveyor belt is coated by conveying the carrier film coated The sheet-like slurry is dried to form a green sheet, and the green sheet is pulled out from the belt conveyor together with the carrier film .

  In the green sheet manufacturing method according to the present invention, a conveyor belt having an arch-shaped support surface is provided below the carrier film in the conveyance direction, and the carrier film coated with slurry is conveyed on the conveyor belt. It is characterized by doing.

  The arch-shaped support surface is provided on the lower side of the carrier film so as to support the carrier film in an arch shape along the conveying direction and prevent the carrier film from causing vertical wrinkles due to the tension applied in the conveying direction. As the support that forms this support surface, there is a large single arch-shaped plate, a large number of support pieces or small-diameter support rollers closely packed and arranged in an arch shape, etc. The carrier film coated with the slurry may be directly conveyed on the surface of the support. Preferably, a conveyor belt is provided between the arch-shaped support and the carrier film coated with the slurry. The conveyor belt itself that supports and conveys the carrier film is formed as an arch-shaped support surface to reduce tension on the carrier film and prevent vertical wrinkles. It may be the top. The conveyor belt is preferably made of a material that does not deform under the applied slurry drying conditions and does not generate unnecessary volatile components, and has a width larger than that of the carrier film. More preferably, the rigidity of the conveyor belt itself should be high enough not to convey defects such as irregularities on the surface of the support structure that supports the conveyor belt, which cause vertical warp, to the carrier film.

Further, in the green sheet manufacturing method according to the present invention, a sheet-like slurry applied by heating means is provided from the carrier film side under the support that forms the arch-shaped support surface of the conveyor belt. It is characterized by.

  The heating means is for heating the coated slurry as a whole from the carrier film side and drying it quickly, so that it becomes a flexible green sheet having a desired size and shape without causing defects such as cracks. For example, a heat source that converts electric energy into heat energy, or a heat source in the form of a pipe or plate using hot water, steam, or other heat medium can be used.

According to the green sheet manufacturing method of the present invention, a conveyor belt having an arch-shaped support surface whose upper surface is curved along the transport direction is provided below the carrier film , and the conveyor belt is moved on the support surface. A carrier film coated with slurry is used to dry the sheet-like slurry coated by transporting the carrier film coated with slurry into a green sheet and pull the green sheet together with the carrier film from the belt conveyor. Is pressed against and supported by the arch-shaped support surface of the conveyor belt, so that it is possible to prevent the occurrence of warp.

In addition, according to the manufacturing method of the present invention, since the sheet-like slurry applied by heating means is heated from the lower side of the support that forms the arch-shaped support surface of the conveyor belt , the above-mentioned heating is performed from the carrier film side. The sheet-like slurry applied from the carrier film side can be heated by the heating means provided on the support while preventing the occurrence of vertical wrinkles of the carrier film by the arch-shaped support surface, and the entire slurry can be evenly distributed without cracking And it can dry quickly.

  According to the green sheet manufacturing method of the present invention, it has a practically excellent effect that can efficiently manufacture a high-quality green sheet having no vertical defects and high thickness dimensional accuracy and having no defects such as cracks. It is what you play.

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

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

  In the case of the present embodiment, the support surface 8 includes a support plate 8a that supports the slurry 4a that has just been applied to the carrier film 1 and still has fluidity, and a plurality of slurry 4b that has been dried and has lost fluidity. The upper surface of the support roller 8b is formed in a gentle arch shape with a radius of curvature 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 surface, while the support roller 8b is composed of a plurality of stainless steel small-diameter rollers, and vertical lines are generated in the carrier film 1 to be supported. The conveyor belt 7 stretched on the support surface 8 is supported by an arch-shaped curved surface and is placed on the carrier film 1 by the tension applied in the conveying direction. Is prevented from occurring.

  The coater unit 3 is disposed on the carrier film 1 and includes a doctor blade 3a. The slurry 4 accumulated therein is moved from the gap 3b between the doctor blade 3a and the carrier film 1 as the carrier film 1 moves. The coating is drawn out to a desired width and thickness.

  The drying unit 5 is generally used to dry the sheet-like slurry 4a applied on the carrier film 1 by hot air or other appropriate heating from the surface side to form a green sheet 10, and in the present invention, In addition, in order to heat and dry the slurry 4a from the carrier film 1 side, a heating means 9 comprising a heating element provided below the support plate 8a is provided.

  The pair of pull-out rollers 6a and 6b is for pulling out the green sheet 10 from the belt conveyor 7 with the carrier film 1 interposed therebetween, and the pulled-out green sheet 10 is wound around the winding roll 10a. Yes.

  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 ceramic powder and a low melting point glass powder, an organic binder, a plasticizer, a dispersing agent and the like, which are mixed with a ceramic powder, and a slurry 4 mixed and prepared in the ceramic powder are stored in a coater unit 3. Is moved out of the gap 3b with the doctor blade 3a and applied to a sheet having a width of 450 mm and a thickness of 200 μm.

  Next, as the conveyor belt 7 moves, the carrier film 1 is conveyed on the arch-shaped support surface 8, and the sheet-like slurry 4 a is heated by the drying unit 5 provided with the heating means 9. The volatile component is quickly evaporated and dried uniformly to obtain the green sheet 10.

  Next, the green sheet 10 is drawn together with the carrier film 1 from the belt conveyor 7 by a pair of drawing rollers 6a and 6b, and is wound around a winding roll 10a.

  When the green sheet manufactured using the above green sheet manufacturing apparatus was measured and inspected, no traces of downspout and cracks on the surface were observed, and the thickness had a desired high dimensional accuracy within 200 μm ± 10 μm. A high-quality green sheet was obtained.

Explanatory drawing of the green sheet manufacturing apparatus used for this invention. Explanatory drawing of the conventional green sheet manufacturing apparatus. It is explanatory drawing of the vertical chisel produced in the green sheet by the conventional manufacturing method, Comprising: (A) is a perspective view which shows the external appearance of the green sheet in which the chisel was produced, (B) is XX cross section of (A). Partial enlarged view.

Explanation of symbols

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

Claims (2)

In a green sheet manufacturing method of applying a slurry containing ceramic powder on a carrier film conveyed in one direction and forming a green sheet by a doctor blade,
The lower side of the carrier film, the upper surface is provided with a conveyor belt having a support surface arched in the curvature along the conveying direction, the carrier film of slurry is coated with a top the support surface with the movement of the conveyor belt A method for producing a green sheet, comprising drying a sheet-like slurry applied by conveyance to form a green sheet, and drawing the green sheet together with a carrier film from a belt conveyor . 2. The green sheet according to claim 1, wherein the sheet-like slurry applied by providing heating means is heated from the carrier film side below the support forming the arch-shaped support surface of the conveyor belt. Production method.

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