Patent Publication Number: US-2009229860-A1

Title: Green sheet for multi-layered electronics parts and manufacturing method for green chip using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2008-0024426 filed with the Korea Intellectual Property Office on Mar. 17, 2008, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a green sheet for multi-layered electronic parts and a manufacturing method for a green chip using the same; and more particularly, to a green sheet for multi-layered electronics parts and a manufacturing method for a green chip using the same to form the green chip by forming a gap in an internal electrode of the green sheet and by cutting the gap. 
     2. Description of the Related Art 
     Generally, an MLCC (Multi-Layered Ceramic Capacity) is a chip-type condenser which is mounted on a printed circuit board of various electronics parts including a mobile communication terminal, a notebook, a computer, a personal digital assistance (PDA) and plays an important role to charge or discharge electricity. The MLCC has various sizes and stacking patterns according to use and capacity. 
     Recently, the MLCC has been subjected to miniaturization and ultra-high capacity and the miniaturization and the ultra-high capacity can be realized by thinning the internal electrode, and thinning and stacking a dielectric layer with high density. 
     A method of manufacturing the MLCC includes a molding process of continuously applying slurry-type ceramic onto a carrier film in a thin thickness of several micrometers to tens micrometers, a printing process of manufacturing a ceramic green sheet by printing a predetermined internal electrode pattern onto a surface of the applied ceramic, a delaminating process of delaminating the ceramic green sheet cut from the carrier film in a predetermined shape, a stacking process of stacking the ceramic green sheet separated from the carrier film in the predetermined number of layers, a compressing process of manufacturing a green bar by compressing the stacked ceramic green sheet at a predetermined pressure, a cutting process of manufacturing green chips by cutting the compressed green bar in a chip size, and a process of plasticizing and sintering the cut green chips after polishing the cut green chips. 
     Herein, in the process of cutting the compressed green bar to manufacture the green chips, since a cutter cuts the green chips with being in direct contact with the internal electrode printed on the green sheet, a stress and a damage remarkably occur on cut surfaces of the green chips and thus a defect rate of the chip is increased, whereby a yield and reliability of the green chip are reduced. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is made to solve the above-mentioned problems. An advantage of the present invention is that it provides a green sheet for a multi-layered electronics parts and a method of manufacturing a green chip using the same, capable of improving a yield and reliability of the green chip by forming a gap in an internal electrode of the green sheet and cutting the gap in the cutting process for manufacturing the green chip to minimize a cutting stress and a cutting damage, and reducing a failure rate of the chip. 
     In order to achieve the above-mentioned advantages, a green sheet for multi-layered electronics parts in accordance with an aspect of the present invention may include a green sheet; and an internal electrode formed on the green sheet and being provided with a gap formed therein. 
     Herein, the gap may be formed in a center portion of the internal electrode. 
     The internal electrode may be formed by a screen printing method or a vacuum thin-film depositing method. 
     In order to achieve the above-mentioned advantages, a method of manufacturing a green chip using a green sheet for multi-layered electronics parts in accordance with another aspect of the present invention includes the steps of: (a) providing a green sheet; (b) forming an internal electrode with a gap formed therein on the green sheet; (c) stacking the green sheet in which the internal electrode is formed; and (d) cutting the stacked green sheet along a center of the gap of the internal electrode, which serves as a cutting line. 
     Herein, the gap may be formed in a center portion of the internal electrode. 
     The internal electrode may be formed by a screen printing method or a vacuum thin-film depositing method. 
     In the step (c), the gap is positioned on the cutting line between adjacent internal electrodes at the time of stacking the green sheet. 
     The method of manufacturing the green chip using the multi-layered electronics parts may further include a polishing step of removing the gap after the step (d). 
     In the step (d), the green sheet may be cut by using a blade along the cutting line and a width of the gap may be equal to or larger than a width of the blade. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of a green sheet for multi-layered electronics parts and a manufacturing method of a green chip using the same in accordance with the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a plan view illustrating a green sheet for multi-layered electronics parts in accordance with an embodiment of the invention; 
         FIG. 2  is a plan view illustrating a mask for forming an internal electrode of the green sheet for the multi-layered electronics parts in accordance with the embodiment of the invention; and 
         FIGS. 3 to 7  are process cross-sectional views sequentially illustrated to explain a method of manufacturing a green chip using the green sheet for the multi-layered electronics parts in accordance with the embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Green Sheet for Multi-Layered Electronics Parts 
     A green sheet for multi-layered electronics parts in accordance with an embodiment of the present invention will be described in detail with reference to  FIG. 1  and  FIG. 2 . 
       FIG. 1  is a plan view illustrating the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention; and  FIG. 2  is a plan view illustrating a mask for forming an internal electrode of the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention. 
     First, as shown in  FIG. 1 , the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention includes a green sheet  10  and a plurality of internal electrodes  11  which are formed on the green sheet  10  and have gaps  12  in the inside thereof. 
     The green sheet  10  may be generally manufactured in a thickness of several micrometers by applying a slurry onto a carrier film and drying the slurry after preparing slurry by mixing BaTiO 3  powder with a ceramic additive, an organic solvent, a plasticizer, a binder, and a dispersant by using a basket mill. 
     The gaps  12  formed in the internal electrodes  11  are areas cut in a cutting process for manufacturing the green chip fabricating the green chip. The gaps  12  may be formed in center portions of the internal electrodes  11 . 
     Herein, as described above, the green chip is manufactured by cutting a green bar manufactured by stacking and compressing the green sheet in a form of a unit element. 
     As shown in  FIG. 2 , the internal electrodes  11  having the gaps  12  formed therein may be formed by using a mask  100  for exposing an internal electrode forming area  110  and covering a gap forming area  120 . 
     The internal electrodes  11  in which the gaps  12  may be formed by a screen printing method or a vacuum thin-film depositing method. 
     Herein, in case of using the screen printing method, metallic powder for forming the internal electrodes  11  is manufactured by using paste and the internal electrodes  11  can be printed on the green sheet  10  by squeezing the paste by using the mask  100  as a screen. 
     In case of using the vacuum thin-film depositing method, a material of the internal electrode  11 , for example, a material such as Ni can be attached to the green sheet  10  in a form of the electrode by covering the green sheet  10  with the mask  100 , positioning the separate green sheet  10  covered with the mask  100 , and heating and evaporating the material by irradiating an electronic beam to the material. 
     As described above, in the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention, a cutting stress and a cutting damage can be minimized by forming the gaps  12  in the internal electrodes  11  of the green sheet  10  and cutting not the internal electrodes  11  but the gaps  12  in the cutting process for manufacturing the green chip. 
     Therefore, the present invention has an advantage in that a yield and reliability can be improved by reducing a defect rate of the green chip. 
     Hereinafter, a method of manufacturing the green chip using the above-mentioned green sheet for the multi-layered electronics parts will be described in detail with reference to  FIGS. 3 to 7 . 
     Method of Manufacturing Green Chip Using Green Sheet for Multi-Layered Electronics Parts 
       FIGS. 3 to 7  are process cross-sectional views sequentially shown to illustrate the method of manufacturing the green chip using the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention. 
     First, as shown in  FIG. 3 , a plurality of green sheets  10  are provided. 
     After then, as shown in  FIG. 4 , the internal electrode  11  having the gap  12  formed therein is formed on each of the green sheets  10 . 
     The gap  12  formed in the internal electrode  11  is an area cut in the cutting process for manufacturing green chips  30  to be described. The gap  12  is preferably formed in a center portion of the internal electrode  11 . 
     As shown in  FIG. 2 , the internal electrode  11  having the gap  12  formed therein may be formed by using the mask  100  for exposing the internal electrode forming area  110  and covering the gap forming area  120 . 
     The internal electrode  11  having the gap  12  formed therein may be formed by the above-mentioned screen printing method or vacuum thin-film depositing method. 
     Next, as shown in  FIG. 5 , each of the plurality of green sheets  10  on which the internal electrode  11  is formed is stacked. 
     Herein, the gap  12  may be positioned on a cutting line D between the adjacent internal electrodes  11  at the time of stacking each of the green sheets  10 . 
     After then, each of the green chips  30  is manufactured as shown in  FIG. 6  by cutting each of the stacked green sheets  10  along a center of the gap  12  of the internal electrode  11 , which serves as the cutting line D. 
     In the cutting process for manufacturing each of the green chips  30 , the green sheet  10  may be cut along the cutting line D by using a blade  200 . 
     At this time, since the blade  200  is in contact with the internal electrode  11  and thus the green chips  30  are difficult to cut in the cutting process for manufacturing the green chips  30  in case that a width l 1  of the gap  12  is smaller than a width l 2  of the blade  200 , the width l 1  of the gap  12  is preferably equal to or larger than the width l 2  of the blade  200 . 
     At this time, by the method for manufacturing the green chips using the green sheet for the multi-layered electronics parts in accordance with the embodiment of the present invention, since the cutting stress and the cutting damage can be minimized by forming the internal electrode  11  having the gap  12  formed therein on the green sheet  10  and cutting not the internal electrode  11  but the gap  12  in the cutting process for manufacturing the green chips  30 , the defect rate of the green chip can be reduced, thereby improving the yield and reliability of the green chip. 
     Then, as shown in  FIG. 7 , a polishing process for removing the gap  12  is performed. The internal electrode  11  may be exposed to the outside by removing the gap  12  remaining after the cutting process in the polishing process. 
     As described above, by the green sheet for the multi-layered electronics parts and the method of manufacturing the same in accordance with the present invention, the cutting stress and the cutting damage can be minimized by forming the gap in the internal electrode of the green sheet and cutting not the internal electrode but the gap in the cutting process for manufacturing the green chips, thereby reducing the failure rate of the chip. 
     Accordingly, the present invention has an advantage in that the yield and reliability of the green chip can be improved. 
     Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.