PATENT ABSTRACT
A method of manufacturing a low-temperature co-fired ceramics (LTCC) substrate includes the following steps of: preparing a plurality of ceramic sheets; forming a plurality of zones and at least one cutting pattern on each of the ceramic sheets, wherein the cutting pattern is formed between neighboring two of the zones; forming at least one conductive pattern on at least one of the ceramic sheets; and stacking the ceramic sheets.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The invention relates to a manufacturing method of a low-temperature co-fired ceramics (LTCC) substrate having a cutting pattern. 
         [0003]    2. Related Art 
         [0004]    With the progress of the technology, the current electronic products have become more miniature and thinner. Taking a mobile phone in the wireless communication industry as an example, the size of the mobile phone is reduced from that of the earliest mobile phone used in the Advance Mobile Phone System (AMPS) to that smaller than one palm. Meanwhile, the function of the mobile phone is developed from the simplest audio transmission to the data, picture and text transmission. Consequently, the key point and the trend in designing the electronic product include the light, thin, short and small properties, and the LTCC technology can satisfy these requirements. 
         [0005]    The LTCC technology has the ability of integrating active devices, modules and passive devices together. In the LTCC technology, a plurality of LTCC substrates is stacked, and the passive devices or integrated circuits (ICs) are embedded into the LTCC substrate. In addition, the LTCC substrate may be advantageously co-fired with the metal having the low impedance and the low dielectric loss, and the passive devices, such as inductors and capacitors, can be advantageously embedded without the limitation of the number of layers. Therefore, the LTCC substrate is very suitable for the application to an integrated device. In addition, the LTCC technology can reduce the size of the electronic product and lower the cost thereof and achieve the object of making the electronic product be light, thin, short and small. 
         [0006]    However, the LTCC substrate has a high-hardness layer and the crumbly property. Thus, when a cutting machine is cutting a harder substrate, a larger friction force between the substrate and a cutting blade is generated, and the stress generated by the friction is transferred to the cutting blade. As a result the electronic product or the cutting blade may be damaged and the manufacturing yield is deteriorated. Thus, it is an important subject to generate a lower resistant force and thus to enhance the yield when the ceramics substrate is being cut. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of the foregoing, the invention is to provide a manufacturing method of a LTCC substrate capable of enhancing the production yield. 
         [0008]    To achieve the above, the invention discloses a method of manufacturing a LTCC substrate. The method includes the steps of: preparing a plurality of ceramic sheets; forming a plurality of zones and at least one cutting pattern on each of the ceramic sheets, wherein the cutting pattern is formed between neighboring two of the zones; forming at least one conductive pattern on at least one of the ceramic sheets; and stacking the ceramic sheets. 
         [0009]    As mentioned above, the manufacturing method of a LTCC substrate according to the invention has the following advantages. Because the cutting pattern is formed on the LTCC substrate, the generated friction stress is smaller when the cutting apparatus is cutting the LTCC substrate. Thus, the possibility of damaging the ceramics substrate is decreased, so that the production yield can be enhanced and the production cost can be decreased. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
           [0011]      FIGS. 1 to 4  are schematic illustrations showing a LTCC substrate according to a preferred embodiment of the invention; 
           [0012]      FIG. 5  is a flow chart showing a manufacturing method of the LTCC substrate according to the preferred embodiment of the invention; 
           [0013]      FIGS. 6A to 6E  are schematic illustrations showing structures in conjunction with the flow chart of  FIG. 5 ; 
           [0014]      FIG. 7  is a schematic illustration showing a semiconductor package according to the preferred embodiment of the invention; and 
           [0015]      FIGS. 8 to 12  are schematic illustrations showing cutting patterns for the semiconductor package. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
         [0017]    Referring to  FIG. 1 , a LTCC substrate  1  according to a preferred embodiment of the invention includes a plurality of substrate units  11  and at least one cutting pattern  12 . In this embodiment, four substrate units  11  are provided. However, the number of the substrate units  11  is not particularly restricted, and the user can increase or decrease the number of the substrate units  11  according to the requirement. 
         [0018]    The cutting pattern  12  is disposed between neighboring two of the substrate unit  11  so that a cutting apparatus can perform a cutting operation along the cutting pattern  12 . The cutting pattern  12  may be a groove  121 , as shown in  FIG. 1 , may have a plurality of holes  122 , as shown in  FIG. 2 , or may have a groove  121  and a cutting path  123 , as shown in  FIG. 3 . Of course, the cutting pattern  12  has a groove  121 , holes  122  and a cutting path  123 , as shown in  FIG. 4 , in order to make the cutting apparatus cut the substrate easily, to reduce the friction stress generated during the cutting process, and to decrease the possibility of damaging the ceramics substrate. 
         [0019]    In this embodiment, the shape of each of the holes  122  may be an elliptic shape, circular shape or a polygonal (rectangular or triangular) shape. Herein, the shape of each hole  122  is the elliptic shape, for example. 
         [0020]    Referring to  FIG. 5 , a method of manufacturing the LTCC substrate according to the preferred embodiment of the invention includes steps S 11  to S 16 . Illustrations will be made by taking  FIG. 5  in conjunction with  FIGS. 6A to 6E . 
         [0021]    As shown in  FIG. 6A , a plurality of ceramic sheets  2  is prepared in step S 11 . As shown in  FIG. 6B , a plurality of zones  21  and at least one cutting pattern  22  are formed on each of the ceramic sheets  2  in step S 12 , wherein the cutting pattern  22  is formed between neighboring two of the zones  21 . 
         [0022]    In this embodiment, the cutting pattern  22  having at least one groove is formed, by the cutting apparatus, on each of the ceramic sheets  2  so that four zones  21  are defined. Herein, the number of the zones  21  is not particularly restricted to four, and the user can increase or decrease the number of the zones  21  according to his/her requirement. In addition, the cutting pattern  22  may also include a plurality of holes punched by a punching apparatus on the ceramic sheets  2 . Furthermore, the cutting pattern  22  has various aspects. When the cutting pattern  22  has the grooves and the holes simultaneously, the cutting apparatus is adopted to form the grooves on the ceramic sheets  2  and then the punching apparatus is adopted to form the holes in each of the grooves. Of course, the order of forming the grooves and the holes may also be adjusted. The aspects of the cutting pattern  22  may include those of the cutting patterns  12 , as shown in  FIGS. 1 to 4 . Herein, the cutting pattern  22  of this embodiment is a groove, for example. 
         [0023]    As shown in  FIG. 6C , at least one conductive pattern  23  is formed on at least one of the ceramic sheets  2  in step S 13 . In this embodiment, the conductive pattern  23  is formed on a surface of the uppermost ceramics sheet  2 . 
         [0024]    As shown in  FIG. 6D , the ceramic sheets  2  are stacked in step S 14 . In step S 15 , the stacked ceramic sheets  2  are baked to form a LTCC substrate  3 . 
         [0025]    As shown in  FIG. 6E , a metal layer  24  is plated on the conductive pattern  23  in step S 16 , wherein the material of the metal layer includes nickel/gold. 
         [0026]    In addition, the user may use the cutting apparatus to cut the LTCC substrate  3  along the cutting pattern  22  into the substrate units  21 . Because the LTCC substrate  3  of the invention has the cutting pattern  22 , the friction stress generated between the cutting tool and the LTCC substrate  3  is smaller when the cutting apparatus is cutting the LTCC substrate  3 . Thus, the LTCC substrate  3  cannot be easily broken, and the production yield can be enhanced. 
         [0027]    It is to be noted that the order of the above-mentioned steps is not particularly restricted, and may be adjusted according to the requirement on the manufacturing process. 
         [0028]    Referring to  FIG. 7 , a semiconductor package  4  according to the preferred embodiment of the invention includes a substrate unit  41 , an electronic unit  42  and an encapsulant  43 . 
         [0029]    The electronic unit  42  is disposed on a surface of the substrate unit  41  and is electrically connected to the substrate unit  41  by way of wire bonding in this embodiment, or by way of flip chip bonding or surface mounting in another embodiment. The encapsulant  43  is disposed on the substrate unit  41  and covers the electronic unit  42 . The electronic unit  42  may be an active chip or an integrated passive device. 
         [0030]    According to the method of manufacturing the LTCC substrate, it is to be noted that the side surface of the substrate unit  41  of this embodiment has a cutting type because the LTCC substrate has a cutting pattern. 
         [0031]    The cutting patterns will be illustrated with reference to  FIGS. 8 to 12 , which are enlarged views showing the zone A of  FIG. 7 . When the cutting apparatus is cutting the LTCC substrate, the width of the cutting tool is smaller than the width of the groove. So, the cutting pattern on the side surface of each substrate unit  41  has a ladder-like structure, as shown in  FIG. 8 , when the LTCC substrate is cut into a plurality of substrate units  41 . Alternatively, as shown in  FIG. 9 , the cutting pattern on the side surface of the substrate unit  41  has a ladder-like structure and a plurality of elliptic curved surfaces A 01 . Alternatively, as shown in  FIG. 10 , the cutting pattern on the side surface of the substrate unit  41  has a ladder-like structure and a plurality of polygonal curved surfaces A 11 . 
         [0032]    Of course, if the precision of the cutting apparatus is higher or the substrate unit  41  is processed after being cut, the side surface thereof does not have the ladder-like structure. As shown in  FIG. 11 , the cutting pattern formed on the side surface of the substrate unit  41  includes a plurality of elliptic curved surfaces A 21 . Alternatively, as shown in  FIG. 12 , the cutting pattern formed on the side surface of the substrate unit  41  includes a plurality of polygonal curved surfaces A 31 . 
         [0033]    In summary, the manufacturing method of a LTCC substrate according to the invention has the following advantages. Because the cutting pattern is formed on the LTCC substrate, the generated friction stress is smaller when the cutting apparatus is cutting the LTCC substrate. Thus, the possibility of damaging the ceramics substrate is decreased, so that the production yield can be enhanced, and the production cost can be decreased. 
         [0034]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.