Abstract:
A method for manufacturing a mold of a light guide plate is disclosed. The method includes following steps: providing a substrate and forming a plurality of microstructures on the substrate; depositing a first metal layer upon the substrate; spreading a photoresist layer on the first metal layer, exposing the photoresist layer to a photomask, and developing a photoresist pattern; removing a part of the first metal layer without cover of the photoresist pattern so as to form a sink pattern; depositing a second metal layer upon the sink pattern; electroforming a metal plate on the second metal layer; and remaining the metal plate and the second metal layer by separating the metal plate from the photoresist layer, the first metal layer, and the substrate so as to generate the mold of the light guide plate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method for manufacturing a mold of a light guide plate, and more particularly, to a method for manufacturing a mold of a light guide plate with a plurality of microstructures thereon. 
         [0003]    2. Description of the Prior Art 
         [0004]    Backlight units are known in the art. The backlight module, which is a key element in the liquid crystal displays (LCDs), is widely used in monitors, notebooks, digital cameras, projectors and so on. The light guide plate is one of the important parts of the backlight module. The light guide plate is capable of guiding light emitted from a light source so as to transform a point light source or a linear light source into a planar light source. 
         [0005]    The methods of manufacturing the light guide plates are typically divided into two major categories: printing process and non-printing process. The non-printing process has advantages of stable quality, high precision, and so on, and is a mainstream manufacturing method of the light guide plates in the market. The non-printing process is to form patterns on a mold first and to manufacture the light guide plates by the mold with an injection molding process. 
         [0006]    The methods of manufacturing the mold of the light guide plates are typically divided into two major categories. One is forming patterns on the mold directly with an etching process. The other is forming patterns on the mold with a semiconducting process, such as a photolithography process. For example, U.S. Pat. No. 5,776,636 discloses related technology. Please refer to  FIG. 1  to  FIG. 6  which are diagrams of manufacturing a mold of a light guide plate in the prior art. As shown in  FIG. 1 , a photoresist layer  11  is spread upon a substrate  10  first. The substrate  10  can be a glass substrate. As shown in  FIG. 2  and  FIG. 3 , a photomask  12  with specified pattern thereon is utilized for forming a photoresist pattern on the substrate  10  with exposing and developing processes. As shown in  FIG. 4 , a metal layer  13  is plated upon the photoresist pattern with a sputtering process or an evaporation process. As shown in  FIG. 5 , a metal plate  14  is electroformed on the metal layer  13 . As shown in  FIG. 6 , the metal layer  13  is separated from the photoresist layer  11  and the substrate  10  so as to generate a mold  15  with a pattern on the surface corresponding to the photoresist pattern. 
         [0007]    However the conventional method of manufacturing the mold of the light guide plates has disadvantages as follows. A height of the pattern on the mold depends on a thickness of the photoresist layer  11 , which causes difficulty in controlling the height of the pattern on the mold. In addition, the pattern on the mold is limited due to a small range of the thickness of the photoresist layer  11 . Furthermore, the pattern on the mold is formed with exposing and developing processes so that microstructures or complicated structures can not be formed on the pattern. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore a primary objective of the claimed invention to provide a method for manufacturing a mold of a light guide plate with a plurality of microstructures thereon for solving the above-mentioned problem. 
         [0009]    According to the claimed invention, a method for manufacturing a mold of a light guide plate includes following steps: providing a substrate and forming a plurality of microstructures on the substrate; depositing a first metal layer upon the substrate; spreading a photoresist layer on the first metal layer, exposing the photoresist layer to a photomask, and developing a photoresist pattern; removing a part of the first metal layer without cover of the photoresist pattern so as to form a sink pattern; depositing a second metal layer upon the sink pattern; electroforming a metal plate on the second metal layer; and remaining the metal plate and the second metal layer by separating the metal plate from the photoresist layer, the first metal layer, and the substrate so as to generate the mold of the light guide plate. 
         [0010]    Other objectives, features and advantages of the present invention will be further understood from the further technology features disclosed by the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  to  FIG. 6  are diagrams of manufacturing a mold of a light guide plate in the prior art. 
           [0012]      FIG. 7  is a flowchart of manufacturing a mold of a light guide plate according to a preferred embodiment of the present invention. 
           [0013]      FIG. 8  to  FIG. 15  are diagrams of manufacturing the mold of the light guide plate according to the preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component facing “B” component directly or one or more additional components is between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components is between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
         [0015]    Please refer to  FIG. 7  to  FIG. 15 .  FIG. 7  is a flowchart of manufacturing a mold of a light guide plate according to a preferred embodiment of the present invention.  FIG. 8  to  FIG. 15  are diagrams of manufacturing the mold of the light guide plate according to the preferred embodiment of the present invention. The method of the present invention includes following steps: 
         [0016]    Step  100 : provide a substrate  20  and form a plurality of microstructures  201  on the substrate  20 . 
         [0017]    Step  102 : deposit a first metal layer  21  upon the substrate  20 . 
         [0018]    Step  104 : spread a photoresist layer  22  on the first metal layer  21 , expose the photoresist layer  22  to a photomask  30 , and develop a photoresist pattern  23 . 
         [0019]    Step  106 : remove a part of the first metal layer  21  without cover of the photoresist pattern  23  so as to form a sink pattern  24 . 
         [0020]    Step  108 : deposit a second metal layer  25  upon the sink pattern  24 . 
         [0021]    Step  110 : electroform a metal plate  26  on the second metal layer  25 . 
         [0022]    Step  112 : remain the metal plate  26  and the second metal layer  25  by separating the metal plate  26  from the photoresist layer  22 , the first metal layer  21 , and the substrate  20  so as to generate a mold  27  of the light guide plate. 
         [0023]    The detailed description of above-mentioned steps is introduced as follows. As shown in  FIG. 8 , the substrate  20  is provided, and the plurality of microstructures  201  is formed on the substrate  20 . The substrate  20  is made of, for example, metal material, such as stainless steel. The plurality of microstructures  201  on the substrate  20  are carved on the metal substrate with, for example, a micro-drill, a laser process, a mold process, or other mechanical process. The microstructure  201  is, for example, a semicircular microstructure, a trapezoid microstructure, a V-grooved microstructure, and so on. 
         [0024]    As shown in  FIG. 9 , the first metal layer  21  is deposited upon the substrate  20 . For example, the first metal layer  21  is electroplated upon the substrate  20 . A thickness of the first metal layer  21  has to be greater than a height of the microstructure  201 . The first metal layer  21  is made of, for example, nickel, copper, and so on. 
         [0025]    As shown in  FIG. 10  and  FIG. 11 , the photoresist layer  22  is spread on the first metal layer  21 . Then the photoresist layer  22  is exposed to the photomask  30 , and the photoresist pattern  23  is developed. The thickness of the first metal layer  21  has to be greater than the height of the microstructure  201  so that the photoresist layer  22  is spread on the first metal layer  21  uniformly for preventing the un-uniform photoresist pattern  23 . 
         [0026]    As shown in  FIG. 12 , a part of the first metal layer  21  without cover of the photoresist pattern  23  is removed so as to form the sink pattern  24 . The part of the first metal layer  21  without cover of the photoresist pattern  23  is etched chemically so as to form the sink pattern  24 . Therefore, some of the microstructures  201  are exposed. As shown in  FIG. 13 , the second metal layer  25  is deposited upon the sink pattern  24 . The second metal layer  25  is deposited upon the sink pattern  24  with, for example, a sputtering process or a chemical coating process. The second metal layer  25  is made of, for example, cladding metal material, such as nickel or copper. The second metal layer  25  forms as an electroforming conductive layer. 
         [0027]    As shown in  FIG. 14  and  FIG. 15 , the metal plate  26  is electroformed on the second metal layer  25 . Then the metal plate  26  and the second metal layer  2  are remained, that is, the second metal layer  25  and the metal plate  26  are separated from the photoresist layer  22 , the first metal layer  21 , and the substrate  20  so as to generate the mold  27  of the light guide plate. The light guide plate with microstructures is generated with the mold  27  by an injection molding process. 
         [0028]    In contrast to the prior art, the method for manufacturing the mold of the light guide plate according to the present invention has advantages that the height of the pattern on the mold does not depend on the thickness of the photoresist layer. Therefore, microstructures or complicated structures can be formed on the mold for manufacturing the light guide plate with corresponding microstructures or complicated structures. 
         [0029]    The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like is not necessary limited the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.