Abstract:
A housing with a metal member is integrated with a plastic member to form a housing. The surface of the metal member carries a plurality of holes and a plurality of nano-depressions, both on the surface of the metal member and on the inner surfaces of each of the holes, which are produced by an electrochemical process. A depth, width, and diameter of each of the holes are controlled to be in preset ranges, and the resistance to bending and the tensile strength of the integrated metal plastic housing are very good. A method for manufacturing the housing is also provided.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    This disclosure relates to housings, particularly to a housing made of metal and plastic, and a method for manufacturing the housing. 
         [0003]    2. Description of Related Art 
         [0004]    Metals, such as aluminum alloy, magnesium alloy, or stainless steel alloy generally have excellent appearance and mechanical performance. Metals are applied for manufacturing housings of touch panel, mobile phone or other electronic devices. Smaller structures which need to be formed in a surface of the housings are usually machined by computer numerical control machine, which will spend a lot of time to machine the smaller structures. Integrated structures of metal and plastic are used in a wide range of industrial applications and fields in order to increase the processing efficiency of the housings. Generally, the metal and the plastic are joined together by adhesive. However, this method cannot supply a high-strength composite of metal and plastic. 
         [0005]    Therefore, there is room for improvement in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like elements of an embodiment. 
           [0007]      FIG. 1  is an isometric, assembled view of a first embodiment of a housing including a metal member. 
           [0008]      FIG. 2  is a partial, cross-sectional view of the housing of  FIG. 1  taken along line II-II. 
           [0009]      FIG. 3  shows a scanning electron microscope (SEM) photograph of an adjoining plane of the housing of  FIG. 1 . 
           [0010]      FIG. 4  is a flowchart of a method for manufacturing the housing of  FIG. 1 . 
           [0011]      FIG. 5  is a photograph of the housing of  FIG. 1  after being treated by laser. 
           [0012]      FIG. 6  is a photograph of a second embodiment of a housing after being treated by laser. 
           [0013]      FIG. 7  shows a scanning electron microscope (SEM) photograph of the metal member of the housing of  FIG. 1  after being etched by an electrochemical process. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIGS. 1 through 3 , a first embodiment of a housing  100  includes a metal member  10  and a plastic member  30  integrated with the metal member  10 . In the illustrated embodiment, the housing  100  is a mobile phone housing. In alternative embodiments, the housing  100  can be a housing used for touch panels, computers, or other electronic devices. 
         [0015]    In the illustrated embodiment, the metal member  10  is substantially a rectangular frame. The metal member  10  defines a plurality of holes  102  in the inner surface of the metal member  10 . The metal member  10  further forms a plurality of nano-depressions  106  in the inner surface of the metal member  10  and the inner surface of each of the holes  102 , respectively, by an electrochemical process. The metal member  10  is made of aluminum alloy. In alternative embodiments, the metal member  10  can be made of magnesium alloy, stainless steel alloy, or other metal or metal alloys. The plastic material for the plastic member  30  can be selected from the group consisting of a composite of polyamide (PA), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET). 
         [0016]    Referring to  FIGS. 5 and 7 , the holes  102  are connected together to form a plurality of grooves intersecting with each other (as shown in  FIG. 5 ). A depth of each of the holes  102  is controlled to be in a range from about 27 μm to about 33 μm. A width of each of the holes  102  is controlled to be in a range from about 42 μm to about 50 μm. A diameter of each of the nano-depressions  106  is controlled to be in a range from about 30 nm to about 60 nm (as shown in  FIG. 7 ). The housing  100  is formed by injection molding. The plastic member  30  is integrated with the inner surface of the metal member  10 , and plastic material fills the holes  102  and the nano-depressions  106  (as shown in  FIG. 3 ). 
         [0017]    Referring to  FIG. 4 , a method for manufacturing the housing  100  of  FIG. 1  is described as follows: 
         [0018]    In step S 201 , the metal member  10  is treated by laser to form a plurality of holes  102  in the inner surface of the metal member  10 . In the illustrated embodiment, the metal member  10  is made of aluminum alloy. The laser power is 25 Watts (W), the laser radiation frequency is 50 KHz, the laser beam diameter of the laser is 10 μm, and the laser scanning speed is 14 mm/s. A depth of each of the holes  102  is controlled to be in a range from about 27 μm to about 33 μm. A width of each of the holes  102  is controlled to be in a range from about 42 μm to about 50 μm. In alternative embodiments, the depth or width of each of the holes  102  can be changed by changing or adjusting the laser power, the laser radiation frequency, and the laser scanning speed. 
         [0019]    In step S 202 , the metal member  10  is cleaned with an alkaline solution to remove grease or metal scraps deposited on the metal member  10 . In the illustrated embodiment, the metal member  10  is immersed in a 5 percent by weight (5 wt %) sodium hydroxide solution. The metal member  10  is washed with water after removal from the sodium hydroxide solution. 
         [0020]    In step S 203 , the metal member  10  is etched by an electrochemical process to form a plurality of nano-depressions  106  in the inner surface of the metal member  10  and the inner surface of the holes  102 , respectively. An electrolyte may contain acetic acid, phosphoric acid, hydrochloric acid, or nitric acid to etch the metal member  10  to form the plurality of nano-depressions  106  in the inner surface of the metal member  10  and the inner surface of the holes  102 . A diameter of each of the nano-depressions  106  is controlled to be in a range from about 30 nm to about 60 nm. 
         [0021]    In step S 204 , the metal member  10  is inserted into a mold, and molten plastic material is injected into the mold and onto the inner surface of the metal member  10  to form the housing  100 . In the illustrated embodiment, the plastic material is polyamide (PA), and the polyamide (PA) is a thermoplastic resin which crystallizes when it cools. The molten plastic material becomes partially embedded in the holes  102  and the nano-depressions  106 , and bonds with the metal member  10 . The plastic material for the plastic member  30  can be selected from the group consisting of a composite of polyamide (PA), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET). 
         [0022]    In an alternative embodiment, step  202  can be omitted if the amounts of grease and metal scraps do not affect the etching of the metal member  10 . 
         [0023]    Samples of housings A and B manufactured by the present method are provided. Contrast samples of housings C, D, and E manufactured by injection molding are also provided. The contrast samples of housings C, D, and E were not treated by laser or etched by an electrochemical process. Investigation of the mechanical test results for the housings (A-E) are applied under a bending test and a split pulling test. The test results of the housings (A-E) are recorded in Table 1. 
         [0000]    
       
         
               
             
               
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Testing Results 
               
             
          
           
               
                   
                 Testing Items 
               
             
          
           
               
                   
                 Bending Test 
                 Split Pulling Test 
               
             
          
           
               
                   
                   
                 Deflection 
                   
                 Deflection 
               
               
                 Sample 
                 Force (Kgf) 
                 (mm) 
                 Force (Kgf) 
                 (mm) 
               
               
                   
               
             
          
           
               
                 A 
                 70.6 
                 2.14 
                 &gt;54.3 
                 1.75 
               
               
                 B 
                 50.4 
                 3.57 
                 &gt;88.3 
                 1.82 
               
               
                 C 
                 23.2 
                 1.16 
                 23.0 
                 1.05 
               
               
                 D 
                 16.2 
                 0.79 
                 28.0 
                 1.02 
               
               
                 E 
                 20.7 
                 0.92 
                 26.0 
                 0.87 
               
               
                   
               
             
          
         
       
     
         [0024]    As shown in Table 1, resistance to bending and anti-tearing properties of the housings A and B are both better than the contrast samples for the housings B-E. Bonding force between the metal member  10  and the plastic member  30  is thus improved. 
         [0025]      FIG. 6  shows a second embodiment of a housing  200 . A method for manufacturing the housing  200  is similar to the method for manufacturing the housing  100 , except that a laser scanning speed for the housing  200  is 14 mm/s, and a plurality of holes  202  defined in a metal member  20  of the housing  200  are circular blind cavities. A depth of each of the holes  202  is controlled to be in a range from about 50 μm to about 60 μm. A diameter of each of the holes  202  is controlled to be in a range from about 38 nm to about 46 nm. 
         [0026]    The nano-depressions  106  have higher population density, which can improve the bonding force between the metal member  10  and the plastic member  30 . In addition, the holes  102  are deeper and wider than the nano-depressions  106 , which improves the resistance to tearing of the housing  100 . 
         [0027]    The present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the embodiments or sacrificing all of its material advantages.