Abstract:
A method for laser machining includes the steps of: providing a workpiece ( 10 ); coating a protective layer ( 102 ) of polyimide on the workpiece; machining the workpiece with laser; and removing the protective layer with acetone solution or hydroxybenzene solution.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method for laser machining, and more particularly to a method for laser machining which reduces environment contamination to workpieces.  
         [0003]     2. Description of the Related Art  
         [0004]     A process such as a process of drilling a workpiece by laser light radiation has been performed heretofore.  FIG. 4  is a schematic view, showing a hole  12 ′ is defined in a workpiece  10 ′ with a laser beam (not shown). The laser beam heats the workpiece  10 ′, substance composing the workpiece  10 ′ begins to melt and gasify, such that the hole  12 ′ is defined therein. However, the melted substance surrounding the hole  12 ′ may not completely evaporate, the remaining melted substance solidifies and forms protrusion  101 ′ atop a surface of the workpiece  10 ′. Furthermore, the evaporated substance solidifies in the air and deposits on the surface to form debris  103 ′. Therefore, the workpiece  10 ′ has to be polished to get smooth surface.  
         [0005]     To address the aforesaid problem, Taiwan Patent No. 400555 discloses a new laser machining method which comprises coating a protective layer on a surface of a workpiece before laser machining. Debris produced in following laser machining deposits on the protective layer instead of the workpiece itself. The debris and the protective layer are removed together to get smooth workpiece surface through wet etch process. The protective layer is silicon oxide or silicon nitride layer. Silicon oxide or silicon nitride is deposited on the workpiece with Chemical Vapor Deposition (CVD) method. However, some poisonous or corrosive gas is used in the CVD method, and the CVD method needs expensive CVD equipment. The wet etch process removes the protective layer through chemical reaction. However, the wet etch process is in a strong acid solution, and the waste solution is corrosive and polluting.  
         [0006]     Furthermore, the laser machining process is usually operated in a closed and clean workroom, for prevention of environment contamination such as dust. It will be desired to provide a process which can be operated in an ordinary workroom.  
         [0007]     Thus, a laser machining process which overcomes the above-mentioned problems is desired.  
       SUMMARY OF THE INVENTION  
       [0008]     Accordingly, an object of the present invention is to provide a laser machining method which reduces environment contamination to workpieces and prevents machining defect.  
         [0009]     A further object of the present invention is to provide a laser machining method which lowers manufacturing cost.  
         [0010]     To achieve the above objects, a process for laser machining in accordance with the present invention comprises the steps of : providing a workpiece; coating a protective layer of polyimide on the workpiece; machining the workpiece with laser; and removing the protective layer with acetone solution or hydroxybenzene solution.  
         [0011]     Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of preferred embodiments of the present invention with the attached drawings, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     FIGS.  1  to  3  explanatorily show a process of laser machining in accordance with a preferred embodiment of the invention; and  
         [0013]      FIG. 4  is an schematic view of a workpiece machined utilizing a conventional laser machining process. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Referring to  FIG. 1 , firstly, a material is coated on a surface of a workpiece  10  to form a protective layer  102  utilizing dip coating method or spin coating method. In the preferred embodiment of the present invention, the material is polyimide, and a thickness of the polyimide layer is 500 angstroms to 500 microns.  
         [0015]     Referring to  FIG. 2 , when a laser machining apparatus drills the workpiece  10  coated with the protective layer  102  to form a hole  12  therein, the laser beam heats the protective layer  102 , and the protective layer  102  is firstly melted and gasified, then the workpiece  10  under the protective layer  102  is melted, such that the hole  12  is defined in the workpiece  10 . The melted substance of the workpiece  102  is scattered on a surface of the protective layer  102 , and then solidifies to form debris  103 .  
         [0016]     Referring to  FIG. 3 , after the hole  12  is formed in the workpiece  10 , acetone solution or hydroxybenzene solution such as cresol solution is provided to dissolve the protective layer  102 . When the protective layer  102  is dissolved in the solution, the debris  103  and environment dust, if any, deposited on the protective layer  102  are removed together with the dissolved protective layer  102 , such that a clean surface of the workpiece  10  is achieved.  
         [0017]     In the preferred embodiment, the protective layer  102  is removed by being dissolved in chemical solution, there is no chemical reaction in such dissolving process, and there is no corrosive or poisonous waste solution. Furthermore, the process is easy to operated, and there is no need for special equipments or machines. Because the environment dirt is deposited on the protective layer  102  in the preferred embodiment instead of the workpiece  10  in the typical process, the machining of the workpiece  10  can be carried out in an ordinary workshop instead of a closed and clean workshop. The polyimide is a common kind of chemical substance, and it is cheap.  
         [0018]     In the preferred embodiment, the workpiece  10  can be metal or nonmetal. The type of machining on the workpiece  10  can also be engraving, cutting, texturing etc. other than drilling. The type of laser can be Nd:YAG, UV YAG, Nd:YVO 4 , CO 2 , etc.  
         [0019]     While the present invention has been illustrated by the description of the preferred embodiment thereof, and while the preferred embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the present invention will readily appear to those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrative examples shown and described.