Patent Publication Number: US-2013230650-A1

Title: Method for manufacturing optical printed circuit board

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a method for manufacturing an optical printed circuit board (OPCB) by using a roller pressing method. 
     2. Description of Related Art 
     OPCBs include core layers for transmitting optical signals. The core layers define optical waveguide patterns. In related art, the optical waveguide pattern is formed using yellow light photolithograph method. However, the yellow light photolithograph method needs much time, which will reduce the manufacturing efficiency of the OPCBs. 
     Therefore, it is desirable to provide a method for manufacturing an OPCB that can overcome the above-mentioned limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments 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 present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a flow chart of a method for manufacturing an OPCB, according to an exemplary embodiment. 
         FIGS. 2-9  are schematic views showing successive stages in the method of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  through  FIG. 9  illustrate a method for manufacturing an optical printed circuit board (OPCB)  100  in accordance to an exemplary embodiment. The method includes the following steps. 
     In step S 1 : a substrate  10  is provided, and the substrate  10  has a loading surface  101  (see  FIG. 2 ). The loading surface  101  is cleaned. The substrate  10  may be flexible or rigid, and has a circuit layer (not shown). The circuit layer may be made of metal material or a conductive compound. The metal material may be gold, silver, or copper. The conductive compound may be indium tin oxide (ITO). 
     In step S 2 : a first cladding solvent layer  20   b  is formed on the loading surface  101  by a spin coating method. Referring to  FIG. 3 , in the illustrated embodiment, the spin coating method is implemented by a spin coater  200 . The spin coater  200  includes a feeder  201  and a rotary platform  202 . The substrate  10  is fixed on the rotary platform  202 , and rotates with respect to the feeder  201 . The feeder  201  is used for providing a first cladding layer forming a solvent  20   a  to the loading surface  101 . The first cladding layer forming a solvent  20   a  is in a liquid state which has high viscosity. The rotary platform  202  is used for rotating to make the first cladding layer forming a solvent  20   a  to be uniformly distributed on the loading substrate  101 , thereby a first cladding solvent layer  20   b  is formed on the substrate  10 . The first cladding layer forming a solvent  20   a  is made of a low refractive index material, such as the following materials without light-sensitive groups: polyacrylate, polysiloxane, polyimide, polycarbonate, fluorinated polymer, or a mixture of the above materials. 
     In step S 3 : the first cladding solvent layer  20   b  is solidified to form a first cladding layer  20 . Referring to  FIG. 4 , in this embodiment, a heating device  401  is positioned on one side of the substrate  10  away from the first cladding solvent layer  20   b . The heating device  401  provides heat to solidify the first cladding solvent layer  20   b.  In other embodiments, an ultraviolet (UV) source can be positioned above the first cladding solvent layer  20   b  to solidify the first cladding solvent layer  20   b.    
     In step S 4 : a core solvent layer  30   b  is formed on the first cladding layer  20  using the spin coating method. Referring to  FIG. 5 , in the illustrated embodiment, the spin coating method is implemented by the spin coater  200 . The refractive index of the core solvent layer  30   b  is greater than the refractive index of the first cladding layer  20 . The core solvent layer  30   b  is made of high refractive index material, such as the following materials with light-sensitive groups: polyacrylate, polysiloxane, polyimide, polycarbonate, fluorinated polymer, or a mixture of the above materials. 
     In step S 5 : the core solvent layer  30   b  is solidified to be in a half-solid state, and thus to form a core layer  30 . The core layer  30  can be solidified by the heater  401  or by an UV source. Referring to  FIG. 6 , in the illustrated embodiment, the core solvent layer  30   b  is solidified to form the core layer  30  by the heater  401 . 
     In step S 6 : an optical waveguide pattern  30   c  is defined on the core layer  30  using a roller pressing method. Referring to  FIG. 7 , in the illustrated embodiment, the roller pressing method is implemented by a roller pressing device  300 . The roller pressing device  300  includes a first pressing roller  301  and a second pressing roller  302 . The first pressing roller  301  and the second pressing roller  302  are spaced at a predetermined distance from each other, and thus to form a molding channel  303  therebetween. The first pressing roller  301  and the second pressing roller  302  are rotated in opposite directions. A circumferential surface of the first pressing roller  301  defines impression patterns coupled with the optical waveguide pattern  30   a.  The substrate  10  formed with the first cladding layer  20  and the core layer  30  enters the molding channel  303  and is cooperatively pressed by the first pressing roller  301  and the second pressing roller  302 . The core layer  30  faces the first pressing roller  301 , and thus the optical waveguide pattern  30   c  is formed on the core layer  30 . In other embodiments, the second pressing roller  302  can be replaced with a stationary plate. 
     In step S 7 , a second cladding solvent layer  40   b  is formed on the core layer  30  using the spin coating method. Referring to  FIG. 8 , in the illustrated embodiment, the spin coating method is implemented by the spin coater  200 . The refractive index of the second cladding solvent layer  40   b  is less than the refractive index of the core layer  30 . The second cladding solvent layer  40   b  is made of low refractive index material, such as the following materials without light-sensitive groups: polyacrylate, polysiloxane, polyimide, polycarbonate, fluorinated polymer, or a mixture of the above materials. In this embodiment, the material of the second cladding solvent layer  40   b  is the same as the material of the first cladding solvent layer  20   b.  In other embodiments, the material of the second cladding solvent layer  40   b  can be different from the material of the first cladding solvent layer  20   b.    
     In step S 8 , the second cladding solvent layer  40   b  is solidified to form a second cladding layer  40 , and by these means obtain an OPCB  100 . The second cladding solvent layer  40   b  can be solidified by a heating device or by an UV source. Referring to  FIG. 9 , in the illustrated embodiment, the second cladding solvent layer  40   b  is solidified to form the second cladding layer  40  by the heating device  401 . 
     By employing the roller pressing method, the optical waveguide pattern  30   c  can be directly formed on the core layer  30 , and thus manufacturing efficiency is greatly improved. At the same time, the roller pressing method does not use toxic chemicals, and will not produce chemical waste, therefore, the environment is not at risk. 
     The above particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.