Abstract:
An embedded optical fiber module is disclosed. The embedded optical fiber module is adapted to fit in a recess of a package substrate. The embedded optical fiber module is configured for optical signal transmission between different chips or electronic devices mounted on the package substrate.

Description:
BACKGROUND 
     Technical Field 
       [0001]    The present invention relates to embedded optical fibers, especially for an embedded optical fiber module adapted to fit in a recess of a package substrate for a chip or chips for optical signal communication. 
       Description of Related Art 
       [0002]      FIG. 1  shows a prior art. 
         [0003]      FIG. 1A  shows that U.S. Pat. No. 7,125,176 disclosed an optical fiber  14  is configured in an elongated mounting groove  20  which is formed in a surface of a stiffening plate  16  made in a printed circuit board  12 . Groove  20  has a generally rectangular shaped cross-section with a depth and width approximately equal to a diameter of the length of the optical fiber  14 . Groove  20  is fabricated with a width and depth slightly greater than the outside diameter of optical fiber  14 . 
         [0004]    The prior art shows that an elongated mounting groove  20  has to be made for housing each optical fiber  14  individually. The complicated fabricating processes cost much. A simpler process to reduce the fabrication cost is desired for a long time. A simpler fabricating process for embedded optical fibers is developed in the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  shows a prior art. 
           [0006]      FIGS. 2A ˜ 4 B show a fabricating process for a first embodiment according to the present invention. 
           [0007]      FIGS. 5A ˜ 5 C show different views of the first embodiment. 
           [0008]      FIGS. 6A ˜ 7 B show the first embodiment embedded in a package substrate. 
           [0009]      FIGS. 8A ˜ 11 B show a fabricating process for a second embodiment according to the present invention. 
           [0010]      FIGS. 12A ˜ 12 C show different views of the second embodiment. 
           [0011]      FIGS. 13A ˜ 14 B show the second embodiment embedded in a package substrate. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    A thin film module embedded with a plurality of optical fibers is disclosed. The embedded optical fiber module is adapted to fit in a recess of a package substrate for optical signal transmission. 
         [0013]      FIGS. 2A ˜ 4 B show a fabricating process for a first embodiment according to the present invention. 
         [0014]      FIG. 2A  shows a top view of  FIG. 2B . 
         [0015]    Firstly, please refer to  FIG. 2B .  FIG. 2B  shows: 
         [0016]    preparing a temporary carrier  33 ; 
         [0017]    applying an adhesive layer  38  on a top surface of the temporary carrier  33 ; 
         [0018]    configuring a plurality of optical fibers  34  on a top surface of the adhesive layer  38 ; wherein 
         [0019]    a first reflection mirror  32 L is configured on a first end of each optical fiber  34 , and a second reflection mirror  32 R is configured on a second end of each optical fiber  34 ; 
         [0020]      FIG. 2A  shows a top view of  FIG. 2B . 
         [0021]      FIG. 2A  shows a plurality of optical fibers  34  configured on a top surface of the adhesive layer  38  which is applied on a top surface of a temporary carrier  33 . A first reflection mirror  32 L is configured in a first end of each optical fiber  34  and a second reflection mirror  32 R is configured in a second end of each optical fiber  34 . 
         [0022]      FIG. 3A  shows: 
         [0023]    applying a thin film protection layer  38  to cover the optical fibers  34 ; 
         [0024]      FIG. 3B  shows: 
         [0025]    detaching the temporary carrier  33 ; 
         [0026]      FIG. 4A  shows: 
         [0027]    yielding an embedded optical fiber module  34 ; and 
         [0028]      FIG. 4B  shows: 
         [0029]    singulating the sheet module; and 
         [0030]    yielding a plurality of embedded optical fiber modules  300 . 
         [0031]      FIGS. 5A ˜ 5 C show different views of the first embodiment. 
         [0032]      FIG. 5A  shows a top view of  FIG. 5B . Firstly, please refer to  FIG. 5B . 
         [0033]      FIG. 5B  shows a thin film module unit  300  of  FIG. 4B   
         [0034]      FIG. 5B  shows a thin film module unit  300  of  FIG. 4B  but configured in a reversed view.  FIG. 5B  shows a thin film module unit with embedded optical fibers  300 . A left reflection mirror  32 L is configured in a first end of each optical fiber  34  to reflect light beams  361  from top into the optical fiber  34 ; a right reflection mirror  32 R is configured in a second end of each optical fiber  34  to reflect the light beams  362  coming from the optical fiber  34  upwards. 
         [0035]      FIG. 5A  shows a top view of  FIG. 5B . 
         [0036]      FIG. 5A  shows a plurality of optical fibers  34  embedded in the thin film protection layer  35 . A top surface of the left reflection mirror  32 L is exposed out of the thin film protection layer  35 . Similarly, a top surface of the right reflection mirror  32 R is exposed out of the thin film protection layer  35 . 
         [0037]      FIG. 5C  shows a section view of  FIG. 5A   
         [0038]      FIG. 5C  shows the thin film protection layer  35  wraps almost the whole optical fiber  34  so that the optical fiber  34  can be hold firmly in position. 
         [0039]      FIGS. 6A ˜ 7 B show the first embodiment embedded in a package substrate. 
         [0040]      FIG. 6A  shows a package substrate  42  having a recess  45 . A plurality of top pads  42 T is configured on a top surface of the package substrate  42 . The top pads  42 T are made according to a design rule matching with a chip to facilitate at least one chip configured thereon. A plurality of bottom pads  42 B is configured on a bottom surface of the package substrate  42 . The bottom pads  42 B are made according to a design rule matching with a circuit board to facilitate the package mounted onto an outside mother board (not shown). A solder resist  44  is applied on a bottom surface of the bottom pads  42 B to expose partial bottom surface of each bottom pad  42 B so that a solder ball  43  can be mounted thereon. 
         [0041]      FIG. 6B  shows a thin film module unit  300  is fitted in the recess  45  of the package substrate  42 . 
         [0042]      FIG. 7A  shows a top view of  FIG. 7B . Firstly, please refer to  FIG. 7B . 
         [0043]      FIG. 7B  shows a light diode  46  is configured on a left top side of the package substrate  42  with a portion configured on a top side of the first reflection mirror  32 L so that light beams emitted from the first chip shall be reflected into the optical fiber  34 . A light sensor  47  is configured on a right top side of the package substrate  42  with a portion configured on a top side of the second reflection mirror  32 R so that light beams reflected by the second reflection mirror  32 R can be detected by the sensor  37 . Chip  1  is exemplified to be configured on a left top side of the package substrate  42 , light diode  46  can be, for example, controlled by chip  1 . Chip  2  is exemplified to be configured on a right top side of the package substrate  42 , light sensor  47  can be, for example, controlled by chip  2 . 
         [0044]    The light diode  46  is configured at least partially on top of the first reflection mirror  32 L so that the light beams emitted from the light diode  46  are able to enter the reflection mirror  32 L. The light sensor  47  is configured at least partially on top of the second reflection mirror  32 R so that the light beams reflected from the second reflection mirror  32 R are able to reach the light sensor  47 . 
         [0045]      FIG. 7A  shows chip  1  and a light diode  46  configured on a left top surface of the package substrate  42 .  FIG. 7A  also shows chip  2  and a light sensor  47  are configured on a right top surface of the package substrate  42 . 
         [0046]      FIGS. 8A ˜ 11 B show a fabricating process for a second embodiment according to the present invention. 
         [0047]      FIG. 8A  shows a top view of  FIG. 8B . Firstly, please refer to  FIG. 8B . 
         [0048]      FIG. 8B  shows: 
         [0049]    preparing a temporary carrier  33 ; 
         [0050]    applying an adhesive layer  38  on a top surface of the temporary carrier  33 ; configuring a plurality of optical fibers  34  on a top surface of the adhesive layer  38 ; wherein 
         [0051]    a first reflection mirror  32 L is configured on a first end of each optical fiber  34 , and a second reflection mirror  32 R is configured on a second end of each optical fiber  34 ; 
         [0052]      FIG. 8A  is the same as  FIG. 2A , for simplification, the description to  FIG. 8A  is omitted herein. 
         [0053]      FIG. 9A  shows: 
         [0054]    applying a seed layer  48  to cover the optical fibers  34 ; 
         [0055]      FIG. 9B  shows: 
         [0056]    plating a protection layer of metal  49  to cover the optical fibers  34 ; 
         [0057]      FIG. 10A  shows: 
         [0058]    flattening the metal layer  49 ; 
         [0059]      FIG. 10B  shows: 
         [0060]    detaching the temporary carrier  33 ; 
         [0061]      FIG. 11A  shows: 
         [0062]    yielding an embedded optical fiber module  34 ; and 
         [0063]      FIG. 11B  shows: 
         [0064]    singulating the sheet module; and 
         [0065]    yielding a plurality of embedded optical fiber modules  400 . 
         [0066]      FIGS. 12A ˜ 12 C show different views of the second embodiment. 
         [0067]      FIG. 12A  shows a top view of  FIG. 12B . Firstly, please refer to  FIG. 12B . 
         [0068]      FIG. 12B  shows a thin film module unit  400  of  FIG. 11B  but configured in a reversed view.  FIG. 12B  shows a thin film module unit with embedded optical fibers  400 . A left reflection mirror  32 L is configured in a first end of each optical fiber  34  to reflect light beams  361  from top into the optical fiber  34 ; right reflection mirror  32 R is configured in a second end of each optical fiber  34  to reflect the light beams  362  coming from the optical fiber  34  upwards. 
         [0069]      FIG. 12A  shows a top view of  FIG. 12B . 
         [0070]      FIG. 12A  shows a plurality of optical fibers  34  embedded in the thin film protection layer  49 . A top surface of the left reflection mirror  32 L is exposed out of the thin film protection layer  49 . Similarly, a top surface of the right reflection mirror  32 R is exposed out of the thin film protection layer  49 . 
         [0071]      FIG. 12C  shows a section view of  FIG. 12A   
         [0072]      FIG. 12C  shows the metal thin film protection layer  49  wraps almost the whole optical fiber  34  so that the optical fiber  34  can be hold firmly in position. 
         [0073]      FIGS. 13A ˜ 14 B show the second embodiment embedded in a package substrate. 
         [0074]      FIGS. 13A ˜ 14 B are similar to  FIGS. 6A ˜ 7 B respectively. A detailed description to  FIG. 13A ˜ 14 B is omitted herein, the only difference is that a thin film module unit  400  is embedded in the recess  45 . 
         [0075]    According to the present invention, the first reflection mirror  32 L can be a first isosceles right angle prism, and the second reflection mirror  32 R can be a second isosceles right angle prism. The thin film protection layer is one selected from a group consisting of molding compound  35  and metal  49 . The molding compound thin film protection layer  35  is one selected from a group consisting of epoxy resin and polyimide. The metal thin film protection layer  49  is selected from a group consisting of Au, Ag, Cu, Al, Pd, Pt, Ni, Co, and Zn. 
         [0076]    While several embodiments have been described by way of example, it will be apparent to those skilled in the art that various modifications may be configured without departs from the spirit of the present invention. Such modifications are all within the scope of the present invention, as defined by the appended claims.