Abstract:
Flat metal strips are used to make connections to a laser diode so that the interconnections are parallel to the surface of the semiconductor device and the structure has a lower profile than a wire-bonded package. The contacts can be made with conducting glue or hard pressed by a lid before sealing with glue.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates to semiconductor packaging, in particular to the interconnection in the package. 
     (2) Description of Related Art 
     In a conventional semiconductor package, the connection to the semiconductor device is by wire bonding as shown FIG.  1 . In this example, several light emitting diodes (LED)  10  are mounted on a substrate  14 . At the corner  102  of each LED is a bonding pad as first electrode of the LED. Outside the corner is the light emitting area  106 . The second electrode  104  of the LED is in the back of the LED and is not shown. The first electrode  102  of the LED  10  wire bonded for electrical connection. The wire-bonding process is very labor intensive. It is desirable to eliminate such a process in fabrication. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to eliminate the wire bonding for connection to a semiconductor device. Another object of this invention is to provide a semiconductor device package which is suitable for mass production. 
     These objects are achieved by using flat metal strips to make contacts to the semiconductor device and as interconnections for the device. The strips are parallel to the surface of the semiconductor device, resulting in a lower profile. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 shows a prior art semiconductor package using wire-bonding connection to the semiconductor device. 
     FIG. 2 shows flat metal strip contacting a light emitting diode based on the present invention. 
     FIG. 3 shows another embodiment of the interconnection in a semiconductor package. 
     FIG. 4 shows a third embodiment of the interconnection. 
     FIG. 5 shows the component parts of FIG.  4 . 
     FIG. 6 shows the series interconnection of more than one semiconductor device in a package. 
     FIG.7 shows a second embodiment of interconnecting more than one semiconductor device in a package. 
     FIG. 8 shows a third embodiment of interconnecting more than one semiconductor device in a package. 
     FIG. 9 shows the top lid of FIG.  8 . 
     FIG. 10 shows the side view of FIG. 8 after the top lid is pressed on the devices. 
     FIG. 11 shows a transparent top lid serving as interconnection. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2 shows two LED  10  mounted on a substrate  14 . The first electrode  102  of the LED is at the right hand top corner of the LED  10 . The second electrode of the LED at the back of the device and is not shown. Outside the top surface of the LED is the light emitting area  106 . The conductor  12  is placed over the second electrodes  102  of more than one LED. The electrodes  102  is painted with conducting glue (not shown). The conductor  12  is pressed against the electrodes  102  of two devices  10 . Thus the package has a flat interconnection without any protruded bonding wires which rise above the flat top surface. The conventional technique of wire-bonding is by thermal compression bonding in which the bonding is made individually. The old process is labor intensive and is not amenable to mass production. 
     FIG. 3 shows is similar to FIG. 2 including the substrate  24 , the light emitting diodes  20 , first electrodes  202  and the light emitting area  206 . The top electrodes of the LED is first covered with a conducting glue (not shown) and pressed against by an interconnection conductor  22 . Then the package is wire-bonded with a flat top. 
     FIG. 4 shows a third embodiment of the present invention. Each light emitting diode  20  has a light emitting area  206  surrounded by a top electrode  202 . The top electrodes  202  of all the LEDs are covered with conductive glue. A thin conductive film  26  having windows  264  (as shown in FIG. 5) against the light emitting areas  206  is pressed against the top electrodes  202 . Thus connection is made to the top electrodes and the light emitting from the LED is not blocked. 
     FIG. 6 shows the flat interconnection as applied to LEDs  30  with both electrodes  302  and  304  at two corners on the top surface. The light emitting area  306  lies between the two corners. These electrodes are first covered with conductive glue. Two straight conductors  32  and  34  are glued to the two rows of corner electrodes.  302  and  304 . The conductors  32  and  34  provide flat top interconnection. 
     FIG. 7 shows how a number of LED with top electrodes and bottom electrodes connected in series. Each LED  10  has a light emitting area  106 , a top electrode  102  at on corner of the top surface and a bottom electrode (not shown). These LEDs are connected in series by means of the flat conductor  40 . These electrodes are first covered with conductive glue, before the flat conductor  40  is glued to these electrodes. The top electrode of the last top electrode and the bottom of the last bottom electrode are not covered with glue and the flat conductor  40  for easy external access. 
     FIG. 8 shows another interconnection for series connection of a number of LED  30 . The two electrodes of the LED  30  are located at the two opposite corners  302  and  304 , outside the light emitting area  306 . A Z-shaped link  50  is used to connect the top right electrode  302  at point  502  to the lower left electrode of the next laser diode at point  504 . Contacts at point  502  and  504  are made by conductive glue. The electrodes at the beginning and the end of the series laser diodes can be connected directly to external circuits. 
     Alternatively, the connection between the link  50  and the electrodes at contacts  502  and  504  can be made without applying conductive glue individually as shown in FIGS. 9 and 10. Spacers  602  and  604  are placed opposite the top electrode corners  502 . When the lid  60  is pressed against the links  50 , contacts are made between the links and the electrodes of the laser diodes  30  as shown in the side view FIG.  10 . Afterwards, sealing glue can be injected into entire structure to fix the positions of the entire package. Alternatively, the positions may be fixed by pressure without using glue. 
     FIGS. 11 and 12 show another embodiment of the present invention. Instead of the flat metal interconnections in FIGS. 2 and 3, a transparent plate  70  is used as the flat interconnection. The transparent plate  70  is covered with transparent or semi-transparent conductive film  702 . 
     The structure can be used as an array of light emitting diodes or be sawed into individual units. 
     While particular embodiments of the invention has been described as applied to LED packaging, the technique is also applicable to other types of semiconductor device packaging such as LED, image sensor chip, photo diode, etc. It will be apparent to those skilled in the art that various modifications may be made in the embodiments without departing from the spirit of the present invention. Such modifications are all within the scope of this invention.