Abstract:
Electronic substrates having cavities located therein and methods of making the substrates are disclosed herein. An embodiment of a method of making the substrate comprises manufacturing a circuit board. An adhesive film is attached to the circuit board, wherein the adhesive film has a first side facing the circuit board and a second side located opposite the first side, and wherein the second side is adhesive. At least one cavity is formed in a material. The material is adhered to the second side of the adhesive film.

Description:
BACKGROUND 
       [0001]    Cavities on electronic substrates are required for many applications. The cavities are typically required to be drilled, into the substrate, but not all the way through. Electronic connections, such as conductive pads may be located within the cavities. As electronic substrates become smaller, the precision required in the drilling operation increases substantially, which causes the drilling operation to become very expensive. In addition, locating the pads within the drilled cavities becomes more difficult as the substrates become smaller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a side cut away view of an embodiment of an electronic substrate. 
           [0003]      FIG. 2  is a top perspective view of the electronic substrate of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0004]    Electronic substrates and methods of making electronic substrates having cavities formed thereon are disclosed herein.  FIG. 1  is a side cut away view of an embodiment of an electronic substrate  100 . The embodiment of the substrate  100  includes a circuit board  104 , an adhesive film  106 , and a material  108 . As described in greater detail below, the adhesive film  106  is located between the circuit board  104  and the material  108 . The circuit board  104 , the adhesive film  106 , and the material  108  may all be laminated together. 
         [0005]    The circuit board  104  may be a rigid-type or flexible-type circuit board. The circuit board  104  has a first side  110  and a second side  112  located opposite the first side  110 . The sides  110 ,  112  are surfaces of the circuit board  104 . The second side  112  of the circuit board  104  is located proximate the adhesive film  106 . Electronic traces and the like (not shown in  FIG. 1 ) may be located on or within the circuit board  104 . For example, electronic traces may be located on the first side, second side  112 , or both sides of the circuit board  104 . The electronic traces serve to connect electronic components to the circuit board  104  and to transmit signals throughout the circuit board  104 . Conductive pads also may be located on the second side  112  of the circuit board  104  and may serve to connect components to the circuit board  104  and to connect wires and the like to the circuit board  104 . 
         [0006]    The adhesive film  106  may he referred to as a bonding film or a lamination material. The adhesive film  106  has a first side  116  and a second side  118  located opposite the first side. The sides  116 ,  118  constitute surfaces of the adhesive film  106 . The first side  116  of the adhesive film  106  is attached to the second side  112  of the circuit board  104 . In some embodiments, the first side  116  of the adhesive film  106  comprises an adhesive and the first side  116  of the adhesive film  106  is adhered to the second side  112  of the circuit board  104 . In some embodiments, an adhesive may be applied to the second side  112  of the circuit board  104  or the first side  116  of the adhesive film  106  and the adhesive film  106  may be subsequently adhered to the second side  112  of the circuit board  104 . 
         [0007]    As described in greater detail below, the adhesive film  106  may have portions cut out so that the adhesive film  106  does not cover any pads or other contacts located on the second side  112  of the circuit board  104  that require electrical connections. In other embodiments, the adhesive film  106  may be applied to the second side  112  of the circuit board  104  as a continuous sheet. Portions of the adhesive film  106  may be cut out of the continuous sheet in order to enable electrical connections to be made to pads or other contact points on the circuit board  104 . 
         [0008]    The material  108  may comprise pre-molded or pre-cut (include drilled), Polyethylene (PET), polyphthalamide, liquid crystal polymer, FR-4 or other materials. In some embodiments, the material  108  is rigid and may be more rigid than the circuit board  104 . In some embodiments, the material  108  may be able to withstand high temperature, such as the temperature required to bond or solder components to the circuit board  104 . 
         [0009]    The material  108  has a first side  122  and a second side  124  located opposite the first side  122 . The sides  122 ,  124  are surfaces of the material  108 . The first side  122  of the material  108  is adhered to the second side  118  of the adhesive film. With additional reference to  FIG. 2 , which is a top perspective view of the substrate  100 , the material has cavities  130  formed therein. In the embodiment described herein, the cavities  130  extend between the first side  122  and the second side  124 . The cavities  130  may be virtually any shape and may be formed by drilling, die-set punch, or other methods. When the material  108  is adhered to the adhesive film  106 , the cavities  132  become part of the substrate  100 . The height of the substrate from the first side  110  of the circuit board  104  to the second side  124  of the material  108  may be approximately 0.6 millimeters. 
         [0010]    The embodiment of the substrate  100  of  FIG. 2  shows traces  140  and pads  142  as described above. The traces  140  serve to conduct electricity throughout the circuit board  104 . The pads  142  serve as connection points for wires or components that are connected to the circuit board  104 . The adhesive film  106  may be cut to substantially the same shape or pattern as a side  122 ,  124  of the material. Thus, there will not be any adhesive film  106  adhered to the second side  112  of the circuit board  104  that would interfere with the electrical connections between the pads  142  and components or wires connected thereto. 
         [0011]    An embodiment of manufacturing the substrate  100  includes manufacturing the circuit board  104 . The adhesive film  106  is then applied to the second side  112  of the circuit board  104 . As stated above, the adhesive film may have portions cut out so as not to interfere with traces  140 , pads  142 , and other conductive points and components located on the second side  112  of the circuit board  104 . In other embodiments, the adhesive film  106  maybe a continuous sheet. 
         [0012]    The material  108  is manufactured to have the cavities  130  located therein. The cavities  130  may extend between the first surface  122  and the second surface  124  of the material  108 . As stated above, the cavities  130  may be drilled or preformed, such as being molded with the material.  108 . The material  108  may also be die set punched. The cavities  130  may be located in areas where contacts or components are located on the second surface  112  of the circuit board  104 . The material  108  is adhered to the second side  118  of the adhesive film  106 . Thus, the substrate now exists with cavities  130  located thereon. In embodiments where the adhesive film  106  is a continuous sheet, portions of the adhesive film  106  located proximate the cavities  130  may be removed. Removal may be accomplished via mechanical or chemical processes. In some embodiments, the circuit board  104 , the adhesive film  106 , and the material  108  are laminated together.