Leadless leadframe electronic package and sensor module incorporating same

Abstract

A leadless optical electronic package includes a lead frame having a die-attach pad and a plurality of leadless connection pads encapsulated in and extending through an encapsulation defining a planar mounting surface that can be soldered directly to a circuit board. The die-attach pad and connection pads define internal surfaces that remain partially exposed through the encapsulation. The internal surfaces are for attaching an electronic die and making electrical connections between the die and the connection pads. A die mounted on the die-attach pad is cooled more effectively and efficiently than dice in prior optical electronic packages. The leadless connection pads reduce the footprint and height of the package compared with prior optical electronic packages. The encapsulation is adapted for receiving a cover having a cover glass to allow light to pass though the cover and illuminate the die. The cover is adapted to receive an optics component for projecting light through the cover glass onto the die.

1 . A leadless lead frame electronic package (LLP), comprising: 
 a lead frame of thermally-and-electrically conductive material encapsulated in an encapsulation of electrically-insulating material to define a planar mounting surface;    the lead frame including parallel internal and external planar surfaces;    the external planar surface of the lead frame remaining exposed through the encapsulation and extending generally co-planar with the mounting surface; and    the internal surface of the lead frame remaining partially exposed through the encapsulation.    
   
   
       2 . The electronic package of  claim 1  including an attachment element structured to engage with an optical component.  
   
   
       3 . The electronic package of  claim 1 , further including an optical component.  
   
   
       4 . The electronic package of  claim 1 , wherein: 
 the lead frame includes at least one cut-out extending from the internal surface to the external surface to define a die-attach pad and at least one connection pad electrically isolated from the die-attach pad; and    the die attach pad and the connection pads extend through the encapsulation, with a portion of the external surfaces thereof exposed and generally coplanar with the encapsulation, and with a portion of the internal surfaces thereof respectively defining an exposed die-attach surface and an exposed bond-connection surface.    
   
   
       5 . The electronic package of  claim 1 , wherein the encapsulation extends through a portion of the at least one cut-out in the lead frame.  
   
   
       6 . The electronic package of  claim 1 , further comprising, a sidewall of electrically insulating material extending above the internal surface of the lead frame to form a die-receiving cavity in the electronic package.  
   
   
       7 . The electronic package of  claim 6 , wherein the encapsulation includes the sidewall.  
   
   
       8 . The electronic package of  claim 6 , further comprising, an optical sensor die attached to the die attach surface of the die pad within the die-receiving cavity.  
   
   
       9 . The electronic package of  claim 6 , further comprising, a cover adapted for engaging the sidewall and having a cover glass mounted therein.  
   
   
       10 . The electronic package of  claim 9 , further comprising an attachment element structured to engage with an optical component.  
   
   
       11 . The electronic package of  claim 9 , further comprising, an optical component.  
   
   
       12 . The optical electronic package of  claim 9 , further comprising, an optical sensor die attached to the internal surface of the lead frame, and an optical component for projecting light through the cover glass onto the optical sensor die.  
   
   
       13 . A leadless optical sensor module, comprising: 
 a lead frame of thermally and electrically conductive material encapsulated in an encapsulation of electrically insulating material to define a planar mounting surface, the lead frame including parallel internal and external planar surfaces, the external planar surface of the lead frame remaining exposed through the encapsulation and extending generally co-planar with the mounting surface, and the internal surface of the lead frame remaining partially exposed through the encapsulation; and    an optical sensor die attached to the internal planar surface of the lead frame.    
   
   
       14 . The optical sensor module of  claim 13 , wherein: 
 the lead frame includes at least one cut-out extending from the internal to the external surfaces to define a die-attach pad and at least one connection pad electrically isolated from the die-attach pad;    the die attach pad and the leadless connection pads extend through the encapsulation, with a portion of the external surfaces thereof exposed and generally coplanar with the encapsulation, and with a portion of the internal surfaces thereof respectively defining an exposed die-attach surface and an exposed bond-connection surface; and    the optical sensor die is attached to the exposed die-attach surface.    
   
   
       15 . The optical sensor module of  claim 13 , further comprising a sidewall of electrically insulating material extending above the internal surface of the lead frame to form a die-receiving cavity.  
   
   
       16 . The optical sensor module of  claim 15 , further comprising a cover adapted for engaging the sidewall and having a cover glass therein for passage of light into the die-receiving cavity.  
   
   
       17 . The optical sensor module of  claim 16 , further comprising an optics component.  
   
   
       18 . A method for attaching an optical sensor module to a circuit board, the method comprising: 
 providing an optical sensor module including an optical sensor die attached to an internal planar surface of a lead frame of thermally-and-electrically-conductive material encapsulated in an encapsulation of electrically-insulating material to define a planar mounting surface, the lead frame including parallel internal and external planar surfaces, the external planar surface of the lead frame remaining exposed through the encapsulation and extending generally co-planar with the mounting surface, and the internal surface of the lead frame remaining partially exposed through the encapsulation; and    soldering at least part of the exposed external surface of the lead frame to the circuit board.    
   
   
       19 . The method of  claim 18 , further comprising attaching a cover to the encapsulation prior to soldering the external surface of the lead frame to the circuit board, the cover enclosing the optical sensor die and including a cover glass for transmitting light to the optical sensor die.  
   
   
       20 . The method of  claim 19 , further comprising, attaching an optical component to the optical sensor module.