Leadframe with lead protruding from the package

Abstract

The present disclosure is directed to a leadframe package having leads with protrusions on an underside of the leadframe. The protrusions come in various shapes and sizes. The protrusions extend from a body of encapsulant around the leadframe to couple to surface contacts on a substrate. The protrusions have a recess that is filled with encapsulant. Additionally, the protrusions may be part of the lead or may be a conductive layer on the lead. In some embodiments a die pad of the leadframe supporting a semiconductor die also has a protrusion on the underside of the leadframe. The protrusion on the die pad has a recess that houses an adhesive and at least part of the semiconductor die. The die pad with a protrusion may include anchor locks at the ends of the die pad to couple to the encapsulant.

1 . A package comprising:
 a die pad having a first side and a second side;   a semiconductor die coupled to the first side of the die pad;   a contact pad positioned on a first side of the semiconductor die;   an electrical lead spaced from the die pad, the electrical lead having a first side and a second side;   a contact pad positioned on the first side of the electrical lead;   an electrical connector extending from the contact pad on the semiconductor die to the contact pad on the electrical lead;   a protrusion extending as a portion of the electrical lead, the protrusion having a convex region that extends from the second side the electrical lead and having a concave region that is on the first side of the lead; and   an encapsulant that overlays the semiconductor die, the die pad, and the first side of the electrical lead, the encapsulant surrounding the electrical connector, being in contact with the first side of the electrical lead and filling the concave region of the protrusion.   
     
     
         2 . The package of  claim 1  wherein the internal surface of the concave region of the protrusion has a shape that is rounded. 
     
     
         3 . The package of  claim 2  wherein the internal surface of the concave region has a semicircular shape that is approximately equal to half of a circle. 
     
     
         4 . The package of  claim 2  wherein the internal surface of the concave region has a rounded shape that is greater than 55% of a circle and less than 75% of a circle with the portion that is greater than 50% of the circle extending inward to overlay other regions of the same internal surface. 
     
     
         5 . The package of  claim 2  wherein the internal surface of the concave region extends in a rounded shape that is less than 40% of a circle. 
     
     
         6 . The package of  claim 1  wherein the internal surface of the concave region extends as a rectangle, the concave portion having two flat sidewalls that are parallel to each other and a bottom wall that is perpendicular to the flat sidewalls. 
     
     
         7 . The package of  claim 1  wherein the internal surface of the concave region extends as a triangle. 
     
     
         8 . The package of  claim 1  wherein the internal surface of the concave region extends as an ellipsoid. 
     
     
         9 . The package of  claim 1  wherein the internal surface of the concave region of the protrusion has two flat sidewalls that extend parallel to each other for a selected distance and has a bottom side with a rounded shape. 
     
     
         10 . The package of  claim 1  wherein the external surface of the convex portion extends in a rounded shape that is greater than 55% of a circle and less than 75% of a circle with the portion that is greater than 50% of the circle extending inward to be above other regions of the same external surface to create an anchor region for a solder that is applied to the convex portion of the electrical lead. 
     
     
         11 - 15 . (canceled) 
     
     
         16 . A system, comprising:
 a leadframe package including a leadframe supporting a semiconductor die, the semiconductor die and the leadframe in an encapsulant, the leadframe including a lead and a die pad, the semiconductor die on the die pad and electrically coupled to the lead, the lead having a protrusion, the encapsulant having a bottom side, a first portion of the protrusion extending away from the bottom side of the encapsulant, a portion of the encapsulant in the protrusion; and   a printed circuit board having a surface contact, the protrusion on the surface contact and coupled to the surface contact with a joint compound.   
     
     
         17 . The system of  claim 16 , wherein the lead includes a conductive layer on the lead, the protrusion including the conductive layer. 
     
     
         18 . The system of  claim 16 , wherein the die pad includes a second protrusion, the second protrusion extending away from the bottom side of the encapsulant. 
     
     
         19 . The system of  claim 18 , wherein a side of the die pad has an anchor, the anchor having a flared tip, the flared tip in the encapsulant. 
     
     
         20 . The system of  claim 16 , wherein the lead has a side orthogonal to the bottom side of the encapsulant, the side of the lead having a side surface with a portion of the side surface having a concave curvature. 
     
     
         21 . A device, comprising:
 a leadframe having a first side and a second side, the leadframe including:
 a die pad; and 
 a lead having a protrusion on the second side of the leadframe and extending away from the lead, the protrusion having a cavity with an opening through the lead to the first side of the leadframe; 
   a semiconductor die on the first side of the leadframe;   an electrical connector coupled to the lead at a first end and the semiconductor die at a second end; and   an encapsulant surrounding the semiconductor die and in the cavity.   
     
     
         22 . The device of  claim 21  wherein the protrusion has a wall thickness measured from the second side of the leadframe at the protrusion to the cavity, the wall thickness less than a thickness of the lead measured from the first side to the second side at a position adjacent to the first end of the electrical connector. 
     
     
         23 . The device of  claim 21  wherein one portion of the protrusion is in the shape of a hollow cylinder. 
     
     
         24 . The device of  claim 21  wherein a tip of the protrusion is rounded. 
     
     
         25 . The device of  claim 24  wherein the cavity extends into the tip, the inner wall of the tip being rounded.