Method of forming a leadframe for a semiconductor package
View Patent ↗A method of forming a leadframe ( 10 ) provides blocking fulcrums ( 21,23 ) adjacent to the leads ( 12,13,14 , and 15 ). During the process of encapsulating the leadframe ( 10 ), the blocking fulcrums ( 21,23 ) restrict encapsulating material from exiting the mold cavity and from attaching to the leads ( 12,13,14 , and 15 ).
1. A method of forming a leadframe for a semiconductor device comprising:
forming a leadframe strip having a main panel and a plurality of cavity sections;
forming a plurality of leads extending from the main panel a first distance into a cavity section of the plurality of cavity sections;
forming three sides of each of the plurality of leads detached from the main panel and forming a proximal end of each of the plurality of leads attached to the main panel; and
forming a blocking fulcrum extending from the main panel adjacent to a side of a lead of the plurality of leads and detached from the side of the lead of the plurality of leads and including terminating the blocking fulcrum no greater than a second distance from the cavity section.
2. The method of claim 1 wherein forming the blocking fulcrum extending from the main panel includes forming the blocking fulcrum to extend less than the first distance into the cavity section.
3. The method of claim 1 wherein forming three sides of each of the plurality of leads detached from the main panel includes cutting at least one side of at least one lead of the plurality of leads away from the blocking fulcrum.
4. The method of claim 3 further including realigning the blocking fulcrum and the least one lead of the plurality of leads subsequent to cutting the at least one side of at least one lead of the plurality of leads away from the blocking fulcrum.
5. The method of claim 1 further including forming a relief feature extending laterally across a portion of a width of the blocking fulcrum near the proximal end of the blocking fulcrum.
6. The method of claim 5 further including forming the relief feature having a shape that is one of a V shape or a U shape.
7. The method of claim 1 further including forming a relief port through the main panel near the proximal end of the blocking fulcrum including forming the relief port having a shape that is one of a circle, a square, a rectangle, or a triangle.
8. The method of claim 7 further including forming a relief opening through the main panel near the proximal end of the side of the lead of the plurality of leads.
9. The method of claim 1 wherein forming the blocking fulcrum extending from the main panel adjacent to the side of the lead of the plurality of leads and detached from the side of the lead of the plurality of leads and including terminating the blocking fulcrum no greater than the second distance from the cavity section includes forming the second distance no greater than 50 microns.
10. A method of forming a semiconductor package from a leadframe comprising:
providing the leadframe having leads and having a blocking fulcrum extending from a main panel of the leadframe toward a cavity section of the leadframe;
encapsulating the cavity section of the leadframe to form a body; and
moving the blocking fulcrum away from a plane of the leads and away from the body.
11. The method of claim 10 further including plating the leads of the semiconductor package.
12. The method of claim 10 further including singulating the body and the leads from the main panel and the blocking fulcrum.
13. The method of claim 10 wherein moving the blocking fulcrum away from the plane of the leads includes bending the blocking fulcrum.