Leadframe design for QFN package with top terminal leads
View Patent ↗A semiconductor package includes a leadframe. A first lead finger has a lower portion, a connecting portion extending vertically upward from the lower portion, and a substantially flat, top portion. The top portion forms a top terminal lead structure. A second lead finger is electrically connected to the first lead finger. A portion of the second lead finger forms a bottom terminal lead structure. A portion of the second lead finger corresponds to a bottom surface of the semiconductor package. A surface of the substantially flat, top portion corresponds to a top surface of the semiconductor package.
1. A method of fabricating a leadframe for a semiconductor package, comprising:
providing a lead finger electrically connected to a conductive bar, the lead finger having a substantially flat first surface;
bending the lead finger to form a lower portion and a substantially vertical portion;
bending the substantially vertical portion of the lead finger to form a top lead structure extending over the lower portion of the lead finger so that a portion of the first surface of the lead finger constituting the top lead structure is disposed opposite a second portion of the first surface of the lead finger constituting the lower portion, and the top lead structure is aligned parallel to the lower portion of the lead finger; connecting a second lead finger to the lead finger and the conductive bar to serve as a lower terminal lead structure for the semiconductor package, and
forming a raised electrical interconnect structure on a surface of the top lead structure.
2. The method of fabrication of claim 1 , further including etching a portion of the second lead finger to reduce an exposed surface of the second lead finger.
3. The method of fabrication of claim 1 , wherein the lower terminal lead structure corresponds to a bottom surface of the semiconductor package.
4. The method of fabrication of claim 1 , further including wire bonding the first and second lead fingers to provide electrical connectivity.
5. The method of fabrication of claim 1 , wherein the top lead structure corresponds to a top surface of the semiconductor package.
6. The method of fabrication of claim 1 , further including forming a dambar structure coupled to the lead finger for structural support during a manufacturing process.
7. The method of fabrication of claim 6 , further including singulating the dambar structure from the lead finger during a manufacturing step.
8. The method of fabrication of claim 1 , wherein the lead finger is bent in a manufacturing step to form a first pivot in the lead finger.
9. A method of fabricating a leadframe for a semiconductor package, comprising:
providing a lead finger electrically connected to a conductive bar, the lead finger having a substantially flat first surface;
bending the lead finger to form a lower portion and an upright portion;
bending the upright portion of the lead finger to form a top lead structure extending over the lower portion of the lead finger so that the top lead structure is aligned parallel to the lower portion of the lead finger; connecting a second lead finger to the lead finger and the conductive bar to serve as a lower terminal lead structure for the semiconductor package, and
forming a raised electrical interconnect structure on a surface of the top lead structure.
10. The method of fabrication of claim 9 , further including etching a portion of the second lead finger to reduce an exposed surface of the second lead finger.
11. The method of fabrication of claim 9 , wherein the lower terminal lead structure corresponds to a bottom surface of the semiconductor package.
12. The method of fabrication of claim 9 , further including wire bonding the first and second lead fingers to provide electrical connectivity.
13. The method of fabrication of claim 9 , wherein the top lead structure corresponds to a top surface of the semiconductor package.
14. The method of fabrication of claim 9 , further including forming a dambar structure coupled to the lead finger for structural support during a manufacturing process.
15. The method of fabrication of claim 14 , further including singulating the dambar structure from the lead finger during a manufacturing step.
16. The method of fabrication of claim 9 , wherein the lead finger is bent in a manufacturing step to form a first pivot in the lead finger.
17. A method of fabricating a leadframe for a semiconductor package, comprising:
providing a lead finger electrically connected to a conductive bar, the lead finger having a substantially flat first surface;
bending the lead finger to form a lower portion, a second portion, and a top lead structure, the top lead structure extending over the lower portion of the lead finger and connecting a second lead finger to the lead finger and the conductive bar to serve as a lower terminal lead structure for the semiconductor package.
18. The method of claim 17 , including forming a raised electrical interconnect structure on a surface of the top lead structure.
19. The method of fabrication of claim 18 , wherein the top lead structure corresponds to a top surface of the semiconductor package.
20. The method of fabrication of claim 17 , further including etching a portion of the second lead finger to reduce an exposed surface of the second lead finger.
21. The method of fabrication of claim 17 , wherein the lower terminal lead structure corresponds to a bottom surface of the semiconductor package.
22. The method of fabrication of claim 17 , further including wire bonding the first and second lead fingers to provide electrical connectivity.