Semiconductor device
View Patent ↗A method includes forming a packaged integrated circuit that includes forming a lead frame by separating an outer portion of the metal structure into a plurality of leads by stamping. The plurality of leads have sides with a first concavity. The lead frame is further formed by performing an etch on the sides of the plurality of leads to achieve a second concavity on the sides of leads. The second concavity is greater than the first concavity. A semiconductor die is attached to a center portion of the metal structure. Electrical attachments are made between the die and the leads.
1. A method of forming a packaged integrated circuit, comprising:
forming a lead frame by:
separating an outer portion of the metal structure into a plurality of leads by stamping, wherein the plurality of leads have sides with a first concavity; and
performing an etch on the sides of the plurality of leads to achieve a second concavity on the sides of the plurality of leads, wherein the second concavity is greater than the first concavity;
attaching a semiconductor die to a center portion of the die;
making electrical attachments between the die and the leads; and
covering the die.
2. The method of claim 1 , wherein the performing the etch results in the second concavity having a depth that is at least 10 percent of a thickness (t) of the plurality of leads.
3. The method of claim 2 , wherein the performing the etch is by applying an etchant comprising one of a group consisting of copper chloride, ammonium chloride, and ferric chloride to the metal structure.
4. The method of claim 3 , wherein the making electrical attachments comprises wire bonding.
5. The method of claim 4 , wherein the covering the die comprises applying a mold compound over the die and the electrical attachments.
6. The method of claim 5 , wherein the plating comprises forming a layer of nickel, palladium, and gold over the top and bottom surfaces.
7. The method of claim 6 , wherein the forming the layer is by plating and performed prior to the separating.
8. The method of claim 6 , wherein the step of forming the layer is performed after the performing the etch and further comprises forming the layer of nickel, palladium, and gold on the sides of the plurality of leads.
9. The method of claim 2 , wherein the performing the etch comprises immersing the metal structure in a liquid etchant.
10. The method of claim 1 , wherein the encapsulating the die comprises:
applying a mold over the leads that encases the die and the electrical attachments; and
inserting mold compound into the mold.
11. A method of using a metal structure having a top surface and a bottom surface in forming a packaged die, comprising:
forming a plurality of leads on an outer portion of the metal structure by stamping the metal structure, wherein the stamping results in sides of the plurality of leads having a concave shape;
increasing a depth of the concave shape by etching;
attaching a die to an inner portion of the metal structure;
attaching wire bonds between the plurality of leads and the die; and
covering the die.
12. The method of claim 11 , further comprising covering the wire bonds.
13. The method of claim 12 , wherein the covering the wire bonds and the covering the die is achieved by applying a mold over the wire bonds and the die and filling the mold with mold compound.
14. The method of claim 11 , wherein the increasing the depth of the concave shape is further characterized by causing the concave shape to have a depth that is at least 10 percent of a thickness (t) of a lead of the plurality of leads.
15. The method of claim 14 , wherein the increasing the depth comprises applying an etchant to the metal structure.
16. The method of claim 15 , wherein the increasing the depth is by applying an etchant comprising one of a group consisting of copper chloride, ammonium chloride, and ferric chloride to the metal structure.
17. The method of claim 11 , wherein the forming the plurality of leads is further characterized by the metal structure comprising copper having a coating comprising nickel, palladium, and gold.
18. A method of forming a packaged die using a metal structure, comprising:
stamping a plurality of leads from an outer portion of the metal structure, wherein sides of the plurality of leads having a concave structure to a first depth;
etching the plurality of leads to increase the concave structure to a second depth greater than the first depth;
attaching a die to an inner portion of the metal structure;
attaching wire bonds between the die and the plurality of leads;
placing a mold over the die and the wire bonds;
filling the mold with molding compound; and
removing the mold.
19. The method of claim 18 , wherein metal structure comprises copper with a coating comprising nickel, palladium, and gold.
20. The method of claim 18 , wherein the second depth is at least 10 percent of a thickness (t) of a first lead of the plurality of leads.