Microelectronic packages and methods therefor
View Patent ↗A microelectronic package includes a microelectronic element having contacts, a flexible substrate spaced from and overlying the microelectronic element and a plurality of conductive posts extending from the flexible substrate and projecting away from the microelectronic element. The conductive posts are electrically interconnected with the microelectronic element. Each conductive post has a conductive base that is in contact with the flexible substrate and a conductive tip that extends from the base, with the base of the conductive post having a larger diameter than the tip of the conductive post. In certain embodiments, the conductive base and the conductive tip have a cylindrical shape.
1. A microelectronic package comprising:
a microelectronic element having contacts;
a flexible substrate spaced from and overlying said microelectronic element;
a plurality of substantially rigid conductive posts extending from said flexible substrate and projecting away from said microelectronic element, said conductive posts being electrically interconnected with said microelectronic element, each said conductive post having a cylindrical base that is in contact with said flexible substrate and a cylindrical tip that extends from said cylindrical base, wherein said base of said conductive post has a larger diameter than said tip of said conductive post.
2. The package as claimed in claim 1 , wherein said bases of said conductive posts comprise a first conductive material and said tips of said conductive posts comprise a second conductive material that is different than said first conductive material.
3. The package as claimed in claim 2 , wherein said bases comprise a first metal and said tips comprise a second metal.
4. The package as claimed in claim 2 , wherein said bases comprise a material having a higher modulus and said tips comprise a material having a lower modulus than said bases.
5. The package as claimed in claim 1 , wherein at least one of said conductive posts comprises a conductive polymer.
6. The package as claimed in claim 1 , wherein said tips of said conductive posts have apexes that are co-planar.
7. The package as claimed in claim 1 , wherein said tips of said conductive posts have a diameter of about 60-100 microns.
8. The package as claimed in claim 7 , wherein said tips of said conductive posts have a diameter of about 80 microns.
9. The package as claimed in claim 1 , further comprising a compliant layer between said microelectronic element and said flexible substrate.
10. The package as claimed in claim 1 , wherein said flexible substrate comprises a dielectric material.
11. The package as claimed in claim 1 , further comprising conductive traces provided on said flexible substrate.
12. The package as claimed in claim 11 , wherein said conductive traces electrically interconnect at least some of said conductive posts and said microelectronic element.
13. The package as claimed in claim 11 , wherein said flexible substrate has a first surface facing said microelectronic element and a second surface facing away from said microelectronic element, said conductive traces overlying the first surface of said flexible substrate.
14. The package as claimed in claim 13 , wherein said flexible substrate has openings extending between said conductive traces and said bases of said conductive posts, said package further comprising conductive elements provided in the openings in said flexible substrate for electrically interconnecting said bases of said conductive posts and said conductive traces.
15. The package as claimed in claim 14 , wherein said conductive elements have diameters that are smaller than the diameters of said tips of said conductive posts.
16. The package as claimed in claim 1 , wherein said microelectronic element is selected from the group consisting of a semiconductor chip and a semiconductor wafer.
17. The package as claimed in claim 1 , further comprising leads for electrically interconnecting said microelectronic element and said conductive posts.
18. The package as claimed in claim 1 , wherein the substantially rigid conductive posts are comprised of copper.
19. A microelectronic package comprising:
a microelectronic element having contacts;
a flexible substrate spaced from said microelectronic element, said flexible substrate having a first surface facing said microelectronic element and a second surface facing away from said microelectronic element, said flexible substrate having vias extending from the first surface to the second surface thereof;
conductive traces overlying the first surface of said flexible substrate;
a compliant layer disposed between said microelectronic element and the first surface of said flexible substrate;
a plurality of substantially rigid conductive posts extending from the second surface of said flexible substrate and projecting away from said microelectronic element, said conductive posts being electrically interconnected with said microelectronic element, each said conductive post having a conductive base that is in contact with the first surface of said flexible substrate and a conductive tip that extends from said conductive base, wherein said base of said conductive post has a larger diameter than said tip of said conductive post; and
conductive elements provided in the vias of said flexible substrate for electrically interconnecting said bases of said conductive posts with said conductive traces.
20. The package as claimed in claim 19 , wherein said conductive tips of said conductive posts have a cylindrical shape.
21. The package as claimed in claim 19 , wherein said conductive bases of said conductive posts have a cylindrical shape.
22. The package as claimed in claim 19 , wherein said contacts on said microelectronic element face toward said flexible substrate.
23. The package as claimed in claim 19 , wherein said bases of said conductive posts comprise a first metal and said tips of said conductive posts comprise a second metal that is different than said first metal.
24. The package as claimed in claim 19 , wherein said conductive elements have diameters that are smaller than the diameters of said tips of said conductive posts.
25. The package as claimed in claim 19 , wherein the substantially rigid conductive posts have a melting point greater than the melting point of solder.
26. A microelectronic assembly comprising:
a microelectronic element having a first surface and contacts accessible at the first surface;
a compliant layer overlying the first surface of said microelectronic element;
substantially rigid conductive posts overlying said compliant layer and projecting away from the first surface of said microelectronic element, each said conductive post having a cylindrical base that is in contact with the first surface of said flexible substrate and a cylindrical tip that extends from said cylindrical base, wherein said base of said conductive post has a larger diameter than said tip of said conductive post, and wherein said conductive posts are electrically interconnected with said contacts of said microelectronic element.
27. The assembly as claimed in claim 26 , wherein said microelectronic element is a semiconductor wafer.
28. The assembly as claimed in claim 26 , wherein said microelectronic element is a semiconductor chip.
29. The assembly as claimed in claim 26 , wherein said compliant layer comprises a material selected from the group consisting of silicones, flexibilized epoxies, polyimides, thermosetting polymers, fluoropolymers and thermoplastic polymers.
30. The assembly as claimed in claim 26 , wherein the top surface of said compliant layer is substantially flat.
31. The assembly as claimed in claim 26 , further comprising electrically conductive traces for electrically interconnecting said conductive posts and said contacts of said microelectronic element.
32. The assembly as claimed in claim 26 , wherein said conductive traces comprises materials selected from the group consisting of copper, gold, nickel and alloys, combinations and composites thereof.
33. The assembly as claimed in claim 32 , wherein said elongated, electrically conductive elements extend over said compliant layer.
34. The assembly as claimed in claim 26 , wherein each said conductive post has a height of about 50-300 microns.
35. The assembly as claimed in claim 26 , wherein the tips of said conductive posts have a height that is greater than a height of the bases of said conductive posts.
36. A microelectronic assembly comprising:
a microelectronic element having a first surface and contacts accessible at the first surface;
a compliant layer overlying the first surface of said microelectronic element, said compliant layer having a top surface spaced from the first surface of said microelectronic element;
substantially rigid conductive posts overlying the top surface of said compliant layer and projecting away from the first surface of said microelectronic element, each said conductive post having a conductive base that is in contact with the first surface of said flexible substrate and a conductive tip that extends from said conductive base, wherein said base of said conductive post has a larger diameter than said tip of said conductive post; and
conductive traces electrically interconnecting said conductive posts and said contacts of said microelectronic element.
37. The assembly as claimed in claim 36 , wherein said conductive tips have a cylindrical shape and said conductive bases have a cylindrical shape.
38. The assembly as claimed in claim 36 , wherein said microelectronic element is a semiconductor wafer or a semiconductor chip.