Multi-sheet conductive substrates for microelectronic devices and methods for forming such substrates
View Patent ↗A substrate is provided having a plurality of sheets. Each sheet has a first major surface containing a plurality of electrically conductive regions and a second major surface that opposes the first major surface. The sheets are arranged such that the first major surface of a sheet faces the second major surface of another. At least one electrically conductive region of each sheet is partially or fully exposed. At least one electrically conductive region of a sheet is partially or fully covered, e.g., by one or more electrically conductive regions of another sheet. A method for forming such a substrate is also provided.
1. A substrate for packaging a microelectronic device, said substrate comprising:
first and second sheets each having opposing first and second major surfaces, each one of the first major surfaces having an associated plurality of electrically conductive regions, the second major surface of at least one of the first and second sheets having no electrically conductive region, the first and second sheets being arranged such that the second major surface of the first sheet faces the first major surface of the second sheet, at least one electrically conductive region of each one of the first and second sheets being partially or fully exposed, and at least one electrically conductive region of the first major surface of the second sheet being partially or fully covered by at least one electrically conductive region of the first major surface of the first sheet.
2. The substrate of claim 1 , wherein the first sheet includes a window extending through the major surfaces thereof and overlying the at least one partially or fully exposed electrically conductive region of the second sheet.
3. The substrate of claim 2 , wherein at least one electrically conductive region of the first sheet is electrically connected to at least one electrically conductive region of the second sheet through the window of the first sheet.
4. The substrate of claim 1 , wherein the electrically conductive surface regions of the first sheet are separated by at least one polymeric region.
5. The substrate of claim 4 , wherein the polymeric region is comprised of polyimide.
6. The substrate of claim 1 , wherein the electrically conductive surface regions are metallic.
7. The substrate of claim 6 , wherein the metallic surface regions are comprised of one or more of gold, copper, silver, nickel, tin, chromium, iron, alloys thereof, or combinations of any of the foregoing.
8. The substrate of claim 1 , wherein the second major surface of another one of the first and second sheets has no electrically conductive regions.
9. The substrate of claim 8 , further comprising a dielectric layer interposed between the first and second sheets.
10. The substrate of claim 9 , wherein the dielectric layer is comprised of a polymer.
11. The substrate of claim 1 , wherein the first and second sheets are movable relative to each other.
12. The substrate of claim 11 , wherein the first and second sheets are movable relative to each other to a substantial fatigue-relieving degree.
13. The substrate of claim 1 , wherein the first and second sheets are substantially immobilized relative to each other.
14. The substrate of claim 1 , further comprising a third sheet having a surface that includes a plurality of electrically conductive regions.
15. The substrate of claim 1 , wherein at least one electrically conductive region of the first sheet is electrically connected to at least one electrically conductive region of the second sheet.
16. The substrate of claim 15 , wherein the at least one electrically conductive region of the first sheet is wire bonded to the at least one electrically conductive region of the second sheet.
17. The substrate of claim 15 , wherein the at least one electrically conductive region of the first sheet is lead bonded to the at least one electrically conductive region of the second sheet.
18. The substrate of claim 1 , wherein at least two electrically conductive regions of the first sheet are electrically connected to the same electrically conductive region of the second sheet.
19. The substrate of claim 1 , wherein at least two electrically conductive regions of the second sheet are electrically connected to the same electrically conductive region of the first sheet.
20. The substrate of claim 1 , having no conductive via extending perpendicularly through the first and second major surfaces of the first sheet.
21. A microelectronic package, comprising a microelectronic device having a plurality of electrical contacts bonded to at least one electrically conductive region of the substrate of claim 1 .
22. The microelectronic device of claim 21 , wherein the electrical contacts are wire bonded to the at least one electrically conductive region.
23. The microelectronic device of claim 21 , wherein the electrical contacts are lead bonded to the at least one electrically conductive region.
24. A reel, comprising a plurality of substrates of claim 1 as a continuous roll.