Method for low stress flip-chip assembly of fine-pitch semiconductor devices
A device including a first body ( 101 ) with terminals ( 102 ) on a surface ( 101 a ), each terminal having a metallic connector ( 110 ), which is shaped as a column substantially perpendicular to the surface. Preferably, the connectors have an aspect ratio of height to diameter of 2 to 1 or greater, and a fine pitch center-to-center. The connector end ( 110 a ) remote from the terminal is covered by a film ( 130 ) of a sintered paste including a metallic matrix embedded in a first polymeric compound. Further a second body ( 103 ) having metallic pads ( 140 ) facing the respective terminals ( 102 ). Each connector film ( 130 ) is in contact with the respective pad ( 140 ), whereby the first body ( 101 ) is spaced from the second body ( 103 ) with the connector columns ( 110 ) as standoff. A second polymeric compound ( 150 ) is filling the space of the standoff.
1. An apparatus comprising:
a columnar connector having a first connector end and a second connector end;
a film of a metallic matrix, with inclusions of a first polymeric compound, covering the second connector end and sleeving over a connector portion contiguous with the second connector end; and
a second polymeric compound surrounding the columnar connector and the film.
2. The apparatus of claim 1 further including a second body in contact with the film covering the second connector end.
3. The apparatus of claim 2 further including a first body in contact with the first connector end.
4. The apparatus of claim 3 further including the second polymeric compound extending from the first body to the second body.
5. The apparatus of claim 1 wherein the columnar connector is metallic.
6. The apparatus of claim 5 wherein the metallic columnar connector is selected from a group including copper, gold, and solder.
7. The apparatus of claim 6 further including a metallic terminal of the first body to contact the first connector end.
8. The apparatus of claim 7 further including a metallic pad of the second body to contact the film covering the second connector end.
9. The apparatus of claim 1 wherein the columnar connector has an aspect ratio of height to diameter of at least 2 to 1.
10. The apparatus of claim 1 wherein the metallic matrix includes contacting particles of copper, tin, and bismuth, and alloys thereof.
11. The apparatus of claim 10 wherein the film of the metallic matrix has a thickness approximately equal throughout the extension of the film.
12. The apparatus of claim 3 wherein the first body is a semiconductor chip.
13. The apparatus of claim 1 wherein the second polymeric compound is different from the first polymeric compound.
14. The apparatus of claim 1 further including an array of columnar connectors aligned in rows, the columnar connectors having a pitch center-to-center.
15. The apparatus of claim 14 wherein the pitch is 30 pm or less.