US 5,347,162 A · Preformed planar structures employing embedded conductors

Abstract

An interposer (preformed planar structure) is disposed between a die and a substrate (which may be another die). Through holes in the interposer facilitate controlled formation of reflow solder joints between conductive bumps on the die and corresponding conductive bumps of the substrate. In one embodiment, conductive elements embedded in the preformed planar structures extend at least partially into the through holes, forming electrical connections with the corresponding solder joints. The conductive elements can be used to electrically connect one solder joint to another within the interposer, and/or may extend beyond an edge of the interposer to provide for electrical probing of or connection to the solder joints. In one embodiment, the conductive elements are extended outside of the preformed planar structure to form "pins" or leads of the flip-chip structure. In another embodiment, a foil is disposed across a through hole, so that otherwise electro-galvanically incompatible solder balls on the die and the substrate will not corrode each other.

Claims20

Dependent claims

A flip-chip structure, comprising:

a chip having first solder balls on a face thereof;
a substrate having corresponding second solder balls on a face thereof;
a separate and distinct preformed planar structure disposed between the chip and the substrate, having two opposite faces, one face in contact with the chip and the opposite face in contact with the substrate;
through holes extending through the preformed planar structure from the one face to the opposite face;
at least one conductive element embedded within the preformed planar structure and extending only partially into at least one corresponding through hole;
and
at least one solder joint consisting essentially of at least one first solder ball and at least one corresponding second solder ball fused within the through holes to each other and to at least one corresponding conductive element to form an electrical connection between the at least one first solder ball, the at least one second solder ball and the at least one corresponding conductive element.

4 more elements

A flip-chip structure, comprising:

a chip having first solder balls on a face thereof;
a substrate having corresponding second solder balls on a face thereof;
a separate and distinct preformed planar structure disposed between the chip and the substrate, having two opposite faces, one face in contact with the chip and the opposite face in contact with the substrate;
through holes extending through the preformed planar structure from the one face to the opposite face;
at least one conductive element embedded midway between the one face and the opposite face of the preformed planar structure and extending fully across at least one corresponding through hole, each conductive element dividing a corresponding through hole into a first through hole portion extending from the one face of the preformed planar structure to the conductive element and a second through hole portion extending from the opposite face of the preformed planar structure to the conductive element;
and
at least one solder joint consisting essentially of at least one first solder ball contacting a one surface of the conductive element and a second solder ball contacting an other, opposite surface of the conductive element, thereby forming an electrical path from the first solder ball to the conductive element and from the conductive element to the second solder ball.

4 more elements

Dependencies are inferred from the claim text.

Preformed planar structures employing embedded conductors

Life of this patent

Preformed planar structures employing embedded conductors

Life of this patent

Abstract

Claims20