# US 8,785,250 B2 · Methods and apparatus for flip-chip-on-lead semiconductor package > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,785,250 B2 - Document ID: US8785250B2 - Status: Granted - Kind: B2 - Application number: 12/112,192 - Filed: 2008-04-30 - Published: 2008-09-25 - Granted: 2014-07-22 - Earliest claimed: 2005-11-01 - Assignees: Allegro MicroSystems, LLC - Applicants: Nirmal Sharma; Virgil Ararao - Inventors: Nirmal Sharma; Virgil Ararao - Web page: https://patentgrep.com/patent/US8785250B2 ## CPC - H10W 70/465: {Bumps or wires} - H10W 70/415: {Leadframe inner leads serving as die pads} - H10W 70/424: {Cross-sectional shapes (H10W70/481 takes precedence)} - H10W 72/01212: {at a different location than on the final device, e.g. forming solder preforms} - H10W 72/072: {of bump connectors} - H10W 72/07236: {Soldering or alloying} - H10W 72/073: {of die-attach connectors} - H10W 72/07337: {using a polymer adhesive, e.g. an adhesive based on silicone or epoxy} - H10W 72/241: {Dispositions, e.g. layouts} - H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu} - H10W 72/287: {Flow barriers} - H10W 72/922: {Bond pads being integral with underlying chip-level interconnections} - H10W 72/923: {Bond pads having multiple stacked layers} - H10W 72/9415: {relative to the surface, e.g. recessed, protruding} - H10W 72/942: {relative to underlying supporting features, e.g. bond pads, RDLs or vias} - H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu} - H10W 74/00: Encapsulations, e.g. protective coatings - H10W 74/15: on active surfaces of flip-chip devices, e.g. underfills - H10W 90/726: {between a chip and a stacked lead frame, conducting package substrate or heat sink} - H10W 90/736: {between a chip and a stacked lead frame, conducting package substrate or heat sink} - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract Fabrication of a semiconductor package includes placing a conductive material on a protrusion from a leadframe to form a first assembly, forming a non-conductive mask about the protrusion, and placing a die on the first assembly, the die having an active area. Fabrication can further include reflowing the conductive material to form a second assembly such that a connection extends from the die active area, through the conductive material, to the protrusion. A semiconductor package includes a leadframe having a protrusion, a conductive material reflowed to the protrusion, and a die having an active area coupled to the protrusion by the reflowed solder. ## Claims ### Claim 1 A method, comprising: placing adhesive on at least one of a generally planar leadframe having a through hole and a generally planar die; disposing first and second non-conductive filler elements having the same size in the adhesive; attaching a first surface of the die to the adhesive, the first surface having an active area, wherein the die and the leadframe are spaced at an equal distance from each other at locations of the first and second non-conductive filler elements, wherein the distance corresponds to the size of the first and second non-conductive filler elements; placing a solder ball in the through hole; and reflowing the solder ball to form a connection between the active area and the leadframe. ### Claim 2 (depends on 1) The method according to claim 1, further including forming an under bump metallization layer at the active area of the die. ### Claim 3 (depends on 2) The method according to claim 2, further including forming a redistribution layer on the die. ### Claim 4 (depends on 1) A semiconductor package fabricated in accordance with claim 1. ### Claim 5 (depends on 1) The method according to claim 1, wherein the at least one filler element is spherical. ### Claim 6 (depends on 1) The method according to claim 1, further including surrounding the at least two filler elements with the adhesive, wherein the adhesive is non-conductive. ### Claim 7 An article, comprising: a generally planar leadframe having a through hole; a generally planar die having a first surface with an active area, the die coupled to the leadframe by an adhesive on the first surface; a reflowed solder ball disposed in the through hole to form a connection between the active area and the leadframe; and first and second non-conductive filler elements having the same size disposed in the adhesive, wherein the die and the leadframe are spaced at an equal distance from each other at locations of the first and second non-conductive filler elements, wherein the distance corresponds to the size of the first and second non-conductive filler elements. ### Claim 8 (depends on 7) The article according to claim 7, further including an under bump metallization layer at the active area of the die. ### Claim 9 (depends on 8) The article according to claim 8, further including a redistribution layer on the die. ### Claim 10 (depends on 7) The article according to claim 7, wherein the at least two filler elements are spherical. ### Claim 11 (depends on 7) The article according to claim 7, wherein the at least two filler elements are surrounded by the adhesive, which is non-conductive. ### Claim 12 A device, comprising: a semiconductor package, including: a leadframe having a through hole; a die having an active area, the die coupled to the leadframe by an adhesive on the same side of the die as the active area; a reflowed solder ball disposed in the through hole to form a connection between the active area and the leadframe; and first and second non-conductive filler elements having the same size disposed in the adhesive, wherein the die and the leadframe are spaced at an equal distance from each other at locations of the first and second non-conductive filler elements, wherein the distance corresponds to the size of the first and second non-conductive filler elements. ### Claim 13 (depends on 12) The device according to claim 12, further including an under bump metallization layer at the active area of the die. ### Claim 14 (depends on 13) The device according to claim 13, further including a redistribution layer on the die. ### Claim 15 (depends on 12) The device according to claim 12, wherein the at least two filler elements are spherical. ### Claim 16 (depends on 12) The device according to claim 12, wherein the at least two filler elements are surrounded by the adhesive, which is non-conductive.