# US 2019/0355651 A1 · Two sided bondable lead frame > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0355651 A1 - Document ID: US20190355651A1 - Status: Published application - Kind: A1 - Application number: 15/985,380 - Filed: 2018-05-21 - Published: 2019-11-21 - Earliest claimed: 2018-05-21 - Applicants: Texas Instruments Incorporated - Inventors: Dolores Babaran Milo; Ernesto Pentecostes Rafael, Jr. - Web page: https://patentgrep.com/patent/US20190355651A1 ## CPC - H10W 70/042: {Etching} - H10W 70/461: {specially adapted for cooling} - H05K 1/181: associated with surface mounted components - H10W 70/411: {Chip-supporting parts, e.g. die pads} - H10W 70/417: {Bonding materials between chips and die pads} - H10W 70/424: {Cross-sectional shapes (H10W70/481 takes precedence)} - H10W 72/50: Bond wires - H10W 90/811: {Multiple chips on leadframes} - H10W 72/073: {of die-attach connectors} - H10W 72/075: {of bond wires} - H10W 72/354: {comprising polymers} - H10W 72/884: {Die-attach connectors and bond wires} - H10W 74/142: {the encapsulations exposing the passive side of the semiconductor body} - H10W 90/736: {between a chip and a stacked lead frame, conducting package substrate or heat sink} - H10W 90/756: {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 - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A lead frame includes a first side having a first die attach pad that is bondable to a die, and a second side that has a second die attach pad that is bondable to another die. The lead frame includes multiple leads on the edges of the lead frame to connect the die. As part of a no-leads device, such as a quad flat no leads (QFN) or dual flat no-leads (DFN), one of the die attach pads is used in binding to a die, and the other die attach pad is used for thermal dissipation and mounting to a structure such as printed circuit board (PCB). ## Claims ### Claim 1 A semiconductor package comprising: a lead frame comprising: a first side and a second side, wherein the first side includes a first die attach pad and the second side opposite to the first side includes a second die attach pad; a die attached to the first die attach pad via a die attach material and electrically connected to at least one of multiple leads; and multiple leads; and a molding that covers portions of the lead frame, the die attach material, and the die, wherein a portion of the second die attach pad is exposed from the package. ### Claim 2 (depends on 1) The semiconductor package of claim 1, wherein as viewed from a cross section of the lead frame, a middle section of the lead frame, the first side, and second side are on different planes. ### Claim 3 (depends on 1) The semiconductor package of claim 1, wherein as viewed from a cross section of the lead frame, the leads of the multiple leads are shaped with an indentation on a top plane of the lead frame and an indentation on a bottom plane of the lead frame. ### Claim 4 (depends on 1) The semiconductor package of claim 1, wherein as viewed from a cross section of the lead frame, the lead frame has a total thickness of about 0.2 millimeters and the first die attach pad and second die attach pad are each about 0.05 millimeters in thickness. ### Claim 5 (depends on 1) The semiconductor package of claim 1, wherein the first die attach pad is different in area than the second die attach pad. ### Claim 6 (depends on 1) The semiconductor package of claim 1, wherein the first die attach pad and second die attach pad are about square in area. ### Claim 7 (depends on 1) The semiconductor package of claim 1, wherein the die attach material is made of epoxy, laminate film, or other adhesion material. ### Claim 8 A semiconductor package comprising: a lead frame comprising: a first side that includes a first die attach pad bondable to a die; a second side that includes a second die attach pad bondable to another die; and multiple leads on the edges of the lead frame used for die connection; and encapsulation that covers the lead frame and exposes at least one of the first die attach pad or the second die attach pad and the multiple leads. ### Claim 9 (depends on 8) The semiconductor package of claim 8 wherein the first die attach pad and second die attach pad are different in size by area and provide different thermal dissipation characteristics. ### Claim 10 (depends on 8) The semiconductor package of claim 8, wherein binding of either the first die attach pad to the die or the second die attach to the another die, uses one of an epoxy, laminate film, or adhesion material. ### Claim 11 (depends on 8) The semiconductor package of claim 8, wherein as viewed from a top or bottom view the first side, the second side, first die attach pad, and second die attach pad are rectangular in area. ### Claim 12 (depends on 8) The semiconductor package of claim 8, wherein the multiple leads are shaped with an indentation on a top plane of the lead frame and an indentation on a bottom plane of the lead frame, wherein the indentation are curved or have a right angled cut. ### Claim 13 (depends on 8) The semiconductor package of claim 8 further comprising through holes for connections for bond pads for a die bound on either the first die attach pad or the second die attach pad. ### Claim 14 (depends on 8) The semiconductor package of claim 8, wherein the semiconductor package is either a quad flat no-leads (QFN) or a dual flat no-leads (DFN). ### Claim 15 A method of fabricating a no-leads device comprising: etching a first side of a lead frame to form a first die attach pad; etching a second side of the lead frame to form a second die attach pad; determining which of the first die attach pad or the second die attach pad to bind a die to; binding the die to the die attach pad that is determined to bind the die to; connecting bond pads on the die to specific leads of a set of leads that are part of the lead frame; and adding a molding over portions of the lead frame and the die, wherein the set of leads and the pad that is not used to bind the die are exposed from the no-leads device. ### Claim 16 (depends on 15) The method of claim 15, wherein the etching is a chemical etching. ### Claim 17 (depends on 15) The method of claim 15, wherein each lead of the set of leads has an indentation coplanar to the first side and an indentation coplanar to the second side, wherein the indentations are generally curved in shape or right angle in shape. ### Claim 18 (depends on 15) The method of claim 15, wherein the first die attach pad provides a different thermal dissipation than the second die attach pad. ### Claim 19 The method of 15, wherein the etching the first die attach pad defines edges of the first die attach pad and through holes for wire connections from the bond pads of a die bound to the first die attach pad, and the etching of the second die attach pad defines edges of the second die attach pad and through holes for wire connections from the bond pads of another die bound to the second die attach pad. ### Claim 20 The method of 15 further comprising plating and polishing the lead frame after etching the first die attach pad and the second die attach pad.