# US 10,312,111 B2 · Method of fabricating low-profile footed power package

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- Number: US 10,312,111 B2
- Document ID: US10312111B2
- Status: Granted
- Kind: B2
- Application number: 16/041,275
- Filed: 2018-07-20
- Published: 2018-11-15
- Granted: 2019-06-04
- Earliest claimed: 2013-03-09
- Assignees: Adventive IPBank
- Applicants: Adventive Technology Ltd.
- Inventors: Richard K. Williams; Keng Hung Lin
- Web page: https://patentgrep.com/patent/US10312111B2

## CPC

- H10W 40/037: {Assembling together parts thereof}
- H10W 40/22: characterised by their shape, e.g. having conical or cylindrical projections
- H10W 70/042: {Etching}
- H10W 70/411: {Chip-supporting parts, e.g. die pads}
- H10W 70/417: {Bonding materials between chips and die pads}
- H10W 70/427: {Bent parts}
- H10W 70/429: {being the outer leads}
- H10W 70/461: {specially adapted for cooling}
- H10W 70/465: {Bumps or wires}
- H10W 70/481: {for devices being provided for in groups H10D8/00 - H10D48/00}
- H10W 74/016: {using moulds}
- H10W 74/114: {by a substrate and the encapsulations}
- H10W 74/40: characterised by their materials
- H10W 72/0198: {batch processes}
- H10W 72/073: {of die-attach connectors}
- H10W 72/07336: {Soldering or alloying}
- H10W 72/07337: {using a polymer adhesive, e.g. an adhesive based on silicone or epoxy}
- H10W 72/075: {of bond wires}
- H10W 72/07552: {changes in structures or sizes}
- H10W 72/07636: {Soldering or alloying}
- H10W 72/07637: {using a polymer adhesive, e.g. an adhesive based on silicone or epoxy}
- H10W 72/07653: {changes in shapes}
- H10W 72/325: {Die-attach connectors having a filler embedded in a matrix}
- H10W 72/352: {comprising metals or metalloids, e.g. solders}
- H10W 72/354: {comprising polymers}
- H10W 72/527: {Multiple bond wires having different sizes}
- H10W 72/536: {the connected ends being ball-shaped}
- H10W 72/5449: {not being orthogonal to a side surface of the chip, e.g. fan-out arrangements}
- H10W 72/5475: {multiple bond wires connected to common bond pads at both ends of the wires}
- H10W 72/5522: {comprising gold [Au]}
- H10W 72/5524: {comprising aluminium [Al]}
- H10W 72/5525: {comprising copper [Cu]}
- H10W 72/652: {comprising metals or metalloids, e.g. silver}
- H10W 72/871: {Bond wires and strap connectors}
- H10W 72/879: {Bump connectors and bond wires}
- H10W 72/884: {Die-attach connectors and bond wires}
- H10W 72/926: {Multiple bond pads having different sizes}
- H10W 74/00: Encapsulations, e.g. protective coatings
- H10W 74/111: {the semiconductor body being completely enclosed}
- 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 90/756: {between a chip and a stacked lead frame, conducting package substrate or heat sink}
- H10W 90/766: {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

A method is disclosed of fabricating a power package which includes a heat tab extending from a die pad exposed on the underside of the package, which facilitates the removal of heat from the die to the PCB or other surface on which the package is mounted. The heat tab has a bottom surface coplanar with the flat bottom surface of the die pad and bottom surface of a lead. The lead includes a horizontal foot segment, a vertical columnar segment, and a horizontal cantilever segment facing the die pad. The heat tab may also have a foot. A die containing a power device is mounted on a top surface of the die pad and may be electrically connected to the lead using a bonding wire or clip. The die may be mounted on the die pad with an electrically conductive material, and the package may also include a lead that extends from the die pad and is thus electrically tied to the bottom of the die. The result is a package with a minimal footprint that is suitable for the technique known as “wave soldering” that is used in relatively low-cost printed circuit board assembly factories.

## Claims

### Claim 1

A method of fabricating a footed power package from a metal sheet, the package comprising a die pad, a lead and a heat tab, the metal comprising:
applying a first metal stamp to a first side of the metal sheet to thin the metal sheet where a cantilever segment of the lead and a gap between the die pad and the lead are to be located; and
applying a second metal stamp to a second side of the metal sheet to sever the metal sheet where the gap between the die pad and the lead is to be located.

### Claim 2 (depends on 1)

The method of claim 1 wherein applying the second metal stamp thins the metal sheet where a foot of the lead is to be located.

### Claim 3 (depends on 2)

The method of claim 2 wherein applying the second metal stamp thins the metal sheet where a foot of the heat tab is to be located.

### Claim 4 (depends on 1)

The method of claim 1 comprising mounting a semiconductor die on a surface of the die pad.

### Claim 5 (depends on 4)

The method of claim 4 comprising connecting an electrically conductive bonding wire between the die and the cantilever segment of the lead.

### Claim 6 (depends on 5)

The method of claim 5 comprising encapsulating the die and the bonding wire in a plastic molding compound, the plastic molding compound covering a surface of die pad and a portion of the lead and filling an area between the die pad and the lead, the plastic molding compound not covering the heat tab and at least a portion of the foot of the lead.

### Claim 7 (depends on 6)

The method of claim 6 wherein the package comprises three of more leads and wherein:
applying the first metal stamp to a first side of the metal sheet thins the metal sheet where a cantilever segment of each of the leads and a gap between each of the leads and the die pad are to be located,
applying the second metal stamp to a second side of the metal sheet severs the metal sheet where the gap between the die pad and each of the leads is to be located: and
wherein encapsulating the die in a plastic molding compound leaves each of the leads at least partially exposed.

### Claim 8 (depends on 7)

The method of claim 7 where the three or more leads are located on at least two sides of the package.

### Claim 9 (depends on 4)

The method of claim 4 comprising connecting an electrically conductive clip between the die and the cantilever segment of the lead.

### Claim 10 (depends on 9)

The method of claim 9 comprising connecting the electrically conductive clip to the surface of the die with solder.

### Claim 11 (depends on 9)

The method of claim 9 comprising connecting the electrically conductive clip to the surface of the die with conductive epoxy.

### Claim 12 (depends on 9)

The method of claim 9 wherein the package comprises a second lead, the method comprising connecting an electrically conductive bonding wire between the die and a cantilever segment of the second lead.

### Claim 13 (depends on 9)

The method of claim 9 comprising encapsulating the die and the conductive clip in a plastic molding compound, the molding compound covering the surface of die pad and a portion of the lead and filling an area between the die pad and the lead, the plastic molding compound not covering the heat tab and at least a portion of the foot of the lead.

### Claim 14 (depends on 13)

The method of claim 13 wherein the package comprises a second lead, the method comprising connecting an electrically conductive bonding wire between the die and a cantilever segment of the second lead.

### Claim 15 (depends on 1)

The method of claim 1, wherein the package comprises a second die pad and wherein applying the first metal stamp to a first side of the metal sheet thins the metal sheet where a die pad extension extending from the die pad is to be located so as to increase the spacing between an exposed underside of the die pad and an exposed underside of the second die pad.

### Claim 16 (depends on 1)

The method of claim 1 comprising encapsulating the lead in a plastic molding compound, a portion of the lead covered by the molding compound being wider than a second portion of the lead not covered by the molding compound.

### Claim 17 (depends on 1)

The method of claim 1 wherein the metal sheet comprises a leadframe and wherein applying the second metal stamp to a second side of the metal sheet thins the metal sheet where a foot of the lead is to be located, the method further comprising sawing through the metal thinned by the second metal stamp so as form the foot of the lead and singulate the package from the leadframe.

### Claim 18 (depends on 17)

The method of claim 17 wherein metal removed during the sawing comprises an extension of the foot of the lead.

### Claim 19 (depends on 18)

The method of claim 18 wherein applying the second metal stamp thins the metal sheet where a foot of the heat tab is to be located and wherein metal removed during the sawing comprises an extension of the foot of the heat tab.

### Claim 20 (depends on 19)

The method of claim 19 wherein the sawing removes metal that forms part of the leadframe but that is not an extension of the foot of the lead or an extension of the foot of the heat tab.