# US 12,183,703 B2 · Leadframes in semiconductor devices

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- Number: US 12,183,703 B2
- Document ID: US12183703B2
- Status: Granted
- Kind: B2
- Application number: 17/505,494
- Filed: 2021-10-19
- Published: 2022-02-03
- Granted: 2024-12-31
- Earliest claimed: 2017-10-05
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Sreenivasan K. Koduri
- Web page: https://patentgrep.com/patent/US12183703B2

## CPC

- H10W 70/042: {Etching}
- H10W 70/40: Leadframes
- H10W 70/421: {Shapes or dispositions}
- H10W 70/424: {Cross-sectional shapes (H10W70/481 takes precedence)}
- H10W 70/435: {of insulating layers on leadframes, e.g. bridging members}
- H10W 70/458: {of insulating layers on leadframes}
- H10W 74/016: {using moulds}
- H10W 74/114: {by a substrate and the encapsulations}
- H10W 74/129: {forming a chip-scale package [CSP]}
- H10W 74/131: {the semiconductor body being only partially enclosed}
- H10W 90/701: {characterised by the relative positions of pads or connectors relative to package parts}
- H10W 70/415: {Leadframe inner leads serving as die pads}
- H10W 70/479: {on or in insulating or insulated package substrates, interposers, or redistribution layers}
- H10W 70/481: {for devices being provided for in groups H10D8/00 - H10D48/00}
- H10W 72/012: {of bump connectors, dummy bumps or thermal bumps}
- H10W 72/01212: {at a different location than on the final device, e.g. forming solder preforms}
- H10W 72/01235: {by plating, e.g. electroless plating or electroplating}
- H10W 72/01255: {by using masks}
- H10W 72/019: {of bond pads}
- H10W 72/01938: {in gaseous form, e.g. by CVD or PVD}
- H10W 72/0198: {batch processes}
- H10W 72/072: {of bump connectors}
- H10W 72/07236: {Soldering or alloying}
- H10W 72/07252: {changes in structures or sizes}
- H10W 72/07253: {changes in shapes}
- H10W 72/07255: {changes in materials}
- H10W 72/222: {Multilayered bumps, e.g. a coating on top and side surfaces of a bump core}
- H10W 72/227: {Multiple bumps having different sizes}
- H10W 72/232: {Plan-view shape, i.e. in top view}
- H10W 72/234: {Cross-sectional shape, i.e. in side view}
- H10W 72/241: {Dispositions, e.g. layouts}
- H10W 72/248: {Top-view layouts, e.g. mirror arrays}
- H10W 72/251: {Materials}
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- H10W 72/267: {Multiple bump connectors having different functions}
- H10W 72/29: Bond pads specially adapted therefor
- H10W 72/923: {Bond pads having multiple stacked layers}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- 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 95/00: Packaging processes not covered by the other groups of this subclass
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

In one instance, a method of forming a semiconductor package with a leadframe includes cutting, such as with a laser, a first side of a metal strip to a depth D1 according to a cutting pattern to form a first plurality of openings, which may be curvilinear. The method further includes etching the second side of the metal strip to a depth D2 according to a photoresist pattern to form a second plurality of openings. At least some of the first plurality of openings are in fluid communication with at least some of the second plurality of openings to form a plurality of leadframe leads. The depth D1 is shallower than a height H of the metal strip, and the depth D2 is also shallower than the height H. Other embodiments are presented.

## Claims

### Claim 1

A method for forming a semiconductor package, the method comprising:
cutting a first side of a leadframe of the semiconductor package to a first depth from a first side of the leadframe according to a cutting pattern to form a plurality of first channels, wherein the first depth is less than a thickness of the leadframe;
etching a second side of the leadframe opposing the first side to form a second plurality of channels to a second depth from the second side, less than the thickness of the leadframe, wherein the etching operation generates openings into the first plurality of channels, the openings separating leads of the leadframe into distinct segments;
coupling a plurality of bumps of a semiconductor die to the first side of the leadframe; and
covering at least a portion of the semiconductor die and at least a portion of the leadframe with a molding compound.

### Claim 2 (depends on 1)

The method of claim 1, wherein the cutting the first side of the leadframe is performed after the etching the second side of the leadframe.

### Claim 3 (depends on 1)

The method of claim 1, wherein the thickness of the metal strip is between the first side and the second side of the metal strip.

### Claim 4 (depends on 1)

The method of claim 1, wherein the plurality of bumps is aligned in multiple rows, at least one of the plurality of bumps from at least two adjacent rows of the multiple rows overlap with each other from a side view of the semiconductor package.

### Claim 5 (depends on 1)

The method of claim 1, wherein the second depth is more than the first depth.

### Claim 6 (depends on 1)

The method of claim 1, wherein the cutting of the first side of the leadframe includes using a laser, a precision water jet, or a plasma cutter.

### Claim 7 (depends on 1)

The method of claim 1, wherein the cutting pattern aligns at least partially with a photoresist pattern.

### Claim 8 (depends on 1)

The method of claim 1, wherein the etching from the second side continues through 50 to 80 percent of the thickness of the metal strip.

### Claim 9 (depends on 1)

The method of claim 1, wherein the cutting of the first side of the leadframe includes forming a cut with a lateral width that is less than 50 microns.

### Claim 10 (depends on 1)

The method of claim 1, wherein the cutting pattern is substantially linear.

### Claim 11 (depends on 1)

The method of claim 1, wherein the first plurality of openings and the second plurality of openings together separate a plurality of leads of the metal strip.

### Claim 12

A method comprising:
forming a leadframe for a semiconductor package, wherein forming the leadframe comprises:
cutting a first side of a metal strip according to a cutting pattern to form a first plurality of openings extending into the first side, the metal strip having the first side and a second side, wherein the second side opposes the first side, and wherein the metal strip has a height H between the first side and the second side,
applying a photoresist on the second side of the metal strip,
applying a chemical etch to the second side of the metal strip according to a photoresist pattern to form a second plurality of openings extending into the second side of the metal strip, wherein the at least a portion of the second plurality of openings align with the first plurality of openings, and wherein a depth D2 of the etching from the second side is less than the height H of the metal strip,
removing the photoresist from the second side of the metal strip, wherein cutting the first side of the metal strip comprises forming a plurality of leads having a plurality of bump landing sites;
attaching a plurality of bumps between a semiconductor die and the plurality of bump landing sites on the leadframe; and
covering at least a portion of the semiconductor die and the leadframe with a molding compound to form the semiconductor package; wherein the plurality of bumps is aligned in multiple rows, at least one of the plurality of bumps from at least two adjacent rows of the multiple rows overlap with each other from a side view of the semiconductor package.

### Claim 13 (depends on 12)

The method of claim 12, wherein cutting the first side of the metal strip comprises using a laser.

### Claim 14 (depends on 12)

The method of claim 12, wherein cutting the first side of the metal strip comprises using a precision water jet or a plasma cutter.

### Claim 15 (depends on 12)

The method of claim 12, wherein the chemical etch is applied until 50 to 80 percent of the height H of the metal strip is removed according to the photoresist pattern.

### Claim 16 (depends on 12)

The method of claim 12, wherein cutting the first side of the metal strip includes forming a cut with a lateral width WI that is less than 50 microns.

### Claim 17 (depends on 12)

The method of claim 12, wherein cutting the first side of the metal strip includes forming a cut with a lateral width WI that is less than 25 microns.

### Claim 18 (depends on 12)

The method of claim 12, wherein the cutting is performed after applying the chemical etch.

### Claim 19 (depends on 12)

The method of claim 12, wherein the cutting pattern includes a nonlinear pattern.

### Claim 20 (depends on 12)

The method of claim 12, wherein the cutting pattern includes substantially a sinusoidal pattern.