# US 12,765,400 B2 · Semiconductor package having partially plated lead flank and method of making the same

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- Number: US 12,765,400 B2
- Document ID: US12765400B2
- Status: Granted
- Kind: B2
- Application number: 18/443,842
- Filed: 2024-02-16
- Published: 2025-08-21
- Granted: 2026-10-13
- Earliest claimed: 2024-02-16
- Assignees: Alpha and Omega Semiconductor International LP
- Applicants: Alpha and Omega Semiconductor International LP
- Inventors: Yan Xun Xue; Madhur Bobde; Long-Ching Wang; Wenjun Li; Xiaoguang Zeng
- Web page: https://patentgrep.com/patent/US12765400B2

## CPC

- H10W 70/481: {for devices being provided for in groups H10D8/00 - H10D48/00}
- H10P 14/47: Electrolytic deposition, i.e. electroplating; Electroless plating
- H10W 70/048: {Mechanical treatments, e.g. punching, cutting, deforming or cold welding}
- H10W 70/457: {of metallic layers on leadframes}
- H10W 74/111: {the semiconductor body being completely enclosed}
- H10W 72/0198: {batch processes}
- H10W 74/014: {using batch processing}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A semiconductor package comprises a lead frame, a chip, and a molding encapsulation. The lead frame comprises one or more die paddles and a plurality of leads. Each of the plurality of leads comprises a base member and a protrusion member. A width of an end surface of the protrusion member of each of the plurality of leads is less than 50% of a width of a corresponding base member so as to improve solderability. A method, for fabricating semiconductor packages, comprises the steps of providing a lead frame array, mounting a chip, forming a molding encapsulation, applying a cutting process or a punching process, applying a plating process, and applying a singulation process.

## Claims

### Claim 1

A method for fabricating a semiconductor package, the method comprising the steps of:
providing a lead frame array comprising
one or more lead frames, each lead frame of the one or more lead frames comprising one or more die paddles;
a first dam bar comprising:
a first plurality of dam bar connecting sections;
a second dam bar comprising:
a second plurality of dam bar connecting sections;
a first plurality of slots between the first dam bar and a first side of said each lead frame;
a second plurality of slots between the second dam bar and a second side of said each lead frame, the second side of said each lead frame being opposite the first side of said each lead frame;
a first plurality of leads extending away from the one or more die paddles along a first direction, each of the first plurality of leads being connected to the first dam bar; and
a second plurality of leads extending away from the one or more die paddles along a second direction opposite the first direction, each of the second plurality of leads being connected to the second dam bar;
mounting a chip on the one or more die paddles;
forming a molding encapsulation enclosing the chip;
applying a cutting process or a punching process removing the first plurality of dam bar connecting sections and the second plurality of dam bar connecting sections;
plating tin on portions of the lead frame array not covered by the molding encapsulation; and
applying a singulation process;
wherein a first plurality of rectangular holes are between the first plurality of dam bar connecting sections and the one or more die paddles, and
wherein a lateral dimension of each of the first plurality of rectangular holes between the first plurality of dam bar connecting sections and the one or more die paddles is smaller than a lateral dimension of a corresponding dam bar connecting section of the first plurality of dam bar connecting sections.

### Claim 2 (depends on 1)

The method of claim 1, before the step of forming the molding encapsulation, applying a wire bonding process or a clip bonding process.

### Claim 3 (depends on 1)

The method of claim 1, wherein each of the first plurality of dam bar connecting sections and the second plurality of dam bar connecting sections comprises
a first end section;
a center section; and
a second end section opposite the first end section;
wherein a cross-sectional area of the first end section is smaller than a cross-sectional area of the center section; and
wherein a cross-sectional area of the second end section is smaller than the cross-sectional area of the center section.

### Claim 4 (depends on 1)

The method of claim 1,
wherein each of the first plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said first plurality of leads;
wherein a width of the protrusion member of said each of the first plurality of leads is less than fifty percent of a width of the base member of said each of the first plurality of leads;
wherein each of the second plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said second plurality of leads; and
wherein a width of the protrusion member of said each of the second plurality of leads is less than fifty percent of a width of the base member of said each of the second plurality of leads.

### Claim 5 (depends on 1)

The method of claim 1, wherein each of the first plurality of dam bar connecting sections comprises:
a first arc portion; and
a second arc portion; and
wherein each of the first plurality of dam bar connecting sections comprises:
a first arc portion; and
a second arc portion.

### Claim 6 (depends on 1)

The method of claim 1, wherein each lead frame of the one or more lead frames further comprises
a first plurality of rectangular holes between the first plurality of dam bar connecting sections and the one or more die paddles;
wherein a lateral dimension of each of the first plurality of rectangular holes is smaller than a lateral dimension of a corresponding dam bar connecting section of the first plurality of dam bar connecting sections.

### Claim 7 (depends on 1)

The method of claim 1, wherein each lead frame of the one or more lead frames further comprises
a third dam bar comprising:
a third plurality of dam bar connecting sections;
a fourth dam bar comprising:
a fourth plurality of dam bar connecting sections;
a third plurality of slots between the third dam bar and a third side of said each lead frame;
a fourth plurality of slots between the fourth dam bar and a fourth side of said each lead frame, the fourth side of said each lead frame being opposite the third side of said each lead frame;
a third plurality of leads extending away from the one or more die paddles along a third direction perpendicular to the first direction, each of the third plurality of leads being connected to the third dam bar; and
a fourth plurality of leads extending away from the one or more die paddles along a fourth direction opposite the third direction, each of the fourth plurality of leads being connected to the fourth dam bar; and
wherein said applying the cutting process or the punching process further removes the third plurality of dam bar connecting sections and the fourth plurality of dam bar connecting sections.

### Claim 8 (depends on 7)

The method of claim 7,
wherein each of the third plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said third plurality of leads;
wherein a width of the protrusion member of said each of the third plurality of leads is less than fifty percent of a width of the base member of said each of the third plurality of leads;
wherein each of the fourth plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said fourth plurality of leads; and
wherein a width of the protrusion member of said each of the fourth plurality of leads is less than fifty percent of a width of the base member of said each of the fourth plurality of leads.

### Claim 9

A method for fabricating a semiconductor package, the method comprising the steps of:
providing a lead frame array comprising
one or more lead frames, each lead frame of the one or more lead frames comprising one or more die paddles;
a first dam bar comprising:
a first plurality of dam bar connecting sections;
a second dam bar comprising:
a second plurality of dam bar connecting sections;
a first plurality of slots between the first dam bar and a first side of said each lead frame;
a second plurality of slots between the second dam bar and a second side of said each lead frame, the second side of said each lead frame being opposite the first side of said each lead frame;
a first plurality of leads extending away from the one or more die paddles along a first direction, each of the first plurality of leads being connected to the first dam bar; and
a second plurality of leads extending away from the one or more die paddles along a second direction opposite the first direction, each of the second plurality of leads being connected to the second dam bar;
mounting a chip on the one or more die paddles;
forming a molding encapsulation enclosing the chip;
applying a cutting process or a punching process removing the first plurality of dam bar connecting sections and the second plurality of dam bar connecting sections;
plating tin on portions of the lead frame array not covered by the molding encapsulation; and
applying a singulation process,
wherein each lead frame of the one or more lead frames further comprises
a first plurality of holes, each of the first plurality of holes being between a respective pair of slots of the first plurality of slots; and
a second plurality of holes, each of the second plurality of holes being between a respective pair of slots of the second plurality of slots.

### Claim 10 (depends on 9)

The method of claim 9, before the step of forming the molding encapsulation, applying a wire bonding process or a clip bonding process.

### Claim 11 (depends on 9)

The method of claim 9, wherein each of the first plurality of dam bar connecting sections and the second plurality of dam bar connecting sections comprises
a first end section;
a center section; and
a second end section opposite the first end section;
wherein a cross-sectional area of the first end section is smaller than a cross-sectional area of the center section; and
wherein a cross-sectional area of the second end section is smaller than the cross-sectional area of the center section.

### Claim 12 (depends on 9)

The method of claim 9,
wherein each of the first plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said first plurality of leads;
wherein a width of the protrusion member of said each of the first plurality of leads is less than fifty percent of a width of the base member of said each of the first plurality of leads;
wherein each of the second plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said second plurality of leads; and
wherein a width of the protrusion member of said each of the second plurality of leads is less than fifty percent of a width of the base member of said each of the second plurality of leads.

### Claim 13 (depends on 9)

The method of claim 9, wherein each of the first plurality of dam bar connecting sections comprises:
a first arc portion; and
a second arc portion; and
wherein each of the first plurality of dam bar connecting sections comprises:
a first arc portion; and
a second arc portion.

### Claim 14 (depends on 9)

The method of claim 9, wherein each lead frame of the one or more lead frames further comprises
a first plurality of rectangular holes between the first plurality of dam bar connecting sections and the one or more die paddles;
wherein a lateral dimension of each of the first plurality of rectangular holes is smaller than a lateral dimension of a corresponding dam bar connecting section of the first plurality of dam bar connecting sections.

### Claim 15 (depends on 9)

The method of claim 9, wherein each lead frame of the one or more lead frames further comprises
a third dam bar comprising:
a third plurality of dam bar connecting sections;
a fourth dam bar comprising:
a fourth plurality of dam bar connecting sections;
a third plurality of slots between the third dam bar and a third side of said each lead frame;
a fourth plurality of slots between the fourth dam bar and a fourth side of said each lead frame, the fourth side of said each lead frame being opposite the third side of said each lead frame;
a third plurality of leads extending away from the one or more die paddles along a third direction perpendicular to the first direction, each of the third plurality of leads being connected to the third dam bar; and
a fourth plurality of leads extending away from the one or more die paddles along a fourth direction opposite the third direction, each of the fourth plurality of leads being connected to the fourth dam bar; and
wherein said applying the cutting process or the punching process further removes the third plurality of dam bar connecting sections and the fourth plurality of dam bar connecting sections.

### Claim 16 (depends on 15)

The method of claim 15,
wherein each of the third plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said third plurality of leads;
wherein a width of the protrusion member of said each of the third plurality of leads is less than fifty percent of a width of the base member of said each of the third plurality of leads;
wherein each of the fourth plurality of leads comprises:
a base member; and
a protrusion member directly connected to the base member of said fourth plurality of leads; and
wherein a width of the protrusion member of said each of the fourth plurality of leads is less than fifty percent of a width of the base member of said each of the fourth plurality of leads.