# US 2014/0191384 A1 · Pre-encapsulated etching-then-plating lead frame structure with island and method for manufacturing the same

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- Number: US 2014/0191384 A1
- Document ID: US20140191384A1
- Status: Published application
- Kind: A1
- Application number: 14/207,484
- Filed: 2014-03-12
- Published: 2014-07-10
- Earliest claimed: 2011-09-13
- Assignees: Jiangsu Changjiang Electronics Technology Co., Ltd.
- Applicants: Jiangsu Changjiang Electronics Technology Co., Ltd.
- Inventors: Xinchao WANG; Zhizhong LIANG
- Web page: https://patentgrep.com/patent/US20140191384A1

## CPC

- H10W 70/435: {of insulating layers on leadframes, e.g. bridging members}
- H10W 70/042: {Etching}
- H10W 70/479: {on or in insulating or insulated package substrates, interposers, or redistribution layers}
- H10W 72/019: {of bond pads}
- H10W 74/016: {using moulds}
- H10W 72/0198: {batch processes}
- H10W 72/5522: {comprising gold [Au]}
- H10W 72/884: {Die-attach connectors and bond wires}
- H10W 74/00: Encapsulations, e.g. protective coatings
- 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

## Abstract

A method for manufacturing a lead frame structure for semiconductor packaging. The method includes providing a metal substrate having a top surface and a back surface, forming a first photoresist film on the top surface of the metal substrate, forming a top surface etching pattern in the first photoresist film using photolithography, forming a second photoresist film on the back surface of the metal substrate, forming a back surface etching pattern in the second photoresist film using photolithography, performing an etching process on the top surface and the back surface of the metal substrate, removing the first photoresist film and the second photoresist film, placing the etched metal substrate in a mold, encapsulating the etched metal substrate using the mold; and performing a plating process on the encapsulated metal substrate.

## Claims

### Claim 1

A method for manufacturing a lead frame structure for semiconductor packaging, the method comprising:
a) providing a metal substrate having a top surface and a back surface;
b) forming a first photoresist film on the top surface of the metal substrate;
c) forming a top surface etching pattern in the first photoresist film using photolithography;
d) forming a second photoresist film on the back surface of the metal substrate;
e) forming a back surface etching pattern in the second photoresist film using photolithography;
f) performing an etching process on the top surface and the back surface of the metal substrate simultaneously using the top surface etching pattern and the back surface etching pattern as the respective masks to form etched regions in the metal substrate, an island, and a plurality of leads;
g) removing the first photoresist film and the second photoresist film;
h) placing the etched metal substrate in a mold;
i) encapsulating the etched metal substrate using the mold such that a molding compound is filled in the etched regions, areas between the island and the plurality leads, and areas between the plurality of leads, while exposing top surfaces and back surfaces of the island and the plurality leads; and
j) performing a plating process on the encapsulated metal substrate to form a first metal layer on the exposed top surfaces of the island and the plurality leads, and a second metal layer on the exposed back surfaces of the island and the plurality leads.

### Claim 2 (depends on 1)

The method of claim 1, wherein the etching process is a full etching process.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the mold is an injection mold comprising an upper mold and a lower mold;
the etched metal substrate is placed between a flat surface of the upper mold and a flat surface of the lower mold; and
a plurality of injection holes are configured on at least one of the flat surfaces of the upper mold and the lower mold.

### Claim 4 (depends on 3)

The method of claim 3, wherein encapsulating the etched metal substrate further comprises:
clamping the upper mold and the lower mold such that the top surface and the back surface of the metal substrate are in contact with the flat surfaces of the upper mold and the lower mold, respectively, such that the surfaces of the island and plurality leads are covered; and
injecting the molding compound into the etched regions, the areas between the island and the plurality leads, and the areas between the plurality of leads to form a flat top surface and a flat back surface on the etched metal substrate.

### Claim 5 (depends on 1)

The method of claim 1, wherein:
the first metal layer comprises an inner surface on the island and a plurality of inner leads on the plurality of leads; and
the second metal layer comprises an outer surface on the island and a plurality of outer leads on the plurality of leads.

### Claim 6 (depends on 1)

The method of claim 1, wherein the plating process uses a plating material from one of gold, nickel-gold, nickel-palladium-gold, and silver.

### Claim 7

A lead frame structure for semiconductor packaging, comprising: an island and a plurality of leads formed based on a metal substrate by an etching process, wherein the etching process comprises the following steps:
1) providing the metal substrate;
2) forming a first photoresist film on a top surface of the metal substrate;
3) forming a top surface etching pattern in the first photoresist film using photolithography;
4) forming a second photoresist film on a back surface of the metal substrate;
5) forming a back surface etching pattern in the second photoresist film using photolithography;
6) etching the top surface and the back surface of the metal substrate simultaneously using the top surface etching pattern and the back surface etching pattern as the respective masks to form etched regions in the metal substrate, an island, and a plurality of leads; and
7) removing the first photoresist film and the second photoresist film;
a molding compound being used to encapsulate the etched metal substrate with the island and plurality of leads by a pre-encapsulation process, wherein the pre-encapsulation process is performed by:
i) placing the etched metal substrate in a mold; and
ii) encapsulating the etched metal substrate using the mold such that the molding compound is filled in the etched regions, areas between the island and the plurality leads, and areas between the plurality of leads, while exposing top surfaces and back surfaces of the island and the plurality leads; and
a first metal layer and a second metal layer formed on the encapsulated metal substrate by a plating process, wherein the first metal layer is formed on the exposed top surfaces of the island and the plurality leads, and the second metal layer is formed on the exposed back surfaces of the island and the plurality leads.

### Claim 8 (depends on 7)

The lead frame structure of claim 7, wherein:
the mold is an injection mold comprising an upper mold and a lower mold;
the etched metal substrate is placed between a flat surface of the upper mold and a flat surface of the lower mold; and
a plurality of injection holes are configured on at least one of the flat surfaces of the upper mold and the lower mold.

### Claim 9 (depends on 8)

The lead frame structure of claim 8, wherein the pre-encapsulation process further comprises:
clamping the upper mold and the lower mold such that the top surface and the back surface of the metal substrate are in contact with the flat surfaces of the upper mold and the lower mold, respectively, such that the surfaces of the island and plurality leads covered; and
injecting the molding compound into the etched regions, the areas between the island and the plurality leads, and the areas between the plurality of leads to form a flat top surface and a flat back surface on the etched metal substrate.

### Claim 10 (depends on 7)

The lead frame structure of claim 7, wherein:
the first metal layer comprises an inner surface on the island and a plurality of inner leads on the plurality of leads; and
the second metal layer comprises an outer surface on the island and a plurality of outer leads on the plurality of leads.

### Claim 11 (depends on 7)

The lead frame structure of claim 7, wherein the first metal layer and the second metal layer are formed by the plating process using a plating material selected from one of gold, nickel-gold, nickel-palladium-gold, and silver.