# US 7,408,248 B2 · Lead frame for semiconductor device

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- Number: US 7,408,248 B2
- Document ID: US7408248B2
- Status: Granted
- Kind: B2
- Application number: 10/559,247
- Filed: 2005-04-19
- Published: 2006-06-15
- Granted: 2008-08-05
- Earliest claimed: 2004-05-27
- Assignees: Shinko Electric Industries Co., Ltd.
- Inventors: Kazumitsu Seki; Takashi Yoshie; Koichi Kadosaki
- Web page: https://patentgrep.com/patent/US7408248B2

## CPC

- H10W 70/457: {of metallic layers on leadframes}
- H10W 72/075: {of bond wires}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- 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 lead frame for semiconductor device is provided with an inner lead part and an outer lead part. A composite plating layer is provided on the entire plane of a base material constituting the lead frame or at least on the outer lead part. The composite plating layer includes a base layer composed of an Ni-based plating layer formed on the entire plane of the base material constituting the lead frame or at least on the outer lead part, a Pd or Pd alloy plating layer formed on an upper plane of the base layer with a thickness of 0.005-0.01 μm, and an Au plating layer formed on an upper plane of the Pd or Pd alloy plating layer with a thickness of 0.02-0.1 μm. The lead frame for semiconductor device has a Pd-PPF structure. In the case of mounting a semiconductor device on a board and the like with a lead-free Sn—Zn based solder or other lead-free solders by using the lead frame, wettability of the lead frame with the lead-free Sn—Zn based solder or other lead-free solders is improved and mountability of the semiconductor device can be improved.

## Claims

### Claim 1

A lead frame for use in a semiconductor device comprising inner leads and outer leads, wherein a whole surface of the substrate constituting the lead frame or at least the outer leads has a composite plated layer applied thereon, and the composite plated layer comprises an underlayer consisting of an Ni-based plating layer deposited on the whole surface of the substrate constituting the lead frame or on at least the outer leads, a Pd— or Pd alloy-plating layer deposited at a thickness of 0.005 to 0.01 μm on an upper surface of the underlayer, and an Ag— or Ag—Au alloy-plating layer of a thickness of not larger than 0.03 μm and an Au-plating layer of a thickness of not larger than 0.03 μm successively deposited on an upper surface of the Pd— or Pd alloy-plating layer.

### Claim 2 (depends on 1)

A lead frame according to claim 1, wherein the Ag— or Ag—Au alloy-plating layer and the Au-plating layer each has a single layer structure.

### Claim 3

A lead frame for use in a semiconductor device comprising inner leads and outer leads, wherein a whole surface of the substrate constituting the lead frame or at least the outer leads has a composite plated layer applied thereon, and the composite plated layer comprises an underlayer consisting of an Ni-based plating layer deposited on the whole surface of the substrate constituting the lead frame or on at least the outer leads, a Pd— or Pd alloy-plating layer deposited at a thickness of 0.005 to 0.01 μm on an upper surface of the underlayer, and Ag-plating layers and Au-plating layers each having a thickness of 0.02 to 0.2 μm, alternately deposited on an upper surface of the Pd— or Pd alloyplating layer.

### Claim 4 (depends on 3)

A lead frame according to claim 3, wherein the Ag-plating layers and the Au-plating layers are each formed as two layers.

### Claim 5 (depends on 1)

A lead frame according to claim 1, wherein the substrate comprises Cu or a Cu alloy.

### Claim 6 (depends on 2)

A lead frame according to claim 2, wherein the substrate comprises Cu or a Cu alloy.

### Claim 7 (depends on 3)

A lead frame according to claim 3, wherein the substrate comprises Cu or a Cu alloy.

### Claim 8 (depends on 4)

A lead frame according to claim 4, wherein the substrate comprises Cu or a Cu alloy.