WO2004077557A1 - A plastics leadframe and an integrated circuit package fabricated using the leadframe - Google Patents
A plastics leadframe and an integrated circuit package fabricated using the leadframe Download PDFInfo
- Publication number
- WO2004077557A1 WO2004077557A1 PCT/SG2003/000038 SG0300038W WO2004077557A1 WO 2004077557 A1 WO2004077557 A1 WO 2004077557A1 SG 0300038 W SG0300038 W SG 0300038W WO 2004077557 A1 WO2004077557 A1 WO 2004077557A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- integrated circuit
- lead frame
- plastics material
- lead portions
- lead
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49572—Lead-frames or other flat leads consisting of thin flexible metallic tape with or without a film carrier
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates to a lead frame, and to an integrated circuit package fabricated using the leadframe.
- a blank sheet 1 of a metal such as copper is stamped to form a lead frame 3.
- the lead frame 3 is then plated with a thin layer consisting of one of more of Ag, Ni or Cu.
- the plated lead frame 3 has die pad portions 5 onto which integrated circuits (dies) can be bonded, and for each die pad portion 5 there are a number of corresponding lead portions 7.
- Fig. 1 there are three lead portions 7 corresponding to each die pad portion 5 (including the lead portion 7 which actually supports the die pad portion 5), and the die pad portions 5 and lead portions 7 are shown hashed.
- the plated lead frame further includes indexing portions 4 to either side including indexing holes 6.
- the lead frame 3 further includes a central portion 8, and elements 2 which are removed during singulation.
- the leadframe 3 is used by bonding an integrated circuit to each respective die pad portion 5. Electrical contacts on each integrated circuit are then wire bonded to respective ones of the lead portions 7 corresponding to the die pad portion 5. A resin body is moulded around each respective integrated circuit and the wire bonds to that integrated circuit. The lead frame is cut to remove the indexing portions 4 and the central portion 8, and thus leave the leads 7 projecting from individual packages containing respective integrated circuits.
- the layer consisting of Ag, Ni and/or Cu is useful to prevent oxidation of the Cu during these steps, and to increase the reliability of the integrated circuit attachment and wire bonding processes.
- the present invention aims to provide a new and useful lead frame, a new and useful method of fabricating a lead frame package, and a new and useful lead frame package.
- the present invention proposes that the lead frame is fabricated from a plastics material (i.e. an polymeric organic material), and then coated with a conductive layer.
- a plastics material i.e. an polymeric organic material
- the invention makes it possible to reduce the amount of metal required to form an integrated circuit package.
- the present invention may reduce the amount of metal required by about 90%, and therefore reduces the cost of fabricating the lead frame.
- the lead frame material accounts for 30% of the total raw material cost, so reducing the amount of metal required offers great potential for reducing the total cost of packaging the semiconductor.
- the present invention contributes to more environmentally friendly packaging, since the plastics material may be degradable or even recyclable.
- the lead frame may be fabricated by a moulding process such as injection moulding.
- a moulding process such as injection moulding.
- Fig. 1 shows the steps in fabrication of a known lead frame
- Fig. 2 shows schematically the steps of a method according to the invention
- Fig. 3 shows the lead frame produced by the invention.
- Fig. 2 illustrates the steps of the method which is an embodiment according to the present invention.
- a sheet 23 made of a non- conductive plastics (organic) material is manufactured by injection moulding.
- the sheet 23 has the configuration shown in Fig. 3.
- This sheet 23 is shaped to have a shape is identical to that of the lead frame 3 shown in Fig. 1, and for that reason the corresponding parts of the organic sheet 23 will be given the same reference numerals used in Fig. 1.
- the organic sheet 23 may be formed of the material Xarec S131 available from the company Idemitsu. This material has a heat resistance of greater than 270°C, is dimensionally stable, has a low specific gravity, a low CTE (coefficient of thermal expansion) of about 25 ppm, and a high soldering resistance.
- the material of the organic sheet may be different but preferably has one or more (most preferably all) of the following properties:
- the sheet 23 is plated with a conductive layer, such as a layer consisting of Cu and/or Ag, to form a lead frame 23.
- a conductive layer such as a layer consisting of Cu and/or Ag
- parts of the sheet 23 which are not required to be conductive later need not be plated.
- the lead frame 23 is used to form an integrated circuit package by steps corresponding to those used in the known packaging technique described above. Specifically, in step 30 integrated circuits are bonded onto respective ones of the die pad portions 5 of the lead frame 23. In step 40 bonds are formed between electrical contacts of the integrated circuit and lead portions 7 corresponding to the die pad portions 5 on which the integrated circuits are mounted. In step 50 the integrated circuit and wire bonds are encased in a resin body (typically, one body for each integrated circuit), and in step 60 the lead frame 23 is cut to singulate the packages, leaving the leads 7 corresponding to each die pad protruding from the package including that die pad.
- a resin body typically, one body for each integrated circuit
- the layer of Cu/Ag assists in the die bonding and wire bonding steps, and provides the conductive path on the leads 7.
- the shape of the lead frame 23 need not be as shown in Fig. 3, but may be of any other shape suitable for fabricating a lead frame. Typically, the shape of the lead frame will be dictated by the requirements of the integrated circuit. Furthermore, although above injection moulding is suggested for forming the leadframe, because its proven technology, high precision and relatively low cost, and that the leadframe is shaped to include at least one die bond portion and a number of lead portions, this is not necessary to the invention. For example, it is alternatively possible to provide the leadframe as a sheet (e.g. rectangular) of plastics material on which is deposited a conductive layer having a pattern including a number of the lead portions.
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Lead Frames For Integrated Circuits (AREA)
Abstract
A leadframe is fabricated by injection moulding a plastics material into a laminar shape (23) including die pad portions (5) and lead portions (7). The frame (23) is then coated with a conductive layer, at least on the lead portions (27). The frame (23) is used to form an integrated circuit package by bonding an integrated circuit to the die pads (5), wire bonding contacts on the integrated circuit to the lead portions (7), moulding a resin body around the integrated circuit and wire bonds, and then cutting the lead frame (23) to singulate it. The invention makes it possible to reduce the amount of metal required to form an integrated circuit package, so reducing the cost of the package. Additionally, the invention contributes to more environmentally friendly packaging, since the plastics material may be degradable or even recyclable.
Description
A PLASTICS LEADFRAME AND AN INTEGRATED CIRCUIT PACKAGE FABRICATED USING THE LEADFRAME
Field of the invention
The present invention relates to a lead frame, and to an integrated circuit package fabricated using the leadframe.
Background of Invention
Conventionally, many integrated circuit packages are fabricated in the steps illustrated in Fig. 1. Firstly, a blank sheet 1 of a metal such as copper is stamped to form a lead frame 3. The lead frame 3 is then plated with a thin layer consisting of one of more of Ag, Ni or Cu.
The plated lead frame 3 has die pad portions 5 onto which integrated circuits (dies) can be bonded, and for each die pad portion 5 there are a number of corresponding lead portions 7. In Fig. 1 , there are three lead portions 7 corresponding to each die pad portion 5 (including the lead portion 7 which actually supports the die pad portion 5), and the die pad portions 5 and lead portions 7 are shown hashed. The plated lead frame further includes indexing portions 4 to either side including indexing holes 6. The lead frame 3 further includes a central portion 8, and elements 2 which are removed during singulation.
The leadframe 3 is used by bonding an integrated circuit to each respective die pad portion 5. Electrical contacts on each integrated circuit are then wire bonded to respective ones of the lead portions 7 corresponding to the die pad portion 5. A resin body is moulded around each respective integrated circuit and the wire bonds to that integrated circuit. The lead frame is cut to remove the indexing portions 4 and the central portion 8, and thus leave the leads 7 projecting from individual packages containing respective integrated circuits.
The layer consisting of Ag, Ni and/or Cu is useful to prevent oxidation of the Cu during these steps, and to increase the reliability of the integrated circuit attachment and wire bonding processes.
Summary of the Invention
The present invention aims to provide a new and useful lead frame, a new and useful method of fabricating a lead frame package, and a new and useful lead frame package.
In general terms, the present invention proposes that the lead frame is fabricated from a plastics material (i.e. an polymeric organic material), and then coated with a conductive layer.
Thus, the invention makes it possible to reduce the amount of metal required to form an integrated circuit package. Typically, the present invention may reduce the amount of metal required by about 90%, and therefore reduces the cost of fabricating the lead frame. In conventional packaging techniques, the lead frame material accounts for 30% of the total raw material cost, so reducing the amount of metal required offers great potential for reducing the total cost of packaging the semiconductor.
Additionally, the present invention contributes to more environmentally friendly packaging, since the plastics material may be degradable or even recyclable.
In particular, the lead frame may be fabricated by a moulding process such as injection moulding. Thus, in contrast to the stamping method described above, no material needs to be discarded at the time of fabricating the lead frame.
Brief Description of The Figures
Preferred features of the invention will now be described, for the sake of illustration only, with reference to the following figures in which:
Fig. 1 shows the steps in fabrication of a known lead frame; Fig. 2 shows schematically the steps of a method according to the invention; and
Fig. 3 shows the lead frame produced by the invention.
Detailed Description of the embodiments
Fig. 2 illustrates the steps of the method which is an embodiment according to the present invention. In the first step (step 10) a sheet 23 made of a non- conductive plastics (organic) material is manufactured by injection moulding. The sheet 23 has the configuration shown in Fig. 3. This sheet 23 is shaped to have a shape is identical to that of the lead frame 3 shown in Fig. 1, and for that reason the corresponding parts of the organic sheet 23 will be given the same reference numerals used in Fig. 1.
The organic sheet 23 may be formed of the material Xarec S131 available from the company Idemitsu. This material has a heat resistance of greater than 270°C, is dimensionally stable, has a low specific gravity, a low CTE (coefficient of thermal expansion) of about 25 ppm, and a high soldering resistance.
More generally, the material of the organic sheet may be different but preferably has one or more (most preferably all) of the following properties:
1. Heat resistance > 270 °C
2. Soldering resistance at 400 °C with no dimension change
3. CTE <55 ppm
4. Flexural strength > 180 Mpa
5. Platable with Ni/Cu/Ag
In step 20 of the embodiment, the sheet 23 is plated with a conductive layer, such as a layer consisting of Cu and/or Ag, to form a lead frame 23. Optionally, parts of the sheet 23 which are not required to be conductive later need not be plated.
In steps 30 to 60 of the embodiment, the lead frame 23 is used to form an integrated circuit package by steps corresponding to those used in the known packaging technique described above. Specifically, in step 30 integrated circuits are bonded onto respective ones of the die pad portions 5 of the lead frame 23. In step 40 bonds are formed between electrical contacts of the integrated circuit and lead portions 7 corresponding to the die pad portions 5 on which the integrated circuits are mounted. In step 50 the integrated circuit and wire bonds are encased in a resin body (typically, one body for each integrated circuit), and in step 60 the lead frame 23 is cut to singulate the packages, leaving the leads 7 corresponding to each die pad protruding from the package including that die pad.
The layer of Cu/Ag assists in the die bonding and wire bonding steps, and provides the conductive path on the leads 7.
Although only a single embodiment of the invention has been described in detail, many variations are possible within the scope of the invention as will be clear to a skilled reader. For example, a number of other plastics materials would be suitable for fabricating the lead frame 23.
Furthermore, just as many different shapes are known for metal lead frames, the shape of the lead frame 23 need not be as shown in Fig. 3, but may be of any other shape suitable for fabricating a lead frame. Typically, the shape of the lead frame will be dictated by the requirements of the integrated circuit.
Furthermore, although above injection moulding is suggested for forming the leadframe, because its proven technology, high precision and relatively low cost, and that the leadframe is shaped to include at least one die bond portion and a number of lead portions, this is not necessary to the invention. For example, it is alternatively possible to provide the leadframe as a sheet (e.g. rectangular) of plastics material on which is deposited a conductive layer having a pattern including a number of the lead portions.
Claims
1. A lead frame for fabricating an integrated circuit,
the lead frame including a sheet of a plastics material including at least one die bond portion and a number of lead portions, and
a layer of conductive material supported on at least the lead portions of the layer of plastics material.
2. A lead frame according to claim 1 in which the layer of conductive material includes at least one of Cu and Ag.
3. A lead frame according to claim 1 or. claim 2 in which the plastics material has a heat resistance of above 270 °C.
4. A lead frame according to claim 1 , claim 2 or claim 3 in which the plastics material has soldering resistance at 400 °C with no dimension change.
5. A lead frame according to claim 4 in which the plastics material is Xarec S131.
6. A method of forming a lead frame package, the method including the steps of:
forming a sheet of a plastics material including at least one die bond portion and corresponding lead portions, and
forming a layer of conductive material on at least the lead portions of the plastics sheet;
bonding an integrated circuit to the die pad portion; electrically connecting electrical contacts on the integrated circuit to corresponding lead portions;
forming a resin body enclosing the integrated circuit and the electrical contacts; and
cutting the sheet.
7. A method according to claim 6 in which the sheet of plastics material is formed by injection moulding.
8. An integrated circuit package comprising:
a lead frame including at least one die pad portion and corresponding lead portions formed from a plastics material and carrying a conductive layer on at least the lead portions;
an integrated circuit bonded to the die pad portion, electrical contacts of the integrated circuit being electrically connected to respective lead portions by wire bonds; and
a resin body enclosing the integrated circuit and wire bonds, the lead portions projecting out of the resin body.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2003216033A AU2003216033A1 (en) | 2003-02-24 | 2003-02-24 | A plastics leadframe and an integrated circuit package fabricated using the leadframe |
| PCT/SG2003/000038 WO2004077557A1 (en) | 2003-02-24 | 2003-02-24 | A plastics leadframe and an integrated circuit package fabricated using the leadframe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/SG2003/000038 WO2004077557A1 (en) | 2003-02-24 | 2003-02-24 | A plastics leadframe and an integrated circuit package fabricated using the leadframe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2004077557A1 true WO2004077557A1 (en) | 2004-09-10 |
Family
ID=32923958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/SG2003/000038 WO2004077557A1 (en) | 2003-02-24 | 2003-02-24 | A plastics leadframe and an integrated circuit package fabricated using the leadframe |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU2003216033A1 (en) |
| WO (1) | WO2004077557A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102969296A (en) * | 2012-11-20 | 2013-03-13 | 无锡市威海达机械制造有限公司 | Lead frame structure |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4089733A (en) * | 1975-09-12 | 1978-05-16 | Amp Incorporated | Method of forming complex shaped metal-plastic composite lead frames for IC packaging |
| GB1511415A (en) * | 1975-06-24 | 1978-05-17 | Siemens Ag | Connecting strips |
| JPS5788752A (en) * | 1980-11-25 | 1982-06-02 | Hitachi Ltd | Lead frame and semiconductor device prepared by using the same |
| US5297008A (en) * | 1991-12-31 | 1994-03-22 | Compaq Computer Corporation (Compaq) | Polymeric composite lead wire and method for making same |
| US5879965A (en) * | 1997-06-19 | 1999-03-09 | Micron Technology, Inc. | Plastic lead frames for semiconductor devices, packages including same, and methods of fabrication |
-
2003
- 2003-02-24 AU AU2003216033A patent/AU2003216033A1/en not_active Abandoned
- 2003-02-24 WO PCT/SG2003/000038 patent/WO2004077557A1/en not_active Application Discontinuation
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1511415A (en) * | 1975-06-24 | 1978-05-17 | Siemens Ag | Connecting strips |
| US4089733A (en) * | 1975-09-12 | 1978-05-16 | Amp Incorporated | Method of forming complex shaped metal-plastic composite lead frames for IC packaging |
| JPS5788752A (en) * | 1980-11-25 | 1982-06-02 | Hitachi Ltd | Lead frame and semiconductor device prepared by using the same |
| US5297008A (en) * | 1991-12-31 | 1994-03-22 | Compaq Computer Corporation (Compaq) | Polymeric composite lead wire and method for making same |
| US5879965A (en) * | 1997-06-19 | 1999-03-09 | Micron Technology, Inc. | Plastic lead frames for semiconductor devices, packages including same, and methods of fabrication |
Non-Patent Citations (1)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN vol. 006, no. 170 (E - 128) 3 September 1982 (1982-09-03) * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102969296A (en) * | 2012-11-20 | 2013-03-13 | 无锡市威海达机械制造有限公司 | Lead frame structure |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2003216033A1 (en) | 2004-09-17 |
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