Casing for integrated circuit chips and method of fabrication

• US 6,049,971 A
• Filed: 06/13/1997
• Issued: 04/18/2000
• Est. Priority Date: 03/31/1995
• Status: Expired due to Term

• Current Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Original Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Inventors: Petit, Luc
• Primary Examiner(s): ARBES, CARL J
• Application Number:
  US08/876,016
• Time in Patent Office: 1,040 Days
• Field of Search: 29/827, 174/52.2, 438/122
• US Class Current: 29/827
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 23/49531 the additional leads being a wiring board
• CPC Class Codes: H01L 23/49541 Geometry of the lead-frame
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/00015 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed as prior art
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device

Abstract

A method for fabricating a lead frame that includes a platform attached thereto for mounting a chip. A base frame is provided for mounting chips of various sizes. The base frame includes connection leads extending toward a central portion, which is substantially of the size of the smallest chip to mount. Connection leads are cut-out about the central portion to form an opening corresponding to the size of the chip to be mounted. A platform is soldered to at least two support leads to form the lead frame.

Claims

1. A method for fabricating a lead frame including a platform for mounting one of a plurality of chips thereon, the plurality of chips including chips of various sizes, the method comprising steps of:

providing a base frame adapted to mount each of the plurality of chips of various sizes, the base frame including a plurality of connection leads and at least two support leads extending toward a central portion of the base frame, the central portion having a size substantially equal to the size of a smallest of the plurality of chips;

cutting the plurality of connection leads about the central portion to form an opening corresponding to the size of the one of the plurality of chips to be mounted;

providing a platform having a periphery slightly larger than the opening and formed from a metal anodized at least at the periphery of the platform; and

soldering the platform to the at least two support leads to form the lead frame, wherein the step of soldering includes soldering the at least two support leads to non-anodized portions of the platform.

2. The method recited in claim 1, wherein the step of soldering is performed after the one of the plurality of chips has been mounted to the platform.

3. The method recited in claim 1, wherein the step of providing the base frame includes providing the base frame to include a solid central portion.

4. A method for fabricating a lead frame for mounting an integrated circuit chip in an integrated circuit casing, the method comprising steps of:

(A) providing a base frame including a central portion, a plurality of connection leads extending outwardly from the central portion, each of the plurality of support leads extending outwardly from the central portion, each of the plurality of connection leads and the plurality of support leads having an inner end attached directly to the central portion;

(B) separating the central portion from the inner ends of the plurality of connection leads and the inner ends of the plurality of support leads and removing the central portion from the base frame to form an opening defined by the inner ends of the plurality of connection leads and the inner ends of the plurality of support leads; and

(C) attaching a platform to the plurality of support leads to form the lead frame.

5. The method recited in claim 4, wherein step (B) includes a step of cutting the plurality of connection leads extending from the central portion.

6. The method recited in claim 5, wherein the step of cutting includes cutting the plurality of support leads to have a length of each of the plurality of connection leads.

7. The method recited in claim 4, wherein step (B) includes a step of forming the opening to have a size corresponding to a size of the integrated circuit chip that is to be mounted to the platform.

8. The method recited in claim 4, wherein steps (B) and (C) include steps of forming the opening and attaching the platform to the plurality of support leads so that, when the platform is attached to the plurality of support leads, the plurality of connection leads so not contact the platform.

9. The method recited in claim 4, wherein steps (B) and (C) include steps of forming the opening and attaching the platform to the plurality of support leads so that, when the platform is attached to the plurality of support leads, at least one of the plurality of connection leads contacts the platform.

10. The method recited in claim 9, wherein the step of forming the opening includes forming the opening to be smaller than the platform.

11. The method recited in claim 4, wherein step (C) includes a step of soldering the platform to the plurality of support leads.

12. The method recited in claim 4, further comprising a step of:

(D) providing the platform to include a center portion and a plurality of tabs extending outwardly from the center portion.

13. The method recited in claim 12, wherein step (C) includes attaching the ends of the plurality of support leads to the plurality of tabs.

14. The method recited in claim 4, further comprising a step of:

(E) providing the platform to include an electrically conductive portion and an electrically nonconducting portion.

15. The recited in claim 14, wherein step (E) includes providing the platform to include an anodized electrically nonconductive portion.