Apparatus for thermally coupling a heat sink to a leadframe

• US 5,442,234 A
• Filed: 04/21/1994
• Issued: 08/15/1995
• Est. Priority Date: 09/10/1992
• Status: Expired due to Fees

• Current Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Original Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Inventors: Liang, Louis H.
• Primary Examiner(s): Limanek, Robert P.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/232,573
• Time in Patent Office: 481 Days
• Field of Search: 257/675, 257/712, 257/722, 257/733, 257/718, 257/719, 257/706, 257/676, 257/670, 361/709, 361/723
• US Class Current: 257/675
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45099 Material
• 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 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/4334 Auxiliary members in encapsulations H01L23/49568 takes precedence
• CPC Class Codes: H01L 23/49568 specifically adapted to facilitate heat dissipation
• CPC Class Codes: H01L 24/48 of an individual wire connector
• 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 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/15747 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device

Abstract

A molded plastic package for an integrated-circuit die includes a lead frame having a central die-attach paddle. One side of the die-attach paddle has an integrated-circuit die fixed thereto. A heat sink member is resiliently fixed to the other side of the die-attach paddle using a layer of viscous thermal grease between the heat sink member and the other side of the die-attach paddle. One or more holes are formed in the lead frame and are engaged by corresponding studs on the heat sink. The stud has a shoulder portion which engages the lead frame to prevent the stud from further passing through the hole in the lead frame.

Claims

1. A molded plastic package for an integrated-circuit die, comprising:

a lead frame having a central die-attach paddle, one side of said die-attach paddle being adapted to having an integrated-circuit die fixed thereto;

a heat sink member positioned adjacent to the other side of said die-attach paddle;

coarse positioning means for loosely positioning said heat sink with respect to said other side of said die-attach paddle, said coarse positioning means including;

one or more studs fixed to said heat sink; and

respective one or more holes which are formed in said lead frame and which are engaged by corresponding studs; and

means for resiliently fixing said heat sink member to said other side of said die-attach paddle, wherein said means for resiliently fixing said heat sink member to said other side of said die-attach paddle includes a layer of viscous thermal grease which is located between said heat sink member and said other side of said die-attach paddle;

wherein said heat sink member has a recessed area centrally located in the top surface thereof for containing a supply of viscous thermal grease between said top surface of said heat sink member and said other side of said die-attach paddle.

2. The package of claim 1 wherein said one or more holes are formed in said central die-attach paddle portion of said lead frame.

3. The package of claim 1 wherein said one or more holes are formed in said tie bar portion of said lead frame.

4. The package of claim 1 wherein said lead frame is clipped to said studs by having said one or more studs engaged with respective holes in said lead frame.

5. The package of claim 1 wherein a stud has a distal end which is larger than the intermediate portion of said stud so that said intermediate portion of said stud is engaged with a corresponding hole.

6. The package of claim 1 including spacing means for spacing and heat sink member away from said other side of said die-attach paddle.

7. The package of claim 6 wherein said spacing means includes a stud fixed to said heat sink and engaging a hole in said lead frame, wherein said stud has a shoulder portion which engages said lead frame to prevent said stud from further passing through said hole in said lead frame.

8. A molded plastic :

package for an integrated-circuit die, comprising;

a lead frame having a central die-attach paddle, one side of said die-attach paddle being adapted to having an integrated-circuit die fixed thereto,

a heat sink member positioned adjacent to the other side of said die-attach paddle, said heat sink member having a recessed area centrally located in the top surface thereof for containing a supply of viscous thermal grease between said top surface of said heat sink member and said other side of said die-attach paddle,

coarse positioning means for loosely positioning said heat sink with respect to said other side of said die-attach paddle, said coarse positioning means further including;

at least one stud coupled to s, aid heat sink, and

respective at least one hole formed in said lead frame and engaged by a corresponding stud,

means for resiliently coupling said heat sink member to said other side of said die-attach paddle, said means including said layer of viscous thermal grease located between said heat sink member and said other side of said die-attach paddle, and

spacing means for spacing said heat sink member away from said other side of said die-attach paddle, said spacing means including a shoulder portion formed on said at least one stud fixed to said heat sink, said shoulder portion engaging said lead frame to prevent said at least one stud from further passing through a respective said at least one hole formed in said lead frame.

9. The package of claim 8 wherein said at least one hole is formed in said central die-attach paddle portion of said lead frame.

10. The package of claim 8 wherein said at least one hole is formed in said tie bar portion of said lead frame.