Method of making integrated circuit die package

• US 5,441,918 A
• Filed: 11/08/1993
• Issued: 08/15/1995
• Est. Priority Date: 01/29/1993
• Status: Expired due to Term

• Current Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Morisaki, Maysayuki, Uegaki, Shoji, Matsumoto, Hiroshi
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): Picardat, Kevin M.
• Application Number:
  US08/148,810
• Time in Patent Office: 645 Days
• Field of Search: 437/209, 437/211, 437/212, 437/213, 437/214, 437/215, 437/216, 437/217, 437/218, 437/219
• US Class Current: 438/118
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• 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 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/24 solid or gel at the normal operating temperature of the device H01L23/3135 takes precedence
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/49861 Lead-frames fixed on or encapsulated in insulating substrates H01L23/4985, H01L23/49805 take precedence
• 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 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/15724 : Aluminium [Al] 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 package for integrated circuit dies is disclosed comprising a ceramic base capable of having an integrated circuit die mounted to a central portion of one surface thereof to provide heat dissipation for the die; a lead frame with a central opening secured to the periphery of the same surface of the ceramic base; a raised frame member secured to both the lead frame and the peripheral portions of the same surface of the ceramic base exposed between the leads on the lead frame; a die mounted to the exposed central portion of the surface of the ceramic base surrounded by the lead frame and the raised frame member, and electrically bonded to leads on the lead frame; and a plastic potting material over and around the edges of the integrated circuit die and in contact with the exposed portion of the surface of the ceramic base adjacent the die, portions of the lead frame; and inner portions of the raised frame member to thereby encapsulate the integrated circuit die. The package is formed by first bonding a lead frame having a central opening (no die paddle) to the ceramic base. A raised frame member having a similarly shaped central opening is then bonded to the lead frame, and the ceramic base, leaving a central exposed portion of the surface of the ceramic base surrounded by the lead frame and raised frame member. The die is then bonded to this exposed surface of the ceramic base and then encapsulated with a potting resin after wire bonding of the die to the leads.

Claims

1. A method of forming a package for an integrated circuit die comprising:

a) providing a planar ceramic base having a first surface thereon and capable of functioning as a heat sink to dissipate heat generated by an integrated circuit die subsequently thermally coupled thereto;

b) bonding to the periphery of said first surface of said ceramic base a lead frame with a central opening;

c) bonding to both said lead frame and the peripheral potions of the same surface of said ceramic base exposed between leads on said lead frame a raised frame member having a thickness greater than the thickness of the integrated circuit die to be bonded to said planar ceramic base, and having a central opening therein to thereby form a recessed opening bounded by said planar ceramic base, said lead frame, and said raised frame member;

d) bonding an integrated circuit die to an exposed central portion of said first surface of said ceramic base in said recessed opening surrounded by said lead frame and said raised frame member using a high purity thermally conductive adhesive;

i) containing no more than 10 ppm of any halogen, alkali metal. Or alkaline earth metal impurity;

ii) capable of withstanding a temperature of at least 300°

C; and

iii) containing a thermally conductive filler capable of enhancing thermal coupling of said die to said ceramic base;

to thereby thermally couple said die to said ceramic base;

e) electrically connecting said die to leads on said lead frame; and

f) placing a curable high purity plastic potting material, containing no more than 10 ppm of any halogen, alkali metal, or alkaline earth metal impurity, in said recessed opening over and around the edges of said integrated circuit die, and in the space between said die and said lead frame and said frame member, and in contact with the exposed portion of said first surface of said ceramic base adjacent said die, whereby said ceramic base and said plastic potting material completely surround said integrated circuit die, said walls of said recessed opening, comprising said lead frame and said raised frame member, acting to form a dam to retain said potting material around and over said die prior to curing of said potting material; and

g) heating said structure to a temperature sufficient to cure said potting material to thereby encapsulate said die without deforming said ceramic base.

2. The method of claim 1 including the further step of securing said lead frame to said ceramic base with a first adhesive capable of withstanding a temperature of as high as 300°

C.

3. The method of claim 2 wherein said further step of securing said lead frame to said ceramic base with a first adhesive further comprises securing said lead frame to said ceramic base with a thermosetting adhesive.

4. The method of claim 3 wherein said step of securing said lead frame to said ceramic base with a thermosetting first adhesive further comprises applying a partially cured thermosetting adhesive to peripheral portions of said first surface of said ceramic base prior to contact with said lead frame.

5. The method of claim 2 including the further step of securing said raised frame member to both said lead frame and said ceramic base with a second adhesive capable of withstanding a temperature of as high as 300°

C.

6. The method of claim 5 wherein said further step of securing said raised frame member to both said lead frame and said ceramic base with a second adhesive capable of withstanding a temperature of as high as 300°

C. further comprises securing said raised frame to both said lead frame and said ceramic base with a second adhesive comprising a thermosetting adhesive.

7. The method of claim 6 wherein said step of securing said raised frame to both said lead frame and said ceramic base with said thermosetting second adhesive further comprises applying a partially cured thermosetting second adhesive to one surface of said raised frame member prior to contact with said lead frame and said ceramic base.

8. The method of claim 5 wherein said first and second adhesives comprise the same adhesive material.

9. The method of claim 5 which further comprises curing both said first and second adhesives at the same time.

10. The method of claim 1 which further comprises selecting said raised frame member from the group of materials consisting of a ceramic material and a plastic material capable of withstanding a temperature of 300°

C.

11. The method of claim 10 which further comprises selecting a ceramic raised frame member.

12. The method of claim 10 which further comprises selecting the same ceramic material for said raised frame member as the ceramic material comprising said ceramic base.

13. The method of claim 1 which further comprises selecting a high purity adhesive containing silver as said thermally conductive filler.

14. The method of claim 1 which further comprises selecting a high purity epoxy adhesive.

15. The method of claim 1 which further comprises selecting a potting material comprising a thermosetting resin capable of withstanding a temperature of as high as 300°

C.

16. The method of claim 15 which further comprises selecting a potting material comprising a thermosetting resin containing from about 50 wt. % to about 75 wt. % of chemically non-reactive fillers to control the viscosity and reduce thermal stress on said die.

17. The method of claim 16 which further comprises selecting an epoxy resin as said potting material.

18. A method of forming a package for an integrated circuit die comprising:

a) providing a planar ceramic base having a first surface thereon and formed from a material capable Of dissipating heat from an integrated circuit die to be bonded thereto;

b) securing a lead frame with a central opening to the periphery of said first surface of said ceramic base with a first epoxy adhesive capable of withstanding a temperature of 300°

C.;

c) securing a ceramic raised frame member, having a thickness greater than the thickness of said integrated circuit die and having a central opening therein, to both said lead frame and the peripheral portions of the same surface of said ceramic base exposed between leads on said lead frame with a second epoxy adhesive capable of withstanding a temperature of 300°

C. to thereby form a central recessed region on said planar ceramic base;

d) mounting an integrated circuit die to an exposed central portion of said first surface of said ceramic base in said recessed region formed by said lead frame and said raised frame member with a high purity silver-filled epoxy adhesive capable of withstanding a temperature of 300°

C. and containing no more than 10 ppm of any halogen, alkali metal, or alkaline earth metal impurity to thermally couple said die to said ceramic base;

e) electrically connecting said integrated circuit die to leads on said lead frame; and

f) placing a curable epoxy potting material over and around the edges of said integrated circuit die, and in the space between said die and said lead frame and said frame member in said recessed region, and in contact with the exposed portion of said first surface of said ceramic base adjacent said die, said recessed region formed by said lead frame and said frame member acting as a dam to retain said curable epoxy potting material around and over said die until mid curable epoxy potting material is cured, said epoxy potting material being capable of withstanding a temperature of 300°

C. and containing no more than 10 ppm of any halogen, alkali metal, or alkaline earth metal impurity, whereby said ceramic base and said epoxy potting resin completely surround said integrated circuit die; and

g) then heating said structure to a temperature not exceeding 300°

C., but sufficient to cure said epoxy potting material to thereby encapsulate said die in said package.

19. The method of claim 18 which further comprises selecting the same epoxy adhesive material for both said first and second epoxy adhesives.

20. The method of claim 18 which further comprising selecting the same ceramic material for said raised ceramic frame member as the ceramic material comprising said ceramic base.