Thermally conductive dielectric mounts for printed circuitry and semi-conductor devices and method of preparation

• US 6,649,325 B1
• Filed: 05/25/2001
• Issued: 11/18/2003
• Est. Priority Date: 05/25/2001
• Status: Expired due to Fees

• Current Assignee: Berquist Company The (Henkel AG & Co KGaA)
• Original Assignee: Berquist Company The (Henkel AG & Co KGaA)
• Inventors: Gundale, Benjamin P., Misra, Sanjay
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US09/865,778
• Time in Patent Office: 907 Days
• Field of Search: 430/311, 430/320, 430/322, 430/330, 428/901, 174/250, 174/255, 252/518.1, 252/516
• US Class Current: 430/311
• CPC Class Codes: H01B 3/301 Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen or carbon in the main chain of the macromolecule, not provided for in group H01B3/302
• CPC Class Codes: H01B 3/306 Polyimides or polyesterimides
• CPC Class Codes: H01L 23/3735 Laminates or multilayers, e.g. direct bond copper ceramic substrates
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H05K 2201/0129 Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2203/0759 Forming a polymer layer by liquid coating, e.g. a non-metallic protective coating or an organic bonding layer
• CPC Class Codes: H05K 3/0061 onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: Y10S 428/901 Printed circuit

Abstract

Methods and formulations for use in preparing thermally conductive dielectric mounts for heat generating semi-conductor devices and associated circuitry. The formulations include a thermoplastic resin selected from the group consisting of polysulfone, poly-ethersulfone, poly-phenylsulfone, and poly-etherimides, with these resins being applied as a dispersion onto the surfaces of opposed metallic members. The dispersion is dried and thereafter treated under heat and pressure at temperatures greater than the glass transition temperature under unit pressures of between 100 psi and 800 psi and for periods in excess of about 30 minutes. The polymer resin may be filled with solid particulate such as alumina and/or boron nitride.

Claims

1. The method of preparing a thermally conductive circuit mounting pad for use in combination with heat generating semi-conductor devices which includes the steps of:

(a) preparing a dispersion of thermoplastic polymer resin having a glass transition temperature greater than 170°

C. and selected from the group consisting of polysulfone (PS), poly-ethersulfone (PES), poly-phenylsulfone (PPSU), and poly-etherimides (PI);

(b) providing first and second metallic members, said first metallic member having a first side and a generally opposing second side, and said second metallic member having a first side and a generally opposing second side;

(c) applying a coating of said dispersion onto said first side of said first metallic member and said second side of said second metallic member;

(d) drying said dispersion coatings to create adherent thermoplastic films on the respective sides of said first and second metallic members;

(e) positioning said first and second metallic members such that said first side of said first metallic member is in facing relationship with said second side of said second metallic member such that the respective thermoplastic films are in face-to-face contact with one another to form a multiple metallic layer pad; and

(f) subjecting said multiple metallic layer pad to a temperature above about 250°

C., and an external pressure of between about 100 psi and 800 psi for a period of greater than 30 minutes to thereby cause said thermoplastic films to commingle and merge into a single uniform thermoplastic film that bondedly secures said two metallic members to one another.

2. The method of preparing a thermally conductive circuit mounting pad as in claim 1 wherein said thermoplastic polymer is loaded with a quantity of finely divided particulate filler selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon carbide, silicon nitride and mixtures thereof.

3. The method of preparing a thermally conductive circuit mounting pad as in claim 2 wherein said filler is incorporated into said thermoplastic polymer in an amount ranging from between about 5% and 80% particulate filler.

4. The method of preparing a thermally conductive circuit mounting pad as in claim 2 wherein said filler has a particle size ranging from 3 to 100 microns.

5. The method of preparing a thermally conductive circuit mounting pad as in claim 1 wherein said metallic members are exposed to a typical subtractive process to form a circuit pattern, including the application of photo resist, acid etching of the exposed circuit and finally stripping off the photo resist.

6. The method of preparing a thermally conductive circuit mounting pad as in claim 1 wherein said metallic layer is selected from the group consisting of aluminum, steel, copper, aluminum-silicon carbide, copper-invar-copper, and copper-molybdenum-copper.

7. The method of preparing a thermally conductive circuit mounting pad as in claim 6 wherein a first of said metallic members has a thickness ranging from between about 25 microns and 400 microns.

8. The method of preparing a thermally conductive circuit mounting pad as in claim 6 wherein a second of said metallic members has a thickness ranging from between about 500 microns and 6300 microns.

9. The method of preparing a thermally conductive circuit mounting pad as in claim 1 wherein said multiple metallic layer pad has a thickness ranging from between about 550 and 7000 microns.

10. The method of preparing a thermally conductive circuit mounting pad as in claim 1 wherein said thermoplastic film has a thickness ranging from between about 20 microns and 300 microns.