Transient liquid phase sintering conductive adhesives

• US 5,853,622 A
• Filed: 08/28/1996
• Issued: 12/29/1998
• Est. Priority Date: 02/09/1990
• Status: Expired due to Fees

• Current Assignee: Ormet Circuits, Inc. (Merck & Co., Inc.)
• Original Assignee: Ormet Corporation
• Inventors: Capote, M. Albert, Matijasevic, Goran, Gallagher, Catherine
• Primary Examiner(s): KOPEC, MARK T
• Application Number:
  US08/704,467
• Time in Patent Office: 853 Days
• Field of Search: 252/512, 252/513, 252/514, 10/1.12, 419/56, 75/303
• US Class Current: 252/512
• CPC Class Codes: B22F 3/1035 Liquid phase sintering
• CPC Class Codes: B23K 35/0222 for use in soldering, brazing B23K35/0205 takes precedence
• CPC Class Codes: B23K 35/36 Selection of non-metallic compositions, e.g. coatings, fluxes B23K35/34 takes precedence; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest selection of soldering or welding materials proper B23K35/24
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 2224/293 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 23/49883 the conductive materials containing organic materials or pastes, e.g. for thick films for printed circuits H05K1/092
• CPC Class Codes: H01L 23/5384 Conductive vias through the substrate with or without pins, e.g. buried coaxial conductors H01L23/5383, H01L23/5385 take precedence; pins attached to insulating substrates H01L23/49811
• 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/01327 Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H05K 2201/0272 Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
• CPC Class Codes: H05K 2201/10378 Interposers
• CPC Class Codes: H05K 2203/0425 Solder powder or solder coated metal powder
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: H05K 3/3489 Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/4623 the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards H05K3/462 takes precedence

Abstract

An inventive method for electrical and thermal electronic component attachment is disclosed. The combination of transient liquid phase sintering (TLPS) and a permanent adhesive flux binder provides the advantages of both conventional soldering technology and conductive adhesives. This hybrid approach delivers electrical and thermal conduction through sintered metal joints and mechanical properties based on a tailorable polymer matrix. These transient liquid phase sintering conductive adhesives can utilize conventional dispensing, placement, and processing equipment. During the reflow process, metal powders in the composition undergo interparticle sintering as well as alloying to the contact pads. This process produces a strong mechanical, thermal, and electrical interconnect which ensures good conductivity that is also resistant to humidity and temperature cycling.

Claims

1. A conductive adhesive composition comprising:

in the range of about 5 up to about 65% by volume of a high melting point metal, wherein said metal is in the form of a substantially spherical powder,

in the range of about 5 up to about 60% by volume of a low melting point metal or metal alloy, wherein said metal or metal alloy is in the form of a substantially spherical powder,

in the range of about 2 up to about 60% by volume of a chemically protected crosslinking agent, wherein said chemically protected crosslinking agent is an acid or strong base which has been chemically modified by the addition of a chemically or thermally triggered species to become reactive only at or near the time the low melting point metal or metal alloy, or an alloy thereof with said high melting point metal melts,

in the range of 0 up to about 35% by volume of a resin,

in the range of 0 up to about 35% by volume of a reactive monomer or polymer that is not the same as said resin, and

in the range of 0 up to about 10% by volume of a metal additive,

with the proviso that said composition must contain either said resin and/or said reactive monomer or polymer, or, in the alternative, said resin and/or said reactive monomer or polymer can be combined with said chemically protected crosslinking agent to produce a single component of said composition.

2. A conductive adhesive composition according to claim 1, wherein said composition comprises:

in the range of about 8 up to about 60% by volume of said high melting point metal,

in the range of about 6 up to about 40% by volume of said low melting point metal or metal alloy,

in the range of about 7 up to about 50% by volume of said chemically protected crosslinking agent,

in the range of 0 up to about 12% by volume of said resin,

in the range of 0 up to about 28% by volume of said reactive monomer or polymer, and

in the range of 0 up to about 5% by volume of said metal additive.

3. A conductive adhesive composition according to claim 1 wherein said metal additive is present in an amount falling in the range of about 0.1 up to about 5% by volume.

4. A conductive adhesive composition according to claim 3, wherein the combined volume percent of said high melting point metal, said low melting point metal or metal alloy, and said metal additive falls in the range of about 14 up to about 75 volume percent, based on the total volume of said composition, and wherein

the volume percent of said chemically protected crosslinking agent falls in the range of 5 up to about 55 volume percent,

the volume percent of said resin falls in the range of 3 up to about 30 volume percent, and

the volume percent of said reactive monomer or polymer falls in the range of 3 up to about 30 volume percent.

5. A conductive adhesive composition according to claim 1 wherein said resin is present in an amount falling in the range of about 3 up to about 35% by volume.

6. A conductive adhesive composition according to claim 5, wherein the volume ratio of the combined volume of said resin, and said reactive monomer or polymer, when present, relative to the volume of the chemically protected crosslinking agent, falls in the range of about 0.1 up to about 10.

7. A conductive adhesive composition according to claim 1 wherein said reactive monomer or polymer is present in an amount falling in the range of about 3 up to about 35% by volume.

8. A conductive adhesive composition according to claim 5, wherein the volume ratio of the combined volume of said reactive monomer or polymer, and said resin, when present, relative to the volume of the chemically protected crosslinking agent, falls in the range of about 0.1 up to about 10.

9. A conductive adhesive composition according to claim 1, wherein said high melting point metal is selected from copper powder, silver powder, aluminum powder, gold powder, platinum powder, palladium powder, beryllium powder, rhodium powder, nickel powder, cobalt powder, iron powder, molybdenum powder, or high-melting point alloys of any two or more of these metals.

10. A conductive adhesive composition according to claim 1, wherein said low melting point metal or metal alloy is any metal or metal alloy having a melting point lower than that of said high melting point metal or metal alloy.

11. A conductive adhesive composition according to claim 10, wherein said low melting point metal or metal alloy is selected from Sn, Bi, Pb, Cd, Zn, Ga, In, Te, Hg, Tl, Sb, Se or Po, or mixtures of any two or more thereof.

12. A conductive adhesive composition according to claim 1, wherein said chemically protected crosslinking agent is a compound bearing one or more functional groups selected from carboxyl, hydroxyl, amine, thiol or cyano groups, or derivatives thereof.

13. A conductive adhesive composition according to claim 1, wherein said chemically protected crosslinking agent is selected from an anhydride, a carboxylic acid, an amide, an imide, an amine, an alcohol, a phenol, an isocyanate, a cyanate ester or a thiol.

14. A conductive adhesive composition according to claim 1, wherein said chemically protected crosslinking agent comprises at least two functionalities selected from anhydride, carboxyl, amine, amide, hydroxyl or cyano.

15. A conductive adhesive composition according to claim 1, wherein said resin is a thermosetting monomer or polymer.

16. A conductive adhesive composition according to claim 1, wherein said resin is selected from an epoxy, a phenolic, a phenolic novalac, a cresolic novalac, a polyurethane, a polyimide, a maleimide, a cyanate ester, a polyvinyl alcohol, a polyester, a polyurea, an acrylic, a polyamide, a polyacrylate, a polysiloxane or a cyanoacrylate.

17. A conductive adhesive composition according to claim 1, wherein said resin is selected from an epoxy, a phenolic, a phenolic novalac, a cresolic novalac, a polyimide, a maleimide, a cyanate ester, a polyester, a polyamide or a polysiloxane.

18. A conductive adhesive composition according to claim 1, wherein said reactive monomer or polymer contains at least one functional group.

19. A conductive adhesive composition according to claim 1, wherein said reactive monomer or polymer contains one or more functional groups selected from epoxides, amides, amines, alcohols, allyls, acrylates, methacrylates, cyanate esters or maleimides.

20. A conductive adhesive composition according to claim 1, wherein said metal additive is selected from boron, aluminum, chromium, iron, nickel, zinc, gallium, silver, palladium, platinum, gold, indium, antimony, bismuth, tellurium, manganese, phosphorous, cobalt or copper.