Compliant bump technology

• US 5,783,465 A
• Filed: 04/03/1997
• Issued: 07/21/1998
• Est. Priority Date: 04/03/1997
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Sheridan, Michael, Hoppes, Charles K., Finley, Donald W., Canning, Everett Joseph
• Primary Examiner(s): Picardat, Kevin
• Application Number:
  US08/826,606
• Time in Patent Office: 474 Days
• Field of Search: 438/108, 438/118, 438/119
• US Class Current: 438/119
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/13144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/1319 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/29099 Material
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29199 Material of the matrix
• CPC Class Codes: H01L 2224/2929 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29299 Base material
• CPC Class Codes: H01L 2224/2939 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29444 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 2224/83101 as prepeg comprising a layer connector, e.g. provided in an insulating plate member
• CPC Class Codes: H01L 2224/8319 Arrangement of the layer connectors prior to mounting
• CPC Class Codes: H01L 2224/838 Bonding techniques
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• 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 24/11 Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/12 : Structure, shape, material or disposition of the bump connectors prior to the connecting process
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 24/29 : of an individual layer connector
• CPC Class Codes: H01L 24/31 : Structure, shape, material or disposition of the layer connectors after the connecting process
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer 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 2924/00013 : Fully indexed content
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/0781 : being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H05K 2201/0314 : Elastomeric connector or conductor, e.g. rubber with metallic filler
• CPC Class Codes: H05K 2201/0367 : Metallic bump or raised conductor not used as solder bump
• CPC Class Codes: H05K 2201/10674 : Flip chip
• CPC Class Codes: H05K 3/0023 : by exposure and development of a photosensitive insulating layer
• CPC Class Codes: H05K 3/323 : by applying an anisotropic conductive adhesive layer over an array of pads

Abstract

The specification describes an interconnection technique using compliant metal coated photodefined polymer bumps for mounting and interconnecting component assemblies on substrates such as glass, printed wiring boards, etc. The polymer chosen for the bump structure has a relatively low T_g and the polymer bump is metallized in a way that substantially encapsulates the polymer.

Claims

1. Method for bonding two elements together, said two elements consisting of an electrical or photonic component and a substrate for supporting said component, the method comprising the steps of:

a. forming a plurality of bonding pad on the first of said elements,

b. depositing a layer of photodefinable polymer on the surface of said second element, said photodefinable polymer having a glass transition temperature T_g,

c. masking said layer of photodefinable polymer with a mask having a plurality of actinic light transparent features corresponding to a plurality of bumps,

d. exposing said masked photodefinable layer to actinic light,

e. developing said photodefinable layer to produce a plurality of bump features on the surface of said second element, each of said plurality of bump features having a to p surface and sidewall surfaces exposed by the developing step e.,

f. coating the top surface and the sidewall surfaces of each of said bumps with a metal coating so that the polymer bump is substantially completely encased in said metal coating,

g. positioning the said plurality of bumps in registration with said plurality of bonding pads,

h. providing a layer of anisotropic conductive film between the plurality of bonding pads and the plurality of bumps,

i. urging said first and second elements together,

j. heating said first and second elements to a bonding temperature, while applying pressure to said elements to bond said plurality of bumps to said plurality of bonding pads.

2. The method of claim 1 in which the glass transition temperature of said polymer is less than the said bonding temperature.

3. The method of claim 2 in which the anisotropic conductive film consists of a polymer material with a glass transition temperature less than the glass transition temperature of said polymer comprising said bumps.

4. The method of claim 2 in which the said bonding temperature is in the range 220°

-240°

C. and the said glass transition temperature of the polymer of said bumps is less than 200°

C.

5. The method of claim 2 in which the said metal coating comprises copper.

6. The method of claim 2 in which the thickness of said photodefinable layer is in the range of 2-400 microns.

7. The method of claim 2 in which the sidewalls of the bumps are sloped.

8. The method of claim 2 in which the said polymer is formed from a mixture comprising twenty to sixty weight percent of triazine and from one to ten weight percent of siloxane-caprolactone copolymer.

9. The method of claim 8 in which the said mixture further includes up to ten weight percent of novolak epoxy acrylate.

10. The method of claim 9 in which the said mixture includes one or more of the following:

two to eight percent by weight of bis-phenol-A diglycidyl ether monoepoxyacrylate, zero to twenty percent by weight of carboxyl-terminated butadiene nitrile rubber, two to six percent of N-vinylpyyrolidone, one to ten percent of trimethylolpropanetriacrylate, zero to five percent glycidoxypropyltrimethoxysilane, 0.05 to five weight percent photoinitiator, zero to two percent pigment, 0.1 to one percent surfactant, zero to 0.3 percent copper benzoylacetonate, and thirty to fifty percent solvent.

11. The method of claim 2 in which the metal coating is selected from the group consisting of Al, Ni, Cu, Ti, Co, Ta, Pt, Pd, and alloys thereof.