Solder bonding of electrical components

• US 5,975,408 A
• Filed: 10/23/1997
• Issued: 11/02/1999
• Est. Priority Date: 10/23/1997
• 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: Goossen, Keith-Wayne
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): Knapp, Jeffrey T.
• Application Number:
  US08/956,527
• Time in Patent Office: 740 Days
• Field of Search: 228/180.22, 228/173.2, 228/174, 29/840, 29/841
• US Class Current: 228/173.2
• CPC Class Codes: B23K 20/023 Thermo-compression bonding
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/131 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 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• 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 2224/73203 Bump and layer connectors
• 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 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83856 Pre-cured adhesive, i.e. B-stage adhesive
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/81 using a bump 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• 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 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• 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 2924/0132 : Binary Alloys
• 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: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/157 : 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 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/1579 : with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2924/3512 : Cracking
• CPC Class Codes: Y10T 29/49144 : by metal fusion
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

The specification describes a technique for solder bump bonding IC chips or chip packages to interconnection substrates. Epoxy prepolymer underfill is applied to the surface of the interconnection substrate prior to the solder bump bonding step. The presence of the prepolymer underfill material does not interfere with effective bonding. This technique reduces substantially the potential for voids in the underfill layer that tend to occur when the underfill is applied to a bonded IC chip/substrate assembly. It also enables curing of the underfill polymer in the same heating step used to effect thermocompression bonding of the solder bumps.

Claims

1. A method for bonding an IC chip package to an interconnection substrate with an array of contact regions on the IC chip package electrically contacting and adhering to a mating array of contact regions on said interconnection substrate comprising the steps of:

a. depositing solder bumps on said array of contact regions on said IC chip package,

b. applying a layer of a prepolymer of a polymer adhesive to the surface of said array of contact regions on said interconnection substrate,

c. placing said IC chip package in contact with said layer of prepolymer on said interconnection substrate with said solder bumps aligned to said array of contacts regions on said interconnection substrate,

d. applying pressure in the range 1-10 mg/mm² between said IC chip package and said interconnection substrate, said pressure being sufficient to cause said solder bumps to penetrate through said layer of prepolymer, and to cause a thermocompression bond between said solder bumps and said array of contact regions on said interconnection substrate, and

e. heating said solder bumps to cause bonding between said solder bumps and said array of contact regions on said interconnection substrate.

2. The method of claim 1 in which steps d. and e. occur simultaneously.

3. The method of claim 1 in which the heating in step e. causes the said prepolymer to cure.

4. The method of claim 3 in which the solder bumps are heated to a temperature in the range 140-170°

C.

6. The method of claim 1 wherein the underfill material is applied to said second surface.

7. The method of claim 1 in which the first surface is the surface of a packaged semiconductor chip.

8. The method of claim 1 in which the underfill material is a prepolymer of an adhesive material.

9. The method of claim 8 in which the adhesive material is an epoxy.

10. The method of claim 8 wherein the bonding step includes the step of heating the solder bumps and the step of heating the solder bumps simultaneously causes curing of said prepolymer.

11. The method of claim 1 in which the second surface is the surface of an interconnection substrate.

12. The method of claim 11 in which the first surface is the surface of an interconnection substrate.

13. The method of claim 12 in which the interconnection substrate is selected from the group consisting of epoxy printed circuit boards, ceramic interconnection substrates and silicon interconnection substrates.

5. A method for solder bonding a first surface to a second surface by applying to said first surface a plurality of solder bumps and bonding said plurality of solder bumps to said second surface thereby creating a gap between said first and second surfaces in between said solder bumps, and filling said gap with an underfill material, the invention characterized in that the underfill material is applied to at least one of said surfaces prior to the step of bonding said plurality of bumps to said second surface and the bonding step comprises applying pressure in the range 1-10 mg/μ

m² between said solder bumps and said second surface and heating said solder bumps to a temperature in the range 140-170°

C. to cause bonding.