No-flow underfill of epoxy resin, anhydride, fluxing agent and surfactant

• US 6,180,696 B1
• Filed: 02/18/1998
• Issued: 01/30/2001
• Est. Priority Date: 02/19/1997
• Status: Expired due to Term

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Shi, Song-Hua, Wong, Ching-Ping
• Primary Examiner(s): SELLERS, ROBERT E
• Application Number:
  US09/025,532
• Time in Patent Office: 1,077 Days
• Field of Search: 523/402, 523/456, 523/466, 523/457, 525/508, 525/533, 525/407
• US Class Current: 523/457
• CPC Class Codes: C08G 59/42 Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
• CPC Class Codes: C08G 59/68 characterised by the catalysts used
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• 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 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 23/293 Organic, e.g. plastic
• CPC Class Codes: H01L 24/29 of an individual 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 2924/01004 Beryllium [Be]
• 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 2924/01021 Scandium [Sc]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01057 Lanthanum [La]
• CPC Class Codes: H01L 2924/01063 Europium [Eu]
• CPC Class Codes: H01L 2924/01066 Dysprosium [Dy]
• CPC Class Codes: H01L 2924/01067 Holmium [Ho]
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/351 : Thermal stress

Abstract

An epoxy material suitable for no-flow underfilling processes with high glass transition temperature can be obtained by curing a solvent free formulation containing an epoxy resin, an organic carboxylic acid anhydride hardener, a curing accelerator, a fluxing agent, a viscosity controlling agent, a coupling agent, and a surfactant.

Claims

1. A no-flow underfill material obtained by curing a formulation comprising:

a. an epoxy resin and/or a mixture of epoxy resins, said epoxy resin or said mixture having more than one 1,2-epoxy group per molecule;

b. an organic carboxylic acid anhydride hardener;

c. a latent curing accelerator adapted to allow a curing reaction of said epoxy resin and/or said mixture to occur at a temperature range of 180°

C. to 240°

C., said curing accelerator being selected from the group consisting of triphenylphosphine, alkyl-substituted imidazoles, imidazolium salts, onium borates, metal chelates, and mixtures thereof;

d. a fluxing agent selected from chemicals having at least one hydroxyl (—

OH) group;

e. fumed silica;

f. a coupling agent; and

g. a surfactant.

2. A no-flow underfill material as claimed in claim 1, wherein said epoxy resin is selected from the group consisting of cycloaliphatic epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, epoxy novolac resins, biphenyl epoxy resins, naphthalene epoxy resins, dicyclopentadiene-phenol epoxy resins, and mixtures thereof.

3. A no-flow underfill material as claimed in claim 1, wherein said organic carboxylic acid anhydride hardener is selected from the group consisting of hexahydrophthalic anydride, methyl hexahydrophthalic anhydride, and mixtures thereof.

4. A no-flow underfill material as claimed in claim 1, wherein said alkyl-substituted imidazole is 2-ethyl-4-methyl imidazole.

5. A no-flow underfill material as claimed in claim 1, wherein said imidazolium salts are selected from the chemicals of the chemical structure as follows:

where R₁, R₂, R₃, R₄, and R₅, can be the same or different and are selected from the group consisting of H, C_1-6 alkyls, and phenyl; and

the anionic counter ion AC⁻

is selected from the group consisting of I⁻

, Br⁻

, Cl⁻

, OAc⁻

, AcAc⁻

, BF₄⁻

, PF₆⁻

, AsF₆⁻

, and SbF₆⁻

.

6. A no-flow underfill material as claimed in claim 1, wherein said onium borate is selected from the chemicals of the chemical structure as follows:

where R₁=R₂=phenyl; and

R₃ and R₄ are selected from the group consisting of phenyl and C_1-10 alkyls.

7. A no-flow underfill material as claimed in claim 1, wherein said metal chelates are selected from the group consisting of metal acetylacetonates, metal acetates, metal halides, metal imidazole complexes, and metal amine complexes and said metal ions are selected from the group consisting of Sc³⁺, Cu²⁺, Mo²⁺, Ru³⁺, Rh³⁺, Cd²⁺, La³⁺, Hf⁴⁺, In³⁺, Tl¹⁺, Tl³⁺, Pb²⁺, Pb³⁺, Ti⁴⁺, Ce³⁺, Ce⁴⁺, Pr³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Lu³⁺, Th³⁺, Co²⁺, Co³⁺, Fe²⁺, Fe³⁺, Ni²⁺, Pd²⁺, Pt²⁺, Ga³⁺, Y³⁺, V³⁺, Sm³⁺, Nd³⁺, Cr³⁺, Li¹⁺, Be²⁺, K¹⁺, Ca²⁺, Na¹⁺, Ba²⁺, Sr²⁺, Zn²⁺, and Mg²⁺.

8. A no-flow underfill material as claimed in claim 1, wherein said fumed silica is selected from the group consisting of treated amorphous fumed silica and untreated amorphous fumed silica.

9. A no-flow underfill material as claimed in claim 1, wherein said coupling agent is selected from the group consisting of silane coupling agents.

10. A no-flow underfill material as claimed in claim 9, wherein said silane coupling agents are selected from the group consisting of epoxy silane coupling agents, amine silane coupling agents, mercapto silane coupling agents, and mixtures thereof.

11. A no-flow underfill material as claimed in claim 1, wherein said surfactant is selected from the group consisting of non-ionic surfactants.

12. A no-flow underfill material as claimed in claim 11, wherein said surfactant is selected from the group consisting of silicones, polyoxyethylene/polyoxypropylene block copolymers, ethylene diamine-based polyoxyethylene/polyoxypropylene block copolymers, polyol-based polyoxyalkylenes, fatty alcohol-based polyoxyalkylenes, and fatty alcohol polyoxyalkylene alkyl ethers.

13. A no-flow underfill material as claimed in claim 1, wherein said fluxing agent is selected from the group consisting of ethylene glycol, glycerol, 3-1,2-propane diol, D-ribose, D-cellobiose, cellulose, and 3-cyclohexene-1,1-dimethanol.

14. A no-flow underfill material as claimed in claim 1, further comprising a filler material.

15. A no-flow underfill material as claimed in claim 14, wherein said filler material is selected from the group consisting of silica particles, silicon nitride particles, and aluminum nitride particles.