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2005 Progress Report: Environmentally Benign Lead-Free Electrically Conductive Adhesive for Electronic Packaging Manufacturing
EPA Grant Number: R831489Title: Environmentally Benign Lead-Free Electrically Conductive Adhesive for Electronic Packaging Manufacturing
Investigators: Wong, C. P.
Institution: Georgia Institute of Technology
EPA Project Officer: Bauer, Diana
Project Period: December 22, 2003 through December 21, 2008
Project Period Covered by this Report: December 22, 2004 through December 21, 2005
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2003)
Research Category: Pollution Prevention/Sustainable Development
Description:
Objective:The objectives of this research project are to: (1) develop low-cost, high-performance electrically conductive adhesives (ECA) as a replacement for lead containing solders for environmentally friendly electronic packaging manufacturing; (2) understand corrosion behavior for ECA joints on various metal surfaces; (3) understand the relationship between corrosion behavior and electrochemical potentials of ECA and various metal surfaces; (4) understand the mechanism of corrosion control by cathode protection method in ECA joints and a role of sacrificial anode materials in the joints; (5) introduce reworkable and repairable resin binders to ECA formulation to reduce the waste of integrated circuit (IC) components produced during manufacturing; (6) introduce short-chain aliphatic or conjugated organic compounds as well as properly functionalized carbon nanotubes into ECA formulations to increase the current carrying capability; (7) understand the thermomechanical failure of ECA joints and improve the thermomechanical performance with conductive particles functionalized with self-assembled monolayer molecules; and (8) realize further energy savings by using variable frequency microwave curing of ECAs.
Progress Summary:Electrical/chemical/physical behaviors of the ECAs for microelectronic packaging applications were investigated. To enhance the performance, realize the fine pitch capability, and enable the device miniaturization, nanoconductive fillers and self-assembled monolayer compounds were studied in Year 2 of the project. By using nanosized fillers, electrical performance of anisotropically conductive adhesives (ACA) joints was enhanced because of the improved interfaces between the filler and the bond pads and between the fillers, which results from low temperature sintering behavior of the nanosized conductive fillers. Further electrical improvements were achieved by employing self-assembled monolayer molecules. Molecular dynamic simulations also were carried out for understanding nano-ECA joints.
A novel nano-ACA material incorporated with in situ-formed nanoconductive adhesive (NCA) particles was investigated as well. By controlling the matrix materials and capping agents with different formation conditions, well-dispersed and uniform-sized nano-Ag conductive fillers are formed in situ in the epoxy matrix. The nano-Ag fillers are at low loading levels (< 5 wt%) relative to the loading level of conventional ACAs (~10-30 wt %). This novel interconnect adhesive combines the electrical conduction along the z-direction (ACA-like) and the ultra-fine pitch (< 100 nm) capability (NCA-like). There are a number of benefits of this novel material. First, the nanoparticles can fill gaps caused by surface asperity. This can improve electrical conduction between bonding pads because of the superior interface properties and the low temperature sintering behavior of the nanoparticles. The joint resistance of the novel NCA was two orders of magnitude lower than that of the typical NCA joints.Second, a much lower bonding pressure is needed to form a joint relative to a typical NCA material. Finally, this novel nano-ACA joint can enhance the performance and reliability of the interconnect package during temperature cycling.
The novel NCAs, with very low loading of in situ-formed nanoscale conductive particles, required a much lower bonding pressure to form a joint than typical NCAs. In addition, the significantly improved electrical performance of the novel NCA joints were obtained.
Future Activities:The investigators will next be studying the effects of self-assembled monolayer (SAMs) and sacrificial anodes on anisotropically conductive film (ACF) joints. ACFs have similar performance and applications to ACAs. However, they have different resin compositions for fast cure and processibility, and thus are more widely used in industrial applications. The effects of different SAM compounds (such as dithiol, dicarboxylic acids) on the contact resistance and current carrying capability of ACF joints will be studied. The behavior of SAM under the processing conditions of ACF will be studied and compared to ACA joints. The effects of SAM on the long term reliability of ACF joints under elevated temperature and humidity (i.e. 85oC/85%RH) will be evaluated. High performance, high reliability, fine pitch ACF joints are expected to be formed with optimized SAMs. We also will explore the synthesis and formulation of nano lead-free alloys with melting depression to reduce the electronic interconnect assembly temperature. This will in turn reduce the stress on the assembled electronic systems.
Journal Articles on this Report: 15 Displayed | Download in RIS Format
| Other project views: | All 49 publications | 22 publications in selected types | All 22 journal articles |
| Type | Citation | ||
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Dong H, Zhang ZQ, Wong CP. Molecular dynamics study of a nano-particle joint for potential lead-free anisotropic conductive adhesives applications. Journal of Adhesion Science and Technology 2005;19(2):87-94 |
R831489 (2004) R831489 (2005) |
not available |
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Dong H, Moon KS, Wong CP. Molecular dynamics study of nanosilver particles for low-temperature lead-free interconnect applications. Journal of Electronic Materials 2005;34(1):40-45 |
R831489 (2004) R831489 (2005) |
not available |
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Jiang HJ, Moon KS, Lu J, Wong CP. Conductivity enhancement of nano silver-filled conductive adhesives by particle surface functionalization. Journal of Electronic Materials 2005;34(11):1432-1439. |
R831489 (2005) |
not available |
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Jiang HJ, Moon KS, Zhang ZQ, Pothukuchi S, Wong CP. Variable frequency microwave synthesis of silver nanoparticles. Journal of Nanoparticle Research 2006;8(1):117-124 |
R831489 (2004) R831489 (2005) |
not available |
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Li Y, Moon KS, Wong CP. Adherence of self-assembled monolayers on gold and their effects for high-performance anisotropic conductive adhesives. Journal of Electronic Materials 2005;34(3):266-271. |
R831489 (2005) |
not available |
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Li Y, Moon KS, Wong CP. Materials science. Electronics without lead. Science 2005;308(5727):1419-1420. |
R831489 (2005) |
not available |
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Li Y, Moon KS, Wong CP. Monolayer-protected silver nano-particle-based anisotropic conductive adhesives: electrical and thermal properties. Journal of Electronic Materials 2005;34(12):1573-1578. |
R831489 (2005) |
not available |
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Li Y, Xiao F, Moon KS, Wong CP. Novel curing agent for lead-free electronics: amino acid. Journal of Polymer Science Part A: Polymer Chemistry 2005;44(2):1020-1027. |
R831489 (2005) R831489 (2006) |
not available |
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Li Y, Moon KS, Wong CP. Reliability improvement of conductive adhesives on tin (Sn) surfaces. Journal of Adhesion Science and Technology 2005;19(16):1427-1444. |
R831489 (2005) |
not available |
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Li Y, Moon KS, Wong CP. Electrical property improvement of electrically conductive adhesives through in-situ replacement by short-chain difunctional acids. IEEE Transactions on Components and Packaging Technologies 2006;29(1):173-178. |
R831489 (2005) R831489 (2006) |
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Li Y, Moon KS, Wong CP. Enhancement of electrical properties of anisotropically conductive adhesive joints via low temperature sintering. Journal of Applied Polymer Science 2006;99(4):1665-1673. |
R831489 (2005) R831489 (2006) |
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Li Y, Wong CP. Recent advances of conductive adhesives as a lead-free alternative in electronic packaging: materials, processing, reliability and applications. Materials Science and Engineering R: Reports 2006;51(1-3):1-35. |
R831489 (2005) R831489 (2006) |
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Moon KS, Dong H, Maric R, Pothukuchi S, Hunt A, Li Y, Wong CP. Thermal behavior of silver nanoparticles for low-temperature interconnect applications. Journal of Electronic Materials 2005;34(2):168-175. |
R831489 (2005) |
not available |
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Moon KS, Li Y, Xu JW, Wong CP. Lead-free interconnect technique by using variable frequency microwave. Journal of Electronic Materials 2005;34(7):1081-1088 |
R831489 (2004) R831489 (2005) |
not available |
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Chiang HW, Chung C-L, Chen LC, Li Y, Wong CP, Fu SL. Processing and shape effects on silver paste electrically conductive adhesives (ECAs). Journal of Adhesion Science and Technology 2005;19(7):565-578. |
R831489 (2005) |
not available |
heavy metals, human health risk, pollution prevention, treatment/control, chemical engineering, economics and business, clean technologies, electronic packaging, energy efficiency, lead reduction, environmentally conscious manufacturing,
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INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Sustainable Industry/Business, Scientific Discipline, RFA, POLLUTION PREVENTION, Technology for Sustainable Environment, Sustainable Environment, Chemical Engineering, Technology, Energy, Environmental Chemistry, Economics and Business, energy conservation, cleaner production, waste reduction, clean technologies, lead reduction, environmentally benign adhesive, environmentally conscious manufacturing, energy efficiency, electronic packaging, corrosion resistant
Progress and Final Reports:
2004 Progress Report
Original Abstract
2006 Progress Report