Fundamental Understanding and Performance Enhancement of Conductive Adhesive for Microelectronic Packaging ApplicationsEPA Grant Number: R831489
Title: Fundamental Understanding and Performance Enhancement of Conductive Adhesive for Microelectronic Packaging Applications
Investigators: Wong, C. P.
Institution: Georgia Institute of Technology
EPA Project Officer: Klieforth, Barbara I
Project Period: December 22, 2003 through December 21, 2008
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2003) RFA Text | Recipients Lists
Research Category: Nanotechnology , Pollution Prevention/Sustainable Development , Sustainability
The primary objectives of this research are to:
· Develop low-cost high performance electrically conductive adhesives
(ECA) as a replacement of lead containing solders for environmentally friendly
electronic packaging manufacturing.
· Understand corrosion behavior for ECA joints on various metal surfaces.
· Understand relationship between corrosion behavior and electrochemical potentials of ECA and various metal surfaces.
· Understand mechanism of corrosion control by cathode protection method in ECA joints and a role of sacrificial anode materials in the joints.
· Introduce reworkable and repairable resin binders to ECA formulation in order to reduce the waste of PCB or IC component to be produced during manufacturing.
· Introduce short chain aliphatic or conjugated organic compounds as well as properly functionalized carbon nanotubes into ECA formulations to increase the current carrying capability.
· Understand the thermomechanical failure of ECA joints, and improve the thermomechanical performance with conductive particles functionalized with self-assembled monolayer molecules.
· Realize further energy savings by using variable frequency microwave curing of ECAs.
Proposed is a study of chemical, physical and thermomechanical properties of ECA materials. The morphological study will be followed by the electrical test, to understand corrosion behavior at the interface between ECAs and the metal surface such as Cu, NiAu, Sn and Sn-alloys. To enhance the stability of the contact resistance under the extreme conditions, the electrical properties of ECAs will be modified via incorporating corrosion inhibitors and sacrificial anode materials for cathodic protection. Mechanism of corrosion control by corrosion inhibitors and sacrificial anode materials will be investigated through electrical, electrochemical and morphological studies. Effect of self-passivating property of sacrificial anode will be studied as well. Introducing short chain aliphatic or conjugated organic compounds into ECA formulations as interfacial self-assembly monolayer modifiers, and properly functionalized carbon nano-tubes will be implemented to increase the current carrying capability of ECAs. The electrical, physical and mechanical properties of the ECAs with functionalized fillers will be studied. Improvement of thermomechanical performance of ECAs is expected with conductive particles functionalized with self-assembled monolayer molecules. The thermomechanical performance of ECAs under the harsh environment will be studied through the fatigue test in a temperature/humid control chamber. In-situ measurement of electrical resistance during the fatigue test will tell us how the thermomechanical stress affects the electrical and mechanical properties of ECAs. For further energy saving concerns, variable frequency microwave will be explored for curing of the ECAs. Reworkability and recyclability of ECAs will be explored by using reworkable polymer matrix or new binder systems. All those proposed researches would enhance the overall competitiveness of ECA materials against metal alloy based interconnect materials.
The intellectual merit of the proposed research lies in the fundamental understanding of properties, performance and reliability of ECAs, which will define the guidelines for developing lead-free interconnect materials for next generation environmentally benign packaging manufacturing.
Reducing the use of lead, and eventually eliminating the use of lead at the source, either mining of lead or other metals for the so-called lead-free alloy solders, are obvious benefits of the proposed research to our society. Total replacement of tin-lead solder has the potential of reducing the US lead consumption by as much as 10% in short term. That is a significant reduction, which will have a long lasting impact on human health and environment. In addition, using ECAs instead of alloy solders decreases the reflow temperature by more than 60% in electronic packaging manufacturing. This represents a significant energy saving for the electronics industry, which will have a positive impact on the environment. The wide application of ECAs for electronic packaging will enable us to manufacture more green-labeled electronic products, and this will be extremely important regarding the technological leadership and global market share of the US microelectronic industry.
Throughout the proposed project students at pre-college, undergraduate and graduate levels, especially those from the underrepresented groups, will be recruited and advised in the research and education activities. In addition to publishing in archived and trade journals, the project results will be disseminated through workshops and short courses. An industrial consortium would also be expected to attract industrial sponsorship and to serve as a vehicle for speedy technology transfer.