Person:
Wong,
C. P.
Wong,
C. P.
Permanent Link
Associated Organization(s)
Organizational Unit
ORCID
ArchiveSpace Name Record
Publication Search Results
Now showing
1 - 4 of 4
-
ItemImproved Stability of Contact Resistance of Low Melting Point Alloy Incorporated Isotropically Conductive Adhesives(Georgia Institute of Technology, 2003-06) Wong, C. P. ; Moon, Kyoung-Sik ; Wu, JialiWith the driving force of “green” revolution in the electronics industry, tremendous efforts have been made in pursuing lead-free alternatives. Although lately lead-free alloys have drawn a lot of attention, their technical weaknesses, such as high processing temperature, poor wetting and high surface tension, limit their applications on the thermally sensitive, flexible, nonsolderable substrates and the ultra-fine pitch size flip chip interconnection. Conventional isotropically conductive adhesives (ICAs) have been used widely in surface mount and die-attach technologies for electrical interconnection and heat dissipation. The low temperature processing of ICAs is one of the major advantages over lead-free solders, which brings a low system stress, simple manufacture process and the like. In order to enhance the contact resistance of ICAs, the low melting point alloy (LMA) incorporating technology has been developed by our group. In this paper, LMA fusing methods were studied, since nonfused LMA in ICAs after a curing process can adversely affect the physical property and contact resistance stability. A differential scanning calorimeter (DSC) was used for the basic examination of depleting rate of LMAs in the typical ICAs. The cross-sectional morphology, LMA distribution and intermetallic compound were investigated by a scanning electron microscope (SEM). In addition, contact resistance for the ICA formulation incorporated with LMAs under elevated temperature and humidity was evaluated.
-
ItemDevelopment of High Performance Interfill Materials for System Chips Technology(Georgia Institute of Technology, 2002-06) Wong, C. P. ; Wu, Jiali ; Bhattacharya, Swapan ; Lloyd, Courtney ; Pogge, H. Bernhard ; Tummala, Rao R.An innovative precisely interconnected chip (PIC) technology is currently under development at IBM to seek more effective means of creating system chips. The objective of this research is developing fabrication methods to permit the realization of high yielding large area chips, as well as chips that may contain very diverse technologies. This paper reports the use of a high-performance interfill material based on epoxy resin, which is used to connect the different chip sector macros that make up the system chip. This novel interfill material remains thermally stable through the subsequent processing temperature hierarchies during the interchip interconnection fabrication. Spherical SiO2 powders are incorporated into the epoxy resin to improve its mechanical properties, reduce coefficient of thermal expansion, and increase thermal conductivity. Adhesion and rheology of the formulated interfill materials are evaluated. Microstructure of SiO2 filled epoxy system is also investigated to confirm the reliability of the composite before and after thermal aging. Initial results indicate that the formulated EPOXY A resin composite is qualified for the system chip manufacturing process in terms of the dispensing processability, structural and mechanical integrity, and reliability.
-
ItemDevelopment of New Low Stress Epoxies for MEMS Device Encapsulation(Georgia Institute of Technology, 2002-06) Wong, C. P. ; Wu, JialiIn this study, a series of new low stress epoxies was introduced as conformal encapsulants, which show a high promise to meet all the requirements for the protection of the pressure sensor system. Mechanical properties such as initial Young’s modulus, toughness and ultimate tensile stress were evaluated. The more critical issue of material’s contamination resistance to the jet fuel was improved. And the mechanism behind materials lowstress and toughness behaviors was investigated from the viewpoint of microstructure.
-
ItemEvaluation and Characterization of Reliable Non-Hermetic Conformal Coatings for Microelectromechanical System (MEMS) Device Encapsulation(Georgia Institute of Technology, 2000-11) Wong, C. P. ; Wu, Jiali ; Pike, Randy T. ; Kim, Namsoo P. ; Tanielian, Minas H.The thrust of this project was to evaluate commercial conformal encapsulation candidates for low cost aerospace applications. The candidate conformal coatings evaluated in this study included silicone elastomers, epoxies, and Parylenes with bi-layer or tri-layer designs. Properties characterized in this study included mobile ion permeation and moisture ingress resistance, interfacial adhesion variation through thermal shock cycling and 85 C/85% RH aging. Surface Insulation Resistance (SIR), Triple Track Resistance (TTR) and die shear strength were used for the corresponding electrical and physical property characterizations. Parylene F displayed excellent properties for environmental protection. Silicone elastomers displayed less resistance to the harsh environment as compared to the Parylene family (N, C, D types), but it could provide advantages for low residual stress applications. The change in adhesion strength between Parylene C and silicone elastomers after exposure to thermal shock cycling or 85 C/85%RH aging for different time periods were conducted from die shear test in terms of the interfacial failure. SIR values of all the candidate materials after 1000 h exposure to 85 C/85%RH, with 100V dc for resistance measurement, range from 1 108–1 109. Leakage current values after 1000 h exposure to 85 C/85%RH, 175 V bias, are in the range of 10 9 to 10 11 Amp. The bi- or tri-layer conformal coating combination investigated in this study showed significant promise for encapsulation of the microelectromechanical system (MEMS) devices.