Papers by Ken JenNi Cheung
International Symposium on Microelectronics, 2017
The calling for smaller form factor, higher I/O density, higher performance and lower cost has ma... more The calling for smaller form factor, higher I/O density, higher performance and lower cost has made fan-out wafer level packaging (FOWLP) technology the trend. Good control of die position accuracy and molded wafer warpage are some of the keys to achieve high-yield production for FOWLP. In this study, 10mm×10mm test chips were fabricated and attached (chip-first and die face-up) onto 12 inch glass wafer carriers using die-attach-film (DAF). These reconfigured wafers were compression-molded with selected epoxy molding compounds (EMC). Cu bumps (contact-pads) were revealed by grinding, and redistribution layers (RDLs) were fabricated by lithography and electroplating process. The fan-out wafers were evaluated and characterized after each process step with main focus on the die-misplacement/die shift, re-configured wafer warpage, compression molding defects and RDL fabrication defects. The root causes of these defects were investigated and analyzed, while the possible solutions to over...
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Proceedings Electronic Components and Technology, 2005. ECTC '05., 2000
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Intense 355-nm excitation of the lowest 4f to 5d transition of Ce(3+):La2Be2O5 leads to a brownis... more Intense 355-nm excitation of the lowest 4f to 5d transition of Ce(3+):La2Be2O5 leads to a brownish coloration of the crystal due to the formation of stable photochromic centers. These centers are characterized by a broadband absorption spectrum that spans the 220-840 nm spectral range. Since they can be readily bleached by optical excitation into their absorption band, the centers are photochromic. They are produced by a two-step photoionization of Ce(3+) ions followed by attachment of the detached electrons at trapping sites in the crystal. The dependence of the number of centers on laser intensity and length of exposure have been measured, and the kinetics of growth have been studied.
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Proceedings of the 4th International Symposium on Electronic Materials and Packaging, 2002., 2002
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CLEO/Pacific Rim 2003. The 5th Pacific Rim Conference on Lasers and Electro-Optics (IEEE Cat. No.03TH8671), 2003
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Fifth International Conference onElectronic Packaging Technology Proceedings, 2003. ICEPT2003., 2003
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International Symposium on Electronic Materials and Packaging (EMAP2000) (Cat. No.00EX458), 2000
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Fifth International Conference onElectronic Packaging Technology Proceedings, 2003. ICEPT2003., 2003
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Twenty Fourth IEEE/CPMT International Electronics Manufacturing Technology Symposium (Cat. No.99CH36330), 1999
We demonstrated that the bonding of gold wires for COB application was feasible at temperatures ~... more We demonstrated that the bonding of gold wires for COB application was feasible at temperatures ~100°C or below by using a wedge bonder with a high frequency ultrasonic transducer (~138 kHz). An automatic rotary bondhead wedge bonder equipped with the transducer was employed to perform wire bonding. Bonding of gold wires was conducted on the aluminum pads of a test
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2005 Conference on High Density Microsystem Design and Packaging and Component Failure Analysis, 2005
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Proceedings of the 4th International Symposium on Electronic Materials and Packaging, 2002., 2002
The wire bondability and surface characteristics were studied of Au/Ni bond pads on organic FR-4 ... more The wire bondability and surface characteristics were studied of Au/Ni bond pads on organic FR-4 PCBs with different gold plating schemes and gold thickness. Three different plating techniques were used to deposit gold layers, namely the electrolytic gold plating, immersion gold plating and immersion gold plating followed by electrolytic gold plating. Process windows for the individual metallisation schemes were established
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Phys. Rev. B, 1992
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Phys. Rev. B, 1993
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Physical Review B, 1994
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2005 6th International Conference on Electronic Packaging Technology, 2005
Thermosonic Au wire bonding is the most widely used interconnection technology in the BGA package... more Thermosonic Au wire bonding is the most widely used interconnection technology in the BGA packages. Compare with Au ball bonding, the lower wire loop and finer bond pitch of Au wedge bond makes its ideal for low profile and high I/O applications, which is the subject of the current study. As bond pad surface cleanliness, substrate materials and wire bonding process parameters play a critical role on the yield of wire bonding, this study compare Au wedge wire bondability of rigid FR-4 and flexible polyimide (PI) substrate and examine the bonding improvements using plasma cleaning by the concept of process windows. Process windows demonstrate the bondability of the substrates at a combinations of varies bonding conditions, such as bonding temperature, bond power and with and without subjected to plasma cleaning. The plasma cleaning condition is optimized based on the process windows. Results indicated that a low plasma cleaning power with a short cleaning time resulted in the widest process window. Significant improvements of bondability were noted after plasma treatment with a substantial reduction in minimum bonding temperature for both substrates. The process window for the flexible substrate was much wider than the rigid substrates in the bonding conditions tested.
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Solid-State Electronics, 2004
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Journal of the Optical Society of America B, 1994
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Papers by Ken JenNi Cheung