Wen-Chin Chen

The design and implementation of a visual MPEG-4 scene-authoring tool

We have implemented an MPEG-4 scene-authoring tool for complete profile in our laboratory. This tool is the extension of the results from our laboratory last year. We changed the system architecture and design for 3D scenes, the event in/out mechanism, visual editing, and friendlier user interface. We believe that such a tool can allow users to produce MPEG-4 contents easily and thus can push the MPEG-4 standard to be widely used. In this paper, we describe the design and implementation of an MPEG-4 scene-authoring tool, and we also introduce some necessary components for an MPEG-4 scene-authoring tool.

Error-resilient MPEG-4 video communication over error-prone wireless networks

This work presents an error-resilient MPEG-4 video communication system. The system comprises an error-resilient encoder, an adaptive error-resilient transcoder, an error-resilient decoder and the PLBP encoder/decoder. It has been evaluated under a configurable network error simulator. In addition, the system integrates the error resilience tools defined in the MPEG-4 visual standard, namely; video packet structure, header extension code (HEC) and NEWPRED, as well as three proposed novel error-resilient techniques, namely; prioritized-level bitstream protection (PLBP), protected data partitioning (PDP) and restorative intra adoption (RIA). In the decoder, three error concealment techniques are implemented. They are temporal replacement, motion replacement, and predictive motion replacement. The decoder also implements an error detection mechanism that has high sensitivity to catch errors. Finally, the performance of the hybrid error-resilient system has been evaluated. The experimental results show that under error-prone networks, acceptable video quality has been successfully retained without incurring much overhead.

Design and implementation of an efficient MPEG-4 interactive terminal on embedded devices

We present an efficient MPEG-4-based interactive player for PDA-like embedded devices in this paper. Our system can receive media from various sources, then decompress and compose them in an object-oriented manner. Embedded devices such as PDA usually have limited computational resources, memory size, power budgets, and multimedia capabilities. To overcome these constraints, two novel mechanisms were introduced, namely adaptive frame rate (AFR) and scene cache graph management (SCGM). Furthermore, a media decoding framework was proposed such that multimedia objects of different formats can be retrieved from different sources and then be decoded. This framework can be extended by add-on components. A semi-pull model was also designed for the synchronization of heterogeneous media objects. Finally, all the key modules were efficiently implemented and optimized. These modules include MPEG-4 video decoder, 2D/3D graphic engine, buffer management, script engine, and streaming service

On the design and implementation of an MPEG-4 scene editor

A prototype of MPEG-4 scene editor has been developed in the joint research of our laboratories and CyberLink Inc. With this scene editor, users can compose and edit object-oriented multimedia contents conforming to the MPEG-4 specification. The system is currently developed on Microsoft Windows platform. We describe the system architecture as well as the design and implementation issues of the scene editor. We believe our development experience can benefit future developers of the MPEG-4 system.

Soldering reactions under space confinement for 3D IC applications

The microstructure features and the IMC kinetics of Cu-Sn and Ni-Sn soldering reaction under space confinement are studied in the present study. Experimentally, Cu/Sn(10 μm)/Cu and Ni/Sn(10 μm)/Ni sandwich structures were prepared through a hot-press bonding. Sn with a thickness of 10 μm was chosen to simulate the joints in 3D IC packages employing a severe space confinement. Microstructure characterisations showed that space confinement does not change the reaction products which are Cu6Sn5 and Cu3Sn for Cu-Sn reactions and Ni3Sn4 for Ni-Sn reactions. However, it was found that the interfacial morphology is very different to that of the conventional joints. IMCs in the space confined reactions occupy a very large or even entirety volume in the joint. In addition, voiding occurs in both Cu/Sn/Cu and Ni/Sn/Ni reactions, which having great impacts on the joint strength. According to the kinetics analysis, the IMCs growth rates measured in the present work are in the range of literature results, suggesting that the space confinement behaviour has very little effects on the IMC growth kinetics.

Systematic investigation of Sn-Ag and Sn-Cu modified by minor alloying element of titanium

Reliability issues of Pb-free solder joints used in microelectronic interconnects, such as BGA, flip-chip, or even 3D-IC, are becoming more critical recently when high performance electronic systems demand more rigorous reliability requirements. The selection of new solder materials has been an important topic in order to enhance the reliability of Pb-free solder joints. In the past few years, numerous studies have been conducted on the beneficial effects of minor alloying elements, including Co, Cu, Fe, Ni, Zn and others, into Sn-rich Pb-free solders [1-6]. Only recently have Liu et al. [7] first reported the beneficial effect of Ti in SAC (Sn-Ag-Cu) solder for BGA applications with superior drop-impact performance. Getting such a superior drop-impact performance usually compromises high temperature mechanical properties such as creep resistance. But they found SAC-Ti having enhanced drop-impact performance without sacrificing a good creep property. Improving simultaneously these two mechanical properties was regarded as an excellent achievement of SAC-Ti. Moreover, considerable suppression of the undercooling and retardation of interfacial IMCs were also reported owing to the addition of Ti to SAC. Nevertheless, V. Vuorinen and his coworkers [8] lately reported the result of a thermal aging experiment on SnAg solder modified with Ti and asserted that the minor addition of Ti cannot change the activities of components nor influence the stability of the IMC layers. This study did not support the beneficial effects of minor alloying addition of Ti in SAC of the previous report [7]. Hence, it is essential to clarify the effect of Ti-addition on Sn-rich solders by further investigation. The objectives of our present work are (a) to understand the intrinsic consequence of Ti-addition on Sn-Ag and Sn-Cu solders, (b) to observe whether Ti-addition can influence the interfacial reactions between solders and under-bump metallurgies (UBMs), and (c) to reveal the contribution of Ti-addition on any other reliability performance, such as electro-migration (EM) resistance. In this study, two Ti-added Sn-Ag and Sn-Cu solders were commercially prepared; Sn-1.0Ag-0.2Ti (wt.%) and Sn-0.7Cu-0.2Ti (wt.%) in the form of solder ingots. They were cut into small pieces and evaluated for their metallurgical properties and interfacial reactions with Cu and Ni UBMs. Pure Sn-1.0Ag (wt.%) and Sn-0.7Cu (wt.%) were also prepared in the form of solder balls as control samples. DSC (differential scanning calorimetry) analysis was used to study the melting/solidification behavior of Ti-added solders. It was confirmed that a small amount of Ti addition can effectively reduce the undercooling to a few degrees, while a large undercooling is persistent in Sn-Ag or Sn-Cu solders without Ti addition. It is worth noting that a small undercooling can lessen a possibility of non-uniform solidification among many neighboring solder joints during reflow, which is beneficial for joint integrity and reliability as well. Some solder samples were also produced in the form of small solder cylinders by the injection-molded-solder (IMS) process [9], which is known for the precursor of IBMs wafer bumping technology, C4NP. Some of the solder cylinders are then exposed at 200 °C for high temperature aging experiment. For Ti-added solders, Ti2Sn3 networks can stabilize the morphology of β-Sn by restraining their grain growth, which implies they may be good candidates for resisting EM failure and maintaining the high-temperature strength of solders. Microhardness of high temperature aged samples are measured to show the trend of hardness change as a function of aging time. The interfacial reactions between different solders and different UBM show interesting results about the effect of Ti addition on the formation of interfacial IMCs. For as-reflowed samples (240 °C, 1 min), significant retardation of interfacial Cu6Sn5 is observed when both the Sn-Ag-Ti and Sn-Cu-Ti solders reacted with Cu UBM. However, Ti addition seems not to be so effective for hindering the formation of Cu3Sn. In the case of Sn-Cu-Ti solders reacted with Ni, the interfacial IMC, (Cu, Ni)6Sn5, is also found to be impeded comparing to the case without Ti addition. When Sn-Ag-Ti solders undergo a reflow process on Ni, Ni3Sn4 forms at the interface as a layer of equilibrium IMC and Ti addition unexpectedly accelerate the formation of Ni3Sn4. The Ti concentration effect and the solid-state growth kinetic of different IMCs will also be discussed in this study. The effects of Ti-addition on electro-migration performance of Sn-Ag and Sn-Cu solder joints will be evaluated with a model joint of Cu wire samples providing a uniform current density during EM stressing in the future.

A visual MPEG-4 scene editor

The Communication and Multimedia Laboratory (CML), National Taiwan University, has been developing an MPEG-4 editor for 5 years since 1998. In 2001, Digimax Production Ltd joined this project and we have addressed ourselves to making the system more complete. We have implemented a visual MPEG-4 scene editor for creating 2D/3D mixed scenes, with the following features: event routing mechanism; visual editing; friendly user interface. With our system, one can easily produce highly interactive MPEG-4 content.