• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.478-480
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• 2004

다이아몬드 톱날을 이용한 얇은 Si 웨이퍼의 기계적인 다이싱은 chipping, crack 등의 문제점을 발생시킨다. 또한 stacked die 나 multi-chip등과 같은 3D-WLP(wafer level package)에서 via를 생성하기 위해 현재 사용되는 화학적 etching은 공정속도가 느리고 제어가 힘들며, 공정이 복잡하다는 문제점을 가지고 있다. 이러한 문제점을 해결하기 위해 현재 연구되고 있는 분야가 레이저를 이용한 웨이퍼 다이싱 및 드릴링이다. 본 논문에서는 UV 레이저를 이용한 얇은 Si 웨이퍼 다이싱 및 드릴링 시스템에 대해 소개하고, 웨이퍼 다이싱 및 드릴링 실험결과를 바탕으로 적절한 레이저 및 공정 매개변수에 대해 설명한다.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.49-60
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• 2010

Semiconductor packages are increasingly moving toward miniaturization, lighter and high performance. Futhermore, packages become thinner. Thin packages will generate serious reliability problems such as warpage, crack and other failures. Reliability problems are mainly caused by the CTE mismatch of various package materials. Therefore, proper selection of the package materials and geometrical optimization is very important for controlling the warpage and the stress of the package. In this study, we investigated the characteristics of the warpage and the stress of several packages currently used in mobile devices such as CABGA, fcSCP, SCSP, and MCP. Warpage and stress distribution are analyzed by the finite element simulation. Key material properties which affect the warpage of package are investigated such as the elastic moduli, CTEs of EMC molding and the substrate. Geometrical effects are also investigated including the thickness or size of EMC molding, silicon die and substrate. The simulation results indicate that the most influential factors on warpage are EMC molding thickness, CTE of EMC, elastic modulus of the substrate. Simulation results show that warpage is the largest for SCSP. In order to reduce the warpage, DOE optimization is performed, and the optimization results show that warpage of SCSP becomes $10{\mu}m$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.89-101
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• 2006

Frequency-variant transmission line parameters are determined. Then the signal transient characterizations of frequency-dependent multi-coupled lines are investigated. With the proposed method, an accurate signal integrity degradation such as signal ringing (overshoot, undershoot) and crosstalk noises relevant to the switching patterns of signals, rising / falling time(tr, tf) and line lengths is investigated. It is shown that there may be approximately 26% discrepancy of signal transients and 260% difference of crosstalk noises between the constant RLC model and frequency-variant RLC model in on-chip global interconnects while those of package lines are 11% and 70%, respectively.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2005.09a
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• pp.67-88
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• 2005

Mold-Flow 3 Die Stack CSP of Mold array packaging with different Gate types. As high density package option such as 3 or 4 die stacking technologies are developed, the major concerning points of mold related qualities such as incomplete mold, exposed wires and wire sweeping issues are increased because of its narrow space between die top and mold surface and higher wiring density. Full 3D rheokinetic simulation of Mold flow for 3 die stacking structure case was done with the rheological parameters acquired from Slit-Die rheometer and DSC of commercial EMC. The center gate showed severe void but corner gate showed relatively better void performance. But in case of wire sweeping related, the center gate type showed less wire sweeping than corner gate types. From the simulation results, corner gate types showed increased velocity, shear stress and mold pressure near the gate and final filling zone. The experimental Case study and the Mold flow simulation showed good agreement on the mold void and wire sweeping related prediction. Full 3D simulation methodologies with proper rheokinetic material characterization by thermal and rheological instruments enable the prediction of micro-scale mold filling behavior in the multi die stacking and other complicated packaging structures for the future application.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.201-205
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• 2015

This paper dealt with the condensing technology of an LED light source that uses a parabolic reflector to replace a searchlight equipped with a xenon lamp. A ray-tracing simulation was conducted to analyze the influence of the diameter of the reflector and the size of the light source on light condensing. The combination of a parabolic reflector with a diameter of 620 mm and a focal distance of 220 mm, and a 9 mm multi-chip package (MCP) with a luminous flux of 7,000 lm showed the narrowest beam angle. The luminous intensity at the center was measured at 7.7×10⁶ cd. The distance between the light source and the point where the illuminance was 1 lx was calculated to be 2.8 km. The power consumption of the system was 95 W, which is only 9.5% of that of the 1 kW xenon searchlight, and the beam angle was 1.03°. In a site experiment, it was confirmed that the light ray reflected from the LED searchlight proceeds forward without any diffusion because of the narrow beam angle.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.4
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• pp.61-68
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• 2002

Thermal shock testing was used to evaluate reliability that appeared in the solder joints of electronic devices when they were subjected to thermal cycling. Recently, mobile devices have come smaller and multi-functional, with the increasing need for high-density packaging, BGA or CSP has become the main trend for surface mounting technology, and therefore mechanical stress life for solder joints in BGA/CSP type packages has required. Reliability of BGA/CSP solder joints was evaluated with electric resistivity change of daisy chain pattern and stress-strain curve measured using strain gage attached on the surface of PCB under mechanical impact loading. In this report, applications of PCB Universal Testing Machine we have developed and experimental datum of SONY estimating dynamic behavior of mechanical stress in BGA/CSP solder joints are introduced.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.661-673
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• 2010

This paper presents recent developments in an extremely compact, wireless impedance sensor node (the WID3, $\underline{W}$ireless $\underline{I}$mpedance $\underline{D}$evice) for use in high-frequency impedance-based structural health monitoring (SHM), sensor diagnostics and validation, and low-frequency (< ~1 kHz) vibration data acquisition. The WID3 is equipped with an impedance chip that can resolve measurements up to 100 kHz, a frequency range ideal for many SHM applications. An integrated set of multiplexers allows the end user to monitor seven piezoelectric sensors from a single sensor node. The WID3 combines on-board processing using a microcontroller, data storage using flash memory, wireless communications capabilities, and a series of internal and external triggering options into a single package to realize a truly comprehensive, self-contained wireless active-sensor node for SHM applications. Furthermore, we recently extended the capability of this device by implementing low-frequency analog-to-digital and digital-to-analog converters so that the same device can measure structural vibration data. The compact sensor node collects relatively low-frequency acceleration measurements to estimate natural frequencies and operational deflection shapes, as well as relatively high-frequency impedance measurements to detect structural damage. Experimental results with application to SHM, sensor diagnostics and low-frequency vibration data acquisition are presented.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.123-132
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• 2012

Gas sensors has been used very differently that depending on following purposes; Automotive (exhaust gas, fuel mixture gas, oxygen, particulates), agriculture / food industry (fresh, stored, CO2, humidity, NH3, nitrogen oxide gas, organic gas, toxic gas emitted from pesticides and insecticides), industrial / medical (chemical gas, hydrogen, oxygen and toxic gases), military (chemical weapon), environmental measurements (CO and other air pollution consisting of sulfur and nitrogen gas), residential (LNG, LPG, butane, indoor air, humidity). The types of industrial toxic substances are known about 700 species and many of these exist in gaseous form under normal conditions. he multi-gas detection sensors will be developed for casualties that detect the most important and find easy three kinds of gases in marine plant; carbon dioxide(CO2), carbon(CO), ammonia(NH3). Package block consists of gas sensing device minor ingredient, rf front end, zigbee chip. Develope interworking technology between the sensor and zigbee chip inside a package. Conduct a performance test through test jig about prototype zigbee sensor module with rf output power and unwanted emission test. This research task available early address when poisonous gas leaked from large industrial site and contribution for workers' safety at the enclosed space.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.503-509
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• 2019

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.242-242
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• 2006

Increasingly complex tasks are performed by computers or cellular phone, requiring more and more memory capacity as well as faster and faster processing speeds. This leads to a constant need to develop more highly integrated circuit systems. Therefore, there have been numerous studies by many engineers investigating circuit patterning. In particular, PCB including module/package substrates such as FCB (Flip Chip Board) has been developed toward being low profile, low power and multi-functionalized due to the demands on miniaturization, increasing functional density of the boards and higher performances of the electric devices. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. The imprint technique. is one of promising candidates, especially due to the fact that the expected resolution limits are far beyond the requirements of the PCB industry in the near future. For applying imprint lithography to FCB, it is very important to control thermal properties and mechanical properties of dielectric materials. These properties are very dependent on epoxy resin, curing agent, accelerator, filler and curing degree(%) of dielectric materials. In this work, the epoxy composites filled with silica fillers and cured with various accelerators having various curing degree(%) were prepared. The characterization of the thermal and mechanical properties wasperformed by thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheometer, an universal test machine (UTM).