• Journal of the Semiconductor & Display Technology
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• v.15 no.4
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• pp.1-9
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• 2016

The warpage on mobile phone camera packages occurs due to the CTE(Coefficient of Thermal Expansion) mismatch between a thin silicon die and a substrate. The warpage in the optical instruments such as camera module has an effect on the field curvature, which is one of the factors degrading the optical performance and the product yield. In this paper, we studied the effect of die bonding epoxy on the package and optical performance of mobile phone camera packages. We calculated the warpages of camera module packages by using a finite element analysis, and their shapes were in good agreement showing parabolic curvature. We also measured the warpages and through-focus MTF of camera module specimens with experiments. The warpage was improved on an epoxy with low elastic modulus at both finite element analysis and experiment results, and the MTF performance increased accordingly. The results show that die bonding epoxy affects the warpage generated on the image sensor during the packaging process, and this warpage eventually affects the optical performance associated with the field curvature.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.176-179
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• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.2
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• pp.93-99
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• 2006

In this paper, we fabricated and evaluated polydimethylsiloxane(PDMS)-based flexible and implantable micro electrodes. The electrode patterning was carried out with the photolithography and chemical etching process after e-beam evaporation of 100 ATi and 1000 A Au. The PDMS substrate was treated by oxygen plasma using reactive ion etching(RIE) system to improve the adhesiveness of PDMS and metal layers. The minimum line width of fabricated micro electrode was 20 $\mu$m. After finished patterning, we did packaging with PDMS and then brought up the electrode's part about 40 $\mu$m with gold electroplating. The Hank's balanced salt solution(HBSS) test was carried out for 6 month for endurance of fabricated micro electrode. We carried out in-vivo test for the evaluation of biocompatibility by implanting electrodes under the ICR mouse skin for 42 days.

• ETRI Journal
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• v.35 no.4
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• pp.625-631
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• 2013

For the formation of solder bumps with a fine pitch of 130 ${\mu}m$ on a printed circuit board substrate, low-volume solder on pad (LVSoP) technology using a maskless method is developed for SAC305 solder with a high melting temperature of $220^{\circ}C$. The solder bump maker (SBM) paste and its process are quantitatively optimized to obtain a uniform solder bump height, which is almost equal to the height of the solder resist. For an understanding of chemorheological phenomena of SBM paste, differential scanning calorimetry, viscosity measurement, and physical flowing of SBM paste are precisely characterized and observed during LVSoP processing. The average height of the solder bumps and their maximum and minimum values are 14.7 ${\mu}m$, 18.3 ${\mu}m$, and 12.0 ${\mu}m$, respectively. It is expected that maskless LVSoP technology can be effectively used for a fine-pitch interconnection of a Cu pillar in the semiconductor packaging field.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.49-58
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• 2011

The workloads of facilities and laborers are important for the capacity planning in a factory. They are always referenced whenever a factory develops a new product, increases the production quantity and makes a plan of new investment. There are many measuring methods for estimating the workload effectiveness of facilities and laborers. In this paper, various measuring methods including survey, work sampling, micro-motion study, data gathering from ERP system and simulation, are analyzed for comparing the accuracy of workload. This case study is conducted in a Korean company that produces semiconductor parts like leadframe and packaging substrate.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.79-84
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• 2017

The solar cells should be protected from the moisture and oxygen in order to sustain the properties and reliability of the devices. In this research, we prepared the protection films on the flexible plastic substrates by spray coating method using organic-inorganic hybrid solutions. The protection characteristics were studied depending on the various process conditions (nozzle distance, thicknesses of the coatings, film structures). The organic-inorganic solutions for the protection film layer were synthesized by addition of $Al_2O_3$ ($P.S+Al_2O_3$) and $SiO_2$ ($P.S+SiO_2$) nano-powders into PVA (polyvinyl alcohol) and SA (sodium alginate) (P.S) organic solution. The optical transmittances of the protection film with the thicknesses of $5{\mu}m$ showed 91%. The optical transmittance decreased from 81.6% to 73.6% with the film thickness increased from $78{\mu}m$ to $178{\mu}m$. In addition, the protective films were prepared on the PEN (polyethylene naphthalate), PC (polycarbonate) single plastic substrates as well as the Acrylate film coated on PC substrate (Acrylate film/PC double layer), and $Al_2O_3$ film coated on PEN substrate ($Al_2O_3$ film/PEN double layer) using the $P.S+Al_2O_3$ organic-inorganic hybrid solutions. The optimum protection film structure was studied by means of the measurements of water vapor transmittance rate (WVTR) and surface morphology. The protective film on PEN/$Al_2O_3$ double layer substrate showed the best water protective property, indicating the WVTR value of $0.004gm/m^2-day$.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.65-71
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• 2016

In this study, Antimony Tin Oxide (ATO) ion storage layer and $TiO_2$ working electrode were fabricated using Nano Particle Deposition System. NPDS is the cutting-edge technology among the dry deposition methods. Accelerated particles are deposited on the substrate through the nozzle using NPDS. The thicknesses for coated layers were measured and layer's morphology was acquired using SEM. The fabricated electrochromic cell's transmittance was measured using UV-Visible spectrometer and power source at 630 nm. As a result, the integrated electrochromic/DSSC hybrid system was successfully fabricated as an energy harvesting system. The fabricated electrochromic cell was self-operated using DSSC as a power source. In conclusion, the electrochromic cell was operated for 500 cycles, with 49% of maximum transmittance change. Also the photovoltaic efficiency for DSSC was measured to be 2.55% while the electrochromic cell on the integrated system had resulted in 26% of maximum transmittance change.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.83-89
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• 2015

In this paper, we propose a fabrication technique for enhanced electrical properties of piezoelectric thick films with excellent patterning property using sol-infiltration and a direct-patterning process. To achieve the needs of high-density and direct-patterning at a low sintering temperature (< $850^{\circ}C$), a photosensitive lead zirconate titanate (PZT) solution was infiltrated into a screen-printed thick film. The direct-patterned PZT films were clearly formed on a locally screen-printed thick film, using a photomask and UV light. Because UV light is scattered in the screen-printed thick film of a porous powder-based structure, there are needs to optimize the photosensitive PZT sol infiltration process for obtaining the enhanced properties of PZT thick film. By optimizing the concentration of the photosensitive PZT sol, UV irradiation time, and solvent developing time, the hybrid films prepared with 0.35 M of PZT sol, 4 min of UV irradiation and 15 sec solvent developing time, showed a very dense with a large grain size at a low sintering temperature of $800^{\circ}C$. It also illustrated enhanced electrical properties (remnant polarization, $P_r$, and coercive field, $E_c$). The $P_r$ value was over four times higher than those of the screen-printed films. These films integrated on silicon wafer substrate could give a potential of applications in micro-sensors and -actuators.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.2
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• pp.25-30
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• 2018

Sn-Pb solder has been used in automotive electronics for decades. However, recently, due to the environmental and health concerns, some international environmental organizations such as the end-of-life vehicle (ELV) enacted legislation banning of the Pb usage in automotive electronics. For this reason, many studies to develop and promote Pb-free soldering have been significantly reported. Meanwhile, because of flexibility and lightweight, flexible printed circuit boards (FPCBs) have been increasingly used in automotive electronics for lightweight to improve fuel efficiency and space utilization. Although the properties of lead-free solders for automotive electronics have been widely studied, there is a lack of research on the reliability performance of the lead-free solder joint on FPCB under user conditions. This study reported the properties of solder joints between Pb-free solders such as Sn3.0Ag0.5Cu, Sn0.7Cu and Sn0.5Cu0.01Al (Si), and various FPCBs finished with organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG). To evaluate on joint properties and reliabilities with different solder compositions and surface-finishing materials, pull strength test, thermal shock test, and bending cycle test were performed and analyzed. After the bending cycle test of solder joint on OSP-finishing, the fractures were occurred in solder and the lifetime of Sn3.0Ag0.5Cu solder joint was the longest.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.17-22
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• 2004

The microwave dielectric properties of $CaZrO_3$ ceramics with addition of $CaTiO_3$ were studied. The effect of glass addition on the low-temperature sintering and microwave dielectric properties of $CaZrO_3-CaTiO_3$ ceramics were also evaluated to develop the materials for functional substrates of low-temperature co-fired ceramics. When $10-20 wt\%$ of lithium borosilicate glass was added, the sintering temperature of the $CaZrO_3-CaTiO_3$ ceramics decreased from $1450^{\circ}C$ to below $900^{\circ}C$. As the $T_f$ of glass frits and $CaZrO_3$ are slightly negative and that of $CaTiO_3$ is significantly positive, zero $T_f$ could be realized by mixing an appropriate amount of $CaTiO_3$ with $CaZrO_3$. The $CaZrO_3-CaTiO_3$ ceramics sintered at $875^{\circ}C$ with $15wt\%$ glass frits showed the relative density of $98\%$, permittivity of 23, quality factor of 2500 GHz, and temperature coefficient of resonant frequency of $ -3 ppm/^{\circ}C$.