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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Microelectronics and Packaging Society
Journal Basic Information
Journal DOI :
The Korean Microelectronics and Packaging Society
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Volume & Issues
Volume 22, Issue 4 - Dec 2015
Volume 22, Issue 3 - Sep 2015
Volume 22, Issue 2 - Jun 2015
Volume 22, Issue 1 - Mar 2015
Selecting the target year
Fabrication for Optical Layer and Packaging Technology of Optical PCB
Kim, Taehoon ; Huh, Seok-Hwan ; Jeong, Myung Yung ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 1~5
DOI : 10.6117/kmeps.2015.22.1.001
Recently, data throughput of smart electric devices increases dramatically. There is a great interest in a new technology which exceeds the limit of electrical transmission method. Optical PCB can supplement the weakness of electrical signal processing, the research for optical PCB is very active. In this paper, we propose the thermal imprint lithography process to fabrication optical layer of optical PCB and experiment to optimize the process conditions. We confirm process time, pressure, process temperature, demolding temperature and fabricate optical interconnection structure which has
tilted mirror surface for confirm the interconnection efficiency.
Recent Trends in Development of Ag Nanowire-based Transparent Electrodes for Flexible·Stretchable Electronics
Kim, Dae-Gon ; Kim, Youngmin ; Kim, Jong-Woong ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 7~14
DOI : 10.6117/kmeps.2015.22.1.007
Recently, advances in nano-material researches have opened the door for various transparent conductive materials, which include carbon nanotube, graphene, Ag and Cu nanowire, and printable metal grids. Among them, Ag nanowires are particularly interesting to synthesize because bulk Ag exhibits the highest electrical conductivity among all metals. Here we reviewed recently-published research works introducing various devices from organic light emitting diode to tactile sensing devices, all of which are employing AgNW for a conducting material. They proposed methods to enhance the stretchability and reversibility of the transparent electrodes, and apply them to make various flexible and stretchable electronics. It is expected that Ag nanowires are applicable to a wide range of high-performance, low-cost, stretchable electronic devices.
Inspection System using CIELAB Color Space for the PCB Ball Pad with OSP Surface Finish
Lee, Han-Ju ; Kim, Chang-Seok ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 15~19
DOI : 10.6117/kmeps.2015.22.1.015
We demonstrated an inspection system for detecting discoloration of PCB Cu ball pad with an OSP surface finish. Though the OSP surface finish has many advantages such as eco-friendly and low cost, however, it often shows a discoloration phenomenon due to a heating process. In this study, the discoloration was analyzed with device-independent CIELAB color space. First of all, the PCB samples were inspected with standard lamps and CCD camera. The measured data was processed with Labview program for detecting discoloration of Cu ball pad. From the original PCB sample image, the localized Cu ball pad image was selected to reduce the image size by the binarization and edge detection processes and it was also converted to device-independent CIELAB color space using
conversion matrix. Both acquisition time and false acceptance rate were significantly reduced with this proposed inspection system. In addition,
values of CIELAB color space were suitable for inspection of discoloration of Cu ball pad.
Bending Fatigue Reliability Improvements of Cu Interconnects on Flexible Substrates through Mo-Ti Alloy Adhesion Layer
Lee, Young-Joo ; Shin, Hae-A-Seul ; Nam, Dae-Hyun ; Yeon, Han-Wool ; Nam, Boae ; Woo, Kyoohee ; Joo, Young-Chang ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 21~25
DOI : 10.6117/kmeps.2015.22.1.021
Bending fatigue characteristics of Cu films and
width Cu interconnects on flexible substrates were investigated, and fatigue reliability improvement was achieved through Mo-Ti alloy adhesion layer. Tensile bending fatigue reliability of Cu interconnects is 3 times lower than that of Cu films, and even compressive bending fatigue reliability of Cu interconnects is 6 times lower than that of Cu films. From these results, mechanical crack formation could be fatal in Cu interconnects. With Mo-Ti adhesion layer, fatigue reliability of Cu films and interconnects were enhanced due to the increase of adhesion strength and the suppression of slip induced crack initiation.
Effect of Localized Recrystallization Distribution on Edgebond and Underfilm Applied Wafer-level Chip-scale Package Thermal Cycling Performance
Lee, Tae-Kyu ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 27~34
DOI : 10.6117/kmeps.2015.22.1.027
The correlation between crack propagation and localized recrystallization are compared in a series of cross section analyses on thermal cycled edgebond and underfilm material applied wafer level chip scale package (WLCSP) components with a baseline of no-material applied WLCSP components. The results show that the crack propagation distribution and recrystallization region correlation can explain potential degradation mechanisms and support the damage accumulation history in a more efficient way. Edgebond material applied components show a shift of damage accumulation to a more localized region, thus potentially accelerated the degradation during thermal cycling. Underfilm material applied components triggered more solder joints for a more wider distribution of damage accumulation resulting in a slightly improved thermal cycling performance compared to no-material applied components. Using an analysis on localized distribution of recrystallized areas inside the solder joint showed potential value as a new analytical approach.
Highly Reliable Solder ACFs FOB (Flex-on-Board) Interconnection Using Ultrasonic Bonding
Kim, Yoo-Sun ; Zhang, Shuye ; Paik, Kyung-Wook ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 35~41
DOI : 10.6117/kmeps.2015.22.1.035
In this study, in order to improve the reliability of ACF interconnections, solder ACF joints were investigated interms of solder joint morphology and solder wetting areas, and evaluated the electrical properties of Flex-on-Board (FOB) interconncections. Solder ACF joints with the ultrasonic bonding method showed excellent solder wetting by broken solder oxide layers on solder surfaces compared with solder joints with remaining solder oxide layer bonded by the conventional thermo-compression (TC) bonding method. When higher target temperature was used, Sn58Bi solder joints showed concave shape due to lower degree of cure of resin at solder MP by higher heating rate. ACFs with epoxy resins and SAC305 solders showed lower degree of resin cure at solder MP due to the slow curing rate resulting in concave shaped solder joints. In terms of solder wetting area, solder ACFs with
diameters and 30-40 wt% showed highest wetted solder areas. Solder ACF joints with the concave shape and the highest wetting area showed lower contact resistances and higher reliability in PCT results than conventional ACF joints. These results indicate that solder morphologies and wetting areas of solder ACF joints can be controlled by adjustment of bonding conditions and material properties of solder and polymer resin to improve reliability of ACF joints.
Ion Migration Failure Mechanism for Organic PCB under Biased HAST
Huh, Seok-Hwan ; Shin, An-Seob ; Ham, Suk-Jin ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 43~49
DOI : 10.6117/kmeps.2015.22.1.043
By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between
is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that
colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by
ion migration lead to a short failure between a pair of Cu nets.
Development of Copper Electro-Plating Technology on a Screen-Printed Conductive Pattern with Copper Paste
Eom, Yong-Sung ; Son, Ji-Hye ; Lee, Hak-Sun ; Choi, Kwang-Seong ; Bae, Hyun-Cheol ; Choi, Jeong-Yeol ; Oh, Tae-Sung ; Moon, Jong-Tae ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 51~54
DOI : 10.6117/kmeps.2015.22.1.051
An electro-plating technology on a cured isotropic conductive pattern with a hybrid Cu paste composed of resin matrix, copper, and solder powders has been developed. In a conventional technology, Ag paste was used to perform a conductive pattern on a PCB or silicon substrate. From previous research, the electrical conductive mechanism and principle of the hybrid Cu paste were concisely investigated. The isotropic conductive pattern on the PCB substrate was performed using screen-printing technology. The optimum electro-plating condition was experimentally determined by processing parameters such as the metal content of the hybrid Cu paste, applied current density, and time for the electroplating in the plating bath. The surfaces and cross-sections were observed using optical and SEM photographs. In conclusion, the optimized processing conditions for Cu electro-plating technology on the conductive pattern were a current density of
and a plating time of 20min on the hybrid Cu paste with a metal content of 44 vol.%. More details of the mechanical properties and processing conditions will be investigated in further research.
A Study on the Electrical Resistivity of Graphene Added Carbon Black Composite Electrode with Tensile Strain
Lee, T.W. ; Lee, H.S. ; Park, H.H. ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 55~61
DOI : 10.6117/kmeps.2015.22.1.055
Stretchable electrode materials are focused to apply to flexible device such as e-skin and wearable computer. Used as a flexible electrode, increase in electrical resistance should be minimalized under physical strain as bend, stretch and twist. Carbon black is one of candidates, for it has many advantages of low cost, simple processing, and especially reduction in resistivity with stretching. However electrical conductivity of carbon black is relatively low to be used for electrodes. Instead graphene is one of the promising electronic materials which have great electrical conductivity and flexibility. So it is expected that graphene added carbon black may be proper to be used for stretchable electrode. In this study, under stretching electrical property of graphene added carbon black composite electrode was investigated. Mechanical stretching induced cracks in electrode which means breakage of conductive path. However stretching induced aligned graphene enhanced connectivity of carbon fillers and maintained conductive network. Above all, electronic structure of carbon electrode was changed to conduct electrons effectively under stretching by adding graphene. In conclusion, an addition of graphene gives potential of carbon black composite as a stretchable electrode.
A Study on Optical Characteristic of Nano Metal Grid Polarizer Film with Different Deposition Thicknes
Kim, Jiwon ; Cho, Sanguk ; Jeong, Myung Yung ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 63~67
DOI : 10.6117/kmeps.2015.22.1.063
In this study, we demonstrate the change of optical characteristic by thickness of metal deposition on nano metal grid polarizer film fabrication. Nano metal grid polarizer film consists of aluminium grid polarizer layer on PET (Polyethylene phthalate) substrate. We aim at metal grid layer formation for the large nano wire grid polarizer fabrication. we draw process conditions of the nano metal grid polarizer film fabrication to improve transmittance and extinction ratio and Nano wire grid polarizer film (NWGP) film is fabricated with 140 nm pitch, 70 nm width, and 70 nm depth of metal grid on optimum design conditions. As a result, we get high optical properties of nano wire grid polarizer which is the maximum transmittance of 80% and the extinction ratio of
at 600 nm wavelength respectively.
Reflow Behavior and Board Level BGA Solder Joint Properties of Epoxy Curable No-clean SAC305 Solder Paste
Choi, Han ; Lee, So-Jeong ; Ko, Yong-Ho ; Bang, Jung-Hwan ; Kim, Jun-Ki ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 69~74
DOI : 10.6117/kmeps.2015.22.1.069
With difficulties during the cleaning of reflow flux residues due to the decrease of the part size and interconnection pitch in the advanced electronic devices, the need for the no-clean solder paste is increasing. In this study, an epoxy curable solder paste was made with SAC305 solder powder and the curable flux of which the main ingredient is epoxy resin and its reflow solderability, flux residue corrosivity and solder joint mechanical properties was investigated with comparison to the commercial rosin type solder paste. The fillet shape of the cured product around the reflowed solder joint revealed that the curing reaction occurred following the fluxing reaction and solder joint formation. The copper plate solderability test result also revealed that the wettability of the epoxy curable solder paste was comparable to those of the commercial rosin type solder pastes. In the highly accelerated temperature and humidity test, the cured product residue of the curable solder paste showed no corrosion of copper plate. From FT-IR analysis, it was considered to be resulted from the formation of tight bond through epoxy curing reaction. Ball shear, ball pull and die shear tests revealed that the adhesive bonding was formed with the solder surface and the increase of die shear strength of about 15~40% was achieved. It was considered that the epoxy curable solder paste could contribute to the improvement of the package reliability as well as the removal of the flux residue cleaning process.
A Study on the Parameters of Design for Warpage reduction of Passive components Embedded Substrate for PoP
Cho, Seunghyun ; Kim, Dohan ; Oh, Youngjin ; Lee, Jongtae ; Cha, Sangsuk ;
Journal of the Microelectronics and Packaging Society, volume 22, issue 1, 2015, Pages 75~81
DOI : 10.6117/kmeps.2015.22.1.075
In this paper, numerical analysis by finite element method and parameter design by the Taguchi method were used to reduce warpage of a two passive components embedded double side substrate for PoP(Package on Package). The effect of thickness of circuit layers (L1, L2) and thickness of solder resist (SR_top, SR_BTM) were analyzed with 4 variations and 3 levels(minimum, average and maximum thickness) to find optimized thickness conditions. Also, paste effect of solder resist on unit area of top surface was analyzed. Finally, experiments was carried out to prove numerical analysis and the Taguchi method. Based on the numerical and experimental results, it was known that circuit layer in ball side of substrate was the most severe determining deviation for reducing warpage. Buried circuit layer in chip side, solder resist and were insignificant effects on warpage relatively. However, warpage decreased as circuit layer in ball side thickness increased but effect of solder resist and circuit layer in chip side thickness were conversely.