Seong-Dae Park

RF Front-End Passive Circuit Implementation Including Antenna for ZigBee Applications

This paper presents a front-end passive circuit module for ZigBee applications using low-temperature co-fired ceramic technology. The front-end part consists of an antenna, a bandpass filter, a switch, and two baluns. In antenna design, the solenoid shape is employed for reducing the size of the antenna, resulting in an overall size of 9times16.4times1.82 mm3 and a gain of -1.4 dBi. As for the filter, two types of filters are suggested. First, the lumped-type filter employing a high-Q spiral inductor has more than 20-dB attenuation at both stopbands, very near to the passband. Secondly, the semilumped-type filter adopting an edge coupled line and a loading capacitor provides a group delay of below 5 ns and is adequate for the full module structure due to the structure flexibility. A balun is evaluated using lumped components instead of a transmission line and, thus, it provides an insertion loss of only 0.3 dB and a phase difference of 180deg between balanced signals. Based on these components, an RF front-end module including attaching pads for an RF integrated circuit (IC) and baseband IC is implemented. In case of using the lumped-type filter, the insertion loss of the front-end module is 6.5 dB, and the group delay is below 7 ns. In case of adopting the semilumped-type filter, the insertion loss is 6.2 dB, and the group delay is below 4 ns. The overall size of the former and latter is 25.14times28.5times0.68 mm3 and 25.66times25.58times1.17 mm3, respectively

Fabrication and Characterization of Ag Nanoparticle Dispersed Polymer Nanofiber and Ag Nanofiber Using Electrospinning Method

Functional nanomaterial is expected to have improved capacities on various fields. Especially, metal nanoparticles dispersed in polymer matrix and metal nanofiber, one of the functional nanomaterials, are able to achieve improvement of property in the electric and other related fields. In this study...

Fabrication of multilayer interconnection materials and bonding film for high integration applications

To meet the demands for increased integration and multi functions for multilayer electronic components the related materials and process technique for layer-to-layer interconnection have to be developed together. Using nano-, micro-sized metal powders and epoxy resins conductive via pastes have been formulated. Via conductance was measured before and after solder floating(288 °C) to observe the change rate after thermal shock. Thermal conductivity of fabricated paste was evaluated by making disk-type pressed specimens. As the results, the electrical conductivities of tested pastes showed the values of about 10−5 Ωcm. Trimodal pastes showed better solder shock resistance thanbimodal pastes. Thermal conductivities over 15 W/mK were obtained from several paste compositions. Also regarding higher integration demands bonding film was developed. Composite material composed of epoxy based resin with inorganic fillers was used due to low process cost, good processability, and low temperature curability. As a result bonding film with glass transition temperature over 170 °C, peel strength above 7N/cm and fine patterning of line space width of 15 μm was fabricated.

Fabrication and characterization of thermally conducting laminate using spherical aluminum nitride powders and synthesized twin mesogenic epoxy oligomer

Thermally conducting insulation laminates with high peel strength as well as high thermal conductivity were fabricated by the addition of sintered spherical A1N powders as fillers into twin mesogenic epoxy matrix. A twin mesogenic epoxy oligomer based on biphenyl structure was synthesized. Bimodal or trimodal fillers were added to the synthesized epoxy resin with a curing agent and formed to an insulation laminate, and the thermal conductivity of the cured laminate was measured. Aluminum nitride powders having average size 50 and 10um were used as the bimodal fillers. In particular, 50um A1N powders are sintered spherical particles with narrow size distribution. In addition, 5um BN powders were used the third fillers. The thermal conductivity of the cured thermoset without fillers was over 0.236 W/m-K and that of the thermally conducting laminate reached about 12.55 W/m-K at 75vol% filler loading. Cu peel strength of about 16 N/cm was obtained by 90° peel method. The 20vol% BN-replaced composite showed the higher thermal conductivity of 15 W/m-K.

Photolithographic Properties of Photosensitive Ag Paste for Low Temperature Cofiring

후막 광식각 기술은 스크린 인쇄 등의 일반적인 후막공정에 노광 및 현상 등의 리소그라피 공정을 접목시킨 새로운 기술이다. 본 연구에서는 후막 광식각 기술을 이용하여 미세라인을 형성할 수 있는 저온동시소성용 Ag 페이스트를 개발하였다. 페이스트를 구성하는 Ag 분말과 폴리머, 모노머, 광개시제 등의 양을 조절하여 미세라인을 형성할 수 있는 최적 조성을 연구하였으며, 또한 노광량과 같은 공정변수가 미세라인 형성에 미치는 영향을 연구하였다. 실험결과 폴리머/모노머비, Ag 분말 중량비, 광개시제의 양 등이 미세라인의 해상도에 영향을 미치는 주요 인자임을 확인할 수 있었다. 개발된 감광성 Ag 페이스트를 저온동시소성용 그린 시트에 전면 인쇄한 후 건조, 노광, 현상, 적층, 소성 과정을 통하여, 소성 후 20 ㎛ 이하의 선폭을 가지는 후막 미세라인을 형성할 수 있었다.