김형수 교수

A novel thiophene-thienylenevinylene copolymer is synthesized and evaluated for use in organic field-effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin-film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. Detailed facts of importance to specialist readers are publ

We measured and demonstrated the great advantages of embedded film capacitors in reducing power/ground inductive impedance and the suppression of SSN at frequencies up to 3 GHz for high-performance multilayer packages and PCBs. Eight-layer test PCBs were fabricated, and their inductive power/ground network impedances were measured as a function of film thickness, via distribution, and combined use with discrete decoupling capacitors, using a two-port self-impedance measurement method. This succe

A dynamic self-assembling process is reported which involves drying a droplet of positively charged colloidal suspension on a flat negatively charged hydrophilic surface. This extremely simple method affords lines of colloidal particles with regular 1.5-4.5 microm line spacing and smaller than 2 microm line width over a broad surface area. The ordered region diffracts light to display an iridescent appearance and generates first-order diffraction spots when illuminated by a He-Ne laser. A period

Physical or covalent adsorption of surface-active block or random copolymers consisting of anchoring units and functional units onto solid surfaces yields polymeric self-assembled monolayers (PSAMs) with designed chemical and morphological structures and functionalities. This tutorial review provides an overview of PSAMs derived from various types of copolymers. It also discusses design principles for PSAMs to tune interfacial and surface interactions of materials for potential applications.

Recently, electromagnetic interference (EMI) and radiated emission has become a major problem for high-speed circuit and package designers, and it is likely to become even severe in the future. However, until recently, designers of integrated circuit and package did not give much consideration to electromagnetic radiated emission and interference in their designs. Decoupling capacitors have been mostly used to reduce the power/ground bounce of high-speed digital system and boards. However, there

The authors introduced a model of simultaneous switching noise (SSN) coupling between the power/ground plane cavities through cutouts in high-speed and high-density multilayer pack-ages and printed circuit boards (PCBs). Usually, the cutouts are used in multilayer plane structures to isolate the SSN of noisy digital circuits from sensitive analog circuits or to provide multiple voltage levels. The noise-coupling model is expressed in terms of the transfer impedance. The proposed modeling and ana

As total system bandwidth increased, memory industry has been imposed to satisfy its requirements. At last, innovative next generation memory named high bandwidth memory (HBM) with extremely fine micro-bump pitch of its bottom die is introduced for terabytes/s bandwidth graphics module. To establish HBM based graphics module, it becomes essential to fabricate silicon interposer due to its capability to process narrow signal width and space. Silicon based HBM interposer becomes the key solution t

A proposal is presented for an effective extraction method for crosstalk model parameters of high-speed interconnection lines. In the extraction procedure, mutual capacitance and mutual inductance of the coupled interconnection lines are extracted based on S-parameter measurement, time-domain-reflectometry (TDR) measurement and subsequent microwave network analysis. The extraction method is useful for characterizing homogeneous guiding structures, where the propagation of coupled transverse elec

Abstract Yttrium oxysulfide upconverting phosphor particles can absorb infrared light and emit dopant‐dependent visible phosphorescence. This unique optical property has been used for particle‐based immunoassay applications. In this study, upconverting phosphor particles were encapsulated with a functionalized polymer (carboxylated polystyrene) shell layer via several approaches, which included the following: (1) the physical adsorption of the carboxylated polystyrene polymer onto the phosphor s

Significant reduction of power/ground inductive impedance and SSN suppression was successfully demonstrated by using embedded capacitor film in high performance package and PCB up to 3GHz frequency range. The reduction of the inductance impedance and SSN are acquired by the help of reduced via inductance in the embedded film capacitor.

Abstract Gold particles were nucleated on functionalized (i.e., sulfonate or imidazole groups) latex particle surfaces. Gold ions were associated with the functional groups present on the surface of the latex particles by metal‐ligand formation and were then reduced to nucleate gold particles on the particle surface. The use of imidazole groups favored the metal‐ligand formation more effectively compared with sulfonic acid groups, so gold nucleation was investigated on the surface of imidazole‐f

We have thoroughly investigated and experimentally demonstrated the great advantages of thin film embedded capacitors of high dielectric constant in reducing power/ground impedance and suppressing SSN and radiated emission up to a frequency of 1 GHz. About 10 dB or more suppression of the radiated emission was acquired for a wide frequency range, including high-numbered harmonics of the clock frequency, by using the thin film embedded capacitor of high dielectric constant.

While multiple-input multiple-output (MIMO) system gives many advantages to wireless communication, the complexity of multiple RF chains gives a burden to the system. Antenna selection is introduced as a technique to reduce the burden. On the transmit antenna selection scheme, the exhaustive search for optimal antenna set quickly becomes impractical as adopting more antennas. To reduce complexity for searching, we propose an efficient transmit antenna selection method. We first make a threshold

Radio-over-fiber (RoF)-based front haul architecture has attracted considerable attention for fifth-generation (5G) cellular systems because of its cost effectiveness, however, it is susceptible to harmonic frequency distortion and intermodulation products (IMs) arising from the nonlinearity of the laser diode. To overcome this limitation, an asymmetric electrical predistortion method, using a single Schottky diode with nonlinear characteristics similar to those of a laser diode, was previously

In this paper, we have demonstrated the accurate measurement of power/ground impedance with embedded film capacitors, using the two-port self-impedance measurement technique. With the two-port self-impedance measurement, it was found that the unwanted series contact resistance between the microprobe and the contact pad on the PCB and package was successfully eliminated.