김산하 교수

Since its invention in ancient times, relief printing, commonly called flexography, has been used to mass-produce artifacts ranging from decorative graphics to printed media. Now, higher-resolution flexography is essential to manufacturing low-cost, large-area printed electronics. However, because of contact-mediated liquid instabilities and spreading, the resolution of flexographic printing using elastomeric stamps is limited to tens of micrometers. We introduce engineered nanoporous microstruc

In this paper, the role of pad topography on material removal rate (MRR) in chemical-mechanical polishing (CMP) is investigated. First, based on the mechanics of pad/particle and particle/wafer sliding contacts at an asperity of the polishing pad a new MRR model is developed. The model is then extended to multi-asperity contacts, taking into account the statistics of the asperity heights. The single-asperity model reveals that the removal rate at relatively low pressure strongly depends on the p

Automated handling of microscale objects is essential for manufacturing of next-generation electronic systems. Yet, mechanical pick-and-place technologies cannot manipulate smaller objects whose surface forces dominate over gravity, and emerging microtransfer printing methods require multidirectional motion, heating, and/or chemical bonding to switch adhesion. We introduce soft nanocomposite electroadhesives (SNEs), comprising sparse forests of dielectric-coated carbon nanotubes (CNTs), which ha

Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser

In chemical-mechanical polishing (CMP), surface asperities of the polishing pad play a key role, for they transmit normal force and impart tangential motion to the hard, nano-scale abrasive particles in the slurry. It has been shown recently, however, that the soft pad asperities themselves often generate micro-scale scratches on the surfaces being polished. To mitigate scratching by pad asperities, therefore, topography control by flattening pad asperities has been proposed and experimentally v

Abstract Li‐metal is gaining attention as a next generation anode active material, of which the primary attribute is its energy density. However, Li dendrite formation is the primary challenge. Herein, a design strategy with increased structural dimensions and hierarchy for Li‐metal anode is investigated to stabilize the dendrite formation for extending the cycle life with high reversibility. For this, diverse structural current collectors (CCs) are fabricated by manipulating structural design i

Hybrid bonding enables the commercialization of ultra‐fine pitch high‐density 3D packages. Cu/SiO 2 hybrid bonding is the standard packing interface recently introduced in the industry. Herein, the Cu/polymer hybrid bonding interface beyond Cu/SiO 2 is proposed in order to have high compatibility for additional processes in the future. Ideally, polymers can provide excellent bonding strength and low permittivity, enabling high‐speed signal transmission with high reliability. To realize it, optim

Abstract Porous carbon nanoframeworks have attracted considerable interest for promising applications such as water purification, catalyst supports, gas adsorption, and energy storage owing to their high surface area and electrical conductivity. Traditional synthetic methods applied for porous carbon commonly involve a number of toxic organic solvents and post‐treatments, which are time‐consuming and energy inefficient. Herein, the authors report a facile synthetic method for generating atomical

Stacking semiconductor chips allows for increased packing density within a given footprint and efficient communication between different functional layers of the chip, leading to higher performance, improved speed, and reduced power consumption. In such vertical stacking, achieving homogeneous electrical and mechanical bonding between heterogeneous chips is crucial, which is termed Cu to Cu direct bonding (CCDB) technology. However, conventional CCDB required a high temperature of over 250 °C to

Miniaturization of polymeric robots leads to difficulties in actuation inside viscous media due to the increased surface drag on the diminutive robot bodies. Herein, agile underwater swimming of polymeric microrobots is presented with the investigation of correlation between the magnetic propulsion and viscous drag on the robot. The polymeric microrobots swim with pivoting and tumbling motions during underwater rotation by in‐plane rotation of two permanent magnets underneath the plane, which re

In chemical-mechanical polishing (CMP), as the rough polymer pad slides over patterned structures of metal interconnects and dielectrics the pad asperities themselves, though soft, may scratch the relatively hard layers. The fully plastically deformed pad asperities with high interfacial friction are the primary sources of pad scratching. In this paper, scratching of Cu/dielectric line structures by pad asperities is investigated. First, the scratching criteria and the scratch-regime maps, const

Multifunctional structural batteries promise advancements in structural energy storage technologies by seamlessly integrating load-bearing and energy-storage functions within a single material, reducing weight, and enhancing safety. Yet, commercialization faces challenges in materials processing, assembly, and design optimization. Here, we report a systematic approach to develop a carbon fiber (CF)-based structural battery impregnated with epoxy-based solid polymer electrolyte (SPE) via robust v