• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1436-1440
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• 2007

Beryllium copper has been known to be an important material for the various fields of industry because it can be used for mechanical and electrical/electronic components that are subjected to elevated temperatures (up to $400^{\circ}C$ for short times). Blade type tip for probing the cells of liquid crystal display(LCD) was fabricated using beryllium copper foil. The dry film resist was employed as a mask for patterning of the blade type tip. The beryllium copper foil was etched using hydrochloric acidic iron-chloride solution. The concentration, temperature, and composition ratio of hydrochloric acidic iron-chloride solution affect the etching characteristics of beryllium copper foil. Nickel with the thickness of $3{\mu}m$ was electroplated on the patterned copper beryllium foil for enhancing its hardness, followed by electroplating gold for increasing its electrical conductivity. Finally, the dry film resist on the bridge was removed and half of the nickel was etched to complete the blade type tip.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.8-11
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• 1994

Disposal of hazardous ions in the aqueous streams is a significant industrial waste problem.. Waste streams from electronics, electroplating, and photographic industries contain metal ions such as copper, nickel, zinc, chromium(IV), cadmium, aluminum, silver, and gold, amongst others in various aqueous solutions such as sulfates, chlorides, fluorocarbons, and cyanides. Typical plating solutions having similar compositions are listed in Table 1. Spent process streams in catalyst manufacturing facilities also contain precious metals such as Ag, Pt, and Pd. Developing an effective recovery process of these metal ions for reuse is important.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.25.1-25.1
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• 2011

Over the past few decades, metallic nanoparticles (NPs) have been of great interest due to their unique mesoscopic properties which distinguish them from those of bulk metals; such as lowered melting points, greater versatility that allows for more ease of processability, and tunable optical and mechanical properties. Due to these unique properties, potential opportunities are seen for applications that incorporate nanomaterials into optical and electronic devices. Specifically, the development of metallic NPs has gained significant interest within the electronics field and technological community as a whole. In this study, gold (Au) pads for surface finish in electronic package were developed by inkjet printing of Au NPs. The microstructures of inkjet-printed Au film were investigated by various thermal treatment conditions. The film showed the grain growth as well as bonding between NPs. The film became denser with pore elimination when NPs were sintered under gas flows of $N_2$-bubbled through formic acid ($FA/N_2$) and $N_2$, which resulted in improvement of electrical conductance. The resistivity of film was 4.79 ${\mu}{\Omega}$-cm, about twice of bulk value. From organic anlayses of FTIR, Raman spectroscopy, and TGA, the amount of organic residue in the film was 0.43% which meant considerable removal of the solvent or organic capping molecules. The solder ball shear test was adopted for solderability and shear strength value was 820 gf (1 gf=9.81 mN) on average. This shear strength is good enough to substitute the inkjet-printed Au nanoparticulate film for electroplating in electronic package.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.58-64
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• 2006

In this study, we describe a low-temperature wafer-level thermocompression bonding using electroplated gold seal line and bonding pads by electroplating method for RF-MEMS devices. Silicon wafers, electroplated with gold (Au), were completely bonded at $320^{\circ}C$ for 30 min at a pressure of 2.5 MPa. The through-hole interconnection between the packaged devices and external terminal did not need metal filling process and was made by gold films deposited on the sidewall of the throughhole. This process was low-cost and short in duration. Helium leak rate, which is measured to evaluate the reliability of bonded wafers, was $2.7{\pm}0.614{\times}10^{-10}Pam^{3}/s$. The insertion loss of the CPW packaged was $-0.069{\sim}-0.085\;dB$. The difference of the insertion loss between the unpackaged and packaged CPW was less than -0.03. These values show very good RF characteristics of the packaging. Therefore, gold thermocompression bonding can be applied to high quality hermetic wafer level packaging of RF-MEMS devices.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.259-267
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• 2002

We present a novel 3D fabrication method with single X-ray process utilizing an X-ray mask in which a micro-actuator is integrated. An X-ray absorber is electroplated on the shuttle mass driven by the integrated micro-actuator during deep X-ray exposures. 3D microstructures are revealed by development kinetics and modulated in-depth dose distribution in resist, usually PMMA. Fabrication of X-ray masks with integrated electrothermal xy-stage and electrostatic actuator is presented along with discussions on PMMA development characteristics. Both devices use $20-\mu\textrm{m}$-thick overhanging single crystal Si as a structural material and fabricated using deep reactive ion etching of silicon-on-insulator wafer, phosphorous diffusion, gold electroplating, and bulk micromachining process. In electrostatic devices, $10-\mu\textrm{m}-thick$ gold absorber on $1mm{\times}1mm$ Si shuttle mass is supported by $10-\mu\textrm{m}-wide$, 1-mm-long suspension beams and oscillated by comb electrodes during X-ray exposures. In electrothermal devices, gold absorber on 1.42 mm diameter shuttle mass is oscillated in x and y directions sequentially by thermal expansion caused by joule heating of the corresponding bent beam actuators. The fundamental frequency and amplitude of the electrostatic devices are around 3.6 kHz and $20\mu\textrm{m}$, respectively, for a dc bias of 100 V and an ac bias of 20 VP-P (peak-peak). Displacements in x and y directions of the electrothermal devices are both around $20{\;}\mu\textrm{m}$at 742 mW input power. S-shaped and conical shaped PMMA microstructures are demonstrated through X-ray experiments with the fabricated devices.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.77-84
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• 2006

Surface roughness and wafer-level thickness distribution of the non-cyanide Au bumps were characterized with variations of the electroplating current density and the bath temperature. The Au bumps, electroplated at $3mA/cm^{2}\;and\;5mA/cm^{2}$, exhibited the surface roughness of $80{\sim}100nm$ without depending on the bath temperature of $40^{\circ}C\;and\;60^{\circ}C$. The Au bumps, electroplated with $8mA/cm^{2}$ at $40^{\circ}C\;and60^{\circ}C$, exhibited the surface roughness of 800nm and $80{\sim}100nm$, respectively. Wafer-level thickness deviation of the Au bumps became larger with increasing the current density from $3mA/cm^{2}\;to\;8mA/cm^{2}$. More uniform thickness distribution of the Au bumps was obtained at a bath temperature of $60^{\circ}C$ than that of $40^{\circ}C$.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.57-64
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• 2000

As integrated circuits become more complex, the number of I/O connections per chip grow. Conventional wire-bonding, lead-frame mounting techniques are unable to keep up. The space saved by shrinking die size is lost when the die is packaged in a huge device with hundreds of leads. The solution is bumps; gold, conductive adhesive, but most importantly solder bumps. Virtually every semiconductor manufacturer in the world is using or planning to use bump technology fur their larger and more complex devices. Several wafer-bumping processes used in the manufacture of bumped wafer. Some of the more popular techniques are evaporative, stencil or screen printing, electroplating, electrodes nickel, solder jetting, stud bumping, decal transfer, punch and die, solder injection or extrusion, tacky dot process and ball placement. This paper will discuss the process steps for bumping wafers using these techniques. Critical cleaning is a requirement for each of these processes. Key contaminants that require removal are photoresist and flux residue. Removal of these contaminants requires wet processes, which will not attack, wafer metallization or passivation. research has focused on enhanced cleaning solutions that meet this critical cleaning requirement. Process parameters defining time, temperature, solvency and impingement energy required to solvate and remove residues from bumped wafers will be presented herein.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.1
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• pp.51-59
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• 2000

As integrated circuits become more complex, the number of I/O connections per chip grow. Conventional wire-bonding, lead-frame mounting techniques are unable to keep up. The space saved by shrinking die size is lost when the die is packaged in a huge device with hundreds of leads. The solution is bumps; gold, conductive adhesive, but most importantly solder bumps. Virtually every semiconductor manufacturer in the world is using or planning to use bump technology for their larger and more complex devices. Several wafer-bumping processes used in the manufacture of bumped wafer. Some of the more popular techniques are evaporative, stencil or screen printing, electroplating, electroless nickel, solder jetting, stud humping, decal transfer, punch and die, solder injection or extrusion, tacky dot process and ball placement. This paper will discuss the process steps for bumping wafers using these techniques. Critical cleaning is a requirement for each of these processes. Key contaminants that require removal are photoresist and flux residue. Removal of these contaminants requires wet processes, which will not attack, wafer metallization or passivation. Research has focused on enhanced cleaning solutions that meet this critical cleaning requirement. Process parameters defining time, temperature, solvency and impingement energy required to solvate and remove residues from bumped wafers will be presented herein.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2187-2193
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• 2002

We present a novel method for 3D microfabrication with LIGA process that utilizes a deep X-ray mask in which a micro-actuator is integrated. The integrated micro-actuator oscillates the X-ray absorber, which is formed on the shuttle mass of the micro-actuator, during X-ray exposures to modify the absorbed dose profile in X-ray resist, typically PMMA. 3D PMMA microstructures according to the modulated dose contour are revealed after GG development. An X-ray mask with integrated comb drive actuator is fabricated using deep reactive ion etching, absorber electroplating, and bulk micromachining with silicon-on-insulator (SOI) wafer. 1mm $\times$ 1 mm, 20 $\mu$m thick silicon shuttle mass as a mask blank is supported by four 1 mm long suspension beams and is driven by the comb electrodes. A 10 $\mu$m thick, 50 $\mu$m line and spaced gold absorber pattern is electroplated on the shuttle mass before the release step. The fundamental frequency and amplitude are around 3.6 kHz and 20 $\mu$m, respectively, for a do bias of 100 V and an ac bias of 20 $V_{p-p}$ (peak-peak). Fabricated PMMA microstructure shows 15.4 $\mu$m deep, S-shaped cross section in the case of 1.6 kJ $cm^{-3}$ surface dose and GG development at 35$^{\circ}C$ for 40 minutes.

• Journal of the Korean institute of surface engineering
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• v.54 no.1
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• pp.1-11
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• 2021

Porous dendrite structure AuCu alloy was formed using a hydrogen bubble template (HBT) technique by electroplating to improve the catalytic performance of gold, known as an excellent oxygen reduction reaction (ORR) catalyst in alkaline medium. The rich Au surface was maximized by selectively electrochemical etching Cu on the AuCu dendrite surface well formed in a leaf shape. The catalytic activity is mainly due to the synergistic effect of Au and Cu existing on the surface and inside of the particle. Au helps desorption of OH- and Cu contributes to the activation of O2 molecule. Therefore, the porous AuCu dendrite alloy catalyst showed markedly improved catalytic activity compared to the monometallic system. The porous structure AuCu formed by the hydrogen bubble template was able to control the size of the pores according to the formation time and applied current. In addition, the Au-rich surface area increased by selectively removing Cu through electrochemical etching was measured using an electrochemical calculation method (ECSA). The results of this study suggest that the alloying of porous AuCu dendrites and selective Cu dissolution treatment induces an internal alloying effect and a large specific surface area to improve catalyst performance.