• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.71.2-71.2
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.167-168
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• 2011

• Korean Journal of Materials Research
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• v.18 no.3
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• pp.117-122
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• 2008

Micro-sized bumps on a multi-layered build-up PCB were fabricated by pulse-reverse copper electroplating. The values of the current density and brightener content for the electroplating were optimized for suitable performance with maximum efficiency. The micro-bumps thus electroplated were characterized using a range of analytical tools that included an optical microscope, a scanning electron microscope, an atomic force microscope and a hydraulic bulge tester. The optical microscope and scanning electron microscope analyses results showed that the uniformity of the electroplating was viable in the current density range of $2-4\;A/dm^2$; however, the uniformity was slightly degraded as the current density increased. To study the effect of the brightener concentration, the concentration was varied from zero to 1.2 ml/L. The optimum concentration for micro-bump electroplating was found to be 0.6 ml/L based on an examination of the electroplating properties, including the roughness, yield strength and grain size.

• Laser Solutions
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• v.15 no.3
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• pp.7-10
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• 2012

Dimensions (line/space) of circuits in IC substrates for high-end chips (e.g. CPU, etc.) are anticipated to decrease as small as $10{\mu}m/10{\mu}m$ in 2014. Since current etch-based circuit-patterning processes are not able to address the urgent requirement from industry, laser-based circuit patterning processes are under active research in which UV laser is used to engrave embedded circuits patterns into IC substrates. In this paper, we used a nanosecond UV laser to directly fabricate embedded circuit patterns into IC substrates with/without ceramic powders. In experiments, we engraved embedded circuit patterns with dimensions (width/depth) of abut $10{\mu}m/10{\mu}m$ and $6{\mu}m/6{\mu}m$ into the IC substrates. Due to the recoil pressure occurring during ablation, the circuit patterning of the IC substrates with ceramic powders showed the higher ablation rate.

• Korean Journal of Materials Research
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• v.19 no.3
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• pp.151-155
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• 2009

Micro-scale copper bumps for build-up PCB were electroplated using a pulse-reverse method. The effects of the current density, pulse-reverse ratio and brightener concentration of the electroplating process were investigated and optimized for suitable performance. The electroplated micro-bumps were characterized using various analytical tools, including an optical microscope, a scanning electron microscope and an atomic force microscope. Surface analysis results showed that the electroplating uniformity was viable in a current density range of 1.4-3.0 A/$dm^2$ at a pulse-reverse ratio of 1. To investigate the brightener concentration on the electroplating properties, the current density value was fixed at 3.0 A/$dm^2$ as a dense microstructure was achieved at this current density. The brightener concentration was varied from 0.05 to 0.3 ml/L to study the effect of the concentration. The optimum concentration for micro-bump electroplating was found to be 0.05 ml/L based on the examination of the electroplating properties of the bump shape, roughness and grain size.