Controlling coking pressure is one of the most important aspects of the cokemaking process, since excessive coking pressure increases the force needed for coke cake pushing and in some cases leads to operational problems such as hard pushes or "stickers," causing wall damage. Against this backdrop, we investigated the selective fine crushing of high coking pressure coal as a way to reduce coking pressure. It was shown on a laboratory scale that the fine crushing of high coking pressure coal increases the permeability of the plastic coal layer, which decreases coking pressure (internal gas pressure). Based on the basic investigation, we tried the fine crushing of high coking pressure coal at commercial cokemaking plants, and it was confirmed during a long-term commercial-scale experiment that the fine crushing of high coking pressure coal decreases coking pressure and decreases the maximum power current of coke pushing. Thus, the selective fine crushing of high coking pressure coal is a promising way to reduce coking pressure and prolong coke oven life.
Eutectic solder flip chip fabrication technology, through bumping to assembly process, has been developed. In bumping process, electroplating method and thick photo resist process could form eutectic solder bumps whose uniformity of height are less than 10 % within wafer. Eutectic solder flip chip assembly process, which includes bonding, cleaning and underfilling, has been also developed. Bonding process of eutectic solder indicates good self-alignment. The excellent rosin cleaning was achieved by the ultrasonic cleaning process with Techno Care @. In underfilling process, the underfill resin which can be applied to small stand-off have been chosen. Reliability tests for CSP and flip chip interconnection were carried out and confirmed the good reliability of fabrication process using eutectic solder flip chip technology.
This paper describes effective thin‐film structure barrier metals for use as eutectic solder
bumps. Shear strength and bump interconnection resistance were evaluated. The mutual
diffusion in metals was investigated. Barrier metal structures —Cu/Ti,Ni/Ti and
Cu/Cr—were evaluated after ageing. The Ni/Ti structure has good reliability
according to ageing test results. Pd is used for improvement of solder wettability and as an
oxidisation barrier. Consequently, it was concluded that a thin‐film Pd/Ni/
Ti barrier metal is suitable for use as eutectic solder bumps. The broken interfaces of the solder
bumps were analysed by scanning auger electron spectrometry. In the thin‐film
Cu/Ti structure, decrease in the shear strength is caused by three mechanisms, as
determined from the broken interface analysis. The three mechanisms are mixed metal
formation, Ti oxidisation and diffusion between barrier metals and Al. Furthermore, TCT and
PCT were carried out on these eutectic solder bumps to confirm the interconnection reliability.
The TCT and PCT results prove that electrical connection is stable.
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