Micro-cellular foaming technology draws attention due to the enhancement of mechanical strength, which has been considered as a weak point of current plastic foaming technology. Foam materials produced by this technology offer improved consistency and homogeneity of cell structure, which can result in products with superior properties and uniformity(1). Thus it is widely used for commercial purposes and its market is now growing significantly. However, since the foamed injection parts have swirl marks on its surface, this technology has limited uses such as interior products, in spite of its diverse merits. In this paper, we propose surface treatment of the mold as a way to remove the swirl mark. We injected simple shape specimens with PP and PC/ABS materials and measured the surface quality values such as roughness and gloss. Also we researched the foaming characteristics of both treated and untreated surface using SEM analysis.

Microcellular technology is an advanced foaming technique which uses inert gas as a foaming agent and brings many merits such as improved impact strength and toughness. Microcellular foaming was developed as a batch process but unfortunately, the time required for foaming is too long. Extrusion and injection molding are under development so that microcellular foaming may be profitably used in industry. In our research, we designed a controllable ratio of flow length to cavity thickness Lit mold for microcellular foaming and measured volume expansion as a function of Lit. We obtained uniformly distributed microcells about 30 pm in size and observed 30.1% volume expansion for Lit=20. Volume expansion data are necessary for designing a mold system that is proper for microcellular foam moldng.

One of the greatest problems facing electronics companies today is the difficulty of successfully transitioning from design to manufacturing. This problem is primarily the result of the combined effect of higher density printed circuit boards, an increase in the functional reliability of both components and assemblies, and an overall miniaturization of products and circuit boards. Additional requirements, such as mass production capabilities and lowering unit costs, require manufacturers to autosolder components onto printed circuit boards and significantly reduce the amount of hand or manual soldering. The design and manufacture of assemblies, which operate reliably at today's complexities, require unique capabilities to validate the design before manufacturing can begin. Computer simulation of circuit designs and manufacturing processes is much less expensive than prototyping. Simulation can uncover design errors before prototyping begins through highly accurate numerical analysis.