This article discusses use of metal matrix composite materials in electronic packaging. Composites can have higher thermal conductivity than traditional materials, low thermal stress, and tailorable coefficients of thermal expansion. They can reduce weight by as much as 80% and size by as much as 65%. They can also be used in low-cost, net-shape fabrication processes. The silicon carbide content can be adjusted to differing percentages to vary the composite's coefficient of thermal expansion. Traditional microelectronic packaging materials used to achieve low coefficients of thermal expansion include blends of copper and tungsten or of copper and molybdenum, and a nickel–cobalt–iron alloy called Kovar, a trademark owned by CRS Holdings Inc., a subsidiary of Carpenter Technology Corp. of Wyomissing, Pennsylvania. A key firm involved in promoting pyrolytic graphite in packaging is Advanced Ceramics Corp. of Cleveland. An expert predicts that, in the future, many of these materials will also be used in the optoelectronics industry. This will be a new market for the materials, but one with enormous potential.
De Ruyter from the University of Groningen in the Netherlands has been studying nervous system of blowflies. These insects have extremely sophisticated visual and tactile perception that is much more sophisticated than our own. De Ruyter placed a tiny tungsten probe into the fly’s head, near one of its motion-sensitive neurons to understand motion control system. With the necessary second probe that acts as a ground (and allows for a current), a nearby oscilloscope feeds the air with an audible indication of voltage. When de Ruyter runs his hand across the fly’s field of vision, the oscilloscope’s output becomes loud and continuous, like old radio static. Davidowitz illustrated how sophisticated these sensory systems are and, therefore, why they would be studied in order to model sense and control systems. Roaches run—when they can—along a wall, with one antenna touching that wall for positioning information. This system checks, feeds information, and makes the control corrections for positioning 25 times a second.