Insulated metal substrates (IMS) are gaining ground in electronics applications thanks to their high thermal conductivity and low cost. However, the organic dielectrics (such as epoxy or polyimide based material) traditionally used on IMS are limited by their maximum operating temperature, generally to below 150–200 °C. Thus in high temperature applications manufacturers are restricted to using expensive inorganic substrates such as alumina (Al2O3), aluminium nitride (AlN) or silicon nitride (Si3N4). A cost-effective IMS with an inorganic dielectric would be an attractive alternative for high temperature electronics. Cambridge Nanotherm has developed an electrochemical process for building inorganic dielectric ceramic onto a metal base. Nanotherm ceramic material is nanocrystalline alumina with a grain size of 20 to 60 nanometres. This grain size plays a critical role in providing the dielectric layer with its unique combination of properties such as high thermal conductivity (6–7 W/mK), high dielectric strength (>50 V/um) and formability when applied on thin, foil-type substrates. The Nanoceramic layer can be built from 3 to 50 microns thick, depending on the breakdown voltage required. This avoids excessive dielectric thickness that unnecessarily increases the thermal resistance of the system. The electric circuit is built onto the ceramic surface using either PVD metal sputtering followed by galvanic metal build up or conventional thick film processing. The result is a cost-effective, easy to process and use inorganic substrate with a thermal conductivity around 150 W/mK and a maximum working temperature above 350 °C. This paper will present an overview of the key electrical and thermal properties of Nanoceramic aluminium substrates and their manufacturing process. Potential use in the thermal management of high temperature electronic devices will be discussed with reference to some applications.

Many high strength aluminium engineering alloys cannot be joined by brazing because they either degrade ol melt at the temperature at which commercially available aluminium brazes are used. A brazing process suitable for joining aluminium engineering alloys has been developed employing two novel low melting point brazes. The brazes are available as ductile foil preforms. The process is fluxless and no post-joining cleaning treatments are necessary. The aluminium components and the brazing foil require a simple chemical treatment before use. The brazing process is tolerant and can be satisfactorily implemented by heating to a temperature of 510-550 degrees C, maintained for a period of 5-45 min, in either vacuum or a furnace chamber that is purged continuously with nitrogen gas. The joints exhibit high strength and adequate resistance to corrosion for most applications. Some promising new applications for aluminium brazing technology based on this new process are described. (C) 1995 The Institute of Materials.

Each year, several billion CMOS image sensors are manufactured to meet the growing demand for cameras in electronics products, notably camera phones, laptops (web cams) and now TVs. Fabricating device packages at the wafer-level provides economic advantage over discrete approaches since the materials and process costs are shared among the good die on the wafer, which can number many thousands for small die. Wafer-level packages also have the technical advantages of smaller dimensions, shorter interconnects and more consistent part-to-part performance. This article discusses the use of wafer-level packages, which satisfy the requirements.

A new software-enhanced lens that combines a special fixed lens design with an algorithm to process the images produced by the specialty lens is discussed. The lens uses the optical rays to provide an intensity distribution on the camera sensor with required features including predefined compensation, distortion or robust point-spread function behavior. The software-enhanced optical zoom lens offers advantages across the zoom range such as for a zoom magnification of 1x, the algorithm has to compress details in the central portion of the field of view, where magnification and resolution are increased by the software-enhanced lens. The benefit offered by a new software-enhanced lens is that the height of the lens stack is extensively smaller than the height required for achieving the same magnification with a mechanically moving zoom apparatus that leads to a much shorter camera module and thinner camera phone. The lens presents a distorted image with enhanced magnification and resolution in the central region.

Increasing demand from consumers to integrate camera modules into electronic devices, such as cell phones, has driven the cost of camera modules down very rapidly. Now that most cell phones include at least one camera, consumers are starting to ask for better image quality - without compromising on the cost. Wafer level optics has emerged over the past few years as an innovative technology enabling simultaneous manufacturing of thousands of lenses, at the wafer level. Using reflow-compatible materials to manufacture these lenses permits a reduction in the cost and size of camera module, thus answering the market demand for lowering the cost. But what about image quality? The author will present image quality analysis that was conducted for both VGA and megapixel camera resolutions. Comparison between conventional camera modules and wafer level camera modules shows wafer level technology brings equivalent, if not better, image quality performance compared to conventional camera modules.