SURFACE TECHNOLOGY
Surface: Their Nature, Roughness, and
Measurement
In manufacturing processes, surface and their properties are as important as the
bulk properties of the materials. A surface not only has a particular shape, roughness,
and appearance, but it also is a layer having properties that can be differ significantly
from those of the bulk material.
Surfaces are exposed to the environment and thus are subject to
environment attack. They also may came into contact with tools and dies (during
processing) or other components (during their service life). Consequently, their geometric
and material properties can significantly affect friction, wear, fatigue, corrosion, and
electrical and thermal conductivity.
Measuring and describing surface features and their characteristics
are among the most important aspect in manufacturing processes. The most common surface
roughness measurement is the arithmetic mean value. Profilometers are commonly used for
measuring surface roughness.
Tribology: Friction, Wear, and
lubrication
Friction and wear are among the most significant factors in
processing materials. Much progress has been made in understanding these phenomena and
identifying the factor that govern them. Among these factors are the affinity and solid
solubility of the two materials in contact, the nature of surface films, the presence of
contaminants, and the process parameters, such as load, speed, and
temperature.
A wide variety of metal working fluids is available for specific
applications, including oils, emulsion, synthetic solutions and solid lubricants. Their
selection and use require careful consideration of many factors in regard to workpiece and
die materials and the particular manufacturing process. These fluids have various
lubrication and cooling characteristics. Biological and environmental considerations are
also important factors.
Surface Treatment, Coating,
And Cleaning
Surface treatment is an important aspect of all
manufacturing processes. It is used to impart certain physical and chemical properties,
such as appearance and corrosion, friction, wear, and fatigue resistance. Several
techniques are available for modifying surface. They include mechanical working and
coating of surfaces, heat treatment, deposition, plating, and coatings such as enamels,
nonmetallic materials, and paints.
Clean surfaces are important to further processing and use of the
product, such as in coating, painting, and welding. Cleaning can have a significant
economic impact on manufacturing operations. Various mechanical and chemical cleaning
methods may be utilized.
Fibrication of Microelectronic
Devices
The microelectronics industry is rapidly developing. The
possibilities for new device concepts and circuit designs appear to be endless. Clearly
fibrication of microelectronic device s and integrated circuits involves many different
type of processes, most of which have been adapted from other fields of manufacturing.
After wafers have been prepared, they undergo repeated oxidation or film deposition,
lithographic, and etching steps to open windows in the oxide layer in order to access the
silicon substrate. When each of these processing cycle is complete, dopants are introduced
into various regions of the silicon structure by diffusion and ion implantation. After all
the doping regions have been established, metal layers interconnect devices, and the
completed circuit is packaged and made accessible through electrical connection. Finally,
the packaged circuit and other discrete devices are soldered to a printed circuit board
for final installation.
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