Microelectronic circuits, environmental

The method can successfully be used in analyses of impurities in metals and alloys, for estimation of minor elements in monomolecular films of oxide layers of Fe-Cr-Ni alloys, for detection of metal impurities in environmental pollution, for studying the depression of high-grade semiconducting materials and for analysis of the corrosion products of contact junction diodes used in microelectronic circuits. Much sophistication is desirable on the instrumental side so as to incorporate an automatic recording device to make an FR polarograph suitable for wider applications and common use. 

Crystal boules are sliced into wafers on which microelectronic circuits and power semiconductor devices are fabricated. An important use of the wafers is for infrared dectors for space, defense, and environmental applications. 

Due to their small feature sizes, microelectronic circuits need protection from environmental hazards such as mechanical damage and adverse chemical influences from moisture and contaminants. Several approaches are currently in use, for example, hermetic encapsulation of the device in sealed metal or ceramic enclosures, application of soft silicone gels as a cover over integrated circuitry, and encapsulation by transfer molding, which is the topic of this report. Both silicone resins and epoxy resins are used for this purpose. As the quality and performance of the epoxy encapsulants improved, the need for the generally more expensive silicone resins diminished. The present work is exclusively devoted to epoxy transfer molding compounds. 

Although adequate materials and devices are essential, successful manufacturing will require other capabilities as well. First, the process must have high yield, which implies low variability, and provide robust stability to environmental factors. To produce the envisioned products, there must be readily available electronic design tools that can adequately simulate both device and circuit performance. Although some of these computer-aided design tools are available from microelectronics technology, others must either be modified, because of the differences in the thin-hlm devices, or created anew because the devices have no equivalent (nanowires and nanotubes). 

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