Hermetic cans, corrosion control

The contact ends of printed circuit boards are copper. Alloys of nickel and iron are used as substrates in hermetic connectors in which glass (qv) is the dielectric material. Terminals are fabricated from brass or copper from nickel, for high temperature appHcations from aluminum, when aluminum conductors are used and from steel when high strength is required. Because steel has poor corrosion resistance, it is always plated using a protective metal, such as tin (see Tin and tin alloys). Other substrates can be unplated when high contact normal forces, usually more than 5 N, are available to mechanically dismpt insulating oxide films on the surfaces and thereby assure metaUic contact (see Corrosion and corrosion control). 

The first installation for nitride powder production was a universal SHS equipment including three various hermetic reactors SHS-30 (301 capacity), SHS-20 (201 capacity), and SHS-8.0 (81 capacity). The SHS-30 reactor is equipped with an automated lock. The reactors can be equipped with the systems controlling the combustion rate and temperature, with personal computer (PC) supervising the parameter changes. They are made of corrosion-resistant refractory steel and can withstand up to 30 MPa. Within carbide or nitride production, this steel is neither carbonized nor nitrided. The temperature on the reactor walls does not exceed 300-500 °C. For laboratory experiments, a reactor of 2.51 (SHS-2.5) is mainly used. 

Ceramic Hermetic-Packaged Microelectronics The meaningful differences between CHP and PEM devices in the context of corrosion are the following (a) A1 wires are used instead of Au so that the prime corrosion vulnerability is the ultrafme 25- im wire instead of the bondpad, (b) the internal environment can theoretically be controlled such that a benign environment will always exist, and (c) the cavity containing the die is unfilled so encapsulation defects are not needed as sites for water condensation. To achieve the environmental control advantage, three factors must be satisfied (a) a hermetic seal, (b) a clean and dry assealed internal... 

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