Hermetic glass

B. Ziaie, J.A. von Arx, M.R. Dokmeci, and K. Najafi, A hermetic glass-silicon micropackage with high-density on-chip feedthroughs for sensors and actuators. J. Microelectromechan. Sys. 5, 66—177 (1996). 

In order to prevent the exchange of ambient air and gas phases in long-term storage, vials, stoppers, boxes, and bags, used as specimen containers and packaging must be made of nonporous materials and sealed hermetically. Glass, plain metal, synthetic rubber, silicon, polyethylene, and plastic-coated aluminum foils are common for this purpose. The packaging material must be dried and desorbed of contaminated gas before use. 

Glass solders and sealants for glass-to-glass joining and hermetic glass-to-metal sealing... 

Classic gels (C) were obtained mixing the TEOS-HjO mixtures with the solution containing the modified TBOT precursor, in the presence of 50% vol. ethanol, at 298 K. Gelling took place in hermetic glass containers, at 323 K, after periods of time ranging between 1 and 5 dt s. 

Terminal tab Epoxy clear Hermetic glass to metal seal... 

Care must be exercised in handling, lead attachment, etc., to prevent mechanical damage to hermetic glass seal feedthroughs. Loss of hermeticity will ultimately make the battery completely inoperable. 

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). 

Insulators. Molded plastics serve as insulators for multicontact connectors and glass is used in hermetic connectors intended for bulkhead... 

Hermetic Seal—an impervious seal made by the fusion of metals of ceramics, which prevents the passage of gas or moisture. The seal can be achieved by brazing, soldering, welding, fusing glass or ceramics. 

Hermetically sealed electrical devices must be verified by a testing laboratory to meet mechanical abuse and to withstand aging and exposure to expected chemicals. Devices potted with common silicones and similar materials by an end user or even a manufacturer, without testing, and devices merely provided with O-rings seldom meet acceptable criteria. Normally, hermetically sealed devices must be sealed through metal-to-metal or glass-to-metal fusion. Many electrical relays, switches, and sensors are available as hermetically sealed devices for common oil and gas producing facility applications. Hermetically sealed devices are often desirable to protect electrical contacts from exposure to salt air and other contaminants. 

Hermetically Sealed. A hermetically sealed device shall be sealed against the entrance of an external atmosphere and the seal shall be made by fusion, e.g., soldering, brazing, welding, or the fusion of glass to metal. 

Moisture in halocarbon circuits will be indicated by the colour trace on the sight glass, where this is fitted. Immediate action is required, especially with a hermetic or semi-hermetic compressor, before damage is caused. The drier should be changed and the... 

The cell is hermetically sealed. This is performed by a glass connection from the / "-alumina ceramic tube to a ring of a-alumina. Metal parts are connected to the a -alumina by thermocompression bonding and the metal parts are either con-... 

Speculum alchymiae = The true glass of alchemy / by Roger Bacon — The admirable efficacy and almost incredible virtue of true oyl, which is made of sulphur-vive, set on fire and called commonly oyl of sulphur per campanem / G. Starkey — Sundry new and artificial remedies against famine / written by Sir H. Platt — The tomb of Semiramis hermetically sealed. 

The arrangement is then placed in a furnace, heated to 800°C, and the pressure decay test is repeated. The setup can be subjected to thermal cycles with pressure decay tests at room temperature and at 800°C. A good hermetic seal, however, will not show any pressure decay at a low pressure differential. The results of one series of tests using a glass composite material that has a glass transition temperature (Tg) of about 700°C, at 5 psi are shown in Figure 5.10. The combination of pressure and thermal cycle tests showed that the seal is capable of withstanding the pressure... 

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