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GLASS-TO-METAL SEALS
IntroductionComus International is now a world-wide supplier of hermetic glass-to-metal seal assemblies for electrical and electronic components and current feed-throughs. With over twenty years of experience in glass-to-metal seal technology and recent and ongoing development with our suppliers, Comus delivers the highest quality glass-to-metal seals at very competitive prices and with short lead times. Comus is capable of manufacturing transistor packages, quartz crystal packages, housings for photodiodes, hybrid packages, diode housings, battery and power feed-throughs, sensor packages, microwave packages, and many other custom designs. Typical applications include opto-electronics, telecommunications, automotive electronics, sensors, and tilt or tip-over switches. Common to all assemblies are excellent electrical insulation, high hermeticity, pressure resistance, corrosion resistance, high operating temperature, mechanical strength, solderability, easy final assembly (i.e. welding or wire bonding). The advantages of glass-to-metal seals include reliability, durability, and low cost; they remain the preferred choice over other options, such as plastics or ceramics. Comus is eager to meet your needs in this growing and dynamic industry. Compression Seals Compression seals are those in which the coefficient of thermal expansion of the header/seal body greatly exceeds that of both the glass and the electrode(s). The external metal component shrinks to form a compression ring around the glass. Assemblies are available in many combinations of materials, including: Header/Body: Cold Rolled Steel, Inconel, Stainless Steel Electrodes: 52 Alloy, Copper Cored 52 Alloy, 42 Alloy, 42-6 Alloy Glass: Alkali Barium, Lead Silicate, Potash Lead, Soda Lime Typical compression seals will withstand extreme temperatures, in some cases -454º F (-270º C) to 842º F (450º C) with no loss in integrity. Matched Seals Matched seals are those in which the coefficient of thermal expansion of the metal components and the glass are similar. The hermetic seal is typically made by forming a bond between the glass and the oxide created on the metal components prior to sealing. Assemblies are available in the following combinations of materials: Header/Body/Electrodes: Kovar, Tungsten, Molybdenum Glass: Borosilicate (Alkali, Barium, Soda, Potash) Matched seals are more susceptible to temperature excursions, and are not recommended for applications exceeding 85º F (-65º C) to 482º F (250º C). Matched seals are generally lighter in weight than compression seals, which may be advantageous, depending upon the application. Combination Seals If required, Comus can manufacture seals with mixed materials (i.e. Stainless Steel header, Molybdenum electrodes, and Alumina Borate glass). Contact Comus Engineering to discuss your particular application. Electrical Properties Standard tests performed by Comus include insulation resistance and hypot/breakdown voltage. Under normal conditions, insulation resistance ranges from 1010 to 1012Ohms. Breakdown voltage varies based on seal design, but, as a general rule, voltage can be safely estimated at 40 VAC/55 VDC per radial .001 of glass between header and electrode. Hermeticity Comus employs two helium mass spectrometer leak detectors to ensure hermeticity. Although our glass-to-metal seals typically test between 1.0 x 10-9 and 1.0 x 10-10, due to varying applications we guarantee that our seals will be hermetic to 1.0 x 10-8 Atm cc/sec (mbar l/s) He.Final FinishVirtually any single or multi layer plating scheme is available. Among the most common requirements are: Electroless Ni Good corrosion protection, good wire bonding, good solderability with flux, uniform thickness, good weldability Electrolytic Ni Good corrosion protection, good solderability, excellent pre-plate for Au Pure Au flash Improved solderability, protects against tarnish/oxidation Pure Au Good wire bonding, excellent solderability without aggressive flux Hard Au Wear protection for contacts, plugs, connectors Ag Excellent solderability, high electrical conductivity Sn Improved corrosion protection, very good solderability Cu Good conductivity, excellent pre-plate for AgFor more information, contact: ddecker@comus-intl.com FOR SPECIFIC INFORMATION, COMPLETE THIS FORM: |