MIL-R-5757J
6.6 Intermetallic contact. The finishing of metallic areas to be placed in intimate contact by assembly presents a special problem, since intermetallic contact of dissimilar metals results in electrolytic couples which promote corrosion through galvanic action. To provide the required corrosion protection, intermetallic couples are restricted to those permitted by MIL-HBK-889.
6.7 Tin whisker growth. The use of alloys with tin content greater than 97 percent, by mass, may exhibit tin whisker growth problems after manufacture. Tin whiskers may occur anytime from a day to years after manufacture and can develop under typical operating conditions, on products that use such materials. Conformal coatings applied over top of a whisker-prone surface will not prevent the formation of tin whiskers. Alloys of 3 percent lead, by mass, have shown to inhibit the growth of tin whiskers. For additional information on this matter, refer to ASTM-B545 (Standard Specification for Electrodeposited Coatings of Tin).
6.8 Fixturing losses. It is known that there is inherent resistance in sockets, wiring, etc.. The qualifying activity will evaluate the manufacturer's system to determine conformance to specification requirements.
6.8 Glossary. The definitions listed below are not a complete glossary of relay terminology, but rather are intended as definitions of the technical terms as applied within the specification.
Adjunct sealant: Any hydrocarbon or silicon material used on the exterior of the unit to improve the hermeticity of a hermetically sealed relay.
Bifilar winding: Two or more windings with the wire of each winding alongside the other, matching turn for turn;
may be either inductive or noninductive.
Bounce time: The time interval between first make of the contact until the uncontrolled making and breaking of the contact ceases.
Chatter, contact: Externally caused, undesired vibration of mating contacts during which there may or may not be actual physical contact opening. If there is no actual opening but only a change in resistance, it is referred to as dynamic resistance.
Coil: One or more windings on a common form.
Contacts: The current-carrying parts of a relay that open or close electrical circuits.
Contact, bifurcated: A forked or branched, contacting member so formed or arranged, as to provide dual contacting.
Contact, closed: A normally-closed contact with the relay released is a closed contact. A normally-open contact with the relay operated is a closed contact.
Contact, open: A normally-closed contact with the relay operated is an open contact. A normally-open contact with the relay released is an open contact.
Contact arrangement: The combination of contact forms that make up the entire relay switching structure. Contact bounce: Intermittent opening of contacts after initial closure due to contact impact.
Contact force: The force exerted by a movable contact against a mating contact when the contacts are closed. Contact gap: The distance between a pair of mating relay contacts when the contacts are open.
Contact weld: A contact failure due to fusing of closed contacts, resulting in their failure to open.
Cycle, relay: A relay cycle is defined as a relay pickup and dropout, (one opening and one closure of a set of contacts). Therefore, a cycle consists of two operations.
Degassing: A process of thermally cleaning a relay (at elevated temperatures) to drive off harmful gasses. Degassing is usually performed using vacuum pumps.
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