ASTM B542-04 pdf free.Standard Terminology Relating to Electrical Contacts and Their Use.
contact，screw—a contact fabricated with an external thread.contact,sliding an elecrre eoidin1.”its primary function during sliding.contact，spring a contact system in which one piece ofmaterial is used for both the driving spring and electriccontact.contact,static an electrn .juneon nseparation and connection.contacts,wiping contaicts tnat nave o.during opening or closing.contact wipe relative tangential motion between contactingsurfaces that occurs during the normal course of contactclosure.corona (discharge) a selfsustaining discharge characterizedby highly asymmetrical electric fields with the result thationization predominantly occurs near the electrode with thehigher potential gradient.dark (or ‘Townsend) discharge a discharge which may ormay not be self-sustaining.It is characterized by a uniformfield, current in the microampere range, and a nonluminousinter electrode space.
electromigration—(1) Current-induced atomic diffusion in asolid metal due to electron momentum and the potentialgradient,(2) electrochemical process of growth of metallicpath across an insulating surface under imposed electricfield.DISCUssIoN The solid state process may cause significant materialtransport in regions of high current density such as a-spots in contacts.In devices with electrical contacts， the electrochemical process mayform shorts between conductors under certain environmental condi-tions.film resistance-that portion of the contact re sist hoth of thedue to the presence of contaminants on one or both of the contact members.fine transfersee material transfer，bridgc.fritting (A-fritting) an electric breakdown between matingmetallic contacts，separated by an insulating film,whichoccurs when the field strength exceedsapproximately1 000 000 V/cm. Metallic bridges are produced through thefilm if the fritting voltage is above the contact meltingvoltage.fritting voltage the voltage at which fritting occurs.glow discharge a self-sustaining discharge characterized byessentially symmetrical electrodes,low current density, anda high cathode fall of about 200 V.
high resistance contact resistance exceeding an arbitrary,specified limit.inrush current a transient current that exists at the instant ofcontact closure and persists for a relatively short time.insertion force the force required to mate two connectorhalves.material transfer a general term to describe the carry-overof material from one electrical contact to another.ASTM B542 pdf download.