Electrical Connector Caps, Inserts, and Covers

Electrical connector caps, inserts and covers are designed to provide mechanical protection for electrical connectors. They are available in many shapes and sizes to accommodate different types of electrical connections. For example, covers for D-subminiature connectors are shaped like the letter D while covers for Bayonet Neill Concelman (BNC) connectors are round. Typically, caps have male threads and plugs have female threads. Caps fit over the ends of electrical connectors, enclosing the pins and contacts as well as the mating surface. Plugs fit inside the ends of electrical connectors, enclosing the pins or contacts but leaving the mating surface exposed. Some electrical connector caps, inserts and covers are designed to dissipate electrostatic charges. Others provide an electrical shield. Common types of electrical connector caps, plugs and covers include devices for D-subminiature socket or pin connectors with 9, 15, 25, 37, or 50 contacts. Covers for 50-pin and 68-pin small computer system interface (SCSI) electrical connectors are also available.   

Electrical connector caps, inserts and covers are made from a variety of metals and plastics. Aluminum is a common industrial metal with good electrical and thermal conductivity, high reflectivity, and resistance to oxidation. Stainless steel is chemical and corrosion resistant and can have relatively high pressure ratings. Ethyl vinyl acetate (EVA) is a transparent thermoplastic elastomer that remains flexible at low temperatures and resists cracking. Polyethylene (PE) is a semi-crystalline, whitish, semi-opaque thermoplastic that is soft, flexible and tough - even at low temperatures - with outstanding electrical properties but poor temperature resistance. Polypropylene (PP) exhibits excellent cold flow, bi-axial strength, and yield elongation properties. Polyetheretherketone (PEEK), another thermoplastic, provides excellent chemical and fatigue resistance and thermal stability. Vinyl exhibits good flexibility and chemical resistance, while polyamides provide strong pressure ratings. Paper caps are frequently used for high-temperature applications that may degrade plastic caps or plugs.

Electrical connector caps, inserts and covers are made of rubbers, silicones, and proprietary products for specialized applications. Natural rubber and styrene butadiene (SBR) provide good resistance to petroleum hydrocarbons, oils, and fuels. Silicones are polymers in which organic groups are bonded to silicone atoms in chains of inorganic siloxanes. They provide excellent electrical insulation, water repellency, and heat and cold weather resistance. It maintains its natural lubricity at a wide range of end-use temperatures and is both resilient and resistant to creep. Electrical connector caps, plugs and covers made from other proprietary materials are also available.