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EET 110 - Survey of Electronics. Chapter 6 – Electric Connections. Objectives. Describe negative effects of poorly formed electric connections Properly remove insulation from a wire Corection install terminal-screw, crimp-on, and mechanical connectors. Explain the principles of soldering
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EET 110 - Survey of Electronics Chapter 6 – Electric Connections.
Objectives • Describe negative effects of poorly formed electric connections • Properly remove insulation from a wire • Corection install terminal-screw, crimp-on, and mechanical connectors. • Explain the principles of soldering • Properly insulate wire repairs. • Assemble, test, and install cables used as part of electronic interconnection systems.
Why have proper connections • Higher than normal resistance • Heat builds at poor connections • Potential danger due to heat - may ignite flammable materials (insulation) • Loss of power for ‘load’ • Example – poor starting power for automobile.
Wire connections • Insulation • PVC • Rubber • Other plastic • Wire strippers • Precision tool that avoids nicking the wire • Nick may weaken the wire integrity
Connections • Terminal Screw connections • Note direction of screw tightening • Crimp Terminals/splices • Butt connector • Mechanical connectors • Twist-on mechanical connectors • Lug connectors
Insulating repairs/bare wire • Plastic tape (electricians tape) • Heat shrink tubing • Heat level needed may vary • Percentage of shrink depends on product • Some types include silicon waterproofing • Requires heat gun or other heat source • Matches don’t work very well.
Soldering • Solder is a tin-lead allow (may have silver added) • Ratio of 60/40 is normal • Most have flux core • Flux cleans connection and allows solder to flow • Prevents oxidation • Resin is the only flux allowed for electrical connections • Soldering gun or iron • Gun for higher heat (100W or greater) • Pencil is recommended for electronic work (~27w)
Soldering • Soldering tip must be clean and ‘tinned’ to provide good heat transfer. • Note: Soldering involves melting metal and high temperatures. Fumes and spatter may be hazardous
Steps to a good solder connection • Make sure metals to be soldered are copper/brass and are clean and free of oil, grease or oxidation • Wire brush or emery cloth may be required • Note – MUST remove chrome plating. • Form a good mechanical connection first • Heat the joint, not the solder • Solder should flow and ‘wick’ into the joint. • Finished solder joint should be smooth and shiny.
Cable Connectors • IDC connections • Multi-wire ‘Insulation Displacement connections’ • Co-axial wire connectors • F-type • BNC • RCA
Other types of wire connections • Wire-wrap • Prototype boards • Solder-less boards • Fiber optic cable • May be a hazardous operation • Many are mechanical/chemical