Connection technology (electrical engineering)
The connection technique in the field of electrical engineering consists of a number of technologies with which an electrical contact is established (permanently or removably). The contact is the safe electrical connection between two conductors .
Detachable electrical connections
- Plugs (plug connectors), some with spring contacts and cable lugs
- Clamps , for example
Conditionally detachable electrical connections
- Soldering, soldering ( threading technology , circuit boards , free wiring)
- Wire wrapping technique (wrapping, Eng. Wire wrap , or "wrapping")
- IDC terminal , IDC technology
- Press-in contacts, press-in technology
Permanent electrical connections
- Welds ( welding )
- Bond connections, bonding (cold pressure welding)
- Adhesive connection (with conductive adhesive )
- Press connection , crimp , riveted
- Butt connector ( cable lugs , ferrule , crimping )
In addition to the division into detachable and non-detachable connections, there is another division into the areas of soldered connections and solderless connections, which is widespread in technology .
The electrical connection technology is an elementary component for the production of electrical assemblies and ultimately electrical devices and ensures the connection of the components to one another as well as the connection technology to the outside world. A large number of electrical contact points can also be found within components, for example in integrated circuits .
Depending on the layout in the design phase, the solvability or the conditional solvability is provided for larger and more expensive systems. In the case of simple electronic circuits, the connection method chosen is more based on the cheapest manufacturing method for the manufacturer and hardly takes into account the ability to be repaired. The trend is increasingly towards the exchange of entire modules or units.
From a reliability point of view , junctions are potential problem areas:
- they are potential local elements (corrosion);
- they can loosen due to changes in temperature or creeping ;
- they can loosen due to mechanical wear and tear with frequent closure and separation ;
- spontaneous oxide and other layers cause an increased contact resistance already during manufacture or later;
- Soldered connections in particular are at risk from fatigue fractures in connection with mechanical stress.
To check the quality , validation tests are often carried out on new assemblies in this context. The preparatory work for electronic devices ( control units ) in motor vehicles is particularly thorough . Temperature shock tests with 1000 changes between −40 ° C and +125 ° C are common there.
Since copper or copper alloys are often used for power lines in electrical engineering, but after a short time an oxide layer with increased resistance forms on "open" copper, plug-in connection points or switching contacts in particular are protected by additional surface coatings. Tin plating and coatings with silver, gold, nickel, platinum and other metals are common here. These metal coatings are often produced using electroplating technology.
Aluminum is particularly difficult to contact because it spontaneously forms hard oxide layers in air. It has therefore disappeared again as a conductor material for house installation, although press connections are reliable. However, it is used in energy transmission; it must be cleaned and / or greased using screws or presses before connecting.
The term contact resistance was coined by Werner von Siemens around 1860. The problem of the safe contact with detachable connections ( commonly known as : loose contact ) is therefore almost as old as the electrical engineering itself.