Wire termination options in ms/mg/vg/5015 circular connectors

Author: Sachin Rai

MIL-C 5015 circular connectors, commonly called ‘MS Connectors’ and ‘VG/MG’ connectors, are widely used since they provide the dual benefit of providing a highly reliable electrical connection at a relatively low cost. Once the number of interconnection points and the type of circular connector to be used has been decided, the other major decision that electrical system designers have to make is the type of wire termination for the connectors.

The following is a summary of the wire termination options available:

SOLDER TERMINATION:

  • Widely used in Defense and Industrial applications. If soldering is done properly the termination can be very robust and secure.
  • Can be used for a wide range of wire sizes – from AWG 20 (0.5 sqmm) to AWG 0 (50 sqmm)
  • Soldering is an inexpensive form of wire termination since it only requires solder wire and an appropriate soldering iron.
  • However, soldering has to be done by a trained user. Dry soldering is a common issue that is faced. Any spillage of solder flux or solder on the outside surface of contacts or on the insulator can lead to electrical shorting.
  • Solder termination is also relatively more time consuming, particularly for high density insert arrangements were a large number of contacts are present over a small area

CRIMP TERMINATION:

  • Used widely in Railway and Industrial Applications
  • Crimp termination can also be used for wire sizes ranging from AWG 20 (0.5sqmm) to AWG 0 (50 sqmm), but only with an appropriate crimping tool.
  • It is a very quick way to terminate wires into contacts, and is therefore preferred for high volume applications or when a large number of high density connectors have to be used
  • Since crimp contacts are supplied loose, the wire termination can be done independently, and insertion into the connector done during the time of mounting the connector on the panel or completion of the cable assembly. This is often a convenient way to complete a cable harness in a speedy manner.
  • If the correct equipment is available, crimping does not require as much skill as solder termination
  • However, an important point for consideration is that crimping requires an initial investment in a crimping tool (which is expensive for larger size pneumatic tools), and in an insertion and extraction tool for the contacts. This cost is generally only justified if the volumes are high

PCB TERMINATION:

  • MS /MG /VG / 5015 connectors can also be terminated directly onto a PCB
  • PCB termination contacts have a long narrow projection which is inserted into holes on the PCB, followed by soldering
  • PCB termination is limited to size 16AWG and size 12AWG contacts
  • Mounting of the connector directly on the PCB helps users eliminate the use of multiple wires – one for each connection – that would otherwise have to be used
  • PCB termination is usually done with specific PCB contacts that have a long projection of a smaller diameter than the rest of the contact. However, customers can even terminate solder/crimp termination contacts onto a PCB – but it requires larger holes on the PCB, and consequently is not possible for high density insert arrangements since the wall thickness of the PCB between the holes would become too small

SCREW TERMINATION:

  • In screw termination contacts, a tapped cross-hole and grub screw is provided on each contact so that on tightening of the grub screw, the wire gets terminated into the contact
  • This type of termination is available in 12AWG and 8AWG contact sizes
  • Screw termination is an easy way of terminating wires, but the termination is not as robust as solder or even crimp termination
  • Screw termination in circular connectors cannot be used for very high density connectors, since the allen key used for tightening the grub screw needs to be able to access each contact from the side

As explained above, the MS/MG/VG/5015 type of circular connectors can have various types of wire termination for the contacts. The decision on which to go for should take into account various factors such as wire size, number of connectors, type of application, skill of the operator, among others.