Small size connectors play increasing role as miniaturisation trend grows

Paul Boughton

Miniaturisation is the basis of a vast range of products and applications in areas such as biomedical equipmentcommunications systemshomeland securitymedical diagnosticsdefenceindustrial and consumer products.

This kind of trend also applies to connectorsin the same way it has for integrated circuits during the past 40years.

Designers and integrators often require reduced sizelightweight interfaces between two or more electrical systems. This is especially relevant as the engineer will first focus on the design of the product itself before considering the necessary interconnects. Selecting the right connector is often one of the final steps of product developmentwhen time schedule is becoming most critical.

High precision manufacturing

Size limitation depends on manufacturing and technological possibilities. Connector manufacturing plants use advanced high speed CNC machines for the production of small metallic connector parts. 

Contacts are high precision manufactured; for high density connectorscontact diameters may be as small as 0.5millimetres with a 25micron tolerance. These contacts are quality controlled in order to sustain a few thousand cycles of connection/disconnection during their normal operating mode. The manufacturing and assembly of these contacts must be done by skilled technicians. 

Selection of the insulating material also has an influence on connector properties and dimensions. Usually the insulator is made of PEEK (Polyetheretherketon). PEEK is known for its good electrical insulation properties and high dielectric strength.

Selection of the plastic material for the insulator may also depend on chemical compatibilitymachinabilityas well as physical requirements (high temperature application or radiation resistance). It is not uncommon to have insulators made of PTFE for high voltagePA.6 or even fluororubber (FPM/FKM) resistant to hydrocarbons. Mechanical and electrical characteristics of thermoplastics can also be improved by adding glass fibres that increase radiation resistance and improve dielectric strength.

Size limitation also depends on the possibility to handle the connector with ease during connection and disconnection. In this instancePush-Pull connectors enable high panel density as well as easy manipulation. By simply pushingthe connector is safely connected without twisting of any kindthus saving space. The

Push-Pull mechanism is a mechanical latch that is released when the user pulls on the outer sleeve of the connector. This can be a significant advantage for applications where quick and easy disconnections are useful. In additionthis system offers safe connection; the locking mechanism cannot vibrate loose as threaded connectors are prone to. Some connectors such as the NIM-CAMAC standard have an overall outside diameter of only 6.4 mm.

Long term product availability

One of the engineer’s concerns during product designing is the product’s life cycle. Is the product designed to have a life cycle of ten years or more? If sohow is it possible to ensure that additional parts are available in the future? What happens if larger volumes with the same graphic design or technical specifications are required in the years to come? At LEMOthe company guarantees to supply connectorshowever specificover a very long period of time since most LEMO connectors are produced with standard components.

A few years agoLEMO electrical engineers developed a new range of connectors that increase pin density while saving panel space by providing a solution inspired by Sub-D connectors. This solution was designed with the Push-Pull latching system and made it possible to connect circular cables rather than flat ribbon cables. Instead of positioning the contacts in a spiral distributionas it is done for circular connectorthe rectangular connector with its ‘linear’ distribution enables positioning the connectors close to one another on the system.

Small size connectors can prove useful in various environmentsfor outside and indoor applications. These types of connectors are found in any system where lightweight and compact design is required. Small size connectors are used in professional RF transmitters/receiverscommunication networksresearch facilities such as universitiescommercial research institutes. In these cases the engineer is looking for small connector that can be patched easily. The sockets are usually placed on a panel and are manipulated every day. 

Otherwise reduced size connectors are used for aerospace applicationsin high tech environments such as laser machiningprecision nanotechnology equipmentrobots and industrial machines or even GPS equipment. Here the product designer requires reliable connections that can sustain harsh environments without deterioration.

Serge Buechli is Product Manager with LEMO SAEcublensSwitzerland.