Traditionally conductor materials in hermetic high-temperature and high-pressure connectors have been chosen based on the coefficients of thermal expansion as related to glass-sealing materials. This was required to maintain the integrity of the brittle glass seal. When manufacturing glass to metal sealed hermetic connectors, extreme temperatures must be considered to ensure full compression of the glass during firing.
Without the constraint of matching thermal expansion coefficients in glass seals, conductor materials can be chosen to fit the application rather than the method of manufacture. Automatic screw machines fabricate conductors from a wide variety of materials.
High-precision equipment and rigorously controlled raw material allow standard tolerances on the order of 0.0015 in. (0.00381 cm) total. The pin of a reliable connector should have uniform, consistent size in order to ensure proper contact force with the spring-finger socket. This allows full interchangeability among mating pins and sockets without variation in contact resistance. Several standard sizes are readily produced. Sizes are numbered to correspond with the American Wire Gage (AWG) standard wire sizes. The following table represents the male pin diameter.
Greene, Tweed utilizes four-way split sockets, unless size dictates moving to a two-way split socket, designed to assure uniform contact under vibration. Nickel-plated, brass cover sleeves protect in most applications.Standard sockets produced to properly engage these pin diameters will have the following load characteristics. The minimum contact force is characterized by the amount of load the socket will retain using the smallest possible male pin diameter. This extraction force is measured using an Ametek Accuforce® III digital force gauge.
Gold plating produces mating contacts with the minimal contact resistance and removes the possibility of corrosion. A ductile nickel underplate minimizes contact resistance and provides excellent adherence to the gold.
In a completely nonmagnetic environment the nickel underplate can be replaced with a copper strike. In the case of certain stainless steels, a copper strike precedes nickel underplate. Unless otherwise specified, a 50 µin thick gold plate will be used per AMS 2422.
End terminations of the conductor may be specified as shown below with pins, sockets, solder cups, eyelets, hooks, crimp barrels, etc., or any combination.