The constituent materials of RF coaxial connectors affect their mechanical, electrical and environmental properties. Therefore, during the initial design of the connector, the selection of the base material will determine how well the entire system unit will operate. As the designer of the RF coaxial connector must consider the material's characteristics, connection requirements, cost and other aspects of the requirements.

The base material is very important for RF transmission, it is the basis of the interruption-free circuit, which can prevent the circuit from being interfered. In this chapter, we will start with the structure of the RF coaxial connector, and specifically introduce the common materials and their characteristics of the parts that make up the connector.

Main body（Coupling nut、Barrel）

Contact pin（inner conduct）

Common metal materials

Among the components of RF coaxial connectors, the coupling nut, main body, contact pin, solder Ferrule and barrel are all metal products. Beryllium bronze, tin-phosphor bronze, brass and stainless steel are the common metal materials in RF coaxial connectors, each with its own advantages.

Beryllium bronze

(1) Beryllium bronze has good electrical and heat transfer properties, fatigue resistance, and strong corrosion resistance (except for ammonia, strong acids and alkalis).

(2) Good heat transfer properties and elasticity make it not to be melted in high temperature environment, and some other properties are not damaged by high temperature.

Beryllium bronze is commonly used in: jacks, flexible pins, conductors of outer interface, etc.

Tin-phosphor bronze

(1) The soft texture of this alloy material allows cold working (pressing, bending) to obtain starting stress.

(2) Because tin-phosphor bronze has certain soft characteristics, making it a substitute for various other copper alloys. When the production budget is insufficient or the electrical performance does not necessarily require the beryllium bronze, tin-phosphor bronze can be used instead.

Tin-phosphor bronze can be used for: larger jacks, flexible contacts or outer conductors.

Brass

(1) Brass is soft and easy to machine, known as "easy to cut brass", and beryllium bronze, brass has good thermal contact and electrical conductivity.

(2) It has a certain corrosion resistance to industrial, marine, agricultural, atmospheric and various oil pollution. It is usually electroplated with gold, silver, ternary alloy or nickel on its surface to improve its corrosion resistance and strength.

Brass is commonly used in: main body, housing, outer conductor and contact pin.

Stainless steel

(1) stainless steel is used in the connector industry where the material hardness requirements are high (such as the outer conductor).

(2) high stability, high melting point and excellent corrosion resistance, some connector shell parts (such as the shell) will use stainless steel.

Stainless steel is generally used as the base material, shell material or outer conductor material.

Aluminum alloys

(1) Aluminum is generally used in the form of alloys, the most typical being the "Anticorodal" alloy.

(2) Aluminum alloys are easy to work, have good electrical properties, heat transfer and self-protective properties (oxidation resistance), are light, and have good machinability. It is sometimes used as a substitute for some metals (brass, stainless steel).

Aluminum alloys are used for: tubes for protection and structural parts.

Comparison of common material properties

 Note: Relative values range from ++ (very good/very low price), + (better/low price), 0 (fair), - (poor) to -- (very poor/very high price).

*Contact resistance must be as small as possible (++ very low, perfect)

Insulator

Seals

Common plastic and rubber materials

 Among the RF coaxial connector materials, plastic and rubber materials is another important basic materials in addition to metal materials, insulators, seals are made of plastic and rubber materials.

PTFE

(1) Excellent thermal stability performance (-200°C-250°C) and non-flammable properties.

(2) Antistatic and anti-adhesive material with good electrical properties, almost unaffected by frequency and temperature. The elasticity coefficient is low, so it is often used as the material of insulators

PTFE is commonly used for: insulators, custom dust caps, and tools

PFA

(1) Compared with FEP, PFA has thermoplastic properties that can be used in injection molds and can be re-injected, and has good thermal stability and electrical properties at -200°C to 250°C.

(2) Compared with PTFE, it has better wear resistance and anti-adhesive properties.

(3) PFA is inert to most elements and climate and air have little effect on it.

PFA is commonly used in: insulators, cable jacket.

PEEK

(1) PEEK is a partially crystalline material with strong tensile strength, excellent thermal stability, high melting point (334°C), and good chemical inertness (except sulfuric acid). High corrosion resistance and high irradiation resistance.

(2) With self-extinguishing property, even without any flame retardant, it can reach 94V-0 grade of UL standard.

(3) It has good electrical insulation properties and maintains to a very high temperature range. Its dielectric loss is also very small in the case of high frequency.

PEEK is commonly used in: radiation shielding layer, insulator.

Silicone Rubber

In RF connections, rubber is generally used only as a gasket material.

The purpose of rubber gaskets for connectors is to insulate them from moisture and other contaminants, and they react only with acids.

Silicone rubber is used for flame retardant purposes.

Comparison of ordinary plastic and silicone rubber

Note: Relative values range from ++ (very good/very low price), + (better/low price), 0 (fair), - (poor) to -- (very poor/very high price).