Related Knowledge of SMA RF Connector

As an important electrical connection component, SMA radio frequency connector plays a pivotal role in various electronic equipment, instruments, and electronic information systems. After decades of development, RF coaxial connectors have formed an independent and complete professional system and become an important part of the connector family.

In addition to pursuing the two key technical projects of miniaturization and high frequency, electrical connector manufacturers are also constantly improving the multi-function and reliability of their products. Nowadays, RF connectors not only serve as signal connection, but also have signal processing functions, such as filtering, phase modulation, mixing, attenuation, detection, and amplitude limiting. In addition, low standing wave, low loss, large capacity, high power and ease of installation have also become the goals of manufacturers' efforts.

The basic parameters of SMA connector

Insulation resistance refers to the resistance value exhibited by applying voltage to the insulating part of the connector, so that leakage current is generated in or on the surface of the insulating part. It is mainly affected by factors such as insulation material, temperature, humidity, and contamination. The insulation resistance value provided on the connector sample is generally an index value under standard atmospheric conditions. Under certain environmental conditions, the insulation resistance value may drop to an unused degree.

1. Safety parameters

Insulation resistance refers to the resistance value exhibited by applying voltage to the insulating part of the connector, so that leakage current is generated in or on the surface of the insulating part. It is mainly affected by factors such as insulation material, temperature, humidity, and contamination. The insulation resistance value provided on the connector sample is generally an index value under standard atmospheric conditions. Under certain environmental conditions, the insulation resistance value may drop to an unused degree. Also pay attention to the test voltage value of the insulation resistance. Depending on the insulation resistance (MΩ) = voltage (V) applied to the insulator (V)/leakage current (μA), applying different voltages will have different results. In the test of milspec connectors, the applied voltage is generally 10V, 100V, and 500V.

2. Withstand voltage

Withstand voltage is the critical voltage that can withstand higher than the rated voltage within a specified time between the mutually insulated parts of the contact pair or between the insulated parts and the ground without causing breakdown. It is mainly affected by contact spacing and creep age distance and geometry, insulator materials, ambient temperature and humidity, and atmospheric pressure.

3. Flammability

Any connector is inseparable from current when it is working, so there is a risk of fire. Therefore, the connector is required not only to prevent ignition, but also to self-extinguish in a short time once it ignites and catches fire. When choosing, pay attention to choosing electrical connectors that use flame-retardant, self-extinguishing insulating materials.

Termination method of SMA RF connector

1. Wiring type

Wiring is divided into welding wire type connectors and crimp style connectors. The wire bonding type is to weld the center conductor and the cable shielding layer. The crimping type is to crimp the center conductor and the cable shielding layer, and the crimping type has good efficiency and high performance. The wire bonding is stable and reliable. Generally, the crimping type is used for flexible cables, and the welding type is used for semi-flexible cables and half steel cables.

2. Connect to PCB (printed circuit board)

When the connector is to be connected to the PCB, it is mostly through hole or SMT. In order to facilitate tinning, the metal connecting with the PCB is mostly gold-plated or tin-plated.

3. Panel type

Panel connectors are mostly installed on the chassis to connect internal and external devices. The flange type is to drill holes on the main panel of the connector for installation and fixation. Another type is to machine screws on the main body of the connector and fix them with the screws. Such connectors often require waterproof functions.

The development trend of SMA RF connectors will have the following characteristics:

1. Miniaturization: With the miniaturization of the overall system, the size of the RF connector is getting smaller and smaller.
2. High frequency.
3. Multi-function: In addition to the role of a bridge, it also has the functions of signal processing, such as filtering, phase modulation, frequency mixing, attenuation, detection, and amplitude limiting.
4. Low standing wave and low loss: meet the needs of weapon systems and precision measurement.
5. Large capacity and high power: Large capacity and high power mainly meet the development needs of the information highway.
6. Surface mount: Mainly meet the development needs of SMT technology (surface mount technology), and help simplify the wiring structure design of multilayer printed boards.