- Introduction
The reliability of RF high frequency connectors is a very important problem in the whole machine or the system use, because as a component, the reliability of the RF connector directly affects or determines the reliability of the whole machine or the system. The reliability of RF connectors is related to their structural design, production process, production technology, selected materials, quality control and their correct application. The structural design is the most important among these factors, which plays a decisive role in the inherent reliability of the product. Therefore, in every stage of development and design or in the reliability growth test, special attention should be paid to how to improve and ensure the inherent reliability and the use reliability of the product.
With the passage of time and the continuous development of science and technology, the design theory and measurement technology are constantly updated and improved through the test of practice and the accumulation of experience, and the defects and limitations in the early designs are gradually exposed. Therefore, it is necessary to adopt new concepts, new technologies and new materials to improve the old products and old structures, and take measures to improve the inherent reliability of products.
2. Measures
2.1 Reinforcement method
Aiming at the outer conductor of the RF connector or the parts of the inner conductor where contact failure is prone to occur, the reinforcement method is to add stiffeners and cut no grooves or narrow grooves to improve the rigidity and mechanical strength of the failure parts and improve their contact reliability and mechanical life without affecting the electrical characteristics (e.g., VSWR, insertion loss) of RF connectors.
Case 1: In the vibration test and the mechanical life test of the Q9 RF connector( an obsoleted type) and the early BNC RF connector, the distortion and flying flake phenomenon often occur at the elastic grooves of the outer conductor end face, which results in the increase of the contact resistance of the outer conductor and the failure. Aiming at this type of failure, reinforcement measures should be taken, that is, reinforcement bars should be added at the end of the connectors such as the BNC RF connectors specified in the current IEC168-8 standard.
2.2 Calibration method
Calibration or alignment method is to shorten the insertion length of pins and extend the axial length of threads in the interface structure design of some micro RF connectors. During the connection process of connectors, this method can make the connector plug contact with the socket first, and alignment the pin and the jack in a straight line before contacting and connecting, so as to prevent the pin from damaging the jack in the connection process, resulting in the failure.
For example, the jack damage shown in Figure 7 is prone to occur in the connection process of SMA connector and APC-3.5 connector. After using the calibration method, the failure caused by the jack damage can be effectively avoided in the connection process of the connectors such as 2.92mm, K, and 1.85mm connectors.
2.3 Balance method
The balance method refers to the structure design of high frequency contacts in high and low frequency hybrid connectors. The adoption of the balance method should meet the requirements of electrical characteristics (such as RVSW) within the applicable frequency range and consider the overall mechanical life of high and low frequency hybrid connectors. The jacks of the inner conductor system should be strengthened and the inherent reliability of high-frequency contacts should be improved as much as possible.
2.4 Coating lubrication method
The coating lubrication method means applying the coating agent or lubricant on the surface of the contact parts of RF connectors to improve the corrosion resistance and wear resistance of the contact parts, so as to improve the contact reliability and mechanical life.
Gold is the most difficult to corrode and tin is the easiest to corrode according to the degree of electrochemical corrosion of gold, silver and tin, but it is quite the opposite that the gold-plated contact is corroded most, while the tin coating is corroded less from the actual use of electroplating contacts. This is because as a precious metal, gold tends to be thin, while tin, as a base metal, is thicker. In the case of general plating quality, the relation curve between the thickness of the coating and the number of pinholes is shown in Figure 9. Thin coatings with more pinholes are easy to be corroded; thick coatings are difficult to be corroded.
2.5 Optimum seeking method
The optimum seeking method refers to choosing the suitable connection mechanism optimally according to use characteristics in the design of the connection mechanism of RF connectors or in the selection of connectors to avoid the contact failure caused by the improper selection of the connection mechanism, so as to improve the use reliability.
The common connecting mechanisms of RF connectors are shown in Table 1. Different connecting mechanisms have different applicable conditions and characteristics, so the applicable connecting mechanism should be selected according to the characteristics of use.
3. Conclusion
Some of the measures and examples listed above have been reflected in the standard interface structures of the products, and in some cases, the two structures coexist in the same product type. As measures to enhance the inherent reliability of products, the methods listed above are not only or unique. Designers can carry out specific analysis according to the contact failure forms occurring in product contacts and adopt methods that are different from the above measures to improve the use reliability. They can also apply one or some of the above measures jointly to improve the use reliability. It is unnecessary to change the structure when the existing structure can meet the use requirements.
The methods above aim at different failure forms, and they can be used as a reference for designers to design products initially. In addition, the methods can be clues in analyzing connector failures and searching for failure causes, and they can also be adopted in reliability growth tests.
Now the price of military connector pins is affordable, if you have needs, please contact us.
If you want to know more types of mil spec connectors, please visit our website.
sunkye 