Top 3 Causes of Micro RF Coaxial Connectors Failure

There are many types of Micro RF Coaxial Connectors, so in the process of connection, the same will also produce many detailed problems, this article will focus on the failure of the components of the coaxial connector, to talk about the reasons.

A. Types of Micro RF Coaxial Connectors

Before understanding the various issues, we need to re-understand the type of Micro RF Coaxial Connectors, so as to better understand the issues involved.

1, threaded connection type: such as: APC-7, N, TNC, SMA, SMC, L27, L16, L12, L8, L6 and other RF coaxial connectors. This connection form of connector has high reliability, good shielding effect, so the most widely used.

2, bayonet connection type: such as: BNC, C, Q9, Q6 and other RF coaxial connectors. This connector has a convenient connection, fast and other characteristics, but also the international application of the earliest form of RF connector connection.

3, push into the connection type: such as: SMB, SSMB, MCX, etc., this connection form of connector has a simple structure, compact, small size, easy to miniaturize and other characteristics.

Reverse polarity BNC socket for RG58, LMR195 series cable, crimp type

Second, the Micro RF Coaxial Connectors failure analysis

We will mainly talk about the principle of the most widely used, the largest variety of threaded connection type failure to analyze. Generally there will be the following scenarios.

1, connection failure

(1) Connection nut off

In daily life, some users reflect that sometimes the connection nut off the phenomenon, resulting in the normal work, especially small connectors, such as SMA, SMC, L6 will appear more, by our analysis of the following reasons caused by the general.

Designers improper selection of materials, in order to reduce costs, the wrong use of non-elastic brass seat snap ring material, so that the nut is easy to fall off.

Processing, nut installation groove groove of the ring is not deep enough, so the connection of a slight torque nut that falls off.

Although the material selection is correct, the process is not stable, the beryllium bronze elastic treatment does not reach the hardness value specified in the drawing, and the snap ring is not elastic, which causes the nut to fall off.

When using the personnel in the test, there is no torque wrench, but use the ordinary wrench to tighten the nut, so that the tightening torque greatly exceeds the value specified in the military standard, so the nut (snap ring) was damaged and fell off.

(2) Matching error

Some customers may mistake the Q9 cable head bought in the market for the international common BNC cable head. Because its shape and BNC cable head is exactly the same, only slightly different in size, so it is not compatible with imported instruments BNC.

(3) The inner conductor is loose or off

Some designers divide the inner conductor into two bodies at the inner conductor media support, and then connect them with threads. But for the small RF coaxial connector, the inner conductor itself is Φ1～2mm in size, and the thread is processed on the inner conductor, if the threaded connection is not coated with conductive adhesive, then the inner conductor connection strength is very poor. Therefore, when the connector is connected several times, the inner conductor threads loosen and fall off under the long-term action of torque and tension, resulting in connection failure.

TNC crimp type plug for RG58 series cable

2、Reflection failure

(1) reflection increase

Any kind of Micro RF Coaxial Connectors have a certain service life. This is because when the connector after long-term use, repeatedly plugging and unplugging more than 500 times, the pins, jacks have caused varying degrees of wear and tear, the contact is no longer the best state, so in use, the reflection may increase sharply.

(2) open circuit

In the past work found individual users to N-type 50Ω plugs mistakenly connected to N-type 75Ω socket. As the 50Ω pin diameter is much larger than the 75Ω jack size, resulting in the jack size exceeds the elastic limit, can not be restored to the original size. Others used again found open circuit, the original 75Ω socket jack has been damaged.

(3) short circuit

There is a part of the connector, sealed connection in the welding of the inner conductor, solder flow to the surface of the glass insulator, resulting in a full or partial short circuit, the performance is not qualified.

3, Micro RF Coaxial Connectors electrical contact failure

Usually the jack parts material should be made of beryllium bronze or tin-phosphor bronze, but there are very few manufacturers to reduce costs with 59-1 brass for the jack, thus plugging one or two times after the jack is in the mouth state, when the pin is connected again, the jack does not contact at all, which will also cause problems in use.