Waterproof connector to have good core"

For a long time, circular waterproof connector manufacturers in the new design is more focused on the design of appearance and structure change on the shape and structure of mold development caused by different customers for product "freshness" and "curiosity", through this way to attract the attention of consumers and achieve the sales objective. This way may soon attract the attention of customers, but an unavoidable fact is that if the customer is a long-term use of the products within the industry, their appearance design changes gradually produced "aesthetic fatigue". The final value orientation will return to the real product design and quality. As a connector, one of the most important quality control points is the design and quality control of the PIN pin for electrical contact.

According to the Suzhou fast (Quick-Contact) as a national waterproof connector CNAS third party fair testing laboratory, with the Xi'an Jiao Tong University has undertaken a number of international cooperation "waterproof connector" research topics. The research team of the laboratory has studied the design and quality reliability of metal PIN pins for waterproof connectors.

First, the understanding and analysis of contact resistance

Fast PIN needle (Quick-Contact) the company's R & D personnel through the microscope observation waterproof connector contact surface, found that although the PIN needle coating surface is very smooth, but can still be observed about 3-10 micron bump. When the parent PIN is inserted, it is found that the contact surface is not "full contact", but it is a contact on the contact surface. The actual contact surface S1 is less than the theoretical calculation of the contact surface S2. According to the degree of surface smoothness and contact pressure, the area gap between S1 and S2 can reach thousands of times. The actual contact surface can be divided into two parts: one is the direct contact between the metal and the metal. The contact points between the metal transition resistance, also known as the contact spot, it is formed by interfacial contact pressure or thermal damage after. This part accounts for about 5-10% of the actual contact area. The two is the contact part of the film after contact with the interface. Because any metal has a tendency to return to the original oxide state. In fact, there is no truly clean metal surface in the atmosphere, even if the clean metal surface, once exposed to the atmosphere, it will soon produce a few microns of the initial oxidation film. For example, as long as 2-3 minutes of copper, nickel about 30 minutes, aluminum takes only 2-3 seconds, thus, from the microscopic analysis of any contact surface is a contaminated surface. To sum up, the real contact resistance can be divided into several parts; concentrated resistance (Rc), coating resistance (Rf), conductor resistance (Rp), the contact resistance test and the purpose of the study is to affect the safety of electric contact resistance produces current through the contact surface to determine the time of system.

If there is a high power current through the high resistance contact, it may produce excessive amounts of heat energy consumption, and make the contact with the risk of overheating. In many applications, the contact resistance is low and stable, so that the voltage drop on the contact does not affect the accuracy of the circuit.

If the contact surface of the weak current circuit, because the contact surface will be accompanied by oxide, oil or other pollutants, two contact surface will produce film resistance. As the film is a poor conductor, with the increase of the film thickness, the contact resistance will increase rapidly, which may cause the circuit flashover.

Two, the influence of PIN needle contact resistance and reliability factors

The contact resistance of PIN is mainly affected by the contact material, vertical pressure, surface morphology, the use of voltage and current.

1) contact material

The technical specification of the electrical connector for the different specifications of the material with the same type of insert contact, the provisions of the different contact resistance assessment indicators. General specification for rapid isolation environment resistant electrical connectors GJB101-86

The provisions for insertion of 1mm diameter, contact resistance, copper alloy is less than or equal to 5m, less than 15m ohm iron alloy.

(2) the vertical pressure on the contact surface

The vertical pressure on the surface of the contact is the force generated by the surface of the contact with each other and perpendicular to the contact surface. With the increase of vertical pressure, contact area and micro quantity increase gradually, and contact points from elastic deformation to plastic deformation. The contact resistance is reduced due to the decrease of the central resistance.

The contact pressure depends mainly on the geometry and material properties of the contact.

3) surface morphology

The surface morphology including the shape design and the environment, the contact surface may be due to surface dust, oil, rosin, in mechanical surface contact attachment formed by loose, this layer of membrane with particulate matter easily embedded in the micro pits at the contact surface, the contact area, contact the resistance increases, and unstable. Two is due to the physical adsorption and chemical adsorption of the formation of the film, the surface of the metal is mainly chemical adsorption, it is in the physical adsorption with the electron migration. Therefore, some of the high reliability of the products, such as aerospace electrical connector assembly must have a clean environment, cleaning process and perfect the necessary structural sealing measures, using the unit must have the conditions of storage and use of good operating environment.

4) use voltage

When the voltage reaches a certain threshold, the contact layer is broken down, and the contact resistance decreases rapidly. However, due to the thermal effect accelerates the chemical reaction in the vicinity of the film, the film has some repair