Sealing scheme for electrical connectors

Sealing scheme for electrical connectors

Low frequency unsealed electrical connectors are widely used in military electronic equipment, and their reliability directly affects the normal operation of the equipment. When the humidity of the surrounding air approaches saturation, or due to the heat exchange between metals and low-temperature objects in the environment, condensation can easily occur on the metal surface, leading to a decrease in the insulation of electrical connectors. Nitrides and sulfides in the atmosphere combine with water vapor to form salt solutions, forming electrolytic corrosion on metal surfaces. When the density of the metal surface coating is low and there are many pores, it provides a micro battery site for salt solution electrolytic corrosion. The greater the potential difference between the gold coating and the intermediate coating, the more severe the electrolytic corrosion. The working environment of military electronic equipment is complex and ever-changing. The sealing level of low-frequency unsealed electrical connectors is not high, and adverse factors such as high temperature, humidity, and salt mist lead to frequent failures of electrical connectors.

At present, some electrical connectors adopt sealed structure design, which improves the reliability of electrical connectors in humid environments. For equipment, upgrading and replacing electrical connector seals involves a wide range and is difficult. In order to explore the sealing protection technology of unsealed electrical connectors, this article takes low-frequency circular electrical connectors as an example to study the sealing process of the rear end of electrical connectors and the sealing process of plug-in surfaces. The sealing effect was verified through environmental tests and electrical insulation performance tests, and recommended methods for sealing protection of electrical connectors were proposed for different working conditions.

The main cause of electrical connector failure is the contact between moisture and salt mist and the conductors in the electrical connector. The typical structure of low-frequency unsealed electrical connectors is shown in Figure 1. Through the analysis of this structure, it can be seen that external water vapor and salt mist mainly enter the shell through two paths: the tail of the electrical connector and the insertion surface, and attach to the surface of the internal conductor. The tail gap of the electrical connector is large, and the conductors and cable cores inside the electrical connector are almost exposed to the external environment; The surface clearance of the electrical connector socket is not obvious. Once it enters, moisture is easy to accumulate and not easily dissipate, causing long-term damage to electrical connectors.

At present, the sealing protection of low-frequency unsealed electrical connectors mainly relies on two component adhesive fillers. Different adhesive solutions need to be deployed proportionally, making it difficult to operate in the field. The tail filling adhesive cannot solve the problem of sealing the insertion surface, and the path of water and salt mist entering the electrical connector housing through the insertion surface still exists. The sealing process used in this article is divided into two aspects: tail sealing and insertion surface sealing. The tail seal adopts single component and dual component filling processes to handle different working environments; The insertion surface seal adopts tape packaging technology to improve the productivity and operability of the sealing effect.