It is well known that automobile manufacturers have increasingly high requirements for their supply bases, which is a well-known fact for automotive parts suppliers. For connector suppliers, this means stricter requirements for product performance, stability, and cost. Suppliers can only be in a competitive position by constantly innovating their products and processes to meet the needs of customers.
Connector manufacturers must identify and analyze physical and mechanical phenomena in the environment that may affect connector performance. According to the application conditions specified by the automobile manufacturer, in order to evaluate the stability of the connector, the connector manufacturer has implemented a sophisticated testing procedure. If a connector failure occurs, it can mostly be determined as one of the following three fault modes: friction corrosion, electrical failure, and connector connection issues.
1. Friction corrosion and electroplating problems. Corrosive gases, high humidity, and strong oscillations are the three major conditions that cause oxidation and friction corrosion, and lead to connector failure. These environmental factors can have a significant impact on the contact surfaces between tin and lead tin, with 90% of connector surfaces falling under this category.
Usually, people use electroplating of precious metals, such as gold or silver plating, because these metals do not undergo oxidation. The thickness of these coatings ranges from 0.5 μ m to 1.27 μ m. However, unfortunately, due to the presence of these precious metals and their processing, this type of electroplating process is expensive, so people try to use these electroplating materials as little as possible. In automotive electrical wiring harness applications, only about 10% of connection points use this type of metal.
As a result, some major connector suppliers, such as FCI, have provided alternative electroplating solutions (such as pure tin electroplating, tin Teflon, NXT, and lamination technology) that not only meet OEM cost requirements, but also have the same performance in their products.
Due to the need to meet high standards of automotive specifications, the compression terminal technology (connector to circuit board) originating from the telecommunications market has attracted much attention. Due to the thinness of automotive PCBs compared to PCBs used in the telecommunications industry, the operating temperature (125oC) is much higher, and the usage environment is subject to vibration, it is not an easy task to introduce this technology into automotive systems.
This technology brings significant process cost-effectiveness by pressing a solderless pin into a metal PCB board hole. To meet strict automotive application conditions, FCI press fit terminals are specially designed to provide fully controllable force when inserted into the PCB, minimizing resistance and deformation, ensuring a stable interface with the PCB.
Due to its cost-effectiveness compared to wave soldering and fully automated process that reduces PCB costs, FCI butterfly solutions (and related application tools) are increasingly favored by automotive manufacturers. In addition to superior performance (compatibility with SMT processes and excellent maintenance of component integrity), it also improves additional process quality due to the absence of thermal shock and tin bridge risks to the PCB.
In addition, FCI found that under the conditions of using the correct electroplating process and pins in compression applications, the resistance of contacts remains relatively small when they are constrained by various external conditions, such as rapid temperature changes, relative humidity changes, long-term exposure to dry environments, and gas corrosion.
To solve this problem, people have developed a new type of contact surface. Teflon microparticles undergo the same treatment in a regular tin bath and are selectively electroplated onto the contact surface. Micro particles can reduce the insertion force of a typical tin plated terminal by more than 40%. This solution allows the connector to have more pins and does not require the insertion of auxiliary devices - enhancing ergonomics and improving connector stability. In addition, measurements have shown that when terminals are susceptible to vibration, tin Teflon surfaces have better anti friction and corrosion properties than any other tin plated contacts.
2. Electrical faults: The connection problem between the reinforced new crimping technology cable and terminal is one of the main causes of warranty and connector system failures. For automotive wiring systems, crimping is a very common method used to connect terminals to cables. This process has been proven to be reliable. Compared with welding method, it is more economical and easy to operate in improving the reliability of crimping. To improve the geometry of the terminal clamp, connector manufacturers have invested a lot of effort. Through extensive analytical experiments, FCI has not only developed a new analytical tool for optimizing crimping, but also proposed an innovative new crimping geometry.
FCI's "two-step" crimping solution proposes a crimping method that can be produced at a typical high-speed crimping rate on traditional crimping presses. When the two-step crimping is completed, there will be two impacts inside the mold.
The first step is to perform a regular crimping operation on either side of the terminal clamp area. Like any other crimping, after the compression stroke, the stamping machine and anvil separate, and the crimping will loosen slightly. Stranded wires are no longer tightly combined as before, and resistors have higher resistance values.
This problem was solved in the second step of the crimping process. The second impact of the crimping mold on the clamp area. There is a clamp part between the previously crimped positions, and this time the impact is on the middle position of this clamp part. Extensive testing has shown that the "two-step" process can achieve the best, long-term compression effect on stranded wires. Due to the elimination of compression rebound, the cold welding generated by the crimping zone has been strengthened and stabilized, and the crimping has high reliability. Two step crimping is suitable for all applications that require extremely low current and transition resistance. The airbag sensor and controller are examples of such applications.
3. Connector insertion issues: Improper insertion of connectors during the installation of wiring into automobiles in assembly plants may lead to connector failure. To overcome this problem, design engineers have developed various connector locking devices, one example of which is the Spring Lock developed by FCI. When the two halves of the connector are plugged together, the spring device will be compressed. If properly plugged in, the connector spring lock will come into play, allowing the two connectors to be joined together. If the connector is not fully inserted, the spring will spring open two halves (when the installer releases the connector), indicating a connection failure.
Another approach is to use a plug-in auxiliary device to simplify the insertion process of larger connectors. FCI's new ErgoMate? The technology adopts a gear type cam and slider device. This slider device enables a fluid power to be obtained from the assembler when the connector is plugged in, eliminating the need for a typical connector to drive a secondary joystick or slider. Compared with other methods, due to the cam, the insertion force of the connector can be reduced by 40%. FCI's latest APEX 24 way Hybrid connector utilizes this technology. When the efficiency design is improved, assembly becomes simple and easy to implement, and the connection stability also increases accordingly.
It is very important to seal the electrical contacts of the connector when applied to the exterior of the car and under the hood. For connector manufacturers, providing low-cost, stable, and easy to assemble submersible connector solutions is a highly challenging task. In high-density or multi pin systems, using gasket seals or porous sealing rings is a standard practice. When designing such seals, there are two main issues that must be addressed.
