About connector friction corrosion and plating problems
It is well known that corrosive gases, high humidity and strong oscillations are three important conditions that cause oxidation and frictional corrosion and lead to connector failure. These environmental factors can have a significant impact on tin and lead-tin contact surfaces, as is the case with 90% of connector surfaces.
Usually, people use electroplated precious metals, such as gold plating or silver plating, because these metals do not oxidize. The thickness of these coatings varies from 0.5 μm to 1.27 μm. However, unfortunately, because of the high price of these precious metals and their processing, such electroplating processes are expensive, so people use such electroplating materials as little as possible. In automotive electrical harness applications, only about 10% of the connection points use this type of metal.
As a result, some major connector suppliers, such as FCI, have other alternative plating solutions (such as pure tin plating, Tin-Teflon, NXT, and press-fit technology) that not only meet OEM cost requirements. And the product has the same performance.
The press-fit terminal technology (connector to board) from the telecom market has attracted attention because it must meet high standards of automotive specifications. Since automotive PCBs are thinner than PCBs used in the telecommunications industry, operating temperatures (125 ° C) are much higher and vibrations are used in the environment, it is not an easy task to introduce this technology into automotive systems.
This technology brings significant process cost benefits by pushing a solderless pin into the metal PCB hole. Designed for demanding automotive applications, the FCI press-fit terminals are designed to provide fully controllable force when inserted into the PCB, minimizing drag and distortion and ensuring a secure interface to the PCB.
FCI butterfly solutions (and related application tools) are increasingly favored by automakers because they are more cost effective than wave soldering and the process is fully automated, reducing PCB costs. In addition to superior performance (compatible with SMT processes and excellent component integrity), it also adds additional process quality due to the absence of thermal shock to the PCB and the risk of solder bridges.
In addition, FCI found that when the correct plating process and pins are used in the press-fit application, the contacts are subject to various external conditions (eg, sharp temperature changes, relative humidity changes, long-term dry conditions, and gas corrosion). At the time of the contact resistance, the contact resistance has remained small.
However, as the number of pins increases, the pressure becomes very large, so be careful when inserting the connector into the base.
FCI has developed a new electroplating process called "NXT". Based on the chemistry of an amorphous nickel, it provides a very smooth and uniform plating surface that significantly reduces the thickness of the gold coating (approximately 80% reduction). This technology supports extremely low signal currents in safety critical applications.
Multi-pin connectors present another test for connecting electroplating systems. For ergonomic considerations, the connector insertion force should be as small as possible, but as the circuit count increases, the force required to insert the connector will increase proportionally. However, electrical performance often indicates that each contact gets a high contact pressure (usually causing high insertion forces), which is incompatible with the goal of achieving low connector insertion force.
To solve this problem, a new type of contact surface has been developed. The Teflon microparticles are treated identically in a common tin bath and selectively plated onto the contact surface. Microparticles reduce the insertion force of a typical tin-plated terminal by more than 40%. This solution allows the electronic connector to have more pins without the need to plug in an auxiliary device - enhancing ergonomics and improving connector stability. In addition, the measurement shows that the Tin-Teflon surface has better anti-friction corrosion than any other tin-plated contact when the terminal is susceptible to vibration.
Usually, people use electroplated precious metals, such as gold plating or silver plating, because these metals do not oxidize. The thickness of these coatings varies from 0.5 μm to 1.27 μm. However, unfortunately, because of the high price of these precious metals and their processing, such electroplating processes are expensive, so people use such electroplating materials as little as possible. In automotive electrical harness applications, only about 10% of the connection points use this type of metal.
As a result, some major connector suppliers, such as FCI, have other alternative plating solutions (such as pure tin plating, Tin-Teflon, NXT, and press-fit technology) that not only meet OEM cost requirements. And the product has the same performance.
The press-fit terminal technology (connector to board) from the telecom market has attracted attention because it must meet high standards of automotive specifications. Since automotive PCBs are thinner than PCBs used in the telecommunications industry, operating temperatures (125 ° C) are much higher and vibrations are used in the environment, it is not an easy task to introduce this technology into automotive systems.
This technology brings significant process cost benefits by pushing a solderless pin into the metal PCB hole. Designed for demanding automotive applications, the FCI press-fit terminals are designed to provide fully controllable force when inserted into the PCB, minimizing drag and distortion and ensuring a secure interface to the PCB.
FCI butterfly solutions (and related application tools) are increasingly favored by automakers because they are more cost effective than wave soldering and the process is fully automated, reducing PCB costs. In addition to superior performance (compatible with SMT processes and excellent component integrity), it also adds additional process quality due to the absence of thermal shock to the PCB and the risk of solder bridges.
In addition, FCI found that when the correct plating process and pins are used in the press-fit application, the contacts are subject to various external conditions (eg, sharp temperature changes, relative humidity changes, long-term dry conditions, and gas corrosion). At the time of the contact resistance, the contact resistance has remained small.
However, as the number of pins increases, the pressure becomes very large, so be careful when inserting the connector into the base.
FCI has developed a new electroplating process called "NXT". Based on the chemistry of an amorphous nickel, it provides a very smooth and uniform plating surface that significantly reduces the thickness of the gold coating (approximately 80% reduction). This technology supports extremely low signal currents in safety critical applications.
Multi-pin connectors present another test for connecting electroplating systems. For ergonomic considerations, the connector insertion force should be as small as possible, but as the circuit count increases, the force required to insert the connector will increase proportionally. However, electrical performance often indicates that each contact gets a high contact pressure (usually causing high insertion forces), which is incompatible with the goal of achieving low connector insertion force.
To solve this problem, a new type of contact surface has been developed. The Teflon microparticles are treated identically in a common tin bath and selectively plated onto the contact surface. Microparticles reduce the insertion force of a typical tin-plated terminal by more than 40%. This solution allows the electronic connector to have more pins without the need to plug in an auxiliary device - enhancing ergonomics and improving connector stability. In addition, the measurement shows that the Tin-Teflon surface has better anti-friction corrosion than any other tin-plated contact when the terminal is susceptible to vibration.
The above is compiled by Konnra Electronics. I hope that through the introduction of this article, you can have a certain understanding of the connector friction corrosion and plating related knowledge.
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