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Some automotive connectors common problems and solving methods
Published：2013-12-13 09:29:52 Views：
Fretting corrosion and electroplating questions
Corrosive gas, high humidity and strong oscillations are caused by oxidation and fretting corrosion and three conditions cause connector failure. These environmental factors will cause great impact surface of Tin and tin-lead contacts, 90% surface of the connector case.
Often, people using electroplating precious metals such as gold or silver, as these metal oxidation does not occur. These coating thicknesses ranging from 0.5 μ m to 1.27 μg/m. However, regrettable is that due to the presence of these precious metals and processing makes this type of plating process is expensive, so this type of plating materials used as little as possible. Automotive electrical wiring harness applications, only about 10% of the connection points using such metals.
As a result, some of the major suppliers of connectors, such as electroplating of FCI gives the alternative solutions (such as pure tin plating, Tin-Teflon TinTeflon, NXT and pressing technology), will not only meet the cost requirements of the OEM, and products with the same performance.
Because they must meet high standards of vehicle specifications, from the telecommunications market pressure Terminal technology (connector to the circuit board) a great deal of attention. Because the motor PCB than applied to the telecommunications industry PCB thinner, operating temperature (125oC) also was much higher, and the use of environmental vibration and want to bring this technology to automotive systems is not an easy thing.
This new technology provides significant process efficiency, it will be a no solder PIN is pressed into the metal holes in the PCB Board. To apply strict conditions of automotive applications, FCI pressing terminal blocks specially designed, provides full control to insert the PCB, the resistance and deformation to a minimum, ensure that the interface with PCB solid.
As more cost-effective than soldering, coupled with the process is completely automated, reducing the cost of PCB, FCI Butterfly solutions (and associated tools) increasingly favored by carmakers. In addition to superior performance (compatible with SMT technology to maintain the integrity of the components and excellent), because there is no risk of thermal shock to the PCB and the Tin bridge, it also improves the quality of additional processes.
In addition, FCI shows used in the lamination applications under the correct conditions of the electroplating process and lead when contacts are affected by various external conditions (for example, drastic changes in temperature, relative humidity, prolonged dry conditions and gas corrosion), changes of contact resistance has remained small.
However, with the increased number of pins, pressure will grow very large, so you should be very careful when you insert the connector into the base.
FCI has developed a name for "NXT" new plating process. Based on a property of amorphous nickel, it can provide very smooth even surface plating, could dramatically reduce the thickness of gold plating (around 80%). In safety-critical applications, this technology can support very low signal current.
Multi-pin connector to connect systems poses another challenge. Due to ergonomic considerations, and connector into the force should be as small as possible, but with the circuit count increases, the force required to insert the connector will increase proportionally. However, it generally suggests that each contact for high contact pressure (usually caused by high insertion force), which gets low power connector into the goal is inconsistent.
To resolve this problem, people have developed a new kind of contact surfaces. PTFE (Teflon) micro-particles in an ordinary tin bath in the same processing time and selectively plated contact surfaces. Micro-particles can be a typical Tin of insertion force terminals to reduce more than 40%. This solution enables the connector has more pins, inserted without assistive devices--and raising connector stability enhanced ergonomics. In addition, the measurements showed that when the terminals vulnerable to vibration impacts, Tin-Teflon (Tin-Teflon) surface than any other Tin plated contacts have better anti-fretting corrosion effect.