Harsh Environment / Remote Locations

How can you tell if a material will avoid corrosion and support long-life? Mixed Flowing Gas is an industry standard test to evaluate a product’s resistance to corrosion caused by gases in the atmosphere. In this test, a product is placed in an environmental chamber and subjected to gases found in the atmosphere, such as chlorine, hydrogen sulfide, nitrogen oxides, and sulfur oxides, as well as varying levels of temperature, airflow, and relative humidity [6]. Connectors subjected to this test are then tested for low-level contact resistance. Anywhere there is accelerated corrosion, it will cause an issue on the plated surface. Samtec’s certified Extended Life Products, for instance, are exposed to 10-year Mixed Flowing Gas, where sulfur dioxide, chlorine, hydrogen sulfide, and nitrogen dioxide flow around parts for 14 days and achieve high mating cycles (250 to 2,500) [7]. The de facto industry standard is to use nickel under cobalt-hardened-gold up to 125 °C. Gold alternatives are being looked at for higher temperatures. For instance, palladium nickel has the potential to be used between the copper and gold to increase operating temperatures up to 150 °C. Beyond that, plating choices typically include silver for applications well over 200 °C, such as electric vehicle charging. SHOCK & VIBRATION Numerous outcomes can result when a connector experiences shock and vibration, and a range of tests can be performed to ensure good performance [8]. Perhaps the most common failure is cracked solder joints. When a gold-plated connector is soldered, some gold will migrate into the solder joint. If there is more than 5% gold in the solder

joint, it becomes brittle, and any vibration will cause the solder to shatter. It is imperative that in processes using gold-plated connectors the solder joints are extremely well controlled. One way to minimize the risk is to only put gold on the contact point of the connector. This selective gold plating is shown in Figure 2, where the manufacturer’s plating lines deposit nickel on the entire pin and tail, and then put gold only on the contact point (to provide corrosion resistance). This is also a more cost-effective solution than gold-plating the entire pin and tail of the connector.

MULTIPLE MATING CYCLES Generally speaking, a connector’s mating cycles are determined by the material used for the connector’s contact, plating material, and the plating thickness. ELP connectors made with BeCu contacts and 30 micro inches of gold plating, for instance, can withstand up to 1,000 mating cycles, while inexpensive pins made with tin plating over copper will typically tolerate up to 15 mating cycles. Figure 2: Selective gold plating of just the contact point, which improves the connector’s performance in the presence of shock and vibration, shown on a Samtec HSEC8-DP Series.


Powered by