1. Mechanical Properties
Regarding the connection function, the insertion and extraction forces are key mechanical properties. These forces are classified into insertion force and extraction force (the latter is also known as separation force), with distinct requirements for each. Relevant standards outline maximum insertion force and minimum separation force, indicating that, from a usability perspective, the insertion force should be minimized (as seen in low insertion force (LIF) and zero insertion force (ZIF) designs). Conversely, if the separation force is too low, it can compromise the reliability of the connection.
Another critical mechanical property is the mechanical lifespan of FPC connectors. This durability indicator, referred to as mechanical operation in the national standard GB5095, considers one insertion and one extraction as a single cycle. The assessment is based on whether the FPC connector can reliably perform its connection function (such as maintaining an acceptable contact resistance) after completing the specified number of plug-in cycles.
1. The insertion and extraction force, along with the mechanical lifespan of FPC connectors, is influenced by the contact structure (positive pressure), the coating quality of the contact area (sliding friction coefficient), and the dimensional accuracy of the contact arrangement (alignment).
2. **Electrical Performance**
The primary electrical characteristics of FPC connectors include contact resistance, insulation resistance, and dielectric strength.
1. **Contact Resistance**: High-quality electrical FPC connectors should exhibit low and stable contact resistance, typically ranging from a few milliohms to tens of milliohms.
2. **Insulation Resistance**: This measures the insulation performance between the contacts of the electrical FPC connector and between the contacts and the shell. It generally falls within the range of hundreds of megohms to several thousand megohms.
3. **Dielectric Strength**: Also known as withstand voltage, dielectric withstand voltage refers to the ability to endure the rated test voltage between the contacts of the FPC connector or between the contacts and the shell.
4. **Other Electrical Properties**: Electromagnetic interference (EMI) leakage attenuation assesses the EMI shielding effectiveness of FPC connectors, typically tested in the frequency range of 100 MHz to 10 GHz.
For RF coaxial FPC connectors, additional electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR) are also relevant.
With advancements in digital technology, high-speed signal FPC connectors have emerged to facilitate the connection and transmission of high-speed digital pulse signals. Consequently, new electrical indicators have been introduced, including crosstalk, transmission delay, and skew.
3. **Environmental Performance**
Common environmental characteristics encompass resistance to temperature, humidity, salt spray, vibration, and shock.
1. **Temperature Resistance**: Currently, the maximum operating temperature for FPC connectors is 200 degrees Celsius (except for some specialized high-temperature models), with a minimum temperature of -65 degrees Celsius. During operation, current generates heat at the contact point, leading to a temperature rise. Therefore, it is generally accepted that the working temperature should equal the sum of the ambient temperature and the contact point’s temperature rise. Some specifications explicitly define the maximum allowable temperature rise under rated operating current.
2. **Humidity Resistance**: Moisture intrusion can compromise insulation performance and lead to corrosion of metal components. Standard test conditions involve relative humidity of 90% to 95% (up to 98% per product specifications), with a temperature of +40±20°C and a minimum test duration of 96 hours. The alternating damp heat test is more stringent.
3. **Salt Spray Resistance**: FPC connectors operating in environments with moisture and salt are susceptible to galvanic corrosion, impacting both physical and electrical properties. To evaluate this, a salt spray test is conducted. The connector is placed in a temperature-controlled chamber, where a sodium chloride solution is aerosolized to create a salt fog atmosphere, with exposure times defined by product specifications, typically lasting at least 48 hours.
4. **Vibration and Shock**: Vibration and shock resistance are crucial performance metrics for electrical FPC connectors, especially in specialized environments such as aviation, aerospace, and transportation. These tests assess the robustness of the mechanical structure and electrical reliability of connectors. Specific test methods outline peak acceleration, duration, shock pulse waveform, and allowable interruption time of electrical continuity.
5. **Other Environmental Performance**: Additional environmental performance requirements for electrical FPC connectors may include airtightness (air leakage, liquid pressure), resistance to specific liquids, and low air pressure, depending on usage requirements.
The information above details the three major performance characteristics of FPC connectors. I hope this is helpful to you.
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