Antenna Reliability Test - Salt Spray Testing!

　　Salt spray testing is an environmental testing method primarily used to evaluate the corrosion resistance of materials or coatings in salt spray environments. For antennas, especially those used outdoors, salt spray testing is crucial because salt can accelerate corrosion of metal components, affecting antenna performance and lifespan.

　　A detailed description of antenna salt spray testing covers the test objectives, standards, procedures, evaluation methods, and practical application recommendations:

　　1. Purpose of Salt Spray Testing

　　Antenna salt spray testing is primarily used to evaluate the corrosion resistance of antennas in salt spray environments, ensuring their reliability in the following scenarios:

　　Coastal or high-humidity areas (salt spray accelerates metal corrosion).

　　Industrially polluted areas (chemical-laden air corrodes).

　　In-vehicle, shipboard, or outdoor communication equipment (long-term exposure to harsh environments).

　　2. Test Standards and Classifications

　　Salt spray testing follows international or industry standards. Common standards include:

　　Standard Scope Test Type

　　ASTM B117 General Salt Spray Test (American Society for Testing and Materials standard) Neutral Salt Spray (NSS)

　　ISO 9227 International General Standard (Divided into neutral, acetic acid salt spray, and copper-accelerated salt spray) NSS, AASS, CASS

　　IEC 60068-2-11 Environmental Testing for Electrical and Electronic Products (Salt Spray) Applicable to communications equipment

　　MIL-STD-810G Environmental Adaptability Testing for Military Equipment Verifies durability in harsh environments

　　Test Type

　　Neutral Salt Spray (NSS): 5% NaCl solution, pH 6.5-7.2, 35°C (basic test).

　　Acetic Acid Salt Spray (AASS): Added acetic acid, pH 3.1-3.3, accelerated corrosion (simulates industrial pollution).

　　Copper Accelerated Salt Spray (CASS): Add copper chloride, pH 3.1-3.3, fastest corrosion rate (harsh test).

　　3. Test Procedure and Parameters

　　Test Steps

　　Sample Preparation:

　　Clean the antenna surface and remove any oil or temporary protective coating.

　　Mark the test area (e.g., metal contacts, welds).

　　If coating adhesion needs to be assessed, scratch the sample (e.g., crosshairs) before testing.

　　Test Conditions:

　　Salt solution concentration: 5% NaCl (simulates seawater salinity).

　　Temperature: 35°C (constant temperature in the salt spray chamber).

　　Spray Method: Continuous spray or periodic spray (e.g., 15 minutes on, 45 minutes off).

　　Duration: 24 to 1000 hours (depending on standard or requirements).

　　Post-Test Treatment:

　　Rinse the sample with clean water to remove salt crystals.

　　After drying, inspect for corrosion, blistering, and coating peeling.

　　4. Evaluation Indicators and Failure Judgment

　　Appearance Inspection:

　　Rust area of metal components (if more than 5% is considered unqualified).

　　Check for blistering or peeling of the coating (classified by grade, such as ISO 4628).

　　Check for discoloration or embrittlement of plastic components.

　　Functional Testing:

　　Electrical performance (such as deterioration of standing wave ratio and gain).

　　Structural integrity (such as loose joints and seal failure).

　　Common Failure Modes

　　Failure Type Cause Corrective Actions

　　Metal Corrosion

　　Insufficient protective coating or non-corrosion-resistant material

　　Use stainless steel or anodized aluminum alloy

　　Coating Peeling

　　Poor adhesion or salt spray penetration

　　Increase coating thickness or use salt spray-resistant coating

　　Seal Failure

　　Aging of the rubber ring or design gaps

　　Optimize the sealing structure (such as IP67 protection).

　　5. Practical Application Recommendations

　　Antenna Design and Material Selection

　　Metal components: Stainless steel (304/316) or anodized aluminum alloy is preferred.

　　Coating Process: Epoxy resin coating, electroplated zinc-nickel alloy, or Dacromet treatment is used.

　　Sealing Design: Silicone seals are used at interfaces to meet IP67/IP68 protection levels.

　　Test Optimization

　　Shortening Test Cycles: Use CASS testing to accelerate verification (1 hour CASS ≈ 24 hours NSS).

　　Real-World Environment Simulation: Combine temperature cycling (such as high temperature and high humidity + salt spray) to improve test accuracy.

　　Industry Case Studies

　　5G base station antennas: Required to pass a 96-hour NSS test to ensure a lifespan of more than 10 years in coastal areas.

　　Automotive antennas: Utilize a 500-hour AASS test to verify resistance to industrial pollution.

　　6. FAQ

　　Q: Can salt spray testing fully simulate real-world conditions?

　　No, but it can be approached by superimposing temperature, humidity, and UV aging tests.

　　Q: Why does the antenna still rust after passing the salt spray test?

　　Long-term exposure may cause salt to penetrate through microcracks in the coating, necessitating regular maintenance (such as cleaning and recoating).

　　Q: Do plastic antennas require salt spray testing?

　　Yes, salt spray may corrode metal connectors or cause plastic embrittlement.