Corrosion tests can be divided into salt spray test and gas corrosion test:
The Salt Spray Test is used to assess the corrosion effects between the metal material and salt particles, or to access the damage resulting from assimilation between non-metal material and salt particles.
The Gas Corrosion Test is used to assess corrosive effects of one or multiple low concentration pollutants in the atmosphere under a specific temperature and relative humidity. The main purpose is to determine the resistance of electronic or FFC/FPC connectors against corrosive gases.
Salt Spray Test
The Salt Spray test is normally used to qualify surface coating finishes or products used on maritime vessels, for resisting salty atmosphere in island climates.
Applications of Salt Spray Test based on USA military specifications:
Salt Spray Test is normally used to assess quality of protective coatings.
Salt Spray Test is neither for substituting a humidity test or mould growth test, nor for assessing
specimens of the entire system.
Salt Spray Test is usually carried out after climate tests for significantly better results in finding coating effects.
For IEC and MIL test conditions, except small differences in the salt concentration used by MIL STD, the testing temperature and salt-water specific gravity are typically the same. In practical experiences, cycling test with alternating humidity and salt spray is more effective than salt spray test carried out at a fixe temperature for detecting coating defects and verifying coating quality.
Then Salt Spray Test normally identifies corrosion extent by visual inspection and low magnification microscope observation both before and after the test. The lower corrosion extent the higher corrosion resistance of the sample. Different classes of severity are defined for the test based on the temperature, concentration of the salt water, humidity/ salt spray cycling, and testing duration.
References: ETSI-300 019 series, IEC 60068-2-11&52, MIL-STD-810, etc.
Machine specifications/ limitations of Salt Spray Test
Temperature: 25oC~ +55 oC
Salt concentration: 5%
Salt solution pH value: 6.5 ~ 7.2
Gas Corrosion Test
When the busbars or connectors of electronic devices are exposed to trace chlorine or vulcanized gas in the atmosphere and corrosion is developed between the joining surfaces, this will cause increased resistance to signal transfer and result in functional anomaly or failure. Major international manufacturers therefore use Gas Corrosion Test to verify products, electronic connectors, FFCs and FPCs. The effectiveness is exceptionally good in verifying the quality of gold plating surfaces. Extensive applications are seen in automobile electronics.
The Gas Corrosion Test is generally carried out by measuring conductor resistances before, during and after the test. In practice, for a defective gold plated connection, the variation of resistances before and after the test can be as high as 20 to 30 times. In case of abnormal corrosion occurs, an Energy-Dispersive X-ray (EDX) is normally used to identify the cause.
Frequently used specifications include: EIA-364-65A, ETSI-300 019, NEBS GR-63/Indoor & Outdoor, IEC 60068-2-42, 43 ,60, ASTM B845, JIS C0048, DIN 40046-36,37, etc.
Machine specifications/ limitations of Gas Corrosion Test
Temperature：25oC ~ +50oC ±2oC
Humidity：50% to 90% (RH) ±3%
Test gas source：