Mixed flowing gas testing
Mixed flowing gas (MFG) is a type of laboratory environmental testing for products, particularly electronics, to evaluate resistance to corrosion due to gases in the atmosphere.
Mixed Flowing Gas (MFG) test is a laboratory test in which the temperature (°C), relative humidity (%RH), concentration of gaseous pollutants (in parts per billion, ppb or parts per million ppm level), and other critical variables (such as volume exchange rate and airflow rate) are carefully defined, monitored and controlled.
The purpose of this test is to simulate corrosion phenomenon due to atmospheric exposure.
The electronic product is exposed to gases such as chlorine, hydrogen sulfide, nitrogen dioxide, and sulfur dioxide at levels in the parts per billion range, in a controlled environmental chamber.
Much of the work was described in a series of “… Progress Report[s] on Studies of Natural and Laboratory Environmental Reactions on Materials and Components,” by Abbott, issued in 1981, ‘83, ‘84 and ‘86.
[7] While standard practice MFG testing requires careful definition, monitoring and control of temperature, humidity, gaseous pollutant concentrations, volume exchange rate and airflow rate, there is considerable potential for variations in mass flow, environmental mixing and gradients in the chambers used.
Metal coupons should ideally have large surface area and small edge thickness.
The weight change for both metals is assumed to be due strictly to the addition of sulfur.
The deposit thickness is determined by multiplying the coupon weight change by the formula weight for the metal sulfide divided by the density of the metal sulfide times the atomic weight of sulfur times the total surface area for the two faces of the coupon (minus any drill hole for hanging).
The levels are “G1” (mild), “G2” (moderate) and “G3” (harsh), reported as equivalent months or years.
For equivalent months, for copper, the thickness of the deposits in Angstrom units is divided by 300 for G1, 1000 for G2 and 2000 for G3.
