MIL-STD-810 Test Method 507 – Humidity
Quick look:
- Tests for resistance to warm and muggy environments
- Includes normal method testing or aggravated testing
- Exposure to humidity may deteriorate materials or short electrical contacts
About MIL-STD-810 Method 507
MIL-STD-810, Method 507 is humidity testing designed to test material that will be used in a warm, muggy environment to test if any potential problems will arise when exposed. This is relatively important to applications where the product will be used in a tropical area, mid-latitude location during certain seasons, and in equipment subjected to changes in pressure or temperature.
A normal humidity test occurs over a 48-hour period where the product is exposed to humid conditions 24 hours, given time to dry and then exposed for an additional 24 hours.
The second testing option is the aggravated method. This test is a full 10 days where you’re actually exposing the product to humidity for the whole duration of the test. This test is not just humidity, but it’s also a temperature process where you’re extending the temperature up and down with the relative humidity rate. This method can be a lot more aggressive on electrical contacts and material that would deteriorate due to moisture and temperature.
Conformal coating is also used to protect the connections and components on the motherboard against any condensation that can occur when changing from very cold to very warm environments, such as when an aircraft descends.
After the testing is complete, the unit is checked for any signs of humidity ingress like corrosion, rusting of screws, or any water exposure to electrical components. The following is an excerpt from MIL-STD-810H, Method 507 on what to look for.
Consider the following typical problems to help determine if this Method is appropriate for the materiel being tested. This list is not intended to be all-inclusive.
a. Surface effects, such as:
- Oxidation and/or galvanic corrosion of metals.
- Increased chemical reactions.
- Chemical or electrochemical breakdown of organic and inorganic surface coatings.
- Interaction of surface moisture with deposits from external sources to produce a corrosive film.
- Changes in friction coefficients, resulting in binding or sticking.
b. Changes in material properties, such as:
- Swelling of materials due to sorption effects.
- Other changes in properties.
- Loss of physical strength.
- Electrical and thermal insulating characteristics.
- De-lamination of composite materials.
- Change in elasticity or plasticity.
- Degradation of hygroscopic materials.
- Degradation of explosives and propellants by absorption.
- Degradation of optical element image transmission quality.
- Degradation of lubricants.
c. Condensation and free water, such as:
- Electrical short circuits.
- Fogging of optical surfaces.
- Changes in thermal transfer characteristics.