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Description / Abstract:
This test method covers a procedure for temperature and humidity
cycling of a membrane switch or printed electronic device.
This test method is performed to evaluate the properties of
materials used in the construction of membrane switch or printed
electronic assemblies as they are influenced by the absorption and
diffusion of moisture and moisture vapor. This is an accelerated
environmental test, accomplished by the continuous exposure of the
test specimen to high relative humidity at an elevated temperature.
Absorption of moisture by many materials results in swelling, which
destroys their functional utility, causes loss of physical
strength, and changes in other mechanical properties. Insulating
materials which absorb moisture may suffer degradation of their
electrical properties.
Physical changes:
Differential contraction or expansion rates or induced strain of
dissimilar materials.
Cracking of surface coatings.
Leaking of sealed compartments.
Deformation or fracture of components.
Chemical changes:
Separation of constituents.
Failure of chemical agent protection.
Electrical changes:
Changes in electronic and electrical components.
Electronic or mechanical failures due to rapid water of
condensate formation.
Excessive static electricity.
This test method is not intended to be a thermal shock
procedure; a ramp rate between temperature extremes should not
exceed 2°C/min.
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.