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ASTM International , 06/01/2015
Publisher: ASTM
File Format: PDF
$33.00$66.00
1.1This test method covers a procedure for temperature and humidity cycling of a membrane switch or printed electronic device.
1.2This 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.
1.2.1Physical changes:
1.2.1.1Differential contraction or expansion rates or induced strain of dissimilar materials.
1.2.1.2Cracking of surface coatings.
1.2.1.3Leaking of sealed compartments.
1.2.1.4Deformation or fracture of components.
1.2.2Chemical changes:
1.2.2.1Separation of constituents.
1.2.2.2Failure of chemical agent protection.
1.2.3Electrical changes:
1.2.3.1Changes in electronic and electrical components.
1.2.3.2Electronic or mechanical failures due to rapid water of condensate formation.
1.2.3.3Excessive static electricity.
1.3This test method is not intended to be a thermal shock procedure; a ramp rate between temperature extremes should not exceed 2°C/min.
1.4This 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.
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