Can the Q-SUN Run “Solar Radiation” Tests Found in Environmental Testing Standards?
“Solar radiation” standards describe tests that are designed to characterize the performance of electronics subject to outdoor use or other harsh environments.
The two most important solar radiation standards are MIL-STD-810G and IEC 60068 2 5. The Q-SUN product line can be used to meet these environmental “solar radiation” tests. A critical fact to note is that these standards are not specific test methods, despite having sections called “test methods.” Both standards spend considerable space discussing the concept of “tailoring”, which gives laboratories and engineers flexibility in designing tests that apply the environmental stresses discussed in each section. Thus, not only are these standards performance-based in allowing multiple hardware designs, it is also possible to alter the actual test conditions if the result meets the general intent of the section.
An important requirement of virtually all military environmental programs, solar radiation testing simulates the deteriorating thermal and physical effects of UV sunlight on products and materials.
A key component in MIL-STD-810 and IEC 60068-2-5, solar radiation tests two major effects of exposure to sunlight: thermal response and photochemical deterioration. Because the heat and aging effects of UV radiation can cause significant changes in plastic and non-metallic materials, testing is critical to avoiding outgassing and overheating, discoloration and deterioration, and loss of structural rigidity.
MIL-STD-810-G clearly states:
“It is important to note that this document does not impose design or test specifications. Rather, it describes the environmental tailoring process that results in realistic materiel designs and test methods based on materiel system performance requirements.”
MIL-STD-810-G and IEC 60068-2-5 both include numerous statements reinforcing this flexibility in selecting test conditions. In fact, the “solar radiation” tests in these standards are impossible to run in any chamber because they have a table showing a target spectral power distribution from 280 to 3000 nm, that no artificial light source can meet. Because no single light source actually meets the specification, the user of the standard must apply sound and reasonable engineering principles to tailor the test by defining how the relevant environmental stresses will be applied.
Q-Lab has prepared two special letters confirming that Q-SUN xenon-arc weathering testers can meet the performance requirements of Method 505.5 of standard MIL-STD-810G, provided that the document’s guidance on “test tailoring” is followed. Laboratories who need to add these standards to their scope of accreditation need to write a procedure that addresses specifically what test tailoring they have selected for their Q-SUN.
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