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Do
We Have an Accelerated Aging Test? In Federal test Standard 101C, Method 4046.1 the original accelerated aging test for ESD packaging materials was born. This is the Static Decay test called out in the Mil-B-81705 series standards. This standard called for: (sic) "Prior to testing, expose one third of the specimens for 12 days in an oven at 160 degrees F ..." Dr. Marv Havens in his definitive paper at the EOS/ESD Symposium in 1989, "Understanding Pink Poly", showed this test actually tested the"'reservoir effect" of pink poly samples. 6 mil pink poly samples began to lose their static decay after 12 days at 160 degrees F. This test evolved the additives (under heat conditions) out of the polyethylene and determined an acceptable level of loading of this thick plastic film. This was designed for these films to simulate one year of package life. The 160 degrees F temperature was chosen to simulate the back of a saleman's car in the southwest in the summer. This specification was never designed to be applied to the resistitivty of ESD packaging films. Over the years, many companies transferred this aging test to the resistance measurements of their specifications for ESD protective materials. Most Type III (static shielding) materials failed this aging test for resistance due to the low coating weights of the outside or the inside sealing layer of the films. This is not a negative statement. It only points out the problem of applying the old static decay tests to today's films. Today some companies have a misunderstanding of this specification in regards to ESD protective packaging films and materials. Make no mistake, this test was designed to determine the amount of antistatic additive in a thick polymer film. It was never designed to test the coatings of thermoformable sheets, static shielding bag films or other thin film materials of today. So... Do we now have any acceptable aging test for ESD protective packaging???????? The qualified answer is .. NO! The following are some discussions of the needs and acceptable expectations of today's packaging films. The new version of Mil-B-81705: Mil-PRF-81705D (1998) , has removed the static decay tests for ay materials except the Type II materials- Static Dissipative. This test is not required for Type I - Moisture Barrier or for Type III - Static Shielding materials. This is an indication of the understanding of the problems associated with accelerated aging of these materials especially in regards to surface resistivity or surface resistance. This does not mean that companies do not wish some sort of accelerated aging tests for all ESD protective materials. A few years ago after many tests performed by Fowler Associates on static shielding films, Hewlett-Packard adopted their new test specification: A-5951-1589-1 Revision H, Appendix P This specification revise the old military specification to state that all ESD protective packaging films will pass for dissipated materials ( less than 10 to the 11 Ohms per ESD S11.11) an accelerated aging test of 12 days at 140 degrees F or 8 days at 160 degrees F. This was in response to the Fowler associates tests showing normal static shielding films will pass this specification. Is this a reasonable test? The qualified answer is .. YES! The ESDJournal therefore states that for ESD protective packaging the accelerated aging tests that will give good discriminatory results are: ESD Protective Materials shall be static dissipative after 8 days at 160 degrees F. Also, the best test are real life tests at the expected humidity and temperature levels. Aging test are best performed live. Let the tests begin......... Do we have an accelerate aging test? NO! But we may begin to establish one!
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