Accelerated Stress Test

Separate Accelerated Stress Test (AST) protocols have been proposed by the US Department of Energy to assess the durability of fuel cell under conditions that promote distinct degradation modes... 

These molding compounds were also used to encapsulate electronic devices for reliability testing. In Figures 4, 5, and 6, stable bromine CEN outperformed "state-of-the-art" resins in the bias pressure cooker device test (BPC), high temperature storage device test (HTS), and the highly accelerated stress test (HAST). 

Figure 6 shows the performance of encapsulated devices under the highly accelerated stress test which utilizes the following conditions 145°C, 85% relative humidity, 37 psig, and electrical bias. The bias on this test is cycled specifically, the bias is initially off to allow for full moisture penetration and then turned on. These cycles are repeated throughout the test. The stable bromine CEN compound took 2500 hours to reach 50% failure rate, compared to the standard resin compound at 1900 hours. 

Figure 6. Highly Accelerated Stress Test - Device Test LF412 Dual Op Amp, 145 C, 85% RH, and Bias...

At the early stages of optimisation, preformulation studies are usually conducted to screen excipients or packaging materials and to select those compatible with the candidate drug, using accelerated stress testing procedures. More details about the preformulation techniques, which can be employed for compatibility studies, are discussed in Chapter 3. The importance of doing compatibility studies is for reducing the number of excipients and formulation options to test in further product optimisation studies. 

Highly Accelerated Stress Test per JEDEC-STD-22-AllO. ... 

Infant-mortality period. In the early period of failures, accelerated stress tests such as burn-in, power cycling, temperature cycling, and vibration as well as highly accelerated stress and life testing are used. These methods are used to screen out parts that are inherently not reliable and prevent the delivery of dead on arrival parts to a customer. While this consumes some early life of an assembly by stress screening, the remaining population begins the useful life period or the flat area of the bathtub. 

Thomsen B, Tryson M (2009) Highly accelerated stress testing (HAST) of DEAP actuators. Proc SPIE 7287 102-113... 

Data describing the reliability of joints assembled with anisotropically conductive adhesives are incomplete. Several papers have been published, but usually the sample size investigated is small, the accelerated stress tests are not standardized, and the results are highly dependent on device type (e.g., flexible circuit to rigid PWB, surface-mounted components, and flip-chip assembles). Further work is required in this area. 

Humidity testing is nearly always carried out at temperatures ranging from 351-100°C with relative humidity from nearly zero to 100 %. Occasionally, steam bombs are used so tests can be run above 100°C. In the last ten years, highly accelerated stress tests have been developed to enable materials to be tested at temperatures above 100°C, but at a noncondensing relative humidity, typically 85 %. The most common applications for these tests are in evaluating coatings, paper, adhesives, adhesion between mechanically or chemically bonded materials, and, in electronics, for evaluating the effectiveness of device encapsulation. 

Table 23.1. Electrocatalyst cycle and metrics [44]. (Reproduced from United States Department of Energy. DOE cell component accelerated stress test protocols for PEM fuel cells electrocatalysts, supports, membranes, and membrane electrode assemblies. 2007. With permission from DOE.)...

Zhang, S., X. Yuan, H. Wang, et al. 2009. A review of accelerated stress tests of MEA durability in PEM fuel cells. Int.. Hydrogen Energy 34 388M04. 

Conducted and led several research activities focused on failure modes including mechanistic imderstanding, accelerated stress test development, influence of operational conditions, control strategies, failure mitigation, and predictive degradation relationships. 

Based on U.S. DRIVE Fuel Cell Tech Team Cell Component Accelerated Stress Test as described in [7]... 

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