Testing accelerated stress test

Alloys containing only a few per cent of zinc may fail if the stresses are high and the environment sufficiently corrosive. Most types of brass, besides the plain copper/zinc alloys, appear to be susceptible to stress corrosion. An extensive investigation of the effect of additions to 70/30 brass was carried out by Wilson, Edmunds, Anderson and Peirce , who found that about 1% Si was markedly beneficial. Other additions were beneficial under some circumstances and none of the 36 additions tested accelerated stress-corrosion cracking. Further results are given in later papers ... 

Three test batches of a chemical were manufactured with the intention of validating the process and having a new product to offer on the market. Samples were put on stability under the accepted ambient (25°C, 60% relative humidity) and accelerated (= stress 40°C, 75% rh) conditions cf. Section 4.20. One of the specification points related to the yellowish tinge imparted by a decomposition product, and an upper limit of 0.2 AU was imposed for the absorption of the mother liquor (the solvent mixture from which the crystalline product is precipitated) at a wavelength near 400 nm. 

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. 

Once the failure mechanisms are identified, it is necessary to select the appropriate acceleration stress determine the test procedures and the stress levels determine the test method, such as constant stress... 

Raymond, L., Accelerated Stress Corrosion Cracking Screening Test Method for HY-130 Steel , under SBIR Phase I tmd Phase n NAVSEA contract No. N00024-89-C-3833, ERA Labs, Final Report No. NAVSEA 80058, Dec. 1989 and Dec. 1993, respectively. 

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. 

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