Reliability tests, electronic devices

Reliability of electronic devices Failure mechanisms and testing... 

One of tlte principal applications of the normal distribution in reliability calculations and liazard and risk analysis is tlte distribution of lime to failure due to wearout. Suppose, for example, tliat a production lot of a certain electronic device is especially designed to withstand liigh temperatures and intense vibrations lias just come off the assembly line. A sample of 25 devices from tlie lot is tested under tlie specified heal and vibration conditions. Time to failure, in hours, is recorded for each of the 25 devices. Application of Eqs. (19.10.1) and... 

Mechanical Properties. Most of electronic IC devices are very fragile. They need strong mechanical protection from the encapsulant to retain their long-term reliability. Encapsulant must provide mechanical protection but still maintain good temperature-cycle and thermal-shock testing, which are part of the routine reliability testing of the embedding electronics. 

A host of novel strained engineered optical and electronic devices have been designed based on this concept and are currently being fabricated and tested. It is interesting to note that the strain is reliably robust up to at least 400-500°C (400°C is the growth temperature of the films). 

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). 

Reliability. The performance of the electronic devices implanted in the body is extremely important. Malfunctioning ean result in death. For hybrid microcircuits andmultichip modules, the qualification tests and accelerated tests required of military and space applications also apply, although some shock and vibration tests are not realistic for humans. In addition, the Food and Drug Administration (FDA) becomes involved in testing and reviewing... 

Bias is frequently added for testing of electronic devices, printed wiring boards, and assemblies of electronic equipment. The 85°C, 85 % RH, bias test has been the predominant one in electronics for many years [8], While it sometimes misses failure mechanisms that later occur in the field, it also finds many weak points in new products. It is especially useful for quality control of seasoned devices for which long-term reliability is known to be high if the product passes this test. There are many commercial suppliers of temperature/humidity/bias test chambers and software is widely available to automate the operation, data collection, and data interpretation. Attention to data management is mandatory when hundreds of devices are tested simultaneously. This is frequently required in electronics to obtain sufficient data to make statistically valid predictions of lifetime and failure rate under use conditions. 

Tables 5.1—5.4 model the system assuming that there is only one fault detection mechanism, i.e., self test or proof test. They are slight approximations but are, having regard to the accuracy of reliability assessment, sufficient for most purposes. However, for completeness, the following is included. If, however, for a particular device some faults are found by self test and others by proof test, then in addition to the equations given in Tables 5.1—5.4 there will be additional terms for undetected combined with detected failures as shown in Tables 5.5 and 5.6. For electronic devices it is quite common that the final result is dominated by the undetected faults along with the common cause failure (if considering a redundant configuration). The ESC software (SIL COMP ) models the full equations.

The selectivity inherent to TNT detection by amplified fluorescent polymers, as described in Section 4, helps to rriinirriize false-positives in land mine detection. These sensor devices respond only to nitroaromatics and similarly small, electron-deficient analytes, which are found typically only in or close to explosives and explosive devices. Field-tests to date have demonstrated that these devices are at least as reliable as trained dogs in detecting explosives that contain nitroaromatics. There is still uncertainty concerning what chemical that dogs actually detect when searching for explosives [17]. This... 

Although SEMs or ESEMs are very powerful in imaging nanoscale materials or particles, caution should be taken to avoid electron beam damage to specimen. This is particularly important when a nanomanipulation system with a force measurement device is to be used to characterise the mechanical properties of particles. Ren et al. (2007, 2008) identified that such damage depended on the electron dose and exposure time, as well as the type of materials under test, and it is extremely important to find a time window in which the damage is negligible to obtain reliable mechanical property data. 

Within the last 25 years of X-ray spectroscopy on fusion devices, the theory of He-like ions has been developed to an impressive precision. The spectra can be modeled with deviations not more than 10% on all lines. For the modeling, only parameters with physical meaning and no additional approximation factors are required. Even the small effects due to recombination of H-like atoms, which contribute only a few percent to the line intensity, can be used to explain consistently the recombination processes and hence the charge state distribution in a hot plasma. The measurements on fusion devices such as tokamaks or stellarators allow the comparison to the standard diagnostics for the same parameters. As these diagnostics are based on different physical processes, they provide sensitive tests for the atomic physics used for the synthetic spectra. They also allow distinguishing between different theoretical approaches to predict the spectra of other elements within the iso-electronic series. The modeling of the X-ray spectra of astronomical objects or solar flares, which are now frequently explored by X-ray satellite missions, is now more reliable. In these experiments, the statistical quality of the spectra is limited due to the finite observation time or the lifetime of... 

In healthcare, we are today at a crossroads of yet, another of many notable technical developments. Personal computers have become ubiquitous and easier to use for healthcare professionals and patients. The newly available mobile or handheld devices have become more practical for real-time computing. Through the Internet or hand-eld device, there is ready access to a patient s medical information. With these tools, the art of practicing medicine is truly about to change. An electronic information resource for the Internet and for handheld devices, as for other platforms, requires that the data meet specific standards of reliability. First DataBank information is tried and true, a tested, authoritative source of such information. 

The electronics industry desires improved flame suppressant additives for microelectronic encapsulants due to bromine induced failure. Epoxy derivatives of novolacs containing meta-bromo phenol have exhibited exceptional hydrolytic and thermal stability in contrast to standard CEN resins with conventional TBBA epoxy resins. When formulated into a microelectronic encapsulant, this stable bromine epoxy novolac contributes to significant enhancements in device reliability over standard resins. The stable bromine CEN encapsulant took about 30% more time to reach 50% failure than the bias pressure cooker device test. In the high temperature storage device test, the stable bromine CEN encapsulant took about 400% more time to reach 50% failure than the standard compound. Finally, the replacement of the standard resins with stable bromine CEN does not adversely affect the desirable reactivity, mechanical, flame retardance or thermal properties of standard molding compounds. 

Mechanical attachment of components, devices, and other parts of an electronic assembly is the prime function of adhesives. Although adhesives are expected to bond a wide variety of materials for electronic applications, they do not need to be structural. They should, however, meet minimum tensile and shear strengths in order to withstand mechanical shock, thermal shock, thermal cycling, and vibration as specified for the intended application. For consumer and commercial products, these stresses may be minimal. For high reliability aerospace and medical systems, more severe tests as defined in MIL-STD-883 and other documents must be used. 

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