Alexander Teverovsky

ASRC, Federal Space and Defense · GSFC

Insertion of new types of commercial, high volumetric efficiency wet tantalum capacitors in space systems requires reassessment of the existing quality assurance approaches that have been developed for capacitors manufactured to MIL-PRF-39006 requirements. The specifics of wet electrolytic capacitors is that leakage currents flowing through electro...

Multilayer ceramic capacitors (MLCCs) constitute the majority of components used in electronic assemblies and most of their failures are related to cracks. It is often assumed that dissipation factor (DF), insulation resistance (IR), and breakdown voltage (VBR) are characteristics that are sensitive to the presence of mechanical defects, and screen...

Microcircuits encapsulated in three plastic package styles were stored in different environments at temperatures varying form 130°C to 225 °C for up to 4,000 hours in some cases. To assess the effect of oxygen, the parts were aged at high temperatures in air and in vacuum chambers. The effect of humidity was evaluated during long-term highly accele...

Fourteen different commercial linear and mixed signal plastic encapsulated microcircuits (PEMs) with lot quantities varying from 85 to more than 3500, have been screened and subjected to reliability qualification testing for several GSFC projects during 2003-2004 period. The testing included electrical measurements at three temperatures, burn-in (B...

The glass transition temperature, Tg, and coefficients of thermal expansion in a glassy state, CTE1, and rubbery state, CTE2, are important characteristics of molding compounds, which affect thermo-mechanical performance and reliability of electronic devices encapsulated in plastics. Temperature increase above Tg of epoxy molding compounds might si...

Hygroscopic swelling characteristics of different types of molding compounds and electrical parameters of voltage reference microcircuits encapsulated in plastics were measured after saturation with moisture at 85 oC and humidity varying from 20% to 90% RH. Sorption of moisture at high humidity conditions and desorption during baking resulted in de...

A significant proportion of metallurgically bonded, glass bodied, axial diodes fail destructive physical analysis (DPA) due to excessive voiding in the attachment media. Internal examination of these diodes typically is performed by cross-sectioning the diodes in several planes parallel to the axis. However the process of cross-sectioning might cha...

This work analyzes swelling and shrinkage of plastic packages of PEMs caused by various environmental conditions. These conditions include moisture sorption during normal storage in laboratory conditions, accelerated environmental stress testing in humidity chambers, bake-outs at 125 oC and 150 oC, and short-term high temperature exposure at temper...

Simple equations to estimate the characteristic times for moisture absorption/release in plastic packages of different shapes have been given. The temperature dependence of moisture diffusion coefficients are similar for different epoxy molding compounds. This allows the adequate bake-out regimens to be estimated for different situations.

A non-isothermal technique for rapid characterization of moisture diffusion in molding compounds of plastic encapsulated microcircuits (PEMs) is suggested. The technique is based on measurements of the weight losses during heating in dry conditions of a polymer sample or plastic package pre-saturated with moisture. It allows calculation of the mois...

Moisture diffusion in epoxy molding compounds (MC) is considered as one of the major reliability concerns in PEMs. The rate of moisture ingress to the die surface and/or moisture release from the package depends on the package geometry and on the coefficient of moisture diffusion, D, of the packaging material. Given the values of D at different tem...

Metallurgically bonded, glass-bodied DO-35 power rectifier diodes were electrically overstressed by applying forward and reverse current pulses. Forward current pulses varied from 0.1 to 3 ms with current amplitudes varying from 200 to 1000 A were applied to one group of diodes. Reverse bias current pulses in the microsecond range with amplitudes f...

Low pressure conditions, as experienced in space applications, are considered benign for many electronic components. However, for switching devices the probability of failure may be significantly larger than at normal atmospheric pressure conditions due to arcing-at-break processes. This study was stimulated by a relay failure in a 60V power bus in...

A new technique for assessing the moisture resistance of PEMs is based on measurements of a time-varying capacitance of an MOS-structure with a large perimeter-to-area ratio of the metal electrode. When an inversion voltage is applied, the capacitance of the structure will increase with time due to lateral charge spreading. The rate of the charge r...