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This paper gave an actual overview of sustainability, robustness, and reliability of GaN-based LED devices. This overview deals with low- and medium-power LED composed of a single chip and details the main functional parameters to regard to estimate performance drifts of the technology related to application. [ABSTRACT FROM PUBLISHER]

Wafer handling during the manufacturing process introduces microcracks and flaws at the wafer edge. This paper aims at determining whether an initial crack would be able to propagate through the silicon active region of power devices when it is subjected to high electrothermal loads during operating conditions or accelerated thermal cycling tests. Failure analysis performed on these power devices has revealed some typical propagation paths. The most critical crack propagation cases (or paths) were determined by finite-element model simulations. The energy release rate has been calculated for different crack lengths, locations, or thermal loads, and then compared with the silicon critical energy release rate. Hence, different critical crack lengths have been determined. The effect of dice design, temperature, or mechanical properties of the materials on crack thresholds has been also investigated. [ABSTRACT FROM AUTHOR]

Embedded passives are becoming increasingly important for the manufacture of highly integrated electronic boards and packages. The need for embedded passives emerges from the growing consumer demand for product miniaturization thus requiring smaller components and space efficient packaging. This can be realized by replacing discrete components that demand a higher volume than embedded passives. Embedded passives have already been investigated in the last few years. However, nowadays used dielectric materials have to be optimized in order to improve the performances of the passive components in terms of dielectric behavior and reliability. The most promising candidates for dielectric materials applied for embedded passives are polymer-ceramic nanocomposites. In this paper, the robustness of embedded capacitors using such commercial dielectrics regarding the environmental conditions (temperature and humidity) is studied. Microwave measurements performed on an embedded structure design for low noise amplifier microwave monolithic integrated circuit decoupling allow to demonstrate clearly the capacity of this new technology. [ABSTRACT FROM PUBLISHER]

Degradation of packaged light-emitting diodes (LEDs) under gamma irradiations has been investigated using usual electro-optical characterizations. Failure mechanisms have been revealed by an accurate degradation model taking into account the Stark effect in electroluminescence spectrum and piezoelectric field in the active zone. Gamma irradiations have induced an additional mechanical stress close to 0.25 MPa in the active layer resulting from the change of the polymer mechanical properties used on the LED package. [ABSTRACT FROM PUBLISHER]

A Design Of Experiments (DOE) methodology was suggested to define an optimized irradiation test plan. In this paper, the proposed test plan was used to model the degradation of the main performances (photo and dark current) of silicon based phototransistors arrays with respect to the Total Ionizing Dose (TID) and to the Displacement Damage Dose (DDD), over a wide range of space-kind environments. The expected performance degradation after an 18-year Low Earth Orbit (LEO) mission was calculated using this model. End-Of-Life (EOL) prediction results were compared to experimental ones obtained on devices irradiated with a proton beam degrader that simulates the 18 year LEO environment. The excellent agreement found between theoretical and experimental data makes this methodology particularly valuable for the space qualification of such devices. [ABSTRACT FROM AUTHOR]

Expertise of packaging for optoelectronic components requires the solution of optical, mechanical, and electrical problems in the same way. The purpose of this paper is to present three-dimensional simulations using finite-element method (FEM) of thermomechanical stresses and strains in 1550-nm laser modules induced by Nd:YAG crystal laser welds and thermal cycles on main subassembly laser submount. Nonlinear FEM computations, taking into account of experimental σ(ε) measured curves, show that thew laser welding process can induce high level of strains in columns of the laser platform, bearing the laser diode, responsible of an optical axis shift and a gradual drop of the optical power in relation with relaxation of accumulated stresses in the subassembly (W. M. Sherry et al., "High performance optoelectronic packaging for 2.5 and 10 Gb/s laser modules," in Proc. Electron. Compon. Technol. Conf., 1996, pp. 620-627). Typical stresses are close to 160 MPa with drift about 5 MPa with the dispersion of energy level of the laser Nd: YAG beam. The introduction of both material and process dispersion in order to evaluate their impact on product lifetime distribution has been taking into account. In the case of thermal cycles, stresses can occur on elements sensitive to coefficient of thermal expansion mismatches such as solder joints between the laser platform and thermoelectric cooler and as fiber glued into the pigtail leading to crack propagation with sudden drop of optical power. A previous paper demonstrated that laser submount is the most sensitive part of optical system (Deshayes, et al., "Three-dimensional FEM simulations of thermal mechanical stresses in 1.55 μm laser modules," Microelectron. Rel., vol. 43, no. 7, pp. 1125-1136, Jul. 2003). Experimental analyses were also conducted to correlate simulation results and monitor the output optical power of laser modules after 500 thermal cycles (-40 °C/ + 85°C VRT). [ABSTRACT FROM AUTHOR]

Focuses on a method for the automatic analysis and characterization of defects due to encapsulation and surface mount processes of microelectronic devices. Pre-processing of the signals by an algorithm based on the Wiener filtering; Experimental results obtained by applying the proposed method on acoustic signals from an electronic structure acquired through an ultrasonic scanning system; Use of ultrasonic microscope.