Nathalie Batut

Modeling of a New SOI Bidirectional Bipolar Junction Transistor for Low-Loss Household Appliances

In this paper, a new monolithic bidirectional bipolar junction transistor with full turn-off control is studied due to technology computer-aided tools. The structure is built on a symmetrical transistor using silicon-on-insulator technology, which functionality relies on reduced surface field and base shielding effects. These concepts allow high drift doping concentrations and a thin and/or lowly doped base. Such a structure is suitable for bidirectional household appliances within a confined environment where power dissipation is a critical parameter.

Aging test results for high temperature TRIACs during power cycling

This paper deals with the functional reliability study of a new 16 A - 600 V high-temperature TRIAC family, subjected to power cycles, simulating the component in harsh real operation conditions. The targeted application is a vacuum cleaner (1800 W - 230 V - 50 Hz). In this kind of application, one of the major issues for TRIAC, which leads to high mechanical stresses for the assembly, occurs when the switch turns-on in ldquojammed nozzle operationrdquo, i.e. when the tube is blocked. In that case, the TRIAC junction temperature reaches at most 180degC, higher than the maximum value specified by the manufacturer (i.e. 150degC). The aim of this study is to evaluate the TRIACs lifetime under these operation conditions. The thermal stresses generate local temperature variations and then, some mechanical stresses (assembly degradation). For TRIACs, the junction-to-case thermal resistance (Rth(j-c)) increase is the signature of such a damage. The lifetime has been studied and fitted with a Lognormale distribution. The components damages, due to the mechanical stresses, have been explained thanks to some qualitative two-dimensional thermo-mechanical simulations using finite elements (ANSYSreg).

Lifetime prediction modeling of non-insulated TO-220AB packages with lead-based solder joints during power cycling

In this paper, a physical model is proposed to estimate the TRIAC solder joint fatigue during power cycling. The lifetime prediction is based on the following assumptions: the case temperature swing (DTcase) is the main acceleration factor, the solder joints are the weakest materials in the non-insulated TO-220AB TRIAC package and the plastic strain within the solder layer due to shearing is the failure cause.

Development and Static Mode Characterization of a New Low-Loss AC Switch Based on Super-gain BJT

This paper deals with an innovative low-loss AC switch, named as TBBS (transistor based bidirectional switch), based on the association of super-gain BJTs developed by the GREMAN laboratory. The main characterization results of the super-gain BJT are reminded to identify the key parameters that are essential to build the TBBS. A complete characterization database in static mode of this new AC switch is discussed. In particular, its forward and reverse-biased features have been measured to see the evolution of the DC current gain as a function of the current density. The TBBS makes sense when using the super-gain BJT (bipolar junction transistor) in reverse mode. It means that the reverse DC current gain has to be sufficient (at least higher than 1 compared with the conventional BJT one). This new AC switch is bidirectional in current and voltage, totally controllable (turn-on and turn-off) and the most attractive solution in terms of on-state power losses. Further, its manufacturing process is as easier as existing device such as triac.

Rise time and dwell time impact on Triac solder joints lifetime during power cycling

In this paper, we analyze the rise time and dwell time impact on 16A–600V high temperature Triacs reliability subjected to power cycling. Experimental tests, performed on two TO-220 packages (insulated or not), show that rise time and dwell time have a negligible contribution on Triacs lifetime. Failure analysis confirms that the physical failure mode (the die-attach fatigue) and the failure location (the solder joints) are similar when rise and dwell durations change. Thermo-mechanical simulations (ANSYS®) were performed to get a better understanding of the effects of various ramp and dwell values on solder joints plastic work and shear stress.

Thermal runaway evaluation for high temperature TRIACS

This paper deals with thermal runaway that could occur for the new high-temperature TRIACs which are used with junction temperatures up to 160degC in transient state. The conditions to avoid thermal runaway for the specific case of alternative voltage are discussed. Experimental measurements are given and compared with a theoretical analysis.

Development and characterization of a new low-loss monolithic AC switch based on super-gain BJT

This article deals with the development of an innovative low-loss monolithic AC switch based on super-gain BJT manufactured on silicon substrate. The GREMAN laboratory has started this study for ten years. Two main categories of AC switch are described: hybrid AC switch (based on the discrete association of 2 super-gain BJTs) and monolithic AC switch. The key criteria to design and process the monolithic power device are particularly discussed taking into consideration its application areas and its manufacturability.

BJT static behavior improvement by modification of the epitaxial layer

In this paper, high voltage Bipolar Junction Transistors are presented and compared in order to suggest a bidirectional switch for household appliances with fully turn-on, turn-off control. A comparative theoretical study, using 2D simulations, shows that concepts like “superjunctions” and “floating islands” improve the static current gain without unwanted behavior like parasitic diodes.

Platinum decoration of silicon direct wafer bonded interfaces

In this paper we investigate the electrical properties of hydrophobic silicon wafer bonded interface. Platinum diffusion, commonly used to enhance fast bipolar P-i-N diodes, is performed to control its electrical properties. The control of the bonded interface properties is a necessary condition to integrate the wafer bonding technique as a new manufacturing process for structures such as bidirectional switch devices. This work is based on spreading Resistance (SR), Deep Level Transient Spectroscopy (DLTS) and Micro-PhotoConductivity Decay (μ-PCD) characterizations of as-bonded and platinum decorated silicon direct wafer bonded interfaces.