Bernard Plano

Failure Analysis-assisted FMEA

In this paper, ordinary FMEA (Failure Mode and Effects Analysis) was applied during the design phase of an electric motor control system for vehicle HVAC (Heating/Ventilation/Air Conditioning). The analysis of the field data from the second year forces to review FMEA. The corrective actions, planned on the basis of the sole failure mode, as usual in FMEA, proved to be inadequate and Failure Analysis was performed to understand the failure mechanism of the indicted component and integrate. New proper corrective actions were devised and successfully implemented.

Improved performances of polymer-based dielectric by using inorganic/organic core-shell nanoparticles

BaTiO3/hyperbranched polyester/methacrylate core-shell nanoparticles were studied by varying the shell thickness and the methacrylate ratio. We demonstrated that coalescence typically observed in traditional composites employing polymer matrices is significantly reduced. By modifying the shell thickness, the equivalent filler fraction was tuned from 7 wt. % to 41 wt. %. Obtained permittivities were compared with reported models for two-phase mixtures. The nonlinear behavior of the dielectric constant as a function of the equivalent filler fraction has been fitted with the Bruggeman equation. Methacrylate groups reduce by a decade the loss factor by improving nanoparticles adhesion. The permittivity reaching 85 at 1 kHz makes core-shell nanoparticles a promising material for embedded capacitors.

Electrically driven matter transport effects in PoP interconnections

The migration issue of Package-on-Package (PoP) is investigated in this article. The migration phenomenon can be amplified as the density of solder bumps increases, while the paths are very finer as well in PoP.

Love Acoustic Wave-Based Devices and Molecularly-Imprinted Polymers as Versatile Sensors for Electronic Nose or Tongue for Cancer Monitoring

Cancer is a leading cause of death worldwide and actual analytical techniques are restrictive in detecting it. Thus, there is still a challenge, as well as a need, for the development of quantitative non-invasive tools for the diagnosis of cancers and the follow-up care of patients. We introduce first the overall interest of electronic nose or tongue for such application of microsensors arrays with data processing in complex media, either gas (e.g., Volatile Organic Compounds or VOCs as biomarkers in breath) or liquid (e.g., modified nucleosides as urinary biomarkers). Then this is illustrated with a versatile acoustic wave transducer, functionalized with molecularly-imprinted polymers (MIP) synthesized for adenosine-5′-monophosphate (AMP) as a model for nucleosides. The device including the thin film coating is described, then static measurements with scanning electron microscopy (SEM) and electrical characterization after each step of the sensitive MIP process (deposit, removal of AMP template, capture of AMP target) demonstrate the thin film functionality. Dynamic measurements with a microfluidic setup and four targets are presented afterwards. They show a sensitivity of 5 Hz·ppm−1 of the non-optimized microsensor for AMP detection, with a specificity of three times compared to PMPA, and almost nil sensitivity to 3′AMP and CMP, in accordance with previously published results on bulk MIP.

Electro- and thermomigration-induced IMC formation in SnAg3.0Cu0.5 solder joints on nickel gold pads

The progress in three dimensional packaging leads to smaller solder joints. A growing part of their volume consists of IMCs (intermetallic compounds). The IMCs are formed through migration processes during the soldering. These phenomena continue during use of the component. As a consequence micro bumps (o < 30 μm) completely consist of intermetallic compounds. Intermetallic compounds also enable electromigration induced void formation at the contacts surfaces of flip chip solder joints. It is essential for the fabrication of micro bumps and for the investigation of failure mechanisms in flip chip solder joints to characterize the migration-induced IMC formation. This study is based on the combination of electromigration, thermomigration and temperature storage tests on SnAg 3.0 Cu 0.5 solder joints with NiAu pads. For the investigation of migration processes due to temperature gradients (thermomigration), alternating current tests for solder joints were developed. Finally, more accurate material parameters for the description of the migration-induced intermetallic compound formation are extracted, namely the activation energy (E A ), the diffusion constant (D 0 ), the effective charge of the moving ions (Z˙) and the heat of transport (Q * ).

Scanning laser ultrasonics experiments for in situ nondestructive analysis of integrated circuits

Scanning experiments on a very large scale integrated (VLSI) circuit are presented using the picosecond ultrasonics technique. This optical nondestructive technique is based on ultrasound generation and detection by ultrashort laser pulses. The experimental setup and methodology are described. The influence of the protection layer for passivated circuits on the experimental results is described and illustrated by experimental data. In order to help in the interpretation of the experimental analysis of microelectronic devices, a simulation tool was developed.

Analytical model for thermally-induced warpage of POP

The thermally-induced deformations of package-on- package (POP) are investigated theoretically, numerically and experimentally in this paper. An analytical model of POP is newly proposed for prediction of the warpage of POP, which can be achieved by solving a few linear multiple polynomial equations rather than building a complex model in ANSYS, and leads to satisfying results. All the parameters needed for the analytical model are temperature-dependant material properties, and geometrical parameters. Measurements of the the warpage of POP under various temperature loads are made with a Profilometer Altisurf 500. Moreover, a 3-D linear finite element model was built. Both measurements and simulation validate our analytical model. The results from the experiments are presented and compared in detail with those from the 3-D linear finite element and theoretical analysis. The good agreements in the experimental and modelling results reveal the validation of 3-D linear finite element model in mechanics sense and the effectiveness of the numerical and theoretical models in physics predictions. The interest lies in a very easy use of this theoretical model to quickly obtain the warpage information for deciding whether the design is suitable and/or comparing the different POP circuits design.

Investigation of stability of GaAs metal/electron/semiconductor field effect transistor gate contacts by high resolution transmission electron microscopy analysis

Abstract The structure of GaAs metal/electron/semiconductor field effect transistor (MESFET) gate contacts has been investigated by high resolution transmission electron microscopy (TEM). A specific technique has been used successfully to prepare thin and proper cross-sections of specific regions within GaAs devices. A significant defect has been observed at the periphery of the recessed gate, which indicates the presence of a non-passivated region of the active layer surface. The presence of an amorphous layer at the gate metallization-GaAs interface has been revealed by a high resolution observation. These structural anomalies have been correlated with parasitic effects of the I-V Schotty gate contact characteristics.

Assessment of Constitutive Properties of Solder Materials Used in Surface-Mount Devices for Harsh Environment Applications

To perform a thermomechanical simulation of surface-mount devices (SMD), relevant solder constitutive properties are needed. This paper reviews some promising Pb and Pb-free solders that are candidates to harsh environment applications. It presents the discrepancy in their common mechanical properties reported in the literature. The mechanical test systems, solder microstructure under test, and the test conditions (temperature and strain rate) are among the major causes for the discrepancy. The use of such variations in the solder thermomechanical properties as input data for simulation studies may cause reliability prediction less meaningful. A novel and reliable test methodology to extract relevant solder properties for surface mount applications is presented in this paper. To fulfill the methodology requirements, lap shear tests with accurate control of the reflow profile and dimensionally accurate solder joint thickness need to be conducted to reproduce the SMD solder joint microstructures for determining solder joint properties for elastic, plastic, and creep model simulations. Two case studies with high-Pb and Pb-free solders are presented. Time-independent yield strength and ultimate tensile strength data obtained from our studies were found to be higher than the reported literature data. This methodology can be extended for other solder material systems with any surface finish plating materials.

Structural analysis of integrated circuits using scanning laser ultrasonics

We present an analysis of a VLSI Circuit using the picosecond ultrasonics technique. This optical non-destructive technique is based on ultrasound generation and detection by ultrashort laser pulses. The experimental setup and methodology are analyzed. The influence of the protection layer for passivated circuits on the experimental results is described. The in-depth and lateral resolutions of the technique are illustrated by experimental results.