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Auersperg J.,Fraunhofer Institute for Electronic Nano Systems | Auersperg J.,AMIC Angewandte Micro Messtechnik GmbH | Vogel D.,Fraunhofer Institute for Electronic Nano Systems | Auerswald E.,Fraunhofer Institute for Electronic Nano Systems | And 2 more authors.
2011 IEEE 13th Electronics Packaging Technology Conference, EPTC 2011 | Year: 2011

The application of copper-TSVs for 3D-IC-integration generates novel challenges for reliability analysis and prediction, i.e. to master multiple failure criteria for combined loading including residual stresses, interface delamination, cracking and fatigue. So, the thermal expansion mismatch between copper and silicon yields to stress situation in silicon surrounding the TSVs which is influencing the electron mobility and as a result the transient behavior of transistors. Furthermore, pumping and protrusion of copper is a challenge for Back-end of Line (BEoL) layers of advanced CMOS technologies already during manufacturing. These effects depend highly on the temperature dependent elastic-plastic behavior of TSV-copper and the residual stresses determined by the electro deposition chemistry and annealing conditions. © 2011 IEEE.

Schlottig G.,IBM | Schindler-Saefkow F.,AMIC Angewandte Micro Messtechnik GmbH | Zurcher J.,IBM | Michel B.,IBM | Brunschwiler T.,IBM
Proceedings of the 2013 IEEE 15th Electronics Packaging Technology Conference, EPTC 2013 | Year: 2013

To ensure functionality and integrity of electronic package interconnects, underfill materials are designed to meet a desired stiffness that bridges the thermal expansion behavior of die, substrates and interconnects. The underfill protects the interconnects from thermal strains and environmental influences. Recently, the thermal conductivity became a critical parameter too, to efficiently dissipate heat from 3D chip stacks. Accordingly, the particle loading is increased beyond the percolation threshold, which was demonstrated by sequentially fabricated materials with a 5fold thermal conductivity improvement. This paper explores the thermo-mechanical properties of the novel percolating thermal underfills considering alumina filler particles. The changing behavior of underfill composites has been well described for various fillers and matrices both theoretically and experimentally. But percolation was excluded so far for lack of relevance. We compare the numerical predictions of composites' Young's moduli around the filler percolation threshold to known effective-medium approximation bounds of polydisperse materials. The simulations were based on 3D unit cells of the face centered cubic packing in different lattice orientations and consider both filler and matrix materials. A significant change in characteristics is observed close to percolation. However, the 100 and the 110 lattice orientations give a 5% Young's modulus difference only. The numerical predictions are within effective-medium approximation bounds, but appear closer to either upper or lower bounds depending on the filler fraction. The presented results extend the possible thermo-mechanical parameter space of conventional underfills to percolating composites. © 2013 IEEE.

Agency: Cordis | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2010-3-ECO-01-007 | Award Amount: 199.99K | Year: 2011

The FATIMA project proposed by the consortium will work on testing and fatigue prediction of carbon fiber reinforced plastics (CFRP) as required in call JTI-CS-2010-3-ECO-01-007. The challenging objective is to go beyond the state of the art in terms of approaches to account for humidity, multi-ply and multi-axiality effects in organic laminate structures. Intensive work in the field resulted in a number of concepts for accelerated lifetime predictions for carbon fiber reinforced polymers. Within FATIMA, these concepts will be adapted to the material provided by the partners of the Clean Sky consortium. The proposed methodology and integration into the fatigue testing procedure will approach expansions addressing humidity effects, different stack-up structures and combined loading of these composite structures. Appropriate models of a multitude of specific laminate structures will be provided as a tool box for composing desired laminates consisting of plies with known behavior. Failure criteria developed for predicting the damage in composite materials due to multi-axial loads will be evaluated, selected and advanced to meet the objectives of the call.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: NMP-2007-2.5-2 | Award Amount: 5.22M | Year: 2008

Micro- and nano-electronic components are multi-scale in nature, caused by the huge scale differences of the individual materials and components in these products. Consequently, product behaviour is becoming strongly dependent on material behaviour at the atomic scale. To prevent extensive trial-and-error based testing for new technology developments, new powerful quantitative knowledge-based modelling techniques are required. Current continuum-based finite element models rely intrinsically on extensive characterisation efforts to quantify the parameters present in these models (top-down approach). On the other hand, state-of-the-art models at atomic scale are able to describe the material behaviour at molecular level, but predictions at product scale are not feasible yet. Through direct coupling of molecular and continuum models, a multi-disciplinary approach in which experimentally validated multi-scale modelling methods will be developed in order to generate new materials and interfaces for System-in-Package (SiP) products with tailored properties and improved reliability within an industrial environment. In this approach, a user-friendly software tool will be realised which incorporates chemical, physical and electrical information from the atomic level into macroscopic models (bottom-up approach). Furthermore, new and efficient micro- and nano-scale measurement techniques are developed for obtaining detailed information about the most important phenomena at micro- and nano-scale and fast characterisation and qualification of SiPs. An additional important distinguishing part of this project is that, due to the composition of the consortium, the whole industrial development chain is covered: from material development, multi-scale models and experimental methods towards a fully functional commercial software package, ready to be used within an industrial environment.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2011.3.1 | Award Amount: 9.51M | Year: 2012

Future electronic power devices and packages will need to demonstrate more performance and functionality at reduced cost, size, weight, energy consumption and thermal budget. Further, increasing reliability demands have also to be met by industry to be competitive in this growing multi-billion Euro market of heterogeneously integrated systems.To respond to these challenges, new innovative nano- and micro-technologies and materials, both of which are key enablers for advanced thermal and mechanical interfaces, have to be developed and compatibly integrated to obtain higher electrical, thermal and reliability performance under harsh environmental conditions.Nanotherms objective is to take up these challenges in design, technology and test:Novel approaches to thermal technologies with superior electrical, thermal and thermo-mechanical properties will be developed in the project and demonstrated on automotive, avionics, solid-state lighting and industrial applications. Parallel routes will be followed addressing nano-sinter-adhesive bonding, phonon-coupled VACNT joining, nano-functionalised nano-filled adhesive die attach and graphene-enhanced surfaces. The main principle common to all technologies is the exploitation of nano-effects to obtain outstanding interconnect properties by especially developed processes.In parallel, a multi-scale and multi-domain modelling framework will furnish guidelines for materials design by various approaches from ab-inito up to continuum modelling and verified by corresponding experimental techniques.The consortium, composed of 18 partners from industry, SME and academia out of 8 European countries, embodies the necessary excellence and interdisciplinarity to address these tasks successfully. We are convinced that Nanotherms results will enable the next generation of heterogeneously integrated power packages, cut down thermal interface resistance at least by 50% and impact also on other power system-in-package configurations.

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