INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDSInt. J. Numer. Model. 2013; 26:519–520Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jnm.1913

EDITORIAL

Guest editorial for the special issue on ‘computational multiphysicsmethods for integrated circuits and packaging’

It is well-known that both the reliability and performance of present-day integrated circuits and theirpackages cannot be completely understood or accurately predicted from electromagnetic consider-ations alone. For example, the physical characteristics of high-density interconnects and micro/nanoelectronic passive and active devices are often affected by heat conduction and mechanicalstresses/deformations, in extreme cases leading to electro-thermo-mechanical breakdown. Under suchcircumstances, predictive simulations must rely on multiphysics computational approaches as opposedto electromagnetics-only methods.

There exist many challenges in developing computational algorithms for rapidly and accuratelyanalyzing electro-thermal and electro-thermo-mechanical phenomena in electronic components andsystems with complex geometries and material properties. For starters, most material parameters, suchas permittivity, permeability, electrical conductivity, thermal conductivity, and thermal expansioncoefficients are temperature dependent. To exasperate the modeling challenge, there exist significantdifferences in length and time scales among electrical, thermal, and mechanical field actions. Needlessto say, special attention must be paid to the choice of spatial discretization and time stepping proce-dures to ensure convergent multiphysics solutions in all but the simplest scenarios.

This special issue reports on recent advances in the area of computational multiphysics methods foranalyzing and designing modern ICs and other structures. After a rigorous peer review process, sixpapers were selected from those submitted in response to the Call for Papers.

The first paper by Ziar and Zaabat et al. presents the application of an iterative method that uses thenotion of transverse waves to analyze package miniaturization effects in active planar circuit structures.The proposed approach relies on the substitution of the active element by one auxiliary sourceconnected by substrate-backed microstrip lines. The usefulness of the method is demonstrated viathe extraction of S-parameters and impedances of an active circuit using MATLAB codes (MathWorks,Natick, MA, USA).

The second paper by Ohnuki and Takeuchi et al. presents a novel algorithm for solving the coupledMaxwell and Schrödinger equations relying on the use of a length gauge form for the coupling betweenan electromagnetic field and electrons. Numerical simulations were performed for a nanoplatesubjected to a pulsed laser field with central frequency close to the plasmon frequency. The proposedalgorithm was shown to reduce the computational time almost by half compared with conventionalmethods.

The third paper by Jianyong Xie and Biancun Xie et al. focuses on electro-thermal modeling ofthrough-silicon via (TSV) arrays. To address thermal effects in TSVs, the proposed method incorporaterealistic system thermal profiles. To obtain temperature estimates for a 3D system, a multigrid methodis employed that uses an initial guess obtained by simulation using an equivalent thermal conductivityto represent critical regions. By considering thermal effects on the electrical conductivities of TSVconductor and silicon substrate, the electro-thermal modeling of a TSV array is carried out usingcylindrical basis functions. The temperature effect on the TSV insertion loss, crosstalk, and resistance,inductance, capacitance, and conductance parameters are discussed with numerical examples that arecorrelated with measurements.

The fourth paper by Chiariello and Maffucci et al. investigates the electrical performance of novelinterconnects composed of carbon nanotubes and graphene nanoribbons. The electronic transport in the

Copyright © 2013 John Wiley & Sons, Ltd.

520 EDITORIAL

carbon materials is modeled using transmission line theory, where the classical per-unit-length circuitparameters are corrected by new terms arising from the quantum nature of the transport. These param-eters are related to the number of conducting channels and the mean free path, which in turn, areexpressed as functions of temperature and size. By coupling this model to the heat equation, a simpleelectro-thermal model is derived. Case studies are carried out for 22-nm technology applications.

The fifth paper by Kocer studies infrared sensors which have been widely used in thermal imagingand sensor applications. The performance of these sensors strongly depends on their noise currents. Inthis study, a p–n long-wave infrared mercury cadmium telluride sensor is evaluated at 77K using aphysics-based numerical modeling and simulation approach. Results of the study showed that 1/f noiseoriginating from the trap-assisted tunneling dominates as the cut-off wavelength and the magnitude ofthe applied reverse bias voltage increase.

The sixth paper by Górecki presents a compact electro-thermal model of a monolithic switching-mode voltage regulator belonging to the TOPS switch family (Power Integrations, Inc. San Jose,CA, USA). A specific model description and experimentally verified results are provided for aTOP222Y switch. The proposed model can be used to calculate the terminal voltages and currentsof the investigated device and the internal temperature of the regulator, too. Good agreement betweenthe calculated and measured characteristics of the switching-mode power supply including theconsidered integrated circuit is observed.

“Qiu Shi” Distinguished Prof. Wen-Yan Yin, IEEE Fellow, GUEST EDITOR

Center of Optical and Electromagnetic Research,Zhejiang University, Hangzhou, China

Center for Microwave and RF Technologies (Adjunct Prof.)Shanghai Jiao Tong University, Shanghai, China

E-mail: wyyin@zju.edu.cn, wyyin@sjtu.edu.cn

Copyright © 2013 John Wiley & Sons, Ltd. Int. J. Numer. Model. 2013; 26: 519–520DOI: 10.1002/jnm