Olgierd A. Palusinski

Analysis of transients in nonuniform and uniform multiconductor transmission lines

The author presents an effective method for computation of the transient response of multiple nonuniform transmission lines. This time-domain analysis technique can predict reflections and crosstalk. The proposed spectral technique is used to transform partial differential equations describing a system of transmission lines into a set of linear ordinary differential equations, which can be solved with one of the many well-developed integration techniques. Numerical experiments performed with the prototype program showed that the method can solve specific problems (lossless, uniform lines) just as fast as less general methods based on modal analysis exploiting the particular properties of lines. >

Electrical Modeling of Interconnections in Multilayer Packaging Structures

An effort toward modeling the interconnections in selected typical multilayer packaging structures is presented. The modeling is based on a quasi-static approximation to the associated electro-magnetic problems. A program for computing capacitance and inductance matrices and the numerical techniques used to improve the program efficiency are described. The results of numerical testing of the program are provided and discussed. The program was also compared with experimental data published in the open literature and the results are shown. The agreement between the model and the experiments is satisfactory.

Simulation of transients in VLSI packaging interconnections

An approach to electrical analysis of VLSI packaging interconnections using computer simulation is discussed. Corresponding simulation software developed during the course of research on VLSI interconnections is described. Examples of application to prototypical interconnections (two-transmission-line systems joined by a lumped-parameter network and a transmission line terminated by a network of bipolar and MOS transistors) are provided. Simulation results for the above examples are presented and analyzed. The current status of work is discussed, and directions of future research are delineated. >

Computation of transients in lossy VLSI packaging interconnections

An efficient method for analyzing the dynamic behavior of lossy electrical interconnects (with frequency-dependent parameters) in VLSI Systems is presented. The method allows for inclusion of the electrical interconnects which are terminated by networks of lumped passive (R, L, C) and active nonlinear devices (diodes, and bipolar and MOS transistors). The method consists of deriving the circuit model for a transmission line from impulse-response data and incorporating this model into the UANTL (University of Arizona simulator for nonlinearly terminated transmission-line networks) computer program, which performs time-domain analysis for coupled transmission lines with nonlinear terminations. Several numerical experiments with this method were performed. Comparisons were made between the results obtained using this method and other published results. >

Scattering parameter-based simulation of transients in lossy nonlinearly terminated packaging interconnections

A new and efficient approach is presented for the transient analysis of coupled transmission line structures frequently encountered in microelectronic packaging applications. Frequency-dependent parameters for the transmission lines, as well as nonuniformities in the cross-section of the structures are taken into account. The method is based on the scattering parameter representation of the lossy and/or nonuniform interconnects, An important advantage of this approach compared to previous scattering parameter formulations is that the scattering parameter models have been fully integrated with the standard SPICE models of nonlinear semiconductor devices such as bipolar and CMOS transistors, thus allowing realistic modeling of the driver and receiver circuits terminating the transmission lines. Moreover, measured scattering parameters and non-TEM models can also be included in the simulation. To illustrate the capabilities of this new method, several simulation studies showing the effects of losses and nonuniform interconnect geometries on the propagating signals in transmission line circuits with nonlinear terminations are included in the paper. >

Electrical Performance of High-Speed Interconnect Systems

Advancing semiconductor technology is increasing both device densities and speeds. As signal risetimes become faster than Ins and interconnect densities on a single chip carrier approach 500 leads or more, extremely careful electrical modeling of the packaging environment becomes critical. Designers are confronted with the practical problems imposed by the interconnect system which may degrade (or limit) the electrical performance of the device/system. To analyze or design a highspeed, high-density interconnect system, a battery of software modules needs to be developed. Several of these software modules are described.

Modification of 'SPICE' for simulation of coupled packaging interconnections

A modification of SPICE program, version 2G.6, that allows simulation of networks with multiconductor, lossless transmission lines is dealt with. Terminating networks may contain nonlinear active devices defined in the SPICE format. All SPICE 2G.6 transient analysis features and transistor models are supported. The authors describe the computational procedure based on the transmission line equivalent circuit, explain the principle of SPICE implementation, and give examples of application. The simulator developed is also useful in determining the upper limit for crosstalk in systems with lossy lines. However, the simulator underestimates the transmission delays in such cases, and corrections might be needed. Such corrections are relatively easy to do in most practical cases, where DC losses are dominant. >

Effect of randomness of Cu-Sn intermetallic compound layer thickness on reliability of surface mount solder joints

A statistical reliability analysis on thermal fatigue lifetime of surface mount solder joints, considering randomness of Cu-Sn intermetallic compound (IMC) layer thickness, is presented. Based on published thermal fatigue life test data, the two-parameter Weibull distribution of the thermal fatigue lifetime for a fixed IMC layer thickness is found, and a K-S goodness-of-fit test is conducted to examine the goodness of fit of the assumed Weibull distribution. Then, the Weibull parameters as functions of IMC layer thickness are obtained. Considering the randomness of IMC layer thickness, the MTTF and reliability of surface mount solder joints on thermal cycles are analyzed. For surface mount solder joints formed under the same conditions and loaded during the same thermal cycling as stated in the publication, numerical results of the MTTF and reliability are presented. The results show that when the mean value of MC layer thickness is low (e.g., smaller than 1.5 /spl mu/m), the effect of randomness of IMC layer thickness is significant; i.e., the MTTF has strong dependence on IMC layer thickness distribution; and the reliability is significantly different at high thermal cycles. When the mean value of IMC layer thickness is high (e.g., greater than 2.0 /spl mu/m), the effect of randomness of IMC layer thickness is negligible. Therefore, the presented results are important to the reliability study of surface mount solder joints. Even though the validity of the presented results based on the test data remains to be verified from other sources of data, the proposed statistical method is generally applicable for thermal fatigue reliability analysis of surface mount solder joints. By combining the proposed method with the forming mechanism of IMC layer under varying manufacturing and loading conditions, a comprehensive reliability analysis on thermal fatigue lifetime of surface mount solder joints can be expected.

A special matrix equation and its application in microelectronics

Abstract A special matrix equation is examined, which arises in designing electrical interconnections between microelectronic circuits and systems. The equation is first rewritten as a fixed point problem. A globally convergent iteration method is then proposed and monotone convergence is proved. A sufficient and necessary condition for the existence of the solution is presented. The solution can be used to minimize the reflection coefficients of the active signals.

Optimization Technique for Dynamic Reconfiguration of Programmable Analog/Digital Arrays

This paper presents an investigation of dynamically reconfigurable mixed-signal circuit constructed using a digital control system and the new technology of Field Programmable Analog Arrays (FPAA). A Motorola FPAA described in this paper can be used to build filters for analog signals as well as other kinds of analog applications implemented in switched capacitor technology (S/C-technology). The experimental studies described, take advantage of performance and programmability of the FPAA for filtering of an analog signal. The circuit structure is based on 2 parallel FPAA chips, analog multiplexer and multiplexers control logic controlled by a digital system such as a PC or a Field Programmable Gate Array (FPGA). Dynamic reconfiguration is used in this system for adaptive filtering, or adaptive processing in general. Modeling and measurements of the transition behavior of the switching process between the 2 FPAA chips and analysis of limitations imposed by hardware imperfections will be presented. The experimental system assembled in this work is an excellent vehicle to learn about intricacies in performance of mixed-signal circuits and is used for verification of theoretical predictions and model validation/modification.