Wire Bond Structure Research Articles

Development of an SiC Multichip Phase-Leg Module for High-Temperature and High-Frequency Applications

This article presents a 1,200-V, 120-A silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) phase-leg module capable of operating at 200°C ambient temperature. Paralleling six 20-A MOSFET bare dice for each switch, this module outperforms the commercial SiC modules in higher operating temperature and lower package parasitics at a comparable power rating. The module's high-temperature capability is validated through the extensive characterizations of the SiC MOSFET, as well as the careful selections of suitable packaging materials. Particularly, the sealed-step-edge technology is implemented on the direct-bonded-copper substrates to improve the module's thermal cycling lifetime. Though still based on the regular wire-bond structure, the module is able to achieve over 40% reduction in the switching loop inductance compared with a commercial SiC module by optimizing its internal layout. By further embedding decoupling capacitors directly on the substrates, the module also allows SiC MOSFETs to be switched twice faster with only one-third turn-off overvoltages compared with the commercial module.

Application of nonlinear fatigue damage models in power electronic module wirebond structure under various amplitude loadings

This paper presents mean fatigue lifetime prediction of a wire-bond structure model in power electronic module using a failure physics approach that integrates high fidelity modelling and reduced order modelling. Loading current with variable amplitudes is applied to a finite element model of simplified wirebond structures. The resulting accumulated fatigue damage due to random loads is predicted by using reduced order modelling based on failure physics, a cycle counting algorithm, and various nonlinear fatigue damage models widely used in the literature. The reduced order modelling approach based on failure physics uses prediction data for the electro-thermo-mechanical behaviour of the wire-bond design of a power module obtained through non-linear transient finite element simulations, in particular for the fatigue life-time of the aluminium wire attached to the silicon chip of the wire in the module. The reduced order models that capture the black box function of the accumulated plastic strain are used in predicting the mean fatigue life time of the wire bond structure under random loads. One of the widely used cycle counting algorithms, rainflow counting algorithm, is used to count cycles of the temperature profile at the specific point of the wire bond structure in a power electronic module. The cycle data from the rainflow algorithm mean life time of the wire bond structure are predicted with various cumulative fatigue models. Non-linear cumulative fatigue models such as damage curve approach (DCA), double linear damage rule (DLDR), and double damage curve approach (DDCA), and linear cumulative fatigue damage model such as Palmgren–Miner rule are used to predict the mean fatigue life of the wire bond structure, and the results are compared.

A Novel Hybrid Packaging Structure for High-Temperature SiC Power Modules

This paper presents a novel hybrid packaging structure for high-temperature SiC power modules that combines the benefits of the wirebond packaging structure and the planar packaging structure. With the proposed hybrid structure, the power modules can achieve the same footprint and similar parasitic to planar structures but with a much easier fabrication process and more reliable top-side interconnections. Meanwhile, no double-side solderable devices are required. The new structure and its fabrication process are presented, and a prototype module is built based on an SiC JFET. Detailed comparisons are also conducted between the hybrid, planar, and wirebond structures. The results reveal better performances of the hybrid structure in smaller parasitic, lower switching loss, and more flexible routing than the wirebond structure and easier fabrication, more reliable top-side connection, and more flexible die attachment material selection than the planar structure. A three-phase multiple-chip SiC JFET hybrid-structure power module is built and tested with 250 °C junction temperature for verification.

Evaluation of Point Field Sensing in IGBT Modules for High-Bandwidth Current Measurement

This paper evaluates field-based current sensing integration in power electronic modules. Point field detectors, such as giant magnetoresistor detectors, can provide high-bandwidth (dc to megahertz) current measurements with a small footprint (1.26 mm2). Magnetic fields surrounding a current-carrying conductor are frequency dependent, so the 5 % flat-bandwidth metric is used to evaluate placement of the point field detectors to maximize the bandwidth of the current measurement. A significant contribution of this paper is an evaluation of the placement of point field detectors inside a power switching module. This paper focuses on detector placement for the interconnect structures commonly found in power switching modules. Experimental and finite-element analysis of wire bond structures with multiple wire bonds and lead frame structures are evaluated for high-bandwidth sensing performance.

Application of Kriging and Radial Basis Function for Reliability Optimization in Power Modules

This paper discusses the design for reliability of a wire bond structure in a power electronic module based on computational approach that integrates methods for high fidelity analysis, reduced order modeling, numerical risk analysis, and optimization. This methodology is demonstrated on a wire bond structure in a power electronic module with the aim of reducing the chance of failure due to the wire bond lift off in a power electronic module. In particular, wire bond reliability of the power module related to the thermal fatigue material degradation of aluminum wire is one of the main concerns. Understanding the performance, reliability, and robustness of wire bond is a key factor for the future development and success of the power electronic module technology. The main focus in this study is on the application of reduced order modeling techniques and the development of the associated models for fast design evaluation and analysis. The discussion is on methods for approximate response surface modeling based on interpolation techniques using Kriging and radial basis functions. The reduced order modeling approach uses prediction data for the electrothermomechanical behavior of the power module wire bond design obtained through nonlinear transient finite element simulations, in particular, for the fatigue lifetime of the aluminum wire attached to the silicon chip and the warpage (displacement) of the wire in the module. These reduced order models are used for the analysis of the effect of design uncertainties on the reliability of these advanced electronics modules. To assess the effect of uncertain design data, different methods for estimating the variation of reliability-related metrics of the wire bond model are researched and tested. Sample-based methods, such as full-scale Monte Carlo and Latin hypercube, and analytical approximate methods, such as first order second moment (FOSM) and point estimation method (PEM), are investigated, and their accuracy is compared. The optimization modeling analyzes the probabilistic nature of the reliability problem of the aluminum wire bond structures under investigation. Optimization tasks with design uncertainty are identified and solved using a particle swarm optimization algorithm. The probabilistic optimization deals with two different characteristic performance metrics of the design, the electrothermomechanical fatigue reliability of the aluminum wire attached to the chip and the thermally induced warpage of the wire in the module structure. The objective in this analysis is to ensure that the design has the required reliability and meets a number of additional requirements.

Finite Element Analysis of Copper Wire Bonding in Integrated Circuit Devices

Axisymmetric finite element models of copper wire-bond-pad structure for an integrated circuit devicewere developed to investigate theeffects of bonding force, initial bonding temperature, Aluminum metallization thickness, bond pad thickness and free air ball (FAB) diameter on induced stresses in the wire-bond structure. The results show that an increase in bonding force greatly increased the induced stresses in the copper FAB and bond pad (aluminum and silicon). However, a change in bonding temperature while keeping the bonding force constant does not result in an appreciable change in the stress. Similarly an increase in aluminium metallization thickness does not yield appreciable variation in the stress and strain in the bond pad. Over the range of FAB diameters studied it is found that bigger FAB yields smaller stress in the overall structure

Application of Kriging and radial basis function in power electronic module wire bond structure reliability under various amplitude loading

This paper discusses life time prediction of wire bond structure in a power electronic module based on computational approach that integrates methods for high fidelity analysis, reduced order modelling, and life time prediction using reduced order model. This methodology is demonstrated for the design of a wire bond structure in a power electronic module with aim of reducing the chance of failure due to the wire bond lift off in power electronic module when a random load is applied to the aluminium wire. In particular, wire bond reliability of the power module related to the thermal fatigue material degradation of aluminium wire is one of the main concerns. In the power electronic module reliability, understanding the performance, reliability and robustness of wire bond is a key factor for the future development and success of the power electronic module technology, because wire bond lift off failure ignites other catastrophic failures.The main focus in this study is on the application of reduced order modelling techniques and the development of the associated models for fast evaluation and analysis. The discussion is on methods for approximate response surface modelling based on interpolation techniques using Kriging and radial basis functions. The reduced order modelling approach uses prediction data for the electro-thermo-mechanical behaviour of the power module wirebond design obtained through non-linear transient finite element simulations, in particular for the fatigue life-time of the aluminium wire attached to the silicon chip of the wire in the module. The reduced order models are used for the analysis of predicting the life time of the wire bond structure under random load. One of the widely used cycle counting algorithm, so called rainflow counting algorithm is utilised to count the cycles of temperature profile at the a specific point of the wire bond structure in a power electronic module. Using the cycle results from rainflow algorithm mean life time of the wire bond structure is predicted by a linear cumulative damage model such as Palmgren–Miner rule. This model is utilised to predict the mean fatigue life of the wire bond structure.