IGBT Chip Research Articles

Experimental Demonstration of 1200V IGBT Module for a Magnetic Energy Recovery Switch Application

A bi-directional magnetic energy recovery switch (MERS) having a bridge configuration with four IGBTs has the feature that a power factor correction is possible regardless of the impedance and power frequency of the load by the automatic synchronized switching. For this application, a new 1200V IGBT module has been successfully designed and fabricated, for the first time. Since the switching frequency in the MERS application is so slow of 50-60 Hz that a lower forward voltage drop characteristic is strongly required for the IGBT and FWD chips even though their fast switching features are sacrificed. Therefore, the superior characteristics of lower on-state voltage drop of 1.54 V in the IGBT chip and 1.20 V in the FWD one can be attained and, as a result of this, total power dissipation can be successfully reduced by approximately more than 40% when compared to the conventional PWM converter application.

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High-frequency leakage current that may cause serious conducted EMI problems flows through an inverter system. The paths of the leakage current are stray capacitors that are formed inside of motors, cables and IGBT modules.This paper proposes a new IGBT module that realizes low conducted emission noise by flipping the IGBT chip of lower-voltage-side to decrease its stray capacitance. The leakage current flowing through the low-noise IGBT module becomes small, since the stray capacitor is a main path of the current. Through an experiment, it is clarified that the conducted emission level is reduced by 13dB at a maximum when the low-noise IGBT module is applied to a resonant-type inverter.

Boundary element analysis of thermal fatigue effects on high power IGBT modules

The technology of high power IGBT modules has been significantly improved these last years against thermal fatigue. The most frequently observed failure modes, due to thermal fatigue, are the solder cracks between the copper base plate and the direct copper bonding (DCB) substrate and bond wire lift-off. Specific simulation tools are needed to carry out reliability researches and to develop device lifetime models. In other respects, accurate temperature and flux distributions are essential when computing thermo-mechanical stresses in order to assess the lifetime of high power modules in real operating conditions. This study presents an analysis method based on the boundary element method (BEM) to investigate thermal behavior of high power semiconductor packages subjected to power cycling loads. The paper describes the boundary integral equation which has been solved using the BEM and applied to the case of a high power IGBT module package (3.3 kV–1.2 kA). A validation of the numerical tool is presented by comparison with experimental measurements. Finally, the paper points out the effect on the thermal stress of the IGBT chips position on the DCB substrate. In particular, a light shifting of the silicon chips may be sufficient to delay significantly the initiation and the propagation of the cracks, allowing a higher device lifetime of the studied module.

600V-IGBT3: trench field stop technology in 70 μm ultra thin wafer technology

The established trench field stop technology ‘IGBT3’ is transferred to 600 V devices and supplements the 1200 V and 1700 V family. Besides an adjustment of cell geometry and pitch for the optimum compromise between on-state loss and short-circuit current, the ability to process ultrathin wafers with a thickness of 70 μm is the most demanding requirement for this device. One of the most important steps with the 600 V device is the extension of the maximum junction temperature to 175°C, which is an increase of 25°C over the more common IGBT chips.

A highly reliable press packed IGBT

A newly developed press packed reverse conducting IGBT (RCIGBT), the ST1000EX21, having ratings of 2500 V and 1000 A, has successfully been introduced in high-reliability application areas. A multiple-chip press packed RCIGBT structure, containing IGBT chips and fast recovery diode (FRD) chips, has been achieved by using basic experimental results and a stress analysis using the finite element structure analysis program ABAQUS. Excellent electrical characteristics, especially a robust turn-off capability, such as Ic = 5000 A, Vcp = 2800 V at Tj = 125 °C, have been obtained. High reliability, withstanding a thermal cycling (fatigue) test of more than 50,000 cycles and a high-temperature voltage blocking test for 2000 hours, has been confirmed. The device is now available and is being successfully used for transportation systems and other applications that require high reliability and long-term stability. Voltage and current ratings in IGBTs and IEGTs (Injection Enhanced Gate Transistors) will be raised in the future. © 2000 Scripta Technica, Electr Eng Jpn, 131(1): 78–85, 2000

A New Concept of Igbt Packaging

The advent of high power density components has required investigation of innovative techniques for removing heat from this devices. With regard to power electronics fields, the definition of the current calibre is directly linked to its thermal environment. One of the aims of this work is to demonstrate that we can use an IGBT with on state current and losses higher than the values given by the manufacturers. We have opted for placing circular channels under an IGBT chip because this solution presents good performances and is easily realisable. In a first time, we analyse the thermal behaviour of this setup, and give the governing laws. Then, we simulate the setup on a finite elements program in order to quantify the temperature drop due to the conduction. Finally, we compare these results with measurements realised on the previous described setup. During the measurements, we determine the junction temperature with a thermal sensitive parameter, and in a second time, it will be obtained with an infra red camera.

2.5 kV-1000 A power pack IGBT (high power flat-packaged NPT type RC-IGBT)

A 2.5 kV-1000 A power pack IGBT (flat-packaged reverse conducting IGBT) has been developed using NPT (non-punchthrough) IGBT chip technology, the gate-source repair technology, the parallel connection technology with no oscillation and the multi-chip assembly technology. The power pack IGBT is specially designed for high power and highly reliable industrial and traction applications. Compared with conventional IGBT modules, this power pack IGBT has high reliability by use of a hermetic package and a press contact structure. In addition to the high reliability, this power pack IGBT is simple and compact for a 2.5 kV-1 kA class device because the assembled IGBT and FWD chips are able to shrink due to the low thermal impedance of both side cooling. The power pack IGBT shows the high blocking voltage of 2.5 kV, the typical saturation voltage of 4.2 V at the collector current (I/sub C/) of 1000 A, the junction temperature (T/sub i/) of 125/spl deg/C, and the turnoff capability of over 3/spl times/I/sub C/.

FE-Modeling and Physical Testing of IGBTs for Press-Packaging

AbstractThe reliability of press-packed IGBTs strongly depends on the solutions adopted in terms of heat dissipation and thermo-mechanical stress management so as to guarantee satisfactory electrical and thermal contact conditions throughout the service life. In this paper, two aspects concerning the design process of a single-chip press-pack IGBT are outlined: i) cyclic stresses and strains occurring in the package and in the chip are discussed on the basis of finite element (FE) simulations, ii) a testing rig developed for accelerated testing of single IGBT chips under controlled contact pressure conditions is presented.

Effects of current density and chip temperature distribution on lifetime of high power IGBT modules in traction working conditions

This paper deals with ageing parameters of high power IGBT modules in traction applications. Using the results of a great number of power cycling tests on 400A modules, it shows that, in addition to the junction temperature excursion, other parameters like the maximal chip temperature and the current density are involved in thermal fatigue failures. Besides, contact temperature measurements achieved on IGBT chip surface in cycling conditions to localise the maximal thermomechanical stress are presented and correlated with modules failure analysis. The role of the current density in the ageing process is finally shown by determining its influence on the temperature gradient on chip surface.