A surgical instrument for use in connection with a pneumatically powered tool having a firing mechanism operably supported therein that is movable between an unactuated position and an actuated position. A pneumatically powered drive system operably communicates with the pneumatically powered tool and is configured to selectively apply at least a firing force to the firing mechanism of the pneumatically powered tool of sufficient magnitude to cause the firing mechanism to move from the unactuated position to the actuated position in response to a flow of gas from a source of gas that is fluidically coupled to the pneumatically powered drive system. At least one feedback device communicates with the pneumatically powered drive system for providing feedback concerning at least one of: (a) the magnitude of the firing force as the pneumatically powered drive system moves the firing mechanism from the unactuated to actuated position; and (b) a relative position of the firing mechanism as the firing mechanism is moved between the unactuated and actuated positions.

Pneumatically powered surgical cutting and fastening instrument with audible and visual feedback features

This paper presents an experimental study on the ageing of insulated-gate bipolar transistor (IGBT) power modules. The aim is to identify the effects of power cycling on these devices with high baseplate temperatures (60 °C to 90 °C) and wide temperature swings (60 °C to 100 °C). These values for thermal stresses have been defined according to automotive applications. The test conditions are provided by two types of test benches that will be described in this paper. The changes in electrical and thermal indicators are observed regularly by a monitoring system. At the end of the test (reaching damage criterion or failure), different analyses are performed (acoustic scanning and SEM imaging), and the damage is listed systematically. Nineteen samples of 600-V 200-A IGBT modules were thus aged using five different power-cycling protocols. The final summary of results shows that ageing mechanisms mainly concern wire bonds and emitter metallization, with gradual impact depending on protocol severity.

Ageing and Failure Modes of IGBT Modules in High-Temperature Power Cycling

Recent growth of the insulated gate bipolar transistor (IGBT) module market has been driven largely by the increasing demand for an efficient way to control and distribute power in the field of renewable energy, hybrid/electric vehicles, and industrial equipment. For safety-critical and mission-critical applications, the reliability of IGBT modules is still a concern. Understanding the physics-of-failure of IGBT modules has been critical to the development of effective condition monitoring (CM) techniques as well as reliable prognostic methods. This review paper attempts to summarize past developments and recent advances in the area of CM and prognostics for IGBT modules. The improvement in material, fabrication, and structure is described. The CM techniques and prognostic methods proposed in the literature are presented. This paper concludes with recommendations for future research topics in the CM and prognostics areas.

Physics-of-Failure, Condition Monitoring, and Prognostics of Insulated Gate Bipolar Transistor Modules: A Review

In order to take the full advantage of the high-temperature SiC and GaN operating devices, package materials able to withstand high-temperature storage and large thermal cycles have been investigated. The temperature under consideration here are higher than 200 °C. Such temperatures are required for several potential applications such as down-hole oil and gas industry for well logging, aircrafts, automotive, and space exploration. This review focuses on the reliability of a selection of potential components or materials used in the package assembly as the substrates, the die attaches, the interconnections, and the encapsulation materials. It reveals that, substrates with low coefficient of thermal expansion (CTE) conductors or with higher fracture resistant ceramics are potential candidates for high temperatures. Die attaches and interconnections reliable solutions are also available with the use of compatible metallization schemes. At this level, the reliability can also be improved by reducing the CTE mismatch between assembled materials. The encapsulation remains the most limiting packaging component since hard materials present thermomechanical reliability issues, while soft materials have low degradation temperatures. The review allows identifying reliable components and materials for high-temperature wide bandgap semiconductors and is expected to be very useful for researchers working for the development on high-temperature electronics.

Survey of High-Temperature Reliability of Power Electronics Packaging Components

The supervision of semiconductor power devices in operation demonstrates an obvious interest to improve the operating safety of electronic power converters used in critical applications. Unfortunately, this is a significant challenge due to the variability of stress conditions on the one hand and to the difficulty to implement accurate measurement systems in power stages on the other. Using VCE measurement as a real-time supervision method is evaluated here by using aging test results obtained on insulated gate bipolar transistor (IGBT) modules stressed by power cycling. These results are related to the aging of bond wires and metallization, on the top part of the module. Results were obtained in original test benches whose characteristics are overviewed briefly in the first part of this paper, along with a description of test conditions. The second part presents selected results extracted from a larger work and focusing on the VCE evolution with respect to degradations of the module's top part. Their analysis highlights the potential of VCE measurement. The last part proposes the principle of a specific system able to achieve real-time VCE supervision in the test benches in operation.

Evaluation of $V_{\rm ce}$ Monitoring as a Real-Time Method to Estimate Aging of Bond Wire-IGBT Modules Stressed by Power Cycling

Reliability model for Al wire bonds subjected to heel crack failures

The invention relates to a method for contacting electrical contact surfaces (21, 112) on a surface (20) of a substrate (1). According to said method, a film (3) based on polyimide or epoxy is laminated onto the surface, under a vacuum, in such a way that the film closely covers the surface comprising the contact surfaces and adheres to the same. Each contact surface to be contacted on the surface is uncovered by opening respective windows (31) in the film, and a contact is established in a plane manner between each uncovered contact surface and a layer (4) of metal. The inventive method is used to establish a large-surface contact for power semiconductor chips, enabling a high current density.

Norbert Seliger

Papers

Reliability model for Al wire bonds subjected to heel crack failures

Method for contacting electrical contact surfaces of a substrate and device consisting of a substrate having electrical contact surfaces

High temperature reliability on automotive power modules verified by power cycling tests up to 150°C

Reliability analysis of power MOSFET’s with the help of compact models and circuit simulation

Hot-Spot Meaurements and Analysis of Electro-Thermal Effects in Low-Voltage Power-MOSFET’s