Reliability Improvement of Aluminum Wirebonds in High‐Power Igbt Modules

1996 ◽  
Vol 445 ◽  
Author(s):  
Yujing Wu ◽  
Gene Thome ◽  
Timothy Scott Savage
Keyword(s):  
Grain Size ◽  
Crack Initiation ◽  
High Power ◽  
Fatigue Testing ◽  
Temperature Cycling ◽  
Grain Structure ◽  
Aluminum Wire ◽  
Significant Deterioration ◽  
Temperature Cycles ◽  
Igbt Modules

AbstractWirebonding is the weakest area of device packaging of power IGBT modules. Accelerated thermal fatigue testing causes cracks to form and propagate in the aluminum wirebond at the foot area. This study examined the relationship of the wirebond reliability and the aluminum wire grain structure, which can be affected by post‐wirebond heat treatment. A series of wirebonded IGBTs were annealed at a temperature range from 280°C to 400°C for up to 60 minutes. Wirebond shear strengths versus temperature cycles were examined. Cross‐sectional SEM was used to examine both aluminum grain size development by annealing and crack initiation and propagation in the wirebonds after temperature cycling. It was found that aluminum grain size was increased by post‐wirebond annealing. With temperature cycling, the wirebond shear strengths of the as‐wirebonded samples decrease rapidly, and lifted wirebonds were present after 1500 temperature cycles. The lifted wirebonds typically break within the aluminum wire near the wire/metallization interface. The shear strength of the wirebonds with post‐wirebond annealing showed no significant change even after 5000 temperature cycles, and there were no signs of significant deterioration of the wirebonds either. The wirebond crack initiation and growth rates were depressed substantially by larger aluminum grains. Annealing of the aluminum wire after wirebonding provided increased aluminum grain size resulting in improved reliability of the wirebonds of high power modules.

Failure Analysis of Aluminum Wire Bonds in High Power Igbt Modules

1995 ◽  
Vol 390 ◽  
Author(s):  
Klaus J. Dittmer ◽  
Max H. Poech ◽  
Frank W. Wulff ◽  
Martin Krumm
Keyword(s):  
High Power ◽  
Fracture Morphology ◽  
Operating Conditions ◽  
Aluminum Wire ◽  
Electron Microscopic ◽  
Bonding Wire ◽  
Infrared Thermal Imaging ◽  
Insulated Gate Bipolar Transistor ◽  
Igbt Modules ◽  
Wire Bonds

ABSTRACTThe reliability of high power Insulated Gate Bipolar Transistor (IGBT) modules is mainly limited by the aluminum wire bonds. Bond failure occurs due to fatigue fracture close to the welded interface inside the large bonding wire caused by thermal cycling at extreme operating conditions. This paper presents the results of the metallographic and electron microscopic examinations of the welded interface as well as fracture morphology investigations of failed parts after power cycling. Infrared thermal imaging and investigations of the stress/strain relationship analyze the differential expansion caused by temperature distribution and thermal expansion mismatch between large bonding wire and semiconductor.

A Testing Apparatus for SEM In-Situ Fatigue Testing of Small Scale Specimens and a Derived Application

2013 ◽  
Author(s):  
Johannes Reiser ◽  
Bernd Maier ◽  
Christoph Guster ◽  
Hans-Peter Gaenser ◽  
Reinhard Pippan
Keyword(s):  
Crack Initiation ◽  
Fatigue Testing ◽  
Ion Beam ◽  
Local Strain ◽  
Fatigue Behaviour ◽  
Grain Structure ◽  
Basic Knowledge ◽  
Small Scale ◽  
Testing Apparatus

The prediction of fatigue strength and fatigue life of materials was the key motivation in this study. Several approaches for fatigue limit prediction at mesoscopic scale have been proposed. All of them incorporate microstructure and grain features. For the purpose of studying plastic local strain accumulation and therefore fatigue behaviour at the grain scale a new testing rig was developed. A key point for understanding fatigue behaviour and crack initiation even at higher load cycles is basic knowledge on strain localization in the grain structure of the material. Till now low testing frequencies of SEM in-situ testing rigs limited tests at higher load cycles. The developed in-situ tension-compression testing apparatus for in-situ SEM use allows testing at higher frequencies and therefore to perform even higher load cycles with less time consumption. Oxygen free high conductivity copper (OFHC) grade 99,99% was chosen for investigation. In addition cuts with a focus ion beam (FIB) were made in distinct orientations representing material defects to get an idea of the influence of micro notches on fatigue behaviour and crack initiation. The results of in-situ fatigue tests will be presented.

Structural and Electrical Characterization of Shaped Beam Laser Recrystallized Polysilicon on Amorphous Substrates

1981 ◽  
Vol 4 ◽  
Author(s):  
T. J. Stultz ◽  
J. F. Gibbons
Keyword(s):  
Grain Size ◽  
Electrical Characterization ◽  
Grain Structure ◽  
Electrical Characteristics ◽  
Shaped Beam ◽  
Beam Laser ◽  
Cw Laser ◽  
Amorphous Substrates ◽  
Circular Beam

ABSTRACTStructural and electrical characterization of laser recrystallized LPCVD silicon films on amorphous substrates using a shaped cw laser beam have been performed. In comparing the results to data obtained using a circular beam, it was found that a significant increase in grain size can be achieved and that the surface morphology of the shaped beam recrystallized material was much smoother. It was also found that whereas circular beam recrystallized material has a random grain structure, shaped beam material is highly oriented with a <100> texture. Finally the electrical characteristics of the recrystallized film were very good when measured in directions parallel to the grain boundaries.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction

2021 ◽  
Vol 13 (14) ◽  
pp. 7889
Author(s):  
Carlos Efrain Contreras Inga ◽  
Gabriel Walton ◽  
Elizabeth Holley
Keyword(s):  
Grain Size ◽  
Grain Shape ◽  
Grain Structure ◽  
Minor Effect ◽  
Unique Contribution ◽  
Structure Generation ◽  
Structure Representation ◽  
The Real ◽  
Study Results ◽  
Block Models

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Xin Li ◽  
Xu Chen ◽  
Guo-Quan Lu
Keyword(s):  
High Power ◽  
Heat Dissipation ◽  
Light Emitting Diode ◽  
Temperature Cycling ◽  
Fluorescent Light ◽  
Light Sources ◽  
Light Emitting ◽  
Die Attach ◽  
Nanosilver Paste ◽  
Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

Degradation mapping in high power IGBT modules using four-point probing

2015 ◽  
Vol 55 (8) ◽  
pp. 1196-1204 ◽  
Author(s):  
Kristian Bonderup Pedersen ◽  
Lotte Haxen Østergaard ◽  
Pramod Ghimire ◽  
Vladimir Popok ◽  
Kjeld Pedersen
Keyword(s):  
High Power ◽  
Igbt Modules

Recrystallization and Grain Growth during Alloy 718 Processing

2007 ◽  
Vol 539-543 ◽  
pp. 3094-3099
Author(s):  
Nho Kwang Park ◽  
Jeoung Han Kim ◽  
Jong Taek Yeom
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heat Treatments ◽  
Grain Structure ◽  
Alloy 718 ◽  
Compression Tests ◽  
Δ Phase ◽  
Grain Boundary Characteristics ◽  
The Difference ◽  
Boundary Characteristics

In Alloy 718 ingot cogging process, dynamic and metadynamic recrystallizations, and static grain growth occur, and also the presence of δ phase plays a key role in controlling the grain size. In this study, the evolution of grain structure in VIM/VAR-processed Alloy 718 ingots during post-cogging heat treatments is dealt with. Compression tests were made on VIM/VAR-processed Alloy 718 ingot at temperatures between 900oC ~ 1150oC. Heat treatments were made on the compression-tested specimens, and the variation of grain size was evaluated. Constitutive equations for the grain growth are established to represent the evolution of microstructures. Special attention is paid to the evolution of grain structure under the condition of dynamic and metadynamic recrystallizations, and grain growth. The grain growth rate depends mainly on the presence of δ-phase below the δ-solvus temperature, and on the difference in the grain boundary characteristics above it.

The Influence of Section Thickness on Microstructure of Elektron 21 and QE22 Magnesium Alloys

2012 ◽  
Vol 191 ◽  
pp. 145-150 ◽  
Author(s):  
Michał Stopyra ◽  
Robert Jarosz ◽  
Andrzej Kiełbus
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Magnesium Alloys ◽  
Statistical Methods ◽  
Wall Thickness ◽  
Light Microscope ◽  
Volume Fraction ◽  
Grain Structure ◽  
Section Thickness ◽  
Gating System

The paper presents analysis of section thickness’ influence on microstructure of Elektron 21 and QE22 magnesium alloys in the form of a stepped casting test. Solid solution grain size and volume fraction of eutectic areas were measured using light microscope and sterological methods. The results showed the significant increase of grain size caused by wall thickness and its slight decrease connected with the distance beetwen analysed section and the gating system. This relationship was confirmed using statistical methods. QE22 alloy demonstrated finer grain structure than Elektron 21 alloy as well as lesser susceptibility of grain size to solidification conditions

Sign in / Sign up

Export Citation Format

Share Document