Impact of Metallurgical and Mechanical Properties of Sintered Silver Joints on Die-Attach Reliability of High-Temperature Power Modules

2016 ◽  
Vol 13 (3) ◽  
pp. 121-127 ◽  
Author(s):  
Hiroaki Tatsumi ◽  
Sho Kumada ◽  
Atsushi Fukuda ◽  
Hiroshi Yamaguchi ◽  
Yoshihiro Kashiba
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Cycling ◽  
Tensile Tests ◽  
High Heat ◽  
Bonding Pressure ◽  
Die Attach ◽  
Power Modules ◽  
Bandgap Semiconductors ◽  
Sintered Silver

Sintered silver bonding processes are expected to offer bonding solutions with high heat endurance for power modules using wide bandgap semiconductors. This study reports the die-attach reliability of the bonding process under thermal cycling tests, focusing on the metallurgical and mechanical properties of sintered silver joints. A nanocrystalline (NC) structure with 150-nm-sized grains was observed in the as-sintered state, while a coarsened structure with microsized grains and pore coalescence was observed after annealing at 350°C for 1 h. In addition, the increase of bonding pressure reduced the number of coarse pores. Transmission electron microscope observations showed favorable crystalline structure along the grain boundaries. Tensile tests at room and high temperature revealed that the sintered silver materials showed the inherent mechanical properties of NC metals. Thermal cycling tests of die-attached specimens demonstrated the temperature dependence of crack resistance at constant amplitude. Furthermore, coalescence of pores and coarsening of grains reduced bonding reliability. It can be inferred from the results that NC structure and minute pore dispersion improves bonding reliability.

Impact of Metallurgical and Mechanical Properties of Sintered Silver Nanoparticles on Die-attach Reliability of High-temperature Power Modules

2015 ◽  
Vol 2015 (1) ◽  
pp. 000842-000847
Author(s):  
Hiroaki Tatsumi ◽  
Sho Kumada ◽  
Atsushi Fukuda ◽  
Hiroshi Yamaguchi ◽  
Yoshihiro Kashiba
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Silver Nanoparticles ◽  
High Temperature ◽  
Thermal Cycling ◽  
Nanocrystalline Structure ◽  
Bonding Pressure ◽  
Die Attach ◽  
Power Modules ◽  
Sintered Silver

Sintered silver bonding processes are expected to offer bonding solutions with high heat resistances for power modules using wide-bandgap semiconductors. This study reports the die-attach reliability of such a bonding process under thermal cycling tests, focusing on the metallurgical and mechanical properties of sintered silver nanoparticles. A nanocrystalline structure with a grain size of approximately 150 nm was observed in the as-sintered state, while a coarsened structure with a grain size of several microns and pore coalescence was observed after annealing at 623 K for 1 h. In addition, the increase of bonding pressure reduced the number of coarse pores. Observations with a transmission electron microscope showed favorable crystalline structure along the grain boundaries. Tensile tests at room and high temperature revealed that the sintered silver nanoparticles showed the inherent mechanical properties of nanocrystalline metals. Thermal cycling tests of die-attached specimens demonstrated the temperature dependence of crack propagation caused by plastic deformation at a constant temperature amplitude. Furthermore, pore coalescence and coarsening reduced bonding reliability. It can be inferred from the results that nanocrystalline structure and minute pore dispersion improves bonding reliability.

A multi-pronged approach to low-pressure Cu sintering using surface-modified particles, substrate and chip metallization

2019 ◽  
Vol 2019 (1) ◽  
pp. 000387-000392 ◽  
Author(s):  
Sri Krishna Bhogaraju ◽  
Omid Mokhtari ◽  
Jacopo Pascucci ◽  
Fosca Conti ◽  
Hiren R Kotadia ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Cost ◽  
Surface Modifications ◽  
Low Pressure ◽  
Bonding Pressure ◽  
High Tendency ◽  
Promising Alternative ◽  
Die Attach ◽  
Bandgap Semiconductors ◽  
Surface Modified

Abstract High temperature power electronics based on wide-bandgap semiconductors have prominent applications, such as automotive, aircrafts, space exploration, oil/gas extraction, electricity distribution. Die-attach bonding process is an essential process in the realization of high temperature power devices. Here Cu offers to be a promising alternative to Ag, especially because of thermal and mechanical properties on par with Ag and a cost advantage by being a factor 100 cheaper than Ag. With the aim to achieve a low-pressure Cu sintering process, a low cost wet chemical etching process is developed to selectively etch Zn from brass to create nano-porous surface modifications to enhance sinterability, enabling sintering with low bonding pressure of 1MPa and at temperatures below 300°C. However, high tendency of Cu to oxidize poses a major challenge in realizing stable interconnects. For this purpose, in this contribution, we present the use of polyethylene-glycol 600 as reducing binder in the formulation of the Cu sintering paste. Finally, we propose a multi-pronged approach based on three crucial factors: surface-modified substrates, nanostructured surface modifications on micro-scale Cu-alloy particles and use of a reducing binder in the Cu particle paste.

Microstructure and Mechanical Properties of Pressureless Sintered Silver Die-attach Materials

2018 ◽  
Vol 2018 (1) ◽  
pp. 000602-000605
Author(s):  
Tomofumi Watanabe ◽  
Keisuke Tanaka ◽  
Masafumi Takesue
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Physical And Mechanical Properties ◽  
External Pressure ◽  
Exposure Test ◽  
High Temperature Exposure ◽  
Die Attach ◽  
Temperature Exposure ◽  
Substantial Change ◽  
Sintered Silver

Abstract Microstructural and mechanical properties of a pressureless sintered silver material were measured. The Microstructure of the pressureless sintered silver material had pores of less than 1 μm in size and some silver matrices sintered with nanoparticles between each other. The pressureless sintered silver material could be bonded on bare copper without applying an external pressure. After subjecting the material to a high temperature exposure test at 250 °C and for 1000 h, it showed no substantial change in microstructure and showed a constant Young's modulus of 14 GPa. The pressureless sintered silver material in this work did not show any embrittlement or increase in pore size after the high temperature exposure test, which demonstrated that the material has reliable physical and mechanical properties at temperatures up to 250 °C.

Package Reliability of the SiC Power Modules in Harsh Environments

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000139-000144
Author(s):  
Fengqun Lang ◽  
Hiroshi Yamaguchi ◽  
Hiroshi Sato
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Electrical Resistivity ◽  
Thermal Cycling ◽  
Isothermal Aging ◽  
Harsh Environments ◽  
Die Attach ◽  
Power Modules ◽  
Almost All ◽  
Package Reliability

To evaluate the package reliability of the SiC power modules in harsh environments, the SiC Schottky Barrier Diodes (SBDs) were die bonded to the Si3N4/Cu/Ni(P) substrate with Au-Ge eutectic solder using a vacuum reflow furnace. The Si3N4/Cu/Ni(P) substrates are active metalized copper (AMC). The bonded samples were isothermally aged at 330°C and tested under thermal cycling conditions in the temperature range of −40–300°C in air. During the isothermal aging, cracks of the Ni(P) layer developed, resulting in oxidation of the Cu power path. Decrease in the die bond strength and increase in the electrical resistivity were observed due to the Cu power path oxidation and the growth of the Ni-Ge intermetalic compound (IMC) in the joint. Under the thermal cycling conditions, the metallization of the substrate suffers from serious surface roughness, which greatly degrades the die-attach reliability. The Al electrode was found to seriously exfoliate from the SiC-SBDs due to the thermal stress. After 521 cycles, almost all the Al electrode exfoliated form the anode. Benefit from the excellent mechanical properties of Si3N4, no detachment of the Cu layer was observed from the Si3N4 substrate after 1079 cycles, while the Cu layer detached from the AlN substrate only after 12 cycles.

Shear Strength and Thermomechanical Reliability of Sintered Ag Joints Containing low CTE Non-metal Additives for Die Attach

2018 ◽  
Vol 2018 (1) ◽  
pp. 000167-000172
Author(s):  
Guangyu Fan ◽  
Christine Labarbera ◽  
Ning-Cheng Lee ◽  
Colin Clark
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Thermal Cycling ◽  
Power Electronics ◽  
Metal Particles ◽  
Mechanical Reliability ◽  
Die Attach ◽  
Silver Sinter ◽  
Metal Additives ◽  
Sintered Silver

Abstract Ag sintering has been paid attention as an alternative to soldering in die attach for decades, especially for high temperature power electronics packages because of its high melting temperature, highly thermal and electrical conductivity of the sintered silver joints, and low process temperature less than 275°C. The coefficient of thermal expansion (CTE) of silver (19.1ppm/°C), however, is much higher than the silicon die (2.6ppm/°C) and the commonly used alumina substrate (7.2ppm/°C). CTE mismatch of the different materials in the various components in a power electronics package lead to the delamination at the interface between interconnection layer and chips or substrate, and/or cracking of the interconnection layer is one of the mostly common causes of failure of power electronics device during thermal cycling or high temperature operation. In recent years we have been developing a series of silver sinter pastes containing low CTE non-metal particles to reduce or adjust CTE of the sintered joints so as to extend the lifetime and reliability of power electronics device in high temperature applications. In the present paper, we will report a new set of silver sinter pastes containing micro scale non-metal particles, a sintering process, microstructural morphologies, thermo-mechanical reliability of the sintered joint and effect of the contents of non-metal particles on shear strength of the sintered silver joints bonding an Ag silicon die on Ni/Au DBC substrates. Shear tests on the sintered joints with and/or without the low CTE non-metal additives have been conducted at room temperature, 200, 250, and 300°C. Thermo-mechanical reliability of the sintered joints was evaluated by thermal cycling, thermal shock, high temperature storage tests (HTS), respectively. X-ray inspection and scanning electronic microscopy (SEM) were used to characterize void, crack and microstructure morphologies of the sintered joints with and/or without the additives.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

Indentation Tests for Sintered Silver in Die-Attach Interconnection After Thermal Cycling

2021 ◽  
Author(s):  
Fei Qin ◽  
Shuai Zhao ◽  
Yanwei Dai ◽  
Lingyun Liu ◽  
Tong An ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Silver Layer ◽  
Thermal Cycles ◽  
Nano Indentation ◽  
Die Attach ◽  
Indentation Tests ◽  
Sintered Silver

Abstract Thermo-mechanical reliability assessment for sintered silver is a crucial issue as sintered silver is a promising candidate of die-attachment materials for power devices. In this paper, the nano-indentation tests are performed for sintered silver in typical die-attach interconnection under different thermal cycles. Based on thermal cycling test, the Young's modulus and hardness of sintered silver layer have been presented. It is found that the Young's modulus and hardness of sintered silver layer changes slightly although the microstructure of sintered silver also presents some variations. The stress and strain curves for different thermal cycling tests for sintered silver based on reverse analysis of nano-indentation are also given. The results show that the elastoplastic constitutive equations change significantly after thermal cycling tests, and the yielding stress decreases remarkably after 70 thermal cycles. The experimental investigation also show that the cracking behaviors of sintered silver depends on its geometry characteristics, which implies that the possible optimization of sintered silver layer could enhance its thermo-mechanical performance.

scholarly journals Thermal Assessment and In-Situ Monitoring of Insulated Gate Bipolar Transistors in Power Electronic Modules

2019 ◽  
Author(s):  
Erick Gutierrez ◽  
Kevin Lin ◽  
Douglas DeVoto ◽  
Patrick McCluskey
Keyword(s):  
Thermal Cycling ◽  
Failure Modes ◽  
Rapid Determination ◽  
Degradation Process ◽  
In Situ Monitoring ◽  
Power Module ◽  
Insulated Gate Bipolar Transistor ◽  
Die Attach ◽  
Power Modules

Abstract Insulated gate bipolar transistor (IGBT) power modules are devices commonly used for high-power applications. Operation and environmental stresses can cause these power modules to progressively degrade over time, potentially leading to catastrophic failure of the device. This degradation process may cause some early performance symptoms related to the state of health of the power module, making it possible to detect reliability degradation of the IGBT module. Testing can be used to accelerate this process, permitting a rapid determination of whether specific declines in device reliability can be characterized. In this study, thermal cycling was conducted on multiple power modules simultaneously in order to assess the effect of thermal cycling on the degradation of the power module. In-situ monitoring of temperature was performed from inside each power module using high temperature thermocouples. Device imaging and characterization were performed along with temperature data analysis, to assess failure modes and mechanisms within the power modules. While the experiment aimed to assess the potential damage effects of thermal cycling on the die attach, results indicated that wire bond degradation was the life-limiting failure mechanism.

Manufacturing and High Temperature Mechanical Properties of Inconel 713C by Using Metal Injection Molding

2012 ◽  
Vol 602-604 ◽  
pp. 627-630 ◽  
Author(s):  
Kyu Sik Kim ◽  
Kee Ahn Lee ◽  
Jong Ha Kim ◽  
Si Woo Park ◽  
Kyu Sang Cho
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Injection Molding ◽  
Room Temperature ◽  
Tensile Tests ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
High Temperature Mechanical Properties ◽  
Inconel 713C

Inconel 713C alloy was tried to manufacture by using MIM(Metal Injection Molding) process. The high-temperature mechanical properties of MIMed Inconel 713C were also investigated. Processing defects such as pores and binders could be observed near the surface. Tensile tests were conducted from room temperature to 900°C. The result of tensile tests showed that this alloy had similar or somewhat higher strengths (YS: 734 MPa, UTS: 968 MPa, elongation: 7.16 % at room temperature) from RT to 700°C than those of conventional Inconel 713C alloys. Above 800°C, however, ultimate tensile strength decreased rapidly with increasing temperature (lower than casted Inconel 713C). Based on the observation of fractography, initial crack was found to have started near the surface defects and propagated rapidly. The superior mechanical properties of MIMed Inconel 713C could be obtained by optimizing the MIM process parameters.

A High Current (>1500A) Power Module for High Temperature, High Performance Applications Using SiC TMOS Power Switches

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000402-000406
Author(s):  
B. Passmore ◽  
J. Hornberger ◽  
B. McPherson ◽  
J. Bourne ◽  
R. Shaw ◽  
...  
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Extreme Environment ◽  
Wide Bandgap ◽  
Power Module ◽  
Power Modules ◽  
Power Switches ◽  
Bandgap Semiconductors ◽  
Transition Times ◽  
Switch Position

A high temperature, high performance power module was developed for extreme environment systems and applications to exploit the advantages of wide bandgap semiconductors. These power modules are rated > 1200V, > 100A, > 250 °C, and are designed to house any SiC or GaN device. Characterization data of this power module housing trench MOSFETs is presented which demonstrates an on-state current of 1500 A for a full-bridge switch position. In addition, switching waveforms are presented that exhibit fast transition times.

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