Test Results of Sintered Nano-Silver Paste Die Attach for High Temperature Applications

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000037-000049
Author(s):  
Paul Croteau ◽  
Sayan Seal ◽  
Ryan Witherell ◽  
Michael Glover ◽  
Shashank Krishnamurthy ◽  
...  
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Wide Band ◽  
Power Converter ◽  
Test Results ◽  
Silver Paste ◽  
Nano Silver ◽  
Strain Behavior ◽  
Die Attach ◽  
Sintered Silver

The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. It is desirable to operate a power inverter at high switching frequencies to reduce passive filter weight and at high temperature to reduce the cooling system requirement. Therefore, materials and components that are reliable at temperatures ranging from −55 to 200 °C, or higher, are needed. Sintered silver is receiving significant attention in the power electronic industry. The porous nature of sintered nano-silver paste with a reduced elastic modulus has the potential to provide strain relief between the die component and substrate while maintaining its relatively high melting point after sintering. The test results presented herein include tensile testing to rupture of sintered silver film to characterize stress strain behavior, as well as die shear and thermal cyclic tests of sintered silver bonded silicon die specimens to copper substrates to determine shear strength and reliability.

Test Results of Sintered Nanosilver Paste Die Attach for High-Temperature Applications

2016 ◽  
Vol 13 (1) ◽  
pp. 6-16 ◽  
Author(s):  
Paul Croteau ◽  
Sayan Seal ◽  
Ryan Witherell ◽  
Michael Glover ◽  
Shashank Krishnamurthy ◽  
...  
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Wide Band ◽  
Power Converter ◽  
Test Results ◽  
Wide Band Gap ◽  
Strain Behavior ◽  
Die Attach ◽  
Nanosilver Paste ◽  
Sintered Silver

The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. It is desirable to operate a power inverter at high switching frequencies to reduce passive filter weight and at high temperature to reduce the cooling system requirement. Therefore, materials and components that are reliable at temperatures ranging from −55°C to 200°C, or higher, are needed. Sintered silver is receiving significant attention in the power electronic industry. The porous nature of sintered nanosilver paste with a reduced elastic modulus has the potential to provide strain relief between the die component and substrate while maintaining its relatively high melting point after sintering. The test results presented herein include tensile testing to rupture of sintered silver film to characterize stress-strain behavior, as well as die shear and thermal cyclic tests of sintered silver-bonded silicon die specimens to copper substrates to determine shear strength and reliability.

High Temperature Reliability of High-power LED Module Using Die Attach Material of Nano-silver Paste

2016 ◽  
Vol 37 (9) ◽  
pp. 1159-1165
Author(s):  
陈佳 CHEN Jia ◽  
李欣 LI Xin ◽  
孔亚飞 KONG Ya-fei ◽  
梅云辉 MEI Yun-hui ◽  
陆国权 LU Guo-quan
Keyword(s):  
High Temperature ◽  
High Power ◽  
Silver Paste ◽  
Nano Silver ◽  
Die Attach ◽  
High Power Led

Study of Thermal Stress in Nano Silver Bonded Silicon Substrates for High Temperature Applications

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000052-000055
Author(s):  
G.D. Liu ◽  
C.H. Wang
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Silver Layer ◽  
Silicon Substrates ◽  
The Finite Element Method ◽  
Nano Silver ◽  
Silicon Chips ◽  
Die Attach ◽  
The Relationship ◽  
Sintered Silver

Abstract The silver nanoparticle paste is a promising material for high temperature die-attach applications. In this paper, the finite element method is used to study the relationship between the thickness of the sintered silver layer and the thermal stress in the sintered silver joint. Silicon chips are bonded together with sintered silver layers of different thicknesses. In the experimental study, strain gauges are attached onto the surface of the upper silicon and used to estimate the effects of the nano silver die-attach layer. The results show that the average stress in the silver layer at the interface decreases with the increasing thickness of the silver layer, while the stress on the silicon surface increases with the increasing thickness of the silver layer.

Design and Testing of a High Temperature Inverter

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000175-000179
Author(s):  
Shashank Krishnamurthy ◽  
Stephen Savulak ◽  
Yang Wang
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Wide Band ◽  
Power Converter ◽  
Power Module ◽  
Paper Test ◽  
Drive Power ◽  
Component Selection ◽  
Variable Voltage ◽  
Functional Components

Abstract The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. It is desirable to operate a power inverter at high switching frequencies to reduce passive filter weight and at high temperature to reduce the cooling system requirement. The paper describes the design and test of a power electronic inverter that converts a fixed input DC voltage to a variable voltage variable frequency three phase output. The component selection and design were constrained such that the inverter can operate at an ambient temperature of 170°C. The design of the key functional components such as the gate drive, power module, controller and communication will be discussed in the paper. Test results for the inverter at high temperature will also be presented.

Metallurgy for SiC Die Attach for Operation at 500°C

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000008-000017 ◽  
Author(s):  
Ping Zheng ◽  
Phillip Henson ◽  
R. Wayne Johnson ◽  
Liangyu Chen
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Failure Surface ◽  
Nano Particle ◽  
Test Results ◽  
Shear Tests ◽  
Die Attach ◽  
Film Layer ◽  
Potential Failure ◽  
Dc Bias

Metallurgy for high temperature SiC die attach involves the substrate metallization, die metallization, and die attach material. This paper examines off-eutectic Au-Sn as the die attach alloy with a PtAu thick film metallization on AlN substrates. A pure Au thick film layer was printed over the PtAu thick film layer. The SiC backside metallizations evaluated were Ti/TaSi/Pt/Au and Cr/NiCr/Au. Die shear tests were performed after aging at 500°C and after thermal cycling. The shear test results and failure surface analysis are discussed. Nanoparticle Ag and liquid transient phase bonding with Ag based metallurgies have been proposed for high temperature die attach. Data on the migration of sintered nano-particle Ag and thin film Ag dc bias during storage in air at 300°C and 375°C are presented. Migration of Ag is a potential failure mechanism for Ag based high temperature metallurgies.

Sintered Silver Die Attach with Extreme Thermal Stability for Extreme and Dynamic Environments

2017 ◽  
Vol 2017 (HiTEN) ◽  
pp. 000168-000176 ◽  
Author(s):  
Khalid Khtatba ◽  
Seyed Amir Paknejad ◽  
Ali Mansourian ◽  
Samjid H. Mannan
Keyword(s):  
High Temperature ◽  
Surface Oxidation ◽  
Migration Route ◽  
Oxidation Treatment ◽  
Contact Metallization ◽  
Die Attach ◽  
High Temperature Storage ◽  
Internal Pore ◽  
Temperature Storage ◽  
Sintered Silver

Abstract: The surface oxidation of internal pore surfaces of nano-scale sintered silver has increased stability for high temperature applications. After treatment, high temperature storage at 400 °C has resulted in no changes to microstructure. By contrast, it is known that the microstructure of untreated pressure-less sintered silver continuously evolves at temperatures above 200 °C. Grain and pore growth occur in this temperature range for conventional sintered silver resulting in coarsening of the microstructure and increased susceptibility to fatigue. However, oxidation treatment of the internal pore surfaces has the effect of freezing the microstructure when the contact metallization is also silver or chemically inert. Oxidation prevents mass transfer by shutting down the fastest atomic migration route along the internal pore surfaces. Samples exhibited no change in microstructure either through continuous observation through glass, or after cross sectioning. The tested specimens under high temperature storage resisted grain growth for the whole duration of the tests of more than 600 h at 300 °C. The only detectable changes in microstructure occurred in a sparse number of isolated grains (1 in 7000 grains), presumably due to non-penetration of oxidising treatment into these closed pore spaces. It is hypothesized that even these can be prevented by minor changes to the sintering paste to slightly increase initial porosity. The oxidising treatment can be performed via many different routes, such as exposure to steam, or even by dipping in water for 10 min.

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.

scholarly journals Heat-Resistant Microporous Ag Die-Attach Structure for Wide Band-Gap Power Semiconductors

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2531 ◽  
Author(s):  
Seungjun Noh ◽  
Hao Zhang ◽  
Katsuaki Suganuma
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
Morphological Evolution ◽  
Void Formation ◽  
Wide Band ◽  
Thermal Reliability ◽  
Power Semiconductors ◽  
Die Attach ◽  
Ag Paste ◽  
Sintered Ag

In this work, efforts were made to prepare a thermostable die-attach structure which includes stable sintered microporous Ag and multi-layer surface metallization. Silicon carbide particles (SiCp) were added into the Ag sinter joining paste to improve the high-temperature reliability of the sintered Ag joints. The use of SiCp in the bonding structures prevented the morphological evolution of the microporous structure and maintained a stable structure after high temperature storage (HTS) tests, which reduces the risk of void formation and metallization dewetting. In addition to the Ag paste, on the side of direct bonded copper (DBC) substrates, the thermal reliability of various surface metallizations such as Ni, Ti, and Pt were also evaluated by cross-section morphology and on-resistance tests. The results indicated that Ti and Pt diffusion barrier layers played a key role in preventing interfacial degradations between sintered Ag and Cu at high temperatures. At the same time, a Ni barrier layer showed a relatively weak barrier effect due to the generation of a thin Ni oxide layer at the interface with a Ag plating layer. The changes of on-resistance indicated that Pt metallization has relatively better electrical properties compared to that of Ti and Ni. Ag metallization, which lacks barrier capability, showed severe growth in an oxide layer between Ag and Cu, however, the on-resistance showed fewer changes.

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.

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