Mass Transport, Creep and Zero-Stress-Point Shifting in a Nano-silver Die-Attach Material During Thermal Cycling

2020 ◽  
Vol 49 (6) ◽  
pp. 3982-3989
Author(s):  
J. R. McCoppin ◽  
D. Young
Author(s):  
Fei Qin ◽  
Shuai Zhao ◽  
Yanwei Dai ◽  
Lingyun Liu ◽  
Tong An ◽  
...  

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.


2020 ◽  
Author(s):  
Hui YANG ◽  
Jihui Wu

Abstract The simulation of nano-silver solder joints in flip-chips is performed by the finite element software ANSYS, and the stress-strain distribution results of the solder joints are displayed. In this simulation, the solder joints use Anand viscoplastic constitutive model, which can reasonably simulate the stress and strain of solder joints under thermal cycling load. At the same time this model has been embedded in ANSYS software, so it is more convenient to use. The final simulation results show that the areas where the maximum stresses and strains occur at the solder joints are mostly distributed in the contact areas between the solder joints and the copper pillars and at the solder joints. During the entire thermal cycling load process, the area where the maximum change in stress and strain occurs is always at the solder joint, and when the temperature changes, the temperature at the solder joint changes significantly. Based on comprehensive analysis, the relevant empirical correction calculation equation is used to calculate and predict the thermal fatigue life of nano-silver solder joints. The analysis results provide a reference for the application of nano-silver solder in the electronic packaging industry.


Author(s):  
Erick Gutierrez ◽  
Kevin Lin ◽  
Douglas DeVoto ◽  
Patrick McCluskey

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.


2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000172-000177
Author(s):  
Koji Sasaki ◽  
Noritsuka Mizumura

Traditional thick film technology is widely used in various electronics products. There are two type of paste based on thick film technology. Typically, over 400°C is required for high temperature sintering type which contains glass for adhesion function. It shows high electrical and thermal performance. On the other hand, 150–300°C range process is used for low temperature process type as silver epoxy. In last decade, nano silver technology shows amazing progress to address low temperature operation by low temperature sintering. This paper will discuss the results on fundamental study of newly developed nano silver pastes with unique approach which uses MO (Metallo-organic) technology and resin reinforcing technology. Nano silver pastes contain several types of dispersant as surface coating to prevent agglomeration of the particles. Various coating technique has been reported to optimize sintering performance and stability. MO technology provides low temperature sintering capability by minimizing the coating material. The nano silver pastes show high electrical and thermal performance. However, degradation of die shear strength has been found by thermal cycling test due to the fragility of porous sintered structure. To improve the mechanical property, resin reinforcing technology has been developed. By adding special resin to the pastes, the porous area is filled with the resin and the sintered structure is reinforced. Degradation of die shear strength was not found by thermal cycling test to 1000 cycles. Nano silver pastes using MO technology and resin reinforcing technology will meet lots of requirement on various thick film applications.


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

2020 ◽  
Vol 9 (5) ◽  
pp. 224-231 ◽  
Author(s):  
Hiroshige SUGIMOTO ◽  
Yoshiharu KARIYA ◽  
Yoshiki ABE ◽  
Ryuichiro HANADA ◽  
Yoshinori YOKOYAMA ◽  
...  

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000128-000133 ◽  
Author(s):  
Hongwen Zhang ◽  
Jonathan Minter ◽  
Ning-Cheng Lee

Abstract BiAgX® paste with the remelting temperature around 262°C has been tested and adopted successfully for die attach applications [1–5]. BiAgX® HT pastes with the enhanced remelting temperature above 265°C have been designed for the application of 200°C or even higher. The joint strength has been well maintained for most of the tested pastes after thermal aging @ 200°C for 1000hrs. The thermal cycling test (from −55°C to 200°C) degrades the bond shear strength but some of the tested pastes can still keep the joint strength well above IEC standard (IEC 60749-19) required. The melting temperature and the reliability have been observed to closely associate with the alloying elements Z%wt. The BiAgX® pastes have also been modified for board level assembly application. BiAgX® solder wire is under development too.


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