Fracture mechanism of microporous Ag-sintered joint in a GaN power device with Ti/Ag and Ni/Ti/Ag metallization layer at different thermo-mechanical stresses

2021 ◽  
Author(s):  
Dongjin Kim ◽  
Sangmin Lee ◽  
Chuantong Chen ◽  
Seung-Joon Lee ◽  
Shijo Nagao ◽  
...  
Keyword(s):  
Fracture Mechanism ◽  
Mechanical Stresses ◽  
Power Device ◽  
Metallization Layer

Interconnect Fatigue Failure Parameter Isolation for Power Device Reliability Prediction in Alternative Accelerated Mechanical Cycling Test

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Mahsa Montazeri ◽  
Cody J. Marbut ◽  
David Huitink
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Mechanical Stresses ◽  
Power Device ◽  
Reliability Test ◽  
Test Duration ◽  
Force Frequency ◽  
Solder Interconnects ◽  
Mechanical Cycling ◽  
Power Cycling

In this work, a rapid and low-cost accelerated reliability test methodology which was designed to simulate mechanical stresses induced in flip–chip bonded devices during the thermal cycling reliability test under isothermal conditions, is introduced and demonstrated using power device analogous test chips. By stressing these devices in a controlled environment, mechanical stresses become decoupled from the design and temperature, such that useful lifetimes can be predictable. Mechanical shear stress was cyclically applied directly to device relevant, flip–chip solder interconnects while monitoring for failure. Herein, finite element analysis (FEA) is used to extract various damage metrics of different solder materials, including PbSn37/63, SAC305, and nanosilver, in both thermal operation and the introduced alternative mechanical testing conditions. Plastic work density and strain are calculated in the critical solder interconnects as factors that indicate the amount of the damage accumulation per cycle during the mechanical cycling, thermal cycling, and power cycling tests. The number of cycles to failure for each test was calculated using the fatigue life model developed by Darveaux for eutectic PbSn solder, while for SAC305 Syed's method was used, and for nanosilver, the Knoerr et al. equations are applied. The effects of environmental temperature and shearing force frequency were studied for the mechanical cycling reliability test, where a modified Norris–Landzberg equation for mechanical cycling tests was explored using the simulation results. Finally, comparing the mechanical cycling with the equivalent thermal cycling and power cycling demonstrated a significant reduction in required test duration to achieve a reliability estimation.

Human Platelets Exposed to Mechanical Stresses Express a Potent Lipoxygenase Product

1992 ◽  
Vol 68 (05) ◽  
pp. 589-594 ◽  
Author(s):  
Alon Margalit ◽  
Avinoam A Livne
Keyword(s):  
Regulatory Volume Decrease ◽  
Human Platelets ◽  
Mechanical Stresses ◽  
Arterial Stenosis ◽  
Platelet Suspension ◽  
Suspension Flows ◽  
Lipoxygenase Product ◽  
Pathological Conditions ◽  
K Permeability ◽  
Volume Decrease

SummaryHuman platelets exposed to hypotonicity undergo regulatory volume decrease (RVD), controlled by a potent, yet labile, lipoxygenase product (LP). LP is synthesized and excreted during RVD affecting selectively K+ permeability. LP is assayed by its capacity to reconstitute RVD when lipoxygenase is blocked. Centrifugation for preparing washed platelets (1,550 × g, 10 min) is sufficient to express LP activity, with declining potency in repeated centrifugations, indicating that it is not readily replenish-able. When platelet suspension flows in a vinyl tubing (1 mm i.d.), at physiological velocity, controlled at 90–254 cm/s, LP formation increases as a function of velocity but declines as result of increasing the tubing length. Stirring the platelets in an aggregometer cuvette for 30 s, yields no LP unless the stirring is intermittent. No associated platelet lysis or aggregation are observed following the mechanical stress applications. These results demonstrate that although mechanical stresses result in LP production, the mode of its application plays a major role. These results may indicate that LP is synthesized under pathological conditions and could be of relevance to platelets behavior related to arterial stenosis.

Role of Mechanical Stresses at Ion Implantation of CdHgTe Solid Solutions

2013 ◽  
Vol 58 (9) ◽  
pp. 872-880 ◽  
Author(s):  
Smirnov A.B. Smirnov A.B. ◽  
◽  
Lytvyn O.S. Lytvyn O.S. ◽  
Morozhenko V.A. Morozhenko V.A. ◽  
Savkina R.K. Savkina R.K. ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Solid Solutions ◽  
Mechanical Stresses

Trends Related to Power Device Technologies (II)

2010 ◽  
Vol 130 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Ikunorii TAKATA ◽  
Gourab Majumdar
Keyword(s):  
Power Device

Trends Related to Power Device Technologies (I)

2009 ◽  
Vol 129 (12) ◽  
pp. 817-820 ◽  
Author(s):  
Ikunori TAKATA ◽  
Gourab Majumdar
Keyword(s):  
Power Device

On the method of ultrasonic control of mechanical stresses

2018 ◽  
Vol 84 (7) ◽  
pp. 62-66
Author(s):  
K. V. Kurashkin
Keyword(s):  
Elastic Wave ◽  
Orientation Distribution ◽  
Elastic Wave Velocity ◽  
Mechanical Stresses ◽  
Material Structure ◽  
Stress Determination ◽  
Welded Steel ◽  
Ultrasonic Control ◽  
Cubic Crystallites ◽  
Proportional Relationship

A method of ultrasonic control of the mechanical stresses which takes into account the heterogeneity of the material structure and does not require unloading of the structure or using reference samples is considered. The procedure is based on echo-method of measuring time of the bulk elastic wave propagation and determination of the relative values ν31 and ν32 related to the material structure and mechanical stresses. It is shown that stresses violate the linearity of the relationship observed between the parameters in the absence of the mechanical stresses in the rolled material. This effect formed a basis for developing a method of the deviator stress determination. The purpose of the study is to demonstrate the main advantages of the developed method against the known ultrasonic techniques used for evaluation of the mechanical stresses, give theoretical grounds to the effect which allows taking into account the heterogeneity of the material structure, and also to exemplify the procedure. An analytical expression is derived using bulk elastic wave velocity in an orthotropic material composed of cubic crystallites and an assumption on the existence of simple proportional relationship between the coefficients of the orientation distribution function in rolled metal. Presented results of the mathematical modeling confirm the experimentally observed linear dependence between the parameters ν31 and ν32 in the absence of mechanical stresses. The results of evaluating residual stresses in a welded steel plate are presented as an example of the applicability of the developed procedure. Data of ultrasonic technique and data of strain gage measurements are compared. The features of the described method of stress determination are marked and the applicability limits are specified.

Research of the Brillouin frequency shift damage dependence from mechanical stresses in an optical sensor

2019 ◽  
Vol 9 (5) ◽  
pp. 512-521
Author(s):  
Ruslan V. Aginey ◽  
◽  
Rustem R. Islamov ◽  
Alexander A. Godunov ◽  
◽  
...  
Keyword(s):  
Frequency Shift ◽  
Optical Sensor ◽  
Mechanical Stresses

Evaluation of the Resistance of Individual Si Die to Cracking

1998 ◽  
Author(s):  
R. Berriche ◽  
R.K. Lowry ◽  
M.I. Rosenfield
Keyword(s):  
Thermal Cycling ◽  
Hardness Test ◽  
Mechanical Stresses ◽  
Test Method ◽  
Processing Conditions ◽  
Micro Hardness ◽  
Test Methodology ◽  
Vickers Micro Hardness

Abstract The present work investigated the use of the Vickers micro-hardness test method to determine the resistance of individual die to cracking. The results are used as an indicator of resistance to failure under the thermal and mechanical stresses of packaging and subsequent thermal cycling. Indentation measurements on die back surfaces are used to determine how changes in wafer backside processing conditions affect cracks that form around impressions produced at different loads. Test methodology and results obtained at different processing conditions are discussed.

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