Comparison of LED package reliability under thermal cycling and thermal shock conditions by experimental testing and finite element simulation

2011 ◽  
Author(s):  
Zhaohui Chen ◽  
Qin Zhang ◽  
Run Chen ◽  
Feng Jiao ◽  
Mingxiang Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Thermal Cycling ◽  
Finite Element Simulation ◽  
Thermal Shock ◽  
Experimental Testing ◽  
Element Simulation ◽  
Package Reliability

Design and Characterization of a Soft Vacuum-Actuated Rotary Actuator

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Liancun Zhang ◽  
Qiang Huang ◽  
Wenkang Wang ◽  
Kangjian Cai
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Simulation Analysis ◽  
Experimental Testing ◽  
Large Change ◽  
Mechanical Analysis ◽  
Ring Structure ◽  
Rotary Actuator ◽  
Element Simulation ◽  
Highly Correlated

Abstract This study provides a type of soft vacuum-actuated rotary actuator. The structures in the actuator are based on different elastomeric structures that comprise a number of interacting elastic radial beams, elastic circumferential beams, and interconnected, deformable sector ring structure air chambers. When negative pressure is applied to the structure, the radial beams bend reversibly into serpentine shapes until adjacent circumferential beams contact each other. This bending results in a large change in the circumferential angle of the structure, but a smaller change in its radial width. Thus, the structure produces rotational motion in its circumferential direction. The design, fabrication, and mechanical analysis of the actuator are introduced, respectively. Moreover, finite element simulation analysis and experimental testing are carried out to study the corresponding relations between the air pressure, rotation angle, and force of the actuator. In addition, the stimulation results and the experimental results of the actuator are statistically analyzed by statistical product and service solutions (spss) statistical software. The test results of the experimental platform are highly correlated with the results of the finite element simulation.

Numerical simulation of ductile fracture in polyethylene pipe with continuum damage mechanics and Gurson-Tvergaard-Needleman damage models

2019 ◽  
Vol 233 (12) ◽  
pp. 2455-2468
Author(s):  
Yi Zhang ◽  
P-Y Ben Jar ◽  
Shifeng Xue ◽  
Lin Li
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Constitutive Equations ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Experimental Testing ◽  
Monotonic Loading ◽  
Test Method ◽  
Strain Level ◽  
Element Simulation

A phenomenon-based hybrid approach of experimental testing and finite element simulations is used to describe the fracture behavior of pipe-grade polyethylene. The experimental testing adopts a modified D-split test method to stretch the pipe ring (notched pipe ring) specimens that have symmetric, double-edged flat notches along the pipe direction. Two series of experimental testing were conducted: (1) monotonic loading till fracture and (2) monotonic loading to a predefined strain level, keeping constant displacement for a period of time, and then unloaded. Crosshead speeds of 0.01, 1, and 100 mm/min were used in both series of tests. Likewise, two series of finite element simulation were conducted to establish the constitutive equations, either with or without considering damage evolution during the deformation process. The constitutive equation without the consideration of damage was established using results from the first series of experimental testing, and that with damage was inspired from the second series which showed the decrease in unloading modulus with the increase of crosshead speed or the predefined strain level. The results show that with the consideration of damage evolution, the constitutive equations enable the finite element simulation to determine the whole stress–strain relationship during both necking and fracture processes.

Effect of Dwell Times and Ramp Rates on the Thermal Cycling Reliability of Pb-Free Wafer-Level Chip Scale Packages: Experiments and Modeling

2006 ◽  
Author(s):  
S. Chaparala ◽  
J. M. Pitarresi ◽  
M. Meilunas
Keyword(s):  
Finite Element ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Dwell Time ◽  
Experimental Testing ◽  
Lead Free ◽  
Temperature Extremes ◽  
Wafer Level ◽  
Ramp Rate ◽  
Free Solder

Lead-free (Pb-free) solder has seen increasing use in interconnect systems for electronic packages due to legislative and marketing pressures. The NEMI selected eutectic Sn3.9Ag0.6Cu alloy (or a close variation near eutectic Sn3.5Ag1.0Cu used in this study) is a leading Pb-free substitute for the Sn/Pb solder candidate. The reliability of this Pb-free solder alloy under accelerated thermal cycling and thermal shock testing as a function of testing parameters such as dwell time and ramp rate is critical in qualifying the performance of these Pb-free alternatives with the traditionally used Sn37Pb solder This paper presents the reliability of Pb-free solder joints in wafer level chip scale packages (WLCSPs), which are extensions of flip-chip packaging technology to standard surface mount technology, with external dimensions equal to that of the silicon device [1]. The reliability of these packages under both liquid-to-liquid thermal shock (LLTS) testing and accelerated air-to-air thermal cycling (AATC) conditions, as a function of dwell times and ramp rates is evaluated using extensive experimental testing in combination with finite element analysis. Besides, two asymmetric cycles in which the cold and hot dwell times differ at two temperature extremes were studied. Along with the Pb-free solder, some test vehicles were built using eutectic Sn-Pb solder and evaluated for comparison purposes. Experimental results show that an increase in ramp rate does not adversely affect the solder joint reliability in the case of Pb-free solder. The reliability of lead-free WLCSPs was highly dependent upon the dwell time at the temperature extremes, with this dependency being considerably greater for the lead-free allow than for Sn/Pb at 0°C and 100°C. Accelerated test results show that increasing the dwell time from 280 to 900 seconds reduced the N63.2 of the Sn/Pb samples by 12% and the Pb-free samples by 65%. Reliability during asymmetric cycles resulted in a trend that is similar in two cases studied. A predictive equation was developed to evaluate the characteristic life of the package with respect to the dwell time. Non-linear, finite element (FE) modeling was conducted using temperature dependent creep constitutive relations for the Pb-free solder to understand the experimental trends observed. The FE results predicted the same trend of the package reliability as observed experimentally, with respect to the changing dwell and ramp times. The finite element predictions demonstrated reasonable correlation with the experimental observations.

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