...Tae-Wook Kim; Jae-Min Kim; Hyeon-Ji Yun; Jong-Sung Lee; Jae-Hak Lee; Jun-Yeob Song; Young-Chang Joo; Won-Jun Lee; Byoung-Joon Kim Although the reliability of flexible electronics during bending deformation is of great interest nowadays, the mechanical reliability that has mainly been investigated...

... bending measurement was performed. Accelerated thermal cycling cycles to failure were documented for all assemblies and the data were used to calculate the characteristic life. In general, a 2X to 3X decrease in reliability was observed for mirror-image assemblies when compared to single-sided assemblies...

... in die strength data and difficulties in differentiating the causes of the low strength between from the wafer grinding and from wafer sawing by either the three-point bending or four-point bending test. The purposes of this study are to develop new, reliable, and simple test methods for determination...

... many reliability issues arise, including warpage of the package, premature interfacial failure, and degraded interconnections. Bimaterial strip bending experiment has been employed successfully to monitor the evolution of the residual stresses in underfrill resins for flip chip applications...

... the forces and bending moments acting on the flip chip connections. The transformation of these forces and moments into stresses is less accurate as the model does not include stress concentrations near the corners. The model simulates very well the different parameter trends such as chip size...

...E. H. Wong The dynamic response of the printed circuit board (PCB) in a standard board-level drop impact test has been modeled as a spring-mass system, a beam, and a plate. Analytical solutions for the time-response and amplification of the deflection, bending moment, and acceleration at any point...

... long-term reliability, the 3D finite element method (FEM) was used to calculate the stress distribution and warpage of the whole package. Both three-point bending and cooling in the manufacturing process were taken into consideration. The LCP has a coefficient of thermal expansion (CTE) close...

... stages: 1) formation of a surface (blind) microcrack (or a grid of surface microcracks) using a double thermal shock method, and 2) splitting the cracked wafer into chips along the microcrack contour by applying small bending stresses. The emphasis was given to splitting of thin wafers with the thickness...

...Santosh Shetty; Tommi Reinikainen This study demonstrates the application of three-point and four-point bending tests for evaluating the reliability of chip scale packages under curvature loads. A three-point bend test is conducted on 0.5-mm-pitch chip-scale packages (CSPs) mounted on FR4 (Flame...

... bending rigidity, the same solution can be used for a thin plate under large cylindrical bending. In addition, a finite element analysis using nonlinear shell elements is also conducted showing the axial strain of the neutral axis to be less than one percent of the overall deformation. Therefore...

.... This critical factor was measured by V-notched three-point bending tests and the displacement extrapolation method along with the three dimensional (3-D) finite element method (FEM). Moisture concentration in the QFP after absorption is analyzed, and vapor pressure caused by the solder reflow process...

...-tin joints. The dynamic impact energy was provided in the form of three-point bending on the PCB using equipment called the split Hopkinson bar. Strain rates of over 4000/s were used for the impact bending test. The action of impact bending was used to simulate the effect on the PCB...

... conditions. We suggest that the maximum induced curvature and the maximum induced acceleration be used as suitable characteristics of the dynamic response of a structural element to an impact load. Indeed, the maximum curvatures determine the level of the bending stresses, and the maximum accelerations...

... the effective local stiffness of ball grid-array assemblies for determining high-cycle fatigue life has been extended. This method simulates a three-point bend test for flexural stiffness calculation. It demonstrates that the force-deflection relationship at the center of the system can be accurately achieved...

... polymers at different temperatures. The experiments involved bending of a polymer strip within a metal cylinder and measurement of the radius of curvature after removal of the strip from the cylinder, using a specially-developed method. The measured radii ranged from infinity to 1.5 cm, and the obtained...

... thermal stresses stress analysis bending thermal management (packaging) composite material interfaces thermal expansion differential equations thermoelasticity The study of thermal mismatch induced stresses and their role in mechanical failure is one relevant topic to composite materials...

... for publication in the JOURNAL OF ELECTRONIC PACKAGING . Manuscript received by the EPPD July 7, 2000. Associate Editor: S. M. Heinrich. 07 July 2000 optical fibres Bragg gratings packaging bimetals optical tuning bending compensation Optical Fiber Fiber Gratings Temperature...

...Mikio Muraoka The maximum stress in optical glass fibers subjected to two-point bending was evaluated by E. Suhir, “Effect of the Nonlinear Behavior of the Material on Two-Point Bending of Optical Glass Fibers,” ASME Journal of Electronic Packaging, Vol. 114, pp. 246–250, taking into account...

...S. Shetty; V. Lehtinen; A. Dasgupta; V. Halkola; T. Reinikainen This study investigates the effect of quasi-static bending loads (strain rate=0.05/s) on the durability of 0.5 mm pitch Chip Scale Package (CSP) interconnects when assembled on FR4 substrates. The substrates have rows of CSPs...

... in an environmental chamber. The displacements of the reflected laser beams from the surface of the package are recorded by four pairs of 2D photo detectors and position indicators. 1 Definition of the lab coordinate and the principal coordinate We define the sample surface before bending as x...