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Femur is leg bone of the human body undergoing more deformation. Being longest and heaviest in size, failure of femur neck is the most common among bone failures in human especially in woman. Orthopedic implantation is done in case of failure. Before implantation it is necessary to analyze the perfectness in case of its material property, size and shape, surface treatment, load resistance and chances...
The goal of this research is to develop a consistent and repeatable method to evaluate: a) effective thermal conductivity, and b) axial and transverse coefficients of thermal expansion (CTE) of SWCNT (single walled carbon nanotube)-Cu composites, with the view to potentially replacing Cu vias with CNT-Cu TSVs (through-silicon vias) in 3D electronics packaging. Finite element models were built using...
According to Solid-State Lighting Manufacturing Roadmap 2009, lower cost and higher reliability are two key necessities for LED lighting. In this paper, an optimization process of thermal design for LED lighting system is carried out from the perspective of system in packaging. Based on the three-dimensional thermo-mechanical model of LED lighting system, the thermal and mechanical performance of...
The rapid assembly of printed circuit boards to meet the desired goal of thinning the board creates more complexity in the reflow process, to control the occurrence of warpage in the board. Therefore, certain methods are preferred for simply yet accurately predicting the amount of warpage inevitable in the reflow process. Responding to such a need, the study was carried out aiming to provide a specific...
Stresses, including thermal, mechanical and combined stress, are the root causes leading to hot forging die failure. Stress amplitude is affected by the material properties, such as thermal expansion coefficient. In order to select die material for improving die service life, a 2D FE model is developed to analyze thermal, mechanical and combined stress of hot forging die with different level thermal...
In the case of embedded chip type CSPs (Chip Scale Packages) made by embedding chips in PCBs (Printed Circuit Boards), problems occur due to differences in the CTE (Coefficient of Thermal Expansion) between the PCBs and the chips. This study tested a method to solve this problem by inserting thermal SBLs (Stress Absorbing Layers) into the embedded chips, thereby improving the reliability of the connection...
Four flexible support units are used for each first wall module bracing to the vacuum vessel of ITER. The support unit consists of fastening bolt, flexible cartridge and collar for compensation of thermal expansion. The collar made of copper alloy operates under considerable compression load. The performed structural analysis shows that stresses in the collar exceed the design allowable value specified...
An array of accelerated temperature cycling (ATC) finite element (FE) simulations using ANSYStrade, and drop-impact finite element simulations using LS DYNAtrade, are used to find the optimum elastic modulus and coefficient of thermal expansion (CTE) for a stacked chip scale package. For the ATC simulations, Anand's constitutive model with properties for Sn96.5Ag3.0Cu0.5 (SAC305) and tin-lead eutectic...
Simple analytical (ldquomathematicalrdquo) stress models are developed for a silicon die embedded into, or surface mounted onto, a thin ldquostretchablerdquo plastic carrier. We consider a situation when the die/carrier assembly is manufactured at an elevated temperature, then cooled down to a low (say, room) temperature and then subjected to an external tensile load applied to the carrier. The induced...
A number of failure mechanisms related to the underfill material in flip chip plastic ball grid array packages are well documented in the literature (underfill-to-chip passivation delamination, underfill-to-substrate soldermask delamination, chip cracking, interconnect fatigue, etc.). This paper discusses the delamination of the underfill from the chip sidewalls, another failure mechanism which has...
Amkor's FCMBGA, flip chip package based on transfer molding for high performance device was developed and introduced to industry in 2008[1,2]. During the molding process, bump deformation was not significant, and voids were not observed under flip chip die. Coplanarity with a low coefficient of thermal expansion, CCTETE, substrate construction was similar to a single piece lidded package construction...
The development of Cu/low-k interconnects to meet continuous tighter specifications (lower RC time delay, power consumption...) and consequently the introduction of mechanically weak materials is widely identified as a contributor of interfacial cracks propagating during manufacturing flow or qualification tests. Moreover, a raise in Front-End/Back-End (FE/BE) compatibility issues has been also observed...
With the increased complexity of SiP (system in package), Finite Element simulations take an important role in predicting the thermo-mechanical package reliability. Failures in flip chip packages such as die cracking and fatigue of solder bumps are specially the result of the mismatch in thermal expansion coefficients between die and the substrate. In some packages, we use an underfill to improve...
Hybrid vehicle traction applications require compact power modules with high reliability. A major challenge is the lifetime under thermal cycles. While the requirements are moderate with respect to (active) power cycles, there are challenging requests for a high lifetime under (passive) temperature cycles. Base plates and solder interfaces limit the stability for temperature cycles in the classical...
For advanced wafer-level chip scale packages (WLCSP), board level solder joint reliability is a major concern, and typical stress-relieving methods such as capillary underfills and molding compounds are costly. One method of low cost reliability improvement for WLCSPs is the use of a wafer level SolderBracetrade coating, which delivers improved reliability with minimal material and capital cost. In...
Thermo-mechanical modeling has been done in a true-symmetry three-dimensional geometry for copper-pillar flip-chip packages to find out package warpage, stress and bump joint strain energy during temperature cycling. Lead-free solder materials, SnAg and SnAgCu were used in the bump joint at the substrate side. The strain energy due to both time-independent plastic and creep had been considered during...
The effect of thinning down the chip thickness, will affect the stress pattern in the chip and causes the chip to deform locally when the thickness of the chip is thinner than a certain critical value. Such a local deformation may cause sharp gradient of residual stress around the solder bumps and thus, various failures. This paper shows that by considering the effect of solder bumps on a 50 mum chip,...
The impact of Chip-Package Interaction (CPI) which is caused by the mismatch in the coefficient of thermal expansion (CTE) between substrate and chip in a Flip Chip Ball Grid Array (FCBGA) on the mechanical reliability of Cu/Ultra low-k in a larger die was investigated using Finite Element Analysis (FEA). In order to associate the deformation and thermal stresses in FCBGA with those in the Cu/Ultra...
Interconnect technology is the key to the reliability of electronic devices. Electronic components are soldered to a printed circuit board (PCB). Major failure mode is thermal fatigue of solder joints since there is a big difference in the coefficient of thermal expansion (CTE) between soldered components. Underfill resin is used to improve the interconnect reliability. Resin can relief stresses in...
A novel capacitive temperature sensor based on multilayer cantilevers is presented. The top and bottom layers are metal and heavily boron doped Si, respectively. A combined SiO2/Si3N4 layer is utilized as the elastic dielectric layers of the sandwich multilayer cantilever. The operation principle of the structure is based on the effect of thermal expansion coefficient mismatch and the available physical...
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