The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A 6.5kV, wire-bondless power electronics module with a double-sided cooling is proposed and evaluated. A direct solder attachment is employed to minimize parasitic circuit elements and increase current handling capability as well as to enable a double-sided cooling capability with mechanical robustness. Finite element simulations were performed to investigate the thermal performance, critical breakdown...
Peculiarities of mandrelling small diameter deep holes with high allowances, production tooling applied, holes accuracy and surface finish provided by the given processing technique are examined.
Isothermal compression of the TC11 titanium alloy has been conducted on Gleebe-1500D hot-simulator at the deformation temperature ranging from 960°C to 1050°C, the strain rate ranging from 0.01s−1 to 10s−1, the maximal engineering strain 50%. Based on dynamic materials model (DMM) theory, the hot processing maps for TC11 titanium alloy were constructed at different strains with the data of hot compression...
A combined method to investigation of localized deformation processes in notched aluminum alloy as well as carbon fiber reinforced composite specimens is applied in order to reveal characteristic stages of strain and fracture. Stress concentrators have the shape of a circular hole and edge crack of various sizes. Carbon fiber reinforced composites (CFRC) with notches of different size were also tested...
An and model was used to establish the constitutive equation of SnAgCu solder, the stress-strain response of soldered joints was analyzed by finite element code. Results indicated that the stress concentrates on the sharp corner of interior part of outermost soldered joint, where is the weakest position at which cracks initiation take place easily and lead to failure owing to thermal fatigue finally...
With electronic production tending to be large scale integration, digital, lightweight, small-lot and diversification, the traditional bumping fabrication technologies aren't compatible with the electronic production such as the personalized, medical implants, military and new product development micro-assembly electronic product for cost problem. And then the single chip bumping technology is introduced,...
In this study, a parametric study of the stress intensity factors (SIFs, KI and KII) at the crack tips of predefined cracks in the IMC layers of ball grid array (BGA) structure joints was performed using linear elastic fracture mechanics (LEFM) method through finite element (FE) simulation. It has been shown that the crack driving force KI is much larger than KII regardless of the crack length, contact...
We consider modeling of a nonlinear thin plate and a nonlinear thin shell under the following assumptions: (a) the materials are nonlinear; (b) the deflections are small (linear strain displacement relations). For a plate with a planar middle surface, we consider the bending of the plate to establish the strain energy, the equilibrium equations, and the motion equations. For a shell with a curved...
Triple junction solar cells (TJSC) are the main components of concentrator photovoltaic (CPV) systems. Metalorganic chemical vapor deposition (MOCVD) is the manufacturing process of choice used to produce state of the art solar cells. An improvement in cell efficiency through improvement in cell design lowers the overall cost of solar electricity and stimulates widespread adoption of solar systems...
This paper studies the feasibility of using GaN/InGaN quantum dot as the Intermediate Band Solar Cell. Different dot sizes and layers are compared and the result shows significant differences due to different quantum confinement strength. The band structure and transition rate in the quantum dot are calculated. The efficiency of the strucutre can reach 31% in this structure. With these information,...
The reliability of complex interconnect structures at all levels of the chip integration hierarchy has become a major concern due to the use of fine feature sizes, diverse materials, and complex 3D architectures. Reliability issues range from stress related failures such as dielectric cracking and interface debonding during manufacturing to electrical and mechanical failures such as electromigration...
Improved fatigue life prediction methods will assist in reducing life cycle costs and increasing the availability of mechanical components. These methods include Stromeyer function, Basquin law, Manson-Coffin law, frequency modified damage function (FMDF) model, strain range partition (SRP) and so on. However, different models are applied to assess the life under high cycle fatigue (HCF) and low cycle...
A new design for a dielectric elastomer actuator with geometrically confining reinforcements is presented. The resulting structures enable complex 3-dimentional motion without the need of the membrane prestretch. An in situ imaging system is used to capture the complex deformation pattern to evaluate the surface curvatures. The deformation mode is analyzed analytically using the bi-laminate theory...
Polymer based materials are widely used in electronic packaging. The molding compound, in particular, comprises a significant portion of the package with the purpose of protecting the chips from the environment. Material characterization of molding compounds, therefore, has been a critical issue in predicting the thermo-mechanical behavior and reliability of electronic packaging. One of the distinctive...
In this work, the viscoelastic mechanical response of a typical underfill encapsulant has been characterized via rate dependent stress-strain testing over a wide temperature range, and via creep testing for a large range of applied stress levels and temperatures. The 60 × 3 × 0.5 mm test specimens were dispensed and cured with production equipment using the same conditions as those used in actual...
Electronic products are subjected to high G-levels during mechanical shock and vibration. Failure-modes include solder-joint failures, pad cratering, chip-cracking, copper trace fracture, and underfill fillet failures. The second-level interconnects may be experience high-strain rates and accrue damage during repetitive exposure to mechanical shock. Industry migration to leadfree solders has resulted...
Three-dimension (3D) integration provides a promising approach to build complex microsystems through bonding and interconnection of individually optimized device layers without sacrificing system performance. The use of traditional underfill processes is expected to suffer an arduous challenge as the filled gap of a large scale chip is narrowed down to several micrometers. Consequently, the subsequent...
This paper proposes to apply parallel transport and statistical atlas techniques to quantify 4D myocardial motion abnormalities. We take advantage of our previous work on cardiac motion, which provided a continuous spatiotemporal representation of velocities, to interpolate and reorient cardiac motion fields to an unbiased reference space. Abnormal motion is quantified using SPM analysis on the velocity...
Lead-free (LF) solder joints of portable devices are frequently subjected to unintentional drop, bend, shear and thermal cycling loading during transportation, handling, and usage. Various underfills are widely used in the electronics industry to deal with these challenges, however, the above approaches have some intrinsic shortcomings such as high material costs, low manufacturing assembly rate,...
Different proportions of LZB-GC nano-silver antibacterial agent was added into the alginate impression materials. The antibacterial ratios of antibacterial alginate impression material on Escherichia coli and Staphylococcus aureus were investigated, and the physical properties, including coagulation time, compressive strength, compressive strain, deformation restorability and fluidity were characterized...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.