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Wafer-level chip-scale package (WLCSP) with solder joint as interconnection process was used to enable, thinner, low cost and fine-pitch for mobile type of information and communication device that assembly into SiP module. However, the lower solder joint reliability performances is the key challenge and more and more serious as increasing WLCSP package size, especially the size is larger than 6mm...
We have investigated finite element method (FEM) modeling of thermal stress analysis in a SiC power module using sintering Ag die-attach, and explored the reliability focusing on the initial cracking point caused by the thermal stress. The analysis results by FEM models support our experimental observations in the reliability tests of the fabricated modules, confirming that using direct-bonded-copper...
The reliability life assessment of electronic packages is a key issue to ensure the mass production quality of packaging components. To meet the time-to-market and long term reliability requirements, using finite element to predict a precise life cycle of solder joints becomes the main trend of electronic packaging product development. Thermal cycling test is a standard test and has been widely used...
The effect of Joule heating (JH) on electromigration (EM) was investigated using copper low-k interconnects. We found Black's empirical EM model works at a very wide stress conditions (I = 0.03 mA ∼ 3.5mA), where the temperature rise by JH ranges from 0°C to 240°C. EM modeling parameters were found to be 1.05eV and 1.4 for EM Ea and n, respectively. Extensive failure analysis and FEM simulations were...
This paper presents a comparison of the performances between IPMSMs (Interior Permanent Magnet Synchronous Machine) with a symmetrical and with two different types of unsymmetrical windings. The aim is to demonstrate that the adoption of slightly unsymmetrical windings does not significantly affect the performances of the machines, both in terms of cogging torque and torque/load angle characteristics,...
The board level reliability of BGA multichip modules was characterized under thermal shock and drop test conditions. The variables studied were BGA pattern, substrate surface finish, solder joint size, and module size. Thermal cycle reliability was quite robust for all test vehicles since the body sizes were less than 7mm on a side. Drop test reliability improved with smaller body size, larger solder...
Lately, a new diagnostic mean has been introduced for reliable fault diagnosis in delta-connected induction motors. This diagnostic mean is the zero-sequence current frequency spectrum. Since this diagnostic mean successfully answers to a variety of reliability demands, a thorough investigation of its harmonic index has to be performed as a function of the rotor geometry. In this work, FEM sinulations...
Accurate estimation of semiconductors' junction temperature is particularly important that the impact of the temperature on their reliability and performance is evident. The analysis in this paper reveals that the using of RC thermal network models with reduced number of layers can be tremendously useful. Additionally, a simple technique for transforming n-layer Foster model to a one-cell Cauer ladder...
Today, high-power LED packages have been widely used in many fields by virtue of its high efficiency, long service life and small size etc. A LED package consists of many different components, which are made of different materials being operated under different conditions. As a result, each component has its own pattern of impact on the reliability problem of LED packages, such as chip failure, package...
Rising with consumer electronics, mobile and wearable devices electronic packaging is developed with high power, high I/O, small size and good reliability performance. Among the various packages adopted by industry, Wafer Level Chip Size Packaging (WLCSP) and Ball Grid Array (BGA) possess characteristics mentioned above and therefore widely used in various kinds of devices. However, concerning different...
The paper demonstrates an analysis example of a flange-sealing structure. Taking the O-ring width and bolt pre-tightening force as tolerance-parameters, obtaining the stress response surface according to the loop analysis results by ANSYS, then extracting the stress results of randomized parameters from the stress response surface, plotting the stress response distribution and calculating the reliability...
In recent years, Lamb wave has shown great potential in structural integrity assessment and life prediction due to the capability of traveling at large distances in structures with little energy loss. However, most of existing researches of Lamb wave based damage detection mainly focus on specific target systems. Physical models which correlate the crack size and damage sensitive features may vary...
The demand for reliable wafer level chip scale packages (WLCSPs) is getting higher due to the need for higher performance and smaller form factor designs. Small WLCSPs have been used with good board-level reliability but larger WLCSPs have not. In the study, a high Tg, low CTE reworkable edgebond adhesive is proposed to enhance the board-level solder joint reliability of a large WLCSP having a chip...
Wafer Level Chip Scale Package (WLCSP) has been widely used in MEMS and SiP packages; application of mobile and consuming products. It advantages in lightweight, reducing manufacturing cost, low I/O density and high performance because the bumps directly interconnect between die and motherboard. However, the lower Temperature Cycling on Board (TCoB) reliability performances because of CTE mismatches...
For the high-power LED applications, TAV (Through-aluminum-nitride-via) substrate with a high thermal conductivity provides better heat dissipation. However, the high thermal expansion coefficient mismatch between the AlN (Aluminum nitride) and copper film may cause the failure, and thus affect the reliability of TAV substrate. The objective of this study is to evaluate the reliability of TAV substrate...
In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purposely fabricated. The temperature distribution produced by such abnormal conditions has been modelled first...
Blakley and Shamir independently introduce the basic idea of a (k, n) threshold secret sharing scheme in 1979. Shamir also recognize the concept of a hierarchical scheme, and suggests accomplishing the scheme by giving the participants of the more capable levels a greater number of shares. Some of hierarchical secret sharing schemes are known in the way that the secret is shared among a group of participants...
With the wide application of microelectronics packaging products in the industry, the chip have been more and more attention in the harsh environment of high temperature, high humidity. Therefore how to rapidly deliver high reliability products to market has been one of the issues of concern in the microelectronics industry. However moisture sensitivity level (MSL) analysis in microelectronics packaging...
With the development of the high-speed rotating machine, the rotor is becoming very sensitive for the mass unbalance caused by the asymmetry design, machining error, assembly error and operational fault. In order to actively reduce the rotor unbalance, a new electromagnetic balancing mechanism is proposed. This balancer is driven by the ring coil and keep the balanced condition by the permanent magnet...
In this work we show some results computed by the finite element method for time-harmonic electromagnetic problems involving rotating spheres. They are compared with the data provided by a semi-analytical technique. The comparisons show the reliability of the numerical method. In the presence of non-canonical rotating axisymmetric objects no comparison is possible but the reliability of finite element...
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