共查询到20条相似文献,搜索用时 93 毫秒
1.
A critical issue in the manufacturing of electronic packages is the warpage induced during the molding process as a result of differences in the shrinkage of the constituent materials. Package warpage causes serious problems such as the quality degradation of devices and yield loss in manufacturing processes. Loss of lead coplanarity happens due to package warpage and causes difficulty in device testing and surface mount assembly. Internal stresses associated with package warpage can also cause device failures such as die cracking, broken circuits and package cracking.Warpage in IC package has drawn intensive attention in the past. Although the effects of thermal shrinkage were extensively investigated in the literatures, the influence of the cure shrinkage on package warpage had received less attention. Accordingly, this study develops a numerical approach for generating more accurate predictions of the package warpage by taking the effects of both thermal shrinkage and cure shrinkage into account. A three-dimensional finite element model of the small outline package (TSOP) DBS-27P is constructed and the proposed numerical approach, which is based on the P–V–T–C (pressure–volume–temperature–conversion) equation and the CTEs (coefficients of thermal expansion) of the package materials, is employed to predict the warpage at each of its corners under various packaging processing conditions. Using the Taguchi method, the relative influences of the transfer pressure, the packing pressure, the mold temperature and the curing time on the degree of package warpage are identified and the optimal processing conditions are established. A series of experimental packaging trials are performed using the optimal processing conditions. It is found that the warpage of the actual package is in good agreement with that predicted numerically. Therefore, the accuracy of the proposed numerical approach is confirmed. Moreover, the results also demonstrate the capability of the Taguchi method to identify the optimal packaging processing parameters on the basis of a limited number of simulation runs. 相似文献
2.
Yan-Kuin Su Yu-Zung Chiou Chia-Sheng Chang Shoou-Jinn Chang Yi-Chao Lin Jone F. Chen 《Solid-state electronics》2002,46(12):2237-2240
Indium–tin-oxide (ITO), Ni/ITO and Ni layers were deposited onto glass and/or SiC substrates by DC sputtering under different deposition conditions. SiC-based metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors were also fabricated using these materials as contract electrodes. It was found that ITO film deposited without oxygen gas could provide us a better optical property and a better electrical property. It was also found that the dark current of the ITO/SiC MSM UV photodetector was extremely large. Furthermore, it was found that the insertion of a 10 nm Ni layer could significantly reduce the dark current. It was also found that the photo-current to dark current contrast was more than 3 orders of magnitude with a 5 V applied bias for the SiC MSM UV photodetector with 10 nm Ni/90 nm ITO contact electrodes. With an even larger 40 V applied bias, the photo-current to dark current contrast could almost reach 4 orders of magnitude. 相似文献
3.
Expressions arising from the Bruggeman approach for the homogenization of dielectric–magnetic composite materials, without ignoring the sizes of the spherical particles, are presented. These expressions exhibit the proper limit behavior. The incorporation of size dependence is directly responsible for the emergence of dielectric–magnetic coupling in the estimated relative permittivity and permeability of the homogenized composite material. 相似文献
4.
Kevin A. Prior 《Microelectronics Journal》1994,25(8):631-641
Current injection lasers operating in the blue and blue-green spectral regions have recently been fabricated from II–VI epitaxial layers grown by MBE. In this paper, these materials developments which have led to the production of the first II–VI lasers are described, followed by a section on the recent introduction of the new quaternary alloy ZnMgSSe. This alloy has allowed the production of CW room temperature lasing and the lifetime of the lasers to be increased. Recent results relating to the development of modulators and SEED devices are also described. 相似文献
5.
《Photonics Technology Letters, IEEE》2009,21(16):1118-1120
6.
The success of heterojunction quantum wells and quantum dots in III–Vs has not been extended to silicon because the ideal barrier, SiO2, is amorphous, preventing the formation of quantum structures with silicon. The possibility of a few monolayers of oxide inserted between adjacent silicon layers was proposed and realized with a superlattice (SL) structure consisting of Si–Si–O–Si–Si–Si, having a monolayer of oxygen in each period introduced by adsorption onto the 2×1 reconstructed surface along the Si(1 0 0). Reduction of the period leads to a slight up-shift of the energy of the emitted light, indicating that the essential objective of boosting the optical transition by promoting direct transitions has not been realized. Annealing in H2+O2 results in significant improvement in PL and EL, showing that specific defects, e.g., Si–O complexes may be responsible for the observed light emission. The role of Si–O complex being the origin of emission is further supported by the observation that the emission of visible light from polycrystalline Si and SiO2 structure is similar to the epitaxial superlattice with oxygen. The computed strain in a new type of superlattices consisting of SiO2, and GeO2 is much lower than the Si–O SL. The EL in Si–O superlattice with the use of a Schottky barrier to provide electron–hole accumulation allows double injection into states higher in energy than the bandgap of Si, a prerequisite for injection laser without the need to use a wide-band pn-junction. 相似文献
7.
Masazumi Amagai Masako Watanabe Masaki Omiya Kikuo Kishimoto Toshikazu Shibuya 《Microelectronics Reliability》2002,42(6):951-966
Recently, preventing environmental pollutions, lead-free (Pb-free) solders are about to replace tin–lead (Sn–Pb) eutectic solders. However, the mechanical properties of Pb-free solders have not been clarified. Hence, the following study was conducted; first, a rate-dependent plasticity was characterized to represent the inelastic deformation behavior for Sn–Ag-based lead-free solders. The material parameters in a constitutive model were determined in a direct method combining both rate-dependent and rate-independent plastic strains. The constitutive model unifies both rate-dependent creep behavior and rate-independent plastic behavior occurring concurrently at the same time in the solders. Secondly, the strength of solders with a variety of plating materials was studied. Intermetallic compounds (IMC) between solder and electrical pads are formed during reflow process and gradually grow in service. By using the Cu-plates on which Cu or Ni or Ni/Au plating was deposited, the specimens of solder joints were fabricated with Sn–Ag-based lead-free solders. After aging the specimens in an isothermal chamber, tensile tests were performed. From scanning electron microscope (SEM) microscope observation and EDX microprobe analysis, the growth and components of the IMC layer were also examined. Based on the experimental tests, the relations between solder joint strength and the aging period were discussed. Furthermore, the validation of fracture strength of solder joints resulting from the tensile tests was verified with package-mounted board level reliability tests. 相似文献
8.
Keun-Soo Kim Takayuki Imanishi Katsuaki Suganuma Mimoru Ueshima Rikiya Kato 《Microelectronics Reliability》2007,47(7):1113-1119
The metallurgical and mechanical properties of Sn–3.5 wt%Ag–0.5 wt%Bi–xwt%In (x = 0–16) alloys and of their joints during 85 °C/85% relative humidity (RH) exposure and heat cycle test (−40–125 °C) were evaluated by microstructure observation, high temperature X-ray diffraction analysis, shear and peeling tests. The exposure of Sn–Ag–Bi–In joints to 85 °C/85%RH for up to 1000 h promotes In–O formation along the free surfaces of the solder fillets. The 85°C/85%RH exposure, however, does not influence the joint strength for 1000 h. Comparing with Sn–Zn–Bi solders, Sn–Ag–Bi–In solders are much stable against moisture, i.e. even at 85 °C/85%RH. Sn–Ag–Bi–In alloys with middle In content show severe deformation under a heat cycles between −40 °C and 125 °C after 2500 cycles, due to the phase transformation from β-Sn to β-Sn + γ-InSn4 or γ-InSn4 at 125 °C. Even though such deformation, high joint strength can be maintained for 1000 heat cycles. 相似文献
9.
Stanislav Tyaginov Viktor Sverdlov Ivan Starkov Wolfgang Gs Tibor Grasser 《Microelectronics Reliability》2009,49(9-11):998-1002
We extend the McPherson model for the silicon–oxygen bond-breakage in a manner to capture the impact of the O–Si–O angle fluctuations (typical for amorphous SiO2) on the breakage rate. In the McPherson model the transition of the Si ion from the 4-fold coordinated position to the 3-fold coordination is considered as rupture of the Si–O bond. We have studied the potential barrier (separating these saddle points) transformation induced by the O–Si–O bond angle variations and found that the secondary minimum occurs at a critical angle of about 107.75°. Since the Si ion “finds” the way corresponding to the highest breakage probability we used the two-dimensional downhill simplex method in order to find the direction of this maximal rate. It was shown that if the O–Si–O angle deviates from its nominal value 109.48° (typical for α-quartz) corresponding to the regular SiO4 tetrahedron the symmetry aggravates and the secondary minimum is rotated. Calculated dependencies of the breakage rate on the electric field demonstrate the linear slope in the log–lin scale thus reflecting the linear reduction of the activation energy for the bond-breakage vs. field. The family of distribution functions for breakage rate calculated with a fixed step of field shows that the curves do not change their form and are shifted in parallel with the field. This tendency supports the thermo-chemical model for the bond-breakage also in the case of strongly fluctuating O–Si–O angles. As a consequence, dependencies of the mean value of the rate, its standard deviation and the nominal rate (calculated for the angle of 109.48°) have the same slope on a log–lin scale. The wide spread of the breakage rate is reflected by the high value of its standard deviation. 相似文献
10.
《Power Electronics, IEEE Transactions on》2009,24(2):358-368
11.
On total reflection from a half-space filled with an isotropic, homogeneous, weakly dissipative, dielectric-magnetic medium with negative phase-velocity (NPV) characteristics, it is shown here that a linearly polarized beam can experience either a negative or a positive Goos-Hauml;nchen shift. The sign of the shift depends on the polarization state of the beam as well as on the signs of the real parts of the permittivity and the permeability of the NPV medium. 相似文献
12.
Yi-Shao Lai Kuo-Ming Chen Chin-Li Kao Chiu-Wen Lee Ying-Ta Chiu 《Microelectronics Reliability》2007,47(8):1273-1279
We examine electromigration fatigue reliability and morphological patterns of Sn–37Pb and Sn–3Ag–1.5Cu/Sn–3Ag–0.5Cu composite solder bumps in a flip–chip package assembly with Ti/Ni(V)/Cu UBM. The flip–chip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4 A/150 °C, 0.5 A/150 °C, 0.6 A/125 °C, 0.6 A/135 °C, and 0.6 A/150 °C. The electrothermal coupling analysis was employed to investigate the current crowding effect and maximum temperature in the solder bump in order to correlate with the experimental electromigration reliability using the Black’s equation as a reliability model. From available electromigration reliability models, we also present a comparison between fatigue lives of Sn–37Pb solder bumps with Ti/Ni(V)/Cu and those with Al/Ni(V)/Cu UBM under different current stressing conditions. 相似文献
13.
We report how ferroelectric materials induce negative differential resistance (NDR) in organic devices. Fluorescein, which exhibits semiconducting current–voltage characteristics, shows NDR effect in a ferroelectric matrix. Here, we vary the concentration of fluorescein in the ferroelectric matrix to study its effect on NDR. We also show how the degree of polarization controls NDR. We infer that under a suitable bias, the ferroelectric polymer becomes polarized to facilitate electron-injection in the device followed by a double-reduction of fluorescein molecules. From the capacitance–voltage measurements, we substantiate the role of polarization in inducing NDR effect in organic molecules. 相似文献
14.
Simo Srkk 《Signal processing》2010,90(1):225-235
This article considers the application of the unscented transformation to approximate fixed-interval optimal smoothing of continuous-time non-linear stochastic dynamic systems. The proposed methodology can be applied to systems, where the dynamics can be modeled with non-linear stochastic differential equations and the noise corrupted measurements are obtained continuously or at discrete times. The smoothing algorithm is based on computing the continuous-time limit of the recently proposed unscented Rauch–Tung–Striebel smoother, which is an approximate optimal smoothing algorithm for discrete-time stochastic dynamic systems. 相似文献
15.
Francesco G. Della Corte Fortunato Pezzimenti Roberta Nipoti 《Microelectronics Journal》2007,38(12):1273-1279
In this work the forward J–V characteristics of 4H–SiC p–i–n diodes are analysed by means of a physics based device simulator tuned by comparison to experimental results. The circular devices have a diameter of 350 μm. The implanted anode region showed a plateau aluminium concentration of 6×1019 cm−3 located at the surface with a profile edge located at 0.2 μm and a profile tail crossing the n-type epilayer doping at 1.35 μm. Al atom ionization efficiency was carefully taken into account during the simulations. The final devices showed good rectifying properties and at room temperature a diode current density close to 370 A/cm2 could be measured at 5 V. The simulation results were in good agreement with the experimental data taken at temperatures up to about 523 K in the whole explored current range extending over nine orders of magnitude. Simulations also allowed to estimate the effect of a different p+ doping electrically effective profile on the device current handling capabilities. 相似文献
16.
Minimal access surgery (MAS), also known as keyhole surgery, offers many advantages over the more traditional open surgery. However, it possesses one very significant drawback––the loss, by the surgeon, of the “sense of feel” that is used routinely in open surgery to explore tissue and organs within the operative site. Because of this, important properties such as tissue compliance, viscosity and surface texture, which give indications regarding the health of the tissue, cannot easily be assessed. Restoring this tactile capability to MAS surgeons by artificial means would bring immense benefits in patient welfare and safety.
Artificial tactile sensing systems for MAS are reviewed. The technology is addressed from different viewpoints including those of the basic transduction of tactile data (tactile sensing), the computer processing of the transduced data to obtain useful information (tactile data processing) and the display to the surgeon of this information (tactile display). Applications of tactile sensing in MAS, both to mediate the manipulation of organs and to assess the condition of tissue, are reviewed. Some attempts to add tactile feedback to laparoscopic surgery simulation systems for MAS surgeon training are also described. 相似文献
17.
《Microwave Theory and Techniques》2009,57(2):262-270
18.
H. Lu K. C. Hung S. Stoyanov C. Bailey Y. C. Chan 《Microelectronics Reliability》2002,42(8):1205-1212
In the flip-chip assembly process, no-flow underfill materials have a particular advantage over traditional underfill: the application and curing of the former can be undertaken before and during the reflow process. This advantage can be exploited to increase the flip-chip manufacturing throughput. However, adopting a no-flow underfill process may introduce reliability issues such as underfill entrapment, delamination at interfaces between underfill and other materials, and lower solder joint fatigue life. This paper presents an analysis on the assembly and the reliability of flip-chips with no-flow underfill. The methodology adopted in the work is a combination of experimental and computer-modeling methods. Two types of no-flow underfill materials have been used for the flip chips. The samples have been inspected with X-ray and scanning acoustic microscope inspection systems to find voids and other defects. Eleven samples for each type of underfill material have been subjected to thermal shock test and the number of cycles to failure for these flip chips have been found. In the computer modeling part of the work, a comprehensive parametric study has provided details on the relationship between the material properties and reliability, and on how underfill entrapment may affect the thermal–mechanical fatigue life of flip chips with no-flow underfill. 相似文献
19.
《Vehicular Technology, IEEE Transactions on》2009,58(7):3186-3197
20.
《Circuits and Systems II: Express Briefs, IEEE Transactions on》2009,56(8):614-618