Wire-Sweep Study Using an Industrial Semiconductor-Chip-Encapsulation Operation

1997 ◽  
Vol 119 (4) ◽  
pp. 247-254 ◽  
Author(s):  
S. Han ◽  
K. K. Wang ◽  
D. L. Crouthamel
Keyword(s):  
Compound A ◽  
Molding Compound ◽  
X Ray ◽  
Commercial Grade ◽  
Semiconductor Chip ◽  
Plastic Package ◽  
Encapsulation Process ◽  
The Wire ◽  
Experimental Values ◽  
Good Agreement

In this study, the wire-sweep problem has been studied by performing experiments using a commercial-grade epoxy molding compound, a real chip assembly, and an industrial encapsulation process. After encapsulating the chip, the deformed wire shape inside the plastic package has been determined by X-ray scanning. A procedure for the wire-sweep calculation during encapsulation process has been developed. The wire sweep values have been calculated using this procedure with material properties measured from experiments. The calculated wire-sweep values are compared with experimental values measured at different mold temperatures, fill times, and cavities. In most cases, the calculated values are in good agreement with the experimental values.

Flow Analysis in a Chip Cavity During Semiconductor Encapsulation

1999 ◽  
Vol 122 (2) ◽  
pp. 160-167 ◽  
Author(s):  
S. Han ◽  
K. K. Wang
Keyword(s):  
Numerical Method ◽  
Flow Analysis ◽  
Cross Flow ◽  
Experimental Results ◽  
Accurate Analysis ◽  
Molding Compound ◽  
Semiconductor Chip ◽  
Encapsulation Process ◽  
Flow Through ◽  
Good Agreement

In this paper, methods to analyze the flow during semiconductor chip encapsulation have been developed. A numerical method is used for the flow analysis in the chip cavity. In this study, for accurate analysis of flow in the chip cavity, models for the cross flow through the leadframe openings have been developed. The models have been verified by comparing with two experiments. In the first experiment, clear polymer and transparent mold have been used for the visualization of flow in a cavity with a leadframe. In the next experiment, actual epoxy molding compound together with an industrial encapsulation process have been used to observe the melt-front advancement shapes. The calculated and experimental results show good agreement. [S1043-7398(00)00902-6]

Red Phosphorous Induced Shorts in Plastic Packages

2004 ◽  
Author(s):  
Rafael Huerta ◽  
Nevil Wu
Keyword(s):  
Three Dimensions ◽  
Red Phosphorus ◽  
Molding Compound ◽  
X Ray ◽  
Analysis Techniques ◽  
Plastic Packages ◽  
Plastic Package ◽  
Wet Chemical ◽  
Inorganic Phosphorous ◽  
Phosphorous Compounds

Abstract Red phosphorous is one of the inorganic phosphorous compounds used as a flame retardant in microelectronic applications. One of the concerns is a red phosphorus induced pin-to-pin short in the molding compound. This paper discusses the red phosphorous-induced shorts in a 100 Lead TQFP (14x20x1.4mm) plastic package. The devices first failed on boards in the field. After de-soldering them from the boards, the devices were tested and found to have resistive pin-to-pin shorts. Common failure analysis techniques, including parallel lapping, cross sectioning, and X-ray, failed to reveal the resistive shorts and the shorting mechanism. Removing the molding compound by means of a wet chemical etching method using sulfuric acid on a hot plate worked very well and enabled to expose particles in three dimensions. It was concluded that the resistive shorts were not necessarily due to a single large phosphorous particle, but due to small and fragmented pieces of phosphorous.

Inhibition of Silver Electrolytic Migration in Ag-Alloy Bonding Wires

2016 ◽  
Vol 863 ◽  
pp. 95-101 ◽  
Author(s):  
Chien Hsun Chuang ◽  
Yan Cheng Lin ◽  
Yu Zhen He ◽  
Chih Hsin Tsai ◽  
Jun Der Lee ◽  
...  
Keyword(s):  
Migration Rate ◽  
Water Drop ◽  
Distilled Water ◽  
Ion Migration ◽  
Molding Compound ◽  
Silicone Gel ◽  
Bonding Wires ◽  
Encapsulation Process ◽  
Drop Tests ◽  
The Wire

Ion migration in Ag-alloy bonding wires was evaluated with water drop tests. The results indicated that water must be present between the wire couple for Ag electrolytic migration to occur. The addition of 1.5 to 4.5% Pd decreased the ion migration rate. Further alloying with about 8% Au enhanced this effect. It seems that the addition of Ni and Pt in Ag-alloy wires does not influence Ag-ion migration. Ag-alloy wires sealed with silicone gel and stressed in air and in distilled water revealed no dendrites after more than 1,000 hr. The ion migration in Ag-alloy bonding wires can be completely inhibited by a suitable encapsulation process with an appropriate molding compound.

Integrated Flow Analysis During Filling and Post-Filling Stage of Semiconductor Encapsulation

1999 ◽  
Vol 122 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Sejin Han ◽  
K. K. Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Flow Analysis ◽  
Rectangular Cavity ◽  
Experimental Results ◽  
Molding Compound ◽  
Filling Stage ◽  
Semiconductor Chip ◽  
Simulation Results ◽  
Good Agreement

In this paper, flow during the filling and post-filling stages in semiconductor chip encapsulation has been analyzed. A finite-element method based on the Hele-Shaw approximation is used for the flow analysis in the chip cavity. The compressibility of the epoxy-molding compound has been considered to analyze the post-filling stage. The model has been verified by comparing resulting predictions with experimental results. Specifically, pressure has been measured in a rectangular cavity and compared with simulation results. The calculated and experimental results show good agreement. [S1043-7398(00)00101-8]

scholarly journals Study the Temperature Dependence of EXAFS Cumulants of Si and Ge by the Anharmonic Correlated Einstein Model

2011 ◽  
Vol 21 (1) ◽  
pp. 25 ◽  
Author(s):  
Vu Van Hung ◽  
Ho Khac Hieu
Keyword(s):  
Fine Structure ◽  
Temperature Dependence ◽  
X Ray ◽  
Einstein Model ◽  
Silicon And Germanium ◽  
Experimental Values ◽  
X Ray Absorption ◽  
Analytical Expressions ◽  
Theoretical Results ◽  
Good Agreement

In present article, the anharmonic correlated Einstein model has been used to study the temperature dependence of Extended X-ray absorption fine structure (EXAFS) cumulants of silicon and germanium crystals. The analytical expressions of the first, second and third cumulants of silion and germanium have been derived. Our numerical calculations are compared with the experimental values and also with other theoretical results showing the good agreement.

Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

2017 ◽  
Author(s):  
Younghee Lee ◽  
Daniela M. Piper ◽  
Andrew S. Cavanagh ◽  
Matthias J. Young ◽  
Se-Hee Lee ◽  
...  
Keyword(s):  
Lithium Ion ◽  
Atomic Layer ◽  
Mass Gain ◽  
Alloy Film ◽  
Ex Situ ◽  
X Ray ◽  
Layer Deposition ◽  
Ion Conducting ◽  
Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH<sub>3</sub>)<sub>3</sub> as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF<sub>3</sub> and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF<sub>3</sub>)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film was measured as σ = 7.5 × 10<sup>-6</sup> S/cm.</div>

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

scholarly journals The influence of exocyclic lone pairs on the bonding and geometry of type A mesoionic rings

2021 ◽  
Author(s):  
Christopher Antony Ramsden ◽  
Wojciech Piotr Oziminski
Keyword(s):  
Ab Initio ◽  
Type A ◽  
Nbo Analysis ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bond Model ◽  
Lone Pairs ◽  
Mp2 Calculations ◽  
Good Agreement

AbstractBased on structures determined by X-ray crystallography, ab initio MP2 calculations on type A mesoionic rings give geometries in good agreement with observed values. A study of four mesoionic ring systems, each with exocyclic oxygen, nitrogen or carbon groups, shows that the presence and configuration of exocyclic lone pairs significantly influences the geometry and configurational preference. Using a localised bond model and NBO analysis, these effects are rationalised in terms of an anomeric interaction of lone pairs with the antibonding orbitals of adjacent σ bonds. In agreement with experiment, similar effects are calculated for pyran-2-imines.

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