Cleaning and Reflow of Pb-Sn C4 Solder Bumps

1995 ◽  
Vol 117 (4) ◽  
pp. 281-287 ◽  
Author(s):  
Caroline S. Lee ◽  
Doug C. Crafts ◽  
T. W. Eagar
Keyword(s):  
Growth Rate ◽  
Surface Layer ◽  
Reaction Rate ◽  
Diffusion Rate ◽  
Primary Component ◽  
Corrosion Layer ◽  
Dense Layer ◽  
Surface Corrosion ◽  
Solder Bumps ◽  
Electroplating Process

The Pb/Sn electroplating process for C4 technology requires the ability to etch Ball Limiting Metallurgy (BLM) in the presence of the Pb/Sn bumps. Upon etching, a surface corrosion layer is formed and an appropriate cleaning acid must be used to remove this layer prior to solder reflow of the bumps. It was found that the morphology of the surface layer formed upon etching on the Pb/Sn solder bumps is critically dependent on the concentration of the etchant. Using a gravimetric test, XPS and AES analysis, PbO containing small amounts of Sn and S, was identified to be the primary component of the surface. The thickness morphology, composition and the growth rate of the layer are critically dependent on the sulfur from the etchant. In H2O2-rich solutions, the surface appears to be loosely packed and the growth rate on the surface of the bump was found to be reaction-rate limited; whereas, in H2SO4-rich solutions, the diffusion rate is the controlling step informing the surface layer on the solder bumps, thus producing a thin and dense layer.

Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

1993 ◽  
Vol 51 ◽  
pp. 1116-1117
Author(s):  
C. S. Lin ◽  
W. A. Chiou ◽  
M. Meshii
Keyword(s):  
Intermetallic Compound ◽  
Reaction Rate ◽  
Diffusion Rate ◽  
Early Stage ◽  
Zinc Bath ◽  
Steel Sheets ◽  
Direct Observations ◽  
Solid Iron ◽  
Iron And Zinc ◽  
Ternary Intermetallic Compound

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

scholarly journals Formation of GW190521 from stellar evolution: the impact of the hydrogen-rich envelope, dredge-up and 12C(α, γ)16O rate on the pair-instability black hole mass gap

2020 ◽  
Author(s):  
Guglielmo Costa ◽  
Alessandro Bressan ◽  
Michela Mapelli ◽  
Paola Marigo ◽  
Giuliano Iorio ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Reaction Rate ◽  
Primary Component ◽  
Mass Reduction ◽  
Black Hole Mass ◽  
Core Mass ◽  
The Core ◽  
Mass Gap ◽  
M Stars ◽  
The Impact

Abstract Pair-instability (PI) is expected to open a gap in the mass spectrum of black holes (BHs) between ≈40 − 65 M⊙ and ≈120 M⊙. The existence of the mass gap is currently being challenged by the detection of GW190521, with a primary component mass of $85^{+21}_{-14}$ M⊙. Here, we investigate the main uncertainties on the PI mass gap: the 12C(α, γ)16O reaction rate and the H-rich envelope collapse. With the standard 12C(α, γ)16O rate, the lower edge of the mass gap can be 70 M⊙ if we allow for the collapse of the residual H-rich envelope at metallicity Z ≤ 0.0003. Adopting the uncertainties given by the starlib database, for models computed with the 12C(α, γ)16O rate −1 σ, we find that the PI mass gap ranges between ≈80 M⊙ and ≈150 M⊙. Stars with MZAMS > 110 M⊙ may experience a deep dredge-up episode during the core helium-burning phase, that extracts matter from the core enriching the envelope. As a consequence of the He-core mass reduction, a star with MZAMS = 160 M⊙ may avoid the PI and produce a BH of 150 M⊙. In the −2 σ case, the PI mass gap ranges from 92 M⊙ to 110 M⊙. Finally, in models computed with 12C(α, γ)16O −3 σ, the mass gap is completely removed by the dredge-up effect. The onset of this dredge-up is particularly sensitive to the assumed model for convection and mixing. The combined effect of H-rich envelope collapse and low 12C(α, γ)16O rate can lead to the formation of BHs with masses consistent with the primary component of GW190521.

Sub-100 μm SnAg Solder Bumping Technology and the Bump Reliability

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Xiaoqin Lin ◽  
Le Luo
Keyword(s):  
Cu6sn5 Phase ◽  
X Ray ◽  
Solder Bumps ◽  
Average Shear Strength ◽  
Average Shear ◽  
Snag Solder ◽  
Packaging Industry ◽  
Negative Impacts ◽  
Free Solder ◽  
Electroplating Process

Lead-free solder bumping and its related interconnection and reliability are becoming one of the important issues in today’s electronic packaging industry. In this paper, alloy electroplating was used as SnAg solder bumping process. Multiple reflow was preformed on as-plated solder bumps. Scanning electron microscopy and energy dispersive X-ray analysis were used to investigate the intermetallic compound and microvoids of cross-sectioned solder bump. Shear test was used to evaluate the reliabilities of the SnAg bumps. The 13×13 area-array Sn/3.0Ag solder bumps of 70 μm in height and 90 μm in diameter were fabricated with a smooth and shiny surface and with a uniform distribution of Ag. During multireflow, the scalloped Cu6Sn5 phase grows by a ripening process. Volume shrinkage was the main reason for the formation of microvoids during multireflow. The average shear strength of solder bumps on TiW/Cu under bump metallurgy (UBM) increased with reflow times. The electroplating process is suitable for mass production of well-controlled geometry and uniformity of SnAg solder bumps. Microvoids have trivial negative impacts on the solder bonds. The combination of TiW/Cu UBM and SnAg solder is reliable.

Effect of Two-Stage Aging on Microstructure and Properties of Al-Mg-Si Alloys

2022 ◽  
Vol 905 ◽  
pp. 51-55
Author(s):  
Li Wang ◽  
Ya Ya Zheng ◽  
Shi Hu Hu
Keyword(s):  
Growth Rate ◽  
Grain Boundary ◽  
Tensile Properties ◽  
Tensile Testing ◽  
Diffusion Rate ◽  
Two Stage ◽  
Precipitated Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Microstructure Characteristic

The effects of two-stage aging on the microstructures, tensile properties and intergranular corrosion (IGC) sensitivity of Al-Mg-Si alloys were studied by tensile testing and IGC experiments and transmission electron microscope (TEM). The results show that the two-stage aging (180°C, 2h+160°C, 120h) can reduce the IGC sensitivity without decrease the tensile properties. The grain is distributed with high-density β′′ phases, and the grain boundary phases are spherical and intermittently distributed. The formation of the microstructure characteristic is due to the lower re-aging temperature, which results in a decline differences in the diffusion rate between the matrix and grain boundaries. As a result, the pre-precipitated phase can maintain a better strengthening effects due to the slower growth rate. The pre-precipitated phase of the grain boundary presents a spherical and intermittent distribution due to the fast coarsening speed.

scholarly journals Infiltrative instability near topography with implication for the drainage of soluble rocks

2008 ◽  
Vol 12 (6) ◽  
pp. 1285-1293 ◽  
Author(s):  
P. Genthon ◽  
A. Ormond
Keyword(s):  
Growth Rate ◽  
Porous Medium ◽  
Reaction Rate ◽  
Drainage Basin ◽  
Sensitivity Study ◽  
Flow Lines ◽  
Initial Flow ◽  
Underground Channel ◽  
Water Saturated ◽  
Channel Structures

Abstract. We present here numerical modeling of infiltration instability near a topographic edge of a water-saturated porous slice by analogy with a limestone formation devoid of initial heterogeneities such as fractures faults or joints and limited by a vertical cliff. In our runs a first dissolution finger develops near the cliff edge, and ends to intersect it above its mid height. Additional fingers develop upstream with a decreasing growth rate and an increasing width. This results from the decrease of the infiltration velocity with distance to the cliff in our models. A sensitivity study shows that a larger permeability contrast between the fingers and the initial undissolved porous medium produces a larger number of fingers, while increasing the dispersivity (lower Peclet number) produces wider fingers. A slower reaction rate (lower Damkhöler number) produces fingers that follow the initial flow lines, since dissolution occurs simultaneously along the entire finger. These results suggest that alteration by dissolution of limestones or other soluble formations may produce different underground channel structures in the same drainage basin due to local changes of the non-dimensional Pe and Da numbers.

In Situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures

2010 ◽  
Vol 645-648 ◽  
pp. 813-816 ◽  
Author(s):  
Keiko Kouda ◽  
Yasuto Hijikata ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida
Keyword(s):  
Growth Rate ◽  
Spectroscopic Ellipsometry ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Early Stage ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Low Oxygen ◽  
Partial Pressures

We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen　partial　pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface.

Stability of reaction-diffusion fronts

1994 ◽  
Vol 446 (1928) ◽  
pp. 517-528 ◽  
Keyword(s):  
Growth Rate ◽  
Diffusion Coefficient ◽  
Stability Analysis ◽  
Linear Stability Analysis ◽  
Reaction Rate ◽  
Reaction Diffusion ◽  
Two Dimensional ◽  
Isothermal Reaction ◽  
Analytic Expression ◽  
Cubic Autocatalysis

Horvath, Petrov, Scott and Showalter (1993) have shown that isothermal reaction-diffusion fronts with cubic autocalysis are linearly unstable to two-dimensional disturbances if the ratio, δ , of the diffusion coefficient of the reactant to that of the autocatalyst, is sufficiently large. However, they were only able to obtain an analytic expression for the growth rate by assuming an infinitely thin reaction zone, which is a poor approximation for cubic autocatalysis. We have carried out a linear stability analysis of such fronts with a finite reaction rate, and find that the critical δ for instability is unchanged, but the range of unstable wavenumbers is larger and increases rather than decreases with δ .

Microstructure and Property of 20CrMo Steel with the Process of Rare Earth Element Carburization

2011 ◽  
Vol 317-319 ◽  
pp. 479-483
Author(s):  
Dian Liang Wang ◽  
Ji Wu Li ◽  
Mei Peng Zhong
Keyword(s):  
Surface Layer ◽  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Diffusion Rate ◽  
Residual Austenite ◽  
Hardened Layer ◽  
Carburized Layer

The microstructures and properties of 20CrMo steel in rare earth catalysis and conventional carburization have been investigated by using the homemade rare earth energizer. The results show that the diffusion rate of carbon increases due to rare earth catalysis, so the time of carburizing decreases by about 30 %, and the martensite microstructures are refined on the surface layer. Also, the amount of residual austenite decreases obviously, and the hardness of the carburized layer is improved about HV150. At the same time, the depth of the hardened layer increased.

Analysis of Surface Layer Defects on Carburized Steel Component after Alkaline Blackening

2017 ◽  
Vol 891 ◽  
pp. 274-277
Author(s):  
Pavel Gejdoš ◽  
Lenka Klakurková ◽  
Martin Juliš ◽  
Miroslava Horynová ◽  
Michaela Remešová ◽  
...  
Keyword(s):  
Surface Layer ◽  
Surface Defects ◽  
Technological Parameters ◽  
Treatment Technology ◽  
Steel Component ◽  
Surface Corrosion ◽  
Carburized Steel ◽  
Matte Surface ◽  
Microstructure Of The Material

Alkaline blackening is one of the most popular surface treatment technology of components with the requirement for higher surface corrosion resistance, increased hardness, and the decorative appearance.This contribution deals with the appearance of surface defects on carburized steel components after the process of alkaline blackening, which appeared to be red shiny stains on an otherwise black matte surface of the component. The occurrence of defects on surface was observed several days after the alkaline blackening process. By means of metallographic methods, direct connection between surface defects and the microstructure of the material was found.Contribution further deals with the influence of microstructure and technological parameters on the quality of the final surface layer of the components.

Study on the Cutting Process for Remanufacture Deposited Materials

2014 ◽  
Vol 716-717 ◽  
pp. 200-203
Author(s):  
Zhi Yuan Wu ◽  
Kang Zhang ◽  
Xiu Jian Tang ◽  
Xin Li Tian ◽  
S.H. Wang
Keyword(s):  
Surface Layer ◽  
Cutting Tools ◽  
Cutting Process ◽  
Homogeneous Material ◽  
Dense Layer ◽  
Distinctive Features

. The systematic experiments for cutting remanufacture deposited materials have been finished. The results show that the deposited materials can be divided into two parts on the view of machining process:surface layer and dense layer. One of the distinctive features on surface layer is impacts to cutting tools in the process. And the process of dense layer cutting is similar with homogeneous material. On the basis of above, the paper puts forward the method which adopts different processing phases for deposited materials.

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