Characterization of the Time-Dependent Rheological Behavior of Fluids for Electronics Packaging

2003 ◽  
Author(s):  
X. B. Chen ◽  
W. J. Zhang ◽  
G. Schoenau ◽  
B. W. Surgenor
Keyword(s):  
Rheological Behavior ◽  
Flow Behavior ◽  
Electronics Packaging ◽  
Structural Theory ◽  
Time Dependent ◽  
Fluid Behavior ◽  
Proposed Model ◽  
Key Issues

To effectively control the dispensing process by which fluids are delivered onto substrates in electronics packaging, one of the key issues is to understand and characterize the flow behavior of the fluids being dispensed. However, this task has proven to be a demanding one as the fluids used for electronics packaging usually exhibit the time-dependent rheological behavior, which has not been well documented in the literature. In this paper, the characterization of time-dependent rheological behavior of fluids is studied. In particular, a model using the structural theory is proposed and applied to the characterization of the decay and recovery of fluid behavior, which are typically encountered in a dispensing process. Experiments are conducted to validate the proposed model.

Time-Dependent Rheological Behavior of Fluids For Electronics Packaging

2005 ◽  
Vol 127 (4) ◽  
pp. 370-374 ◽  
Author(s):  
X. B. Chen
Keyword(s):  
Rheological Behavior ◽  
Printed Circuit Boards ◽  
Flow Behavior ◽  
Electronics Packaging ◽  
Time Dependent ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Fluid Behavior ◽  
Surface Mounting

In electronics packaging, one of the key processes is dispensing fluid materials, such as adhesive, epoxy, encapsulant, onto substrates or printed circuit boards for the purpose of surface mounting or encapsulation. In order to precisely control the dispensing process, the understanding and characterization of the flow behavior of the fluid being dispensed is very important, as the behavior can have a significant influence on the dispensing process. However, this task has proven to be very challenging due to the fact that the fluids for electronics packaging usually exhibit the time-dependent rheological behavior, which has not been well defined in literature. In the paper a study on the characterization of the time-dependent rheological behavior of the fluids for electronics packaging is presented. In particular, a model is developed based on structural theory and then applied to the characterization of the decay and recovery of fluid behavior, which happen in the dispensing process due to the interruption of process. Experiments are carried out to verify the effectiveness of the model developed.

INFLUENCE OF SPACE HOLDER ON RHEOLOGICAL BEHAVIOR OF COPPER FEEDSTOCKS FOR METAL INJECTION MOLDING

2015 ◽  
Vol 76 (6) ◽  
Author(s):  
Mohammad Dahar Kamal Bahrin ◽  
Nor ‘Aini Wahab ◽  
Nor Amalina Nordin ◽  
Muhammad Hussain Ismail ◽  
Ismail Nasiruddin Ahmad
Keyword(s):  
Injection Molding ◽  
Rheological Behavior ◽  
Flow Behavior ◽  
Palm Stearin ◽  
Metal Injection Molding ◽  
Plastic Behavior ◽  
Flow Behavior Index ◽  
Space Holder ◽  
Porous Copper

The characterization of MIM feedstock consisting of 63 vol% of copper powder with a binder system consisting of palm stearin (PS) and low density polyethylene (LDPE) was studied. To achieve porous structure, sodium chloride (NaCl) was added as a space holder. The effect of shear rate (s-1), temperature (oC) and viscosity (Pa.s) on the rheological behavior of solid and porous copper feedstocks were investigated by using the Rosand RH2000 Capillary Rheometer at temperatures of 160, 170 and 180oC. The feedstocks achieved desirable injection molding characteristics such as pseudo-plastic behaviour, stable flow, flow behavior index less than 1 (n<1) and low activation energy (E). It can be concluded from the analysis that both feedstocks showed a good pseudo-plastic behavior within acceptable ranges in MIM. 

Rheological Behavior of Yttria Stabilized Zirconia (YSZ) Feedstock for Ceramic Injection Moulding (CIM) Process

2017 ◽  
Vol 882 ◽  
pp. 119-123
Author(s):  
Mahfuzah Zainudin ◽  
Muhammad Hussain Ismail
Keyword(s):  
Rheological Behavior ◽  
Injection Moulding ◽  
Flow Behavior ◽  
Palm Stearin ◽  
Stabilized Zirconia ◽  
Flow Behavior Index ◽  
Green Strength ◽  
Ceramic Injection Moulding ◽  
Behavior Index

The characterization of CIM feedstock consisting 58, 59, 60vol% of YSZ powder with binder system comprising a palm stearin (PS) and low density polyethylene (LDPE) were studied. The effects of powder loading and temperature (°C) on the rheological behavior of the YSZ were investigated by using Rosand RH2000 Capillary Rheometer. The results showed all the feedstock achieved desirable injection moulding characteristics such as pseudoplastic behavior, flow behavior index (n) less than 1 and low activation energy (E). The rectangular parts were successfully injected moulded at optimum temperature of 170°C with the highest green strength was 12.7 N, obtained from 60 vol% powder loading which correspond to greater density and low porosity of the samples.

Rheological and microstructural characterization of WPI-stabilized O/W emulsions exhibiting time-dependent flow behavior

LWT ◽  
2012 ◽  
Vol 46 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Pablo Bellalta ◽  
Elizabeth Troncoso ◽  
Rommy N. Zúñiga ◽  
José M. Aguilera
Keyword(s):  
Flow Behavior ◽  
Microstructural Characterization ◽  
Time Dependent ◽  
Dependent Flow

scholarly journals Effect of grasshopper (Sphenarium purpurascens Charpentier) paste addition on rheological behavior of Mole Poblano

2021 ◽  
Author(s):  
Eliza Guadalupe Arcos-Estrada ◽  
Mayra Díaz-Ramírez ◽  
Judith Jiménez-Guzmán ◽  
Erika Berenice León-Espinosa ◽  
Mariano García-Garibay ◽  
...  
Keyword(s):  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Design Methodology ◽  
Water Retention ◽  
Flow Behavior ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Emulsifying Capacity ◽  
Behavior Index

Objective: Analyze the effect of grasshopper (Sphenarium purpurascens Charpentier) paste addition on the rheological behavior of Mole Poblano (MP) and its relation with the technological properties of the grasshopper paste. Design/methodology/approach: The addition of grasshopper paste was done at different proportions as follows: T0= 0% of grasshopper paste (GP) and 100% of mole Poblano (MP); T10=10% GP and 90% MP; T15=15% GP and 85% MP, T20=20% GP and 80% MP, T25=25% GP and 75 % MP, T30=30% GP and 70% MP. Water retention and emulsifying capacity of grasshopper paste were evaluated. Density, kinematic and apparent viscosity, and rheological behavior were analyzed at 25ºC; rheological parameters (consistency index (k) and flow behavior index (n)) were calculated by performing a regression analysis to adjust the graphs to a power-law model. Findings/conclusion: Grasshopper paste had higher emulsifying capability than water retention capability.  Apparent viscosity of all formulations decreased as shear rate increased, so all mixtures of GP and MP demonstrated No-Newtonian behavior and pseudoplastic performance. Index consistency increased as GP content increased, these results are related with protein content because GP had a good emulsifying capability. Limitations on study/implications: More studies about the characterization of the proteins of GP and their interaction with other components are required.

scholarly journals Rheological Characterization of a Concentrated Phosphate Slurry

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 178
Author(s):  
Souhail Maazioui ◽  
Abderrahim Maazouz ◽  
Fayssal Benkhaldoun ◽  
Driss Ouazar ◽  
Khalid Lamnawar
Keyword(s):  
Flow Behavior ◽  
Continuous Phase ◽  
Raw Material ◽  
Rheological Characterization ◽  
Phosphate Ore ◽  
Insoluble Particles ◽  
Experimental Protocols ◽  
Solid Liquid

Phosphate ore slurry is a suspension of insoluble particles of phosphate rock, the primary raw material for fertilizer and phosphoric acid, in a continuous phase of water. This suspension has a non-Newtonian flow behavior and exhibits yield stress as the shear rate tends toward zero. The suspended particles in the present study were assumed to be noncolloidal. Various grades and phosphate ore concentrations were chosen for this rheological investigation. We created some experimental protocols to determine the main characteristics of these complex fluids and established relevant rheological models with a view to simulate the numerical flow in a cylindrical pipeline. Rheograms of these slurries were obtained using a rotational rheometer and were accurately modeled with commonly used yield-pseudoplastic models. The results show that the concentration of solids in a solid–liquid mixture could be increased while maintaining a desired apparent viscosity. Finally, the design equations for the laminar pipe flow of yield pseudoplastics were investigated to highlight the role of rheological studies in this context.

scholarly journals Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 35 ◽  
Author(s):  
Anshul Sharma ◽  
Irvine Lian Hao Ong ◽  
Anupam Sengupta
Keyword(s):  
Phase Transition ◽  
Aspect Ratio ◽  
Temporal Dynamics ◽  
Initial Conditions ◽  
Flow Behavior ◽  
Medical Diagnostics ◽  
Time Dependent ◽  
Disodium Cromoglycate ◽  
M Phase ◽  
Static Conditions

Nematic and columnar phases of lyotropic chromonic liquid crystals (LCLCs) have been long studied for their fundamental and applied prospects in material science and medical diagnostics. LCLC phases represent different self-assembled states of disc-shaped molecules, held together by noncovalent interactions that lead to highly sensitive concentration and temperature dependent properties. Yet, microscale insights into confined LCLCs, specifically in the context of confinement geometry and surface properties, are lacking. Here, we report the emergence of time dependent textures in static disodium cromoglycate (DSCG) solutions, confined in PDMS-based microfluidic devices. We use a combination of soft lithography, surface characterization, and polarized optical imaging to generate and analyze the confinement-induced LCLC textures and demonstrate that over time, herringbone and spherulite textures emerge due to spontaneous nematic (N) to columnar M-phase transition, propagating from the LCLC-PDMS interface into the LCLC bulk. By varying the confinement geometry, anchoring conditions, and the initial DSCG concentration, we can systematically tune the temporal dynamics of the N- to M-phase transition and textural behavior of the confined LCLC. Overall, the time taken to change from nematic to the characteristic M-phase textures decreased as the confinement aspect ratio (width/depth) increased. For a given aspect ratio, the transition to the M-phase was generally faster in degenerate planar confinements, relative to the transition in homeotropic confinements. Since the static molecular states register the initial conditions for LC flows, the time dependent textures reported here suggest that the surface and confinement effects—even under static conditions—could be central in understanding the flow behavior of LCLCs and the associated transport properties of this versatile material.

The Constitutive Model for High Temperature Flow Behavior of SiC/6168Al Composite

2015 ◽  
Vol 1089 ◽  
pp. 37-41
Author(s):  
Jiang Wang ◽  
Sheng Li Guo ◽  
Sheng Pu Liu ◽  
Cheng Liu ◽  
Qi Fei Zheng
Keyword(s):  
Constitutive Model ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Type Equation ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Stress Strain ◽  
Hollomon Parameter ◽  
Proposed Model ◽  
Relationship Of

The hot deformation behavior of SiC/6168Al composite was studied by means of hot compression tests in the temperature range of 300-450 °C and strain rate range of 0.01-10 s-1. The constitutive model was developed to predict the stress-strain curves of this composite during hot deformation. This model was established by considering the effect of the strain on material constants calculated by using the Zenter-Hollomon parameter in the hyperbolic Arrhenius-type equation. It was found that the relationship of n, α, Q, lnA and ε could be expressed by a five-order polynomial. The stress-strain curves obtained by this model showed a good agreement with experimental results. The proposed model can accurately describe the hot flow behavior of SiC/6168Al composite, and can be used to numerically analyze the hot forming processes.

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