The Experts below are selected from a list of 53349 Experts worldwide ranked by ideXlab platform
Hamed Mirzadeh - One of the best experts on this subject based on the ideXlab platform.
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hot deformation and dynamic recrystallization of niti intermetallic compound
Journal of Alloys and Compounds, 2014Co-Authors: Hamed Mirzadeh, M H ParsaAbstract:Abstract The hot deformation behavior of a binary nitinol alloy with chemical composition of 50.5 at.% Ni–49.5 at.% Ti was studied using the hot Compression Flow curves corresponding to the temperature range of 700–1000 °C under strain rate of 0.1 s −1 . The typical single-peak dynamic recrystallization (DRX) behavior was seen in the resultant Flow curves. The strain hardening rate analysis was used to reveal if DRX occurred. The effect of the Zener–Hollomon parameter ( Z ) on the characteristic points of Flow curves was studied using the power law relations. The normalized critical stress and strain for initiation of DRX were respectively found to be 0.98 and 0.73. A power law constitutive equation, which relates the peak stress to Z with a Z exponent of 0.15, was proposed to characterize the hot working response of the investigated material.
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hot deformation behavior of a medium carbon microalloyed steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: J M Cabrera, Hamed Mirzadeh, J M Prado, A NajafizadehAbstract:Abstract The hot deformation behavior of a medium carbon microalloyed steel was studied using the hot Compression Flow curves corresponding to the temperature range of 850–1150 °C under strain rates from 0.0001 to 3 s −1 . A step-by-step procedure for data analysis in hot deformation was also given. The work hardening rate versus stress curves were used to reveal if dynamic recrystallization (DRX) occurred. The application of constitutive equations to determine the hot working constants of this material was critically discussed. Furthermore, the effect of Zener–Hollomon parameter ( Z ) on the characteristic points of Flow curves was studied using the power law relation. The deformation activation energy of this steel was determined as 394 kJ/mol and the normalized critical stress and strain for initiation of DRX were found to be 0.89 and 0.62, respectively. Some behaviors were also compared to other steels.
Nathan W. Pascarella - One of the best experts on this subject based on the ideXlab platform.
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Compression Flow modeling of underfill encapsulants for low cost flip chip assembly
Electronic Components and Technology Conference, 1998Co-Authors: Nathan W. Pascarella, Daniel F AldwiAbstract:Flip-chip technology represents a rapidly advancing area in commercial electronics. Flip-chip on board (FCOB) technology also called direct chip attach (DCA) involves the direct interconnection of integrated circuits to low cost organic substrates. In order to ensure adequate reliability, these flip-chip assemblies undergo an underfill encapsulation process in which a polymer material is placed between the chip and the substrate. Conventional underfill processing is achieved through chip site to chip site dispensing and underfill Flow via capillary action, making it a costly and time consuming process particularly as device sizes increase and standoff gaps decrease. Extensive cost modeling of conventional flip-chip process technology has shown underfill processing, cleaning, and electroplating solder bumps and substrates to be the major cost driving factors. As part of the Low Cost Next Generation Flip-Chip Processing Program, an advanced flip-chip assembly process is being developed. This process eliminates the need for time consuming capillary Flow processing using a Compression Flow technique where the underfill is applied prior to chip placement. The innovative process integrates the chip placement and polymer underfill processes using a Compression or squeeze Flow technique. It results in significantly lower assembly costs and reduced cycle time. In general, the Compression Flow of the underfill material governs assembly yield and reliability. This paper focuses on Flow simulation studies of the Compression Flow chip placement process. It represents a fundamental advancement in Compression Flow simulation of polymers in its successful application to the complex geometries and surface topologies demanded by miniaturized flip-chip assembly. Here a simulation methodology is developed and simulation studies are conducted to characterize the Compression Flow of the underfill, estimate required chip placement forces, evaluate the effect of underfill geometry, and assess the potential formation of voids. Results yield design guidelines that give insight into process parameters such as the limits on underfill deposition geometry and underfill viscosity, and provided an initial process window.
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Compression Flow modeling of underfill encapsulants for low cost flip chip assembly
International Symposium on Advanced Packaging Materials. Processes Properties and Interfaces, 1998Co-Authors: Nathan W. Pascarella, Daniel F AldwiAbstract:Currently, underfill dispense processing is achieved through capillary action, making it a costly and time consuming process particularly as device size increases and standoff gaps decrease. As part of the Low Cost Next Generation Flip Chip Processing Program at Georgia Tech, an advanced flip chip assembly process is being developed. This process eliminates the need for time consuming capillary Flow processing, and integrates the simultaneous reFlow and cure of the solder interconnect and polymer underfill. The advanced process results in a significantly lower assembly cost combined with reduced throughput time. Reduced throughput time and cost are achieved through the Compression Flow of the underfill material. Since the Flow of the material governs assembly yield and reliability, this work focused on Flow simulation studies of the placement process. Here a simulation methodology and simulation studies were conducted to characterize the Compression Flow of the underfill and predict void formation. Results yielded design guidelines that gave insight into process parameters such as the limits on underfill deposition geometry and underfill viscosity. The results indicated the initial limits of an overall process window for Compression Flow chip placement.
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MANUFACTURING ANALYSIS OF UNDERFILL PROCESSING FOR LOW-COST FLIP CHIP ASSEMBLY
Journal of Electronics Manufacturing, 1998Co-Authors: Daniel F. Baldwin, Nathan W. PascarellaAbstract:Advanced electronics assembly based on direct attachment of semiconductor devices to printed circuit boards is a rapidly growing technology. Direct chip attach (DCA) or flip chip on board (FCOB) processing typically requires the application of underfill materials in order to achieve adequate reliability for commercial electronic applications. Unfortunately, flip chip on board processing has yet to become a low-cost, high-throughput process compatible with high-volume electronics packaging and high-volume surface mount processing. In order for FCOB processing to be high volume, electronics packaging and SMT-compatible, innovative techniques for underfill processing are required. This paper analyzes underfill processing in order to assess manufacturablity in terms of productivity and cost. In particular, four techniques for underfill processing are analyzed, including capillary Flow, vacuum-assisted capillary Flow injection Flow, and Compression Flow processing.
Daniel F Aldwi - One of the best experts on this subject based on the ideXlab platform.
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Compression Flow modeling of underfill encapsulants for low cost flip chip assembly
Electronic Components and Technology Conference, 1998Co-Authors: Nathan W. Pascarella, Daniel F AldwiAbstract:Flip-chip technology represents a rapidly advancing area in commercial electronics. Flip-chip on board (FCOB) technology also called direct chip attach (DCA) involves the direct interconnection of integrated circuits to low cost organic substrates. In order to ensure adequate reliability, these flip-chip assemblies undergo an underfill encapsulation process in which a polymer material is placed between the chip and the substrate. Conventional underfill processing is achieved through chip site to chip site dispensing and underfill Flow via capillary action, making it a costly and time consuming process particularly as device sizes increase and standoff gaps decrease. Extensive cost modeling of conventional flip-chip process technology has shown underfill processing, cleaning, and electroplating solder bumps and substrates to be the major cost driving factors. As part of the Low Cost Next Generation Flip-Chip Processing Program, an advanced flip-chip assembly process is being developed. This process eliminates the need for time consuming capillary Flow processing using a Compression Flow technique where the underfill is applied prior to chip placement. The innovative process integrates the chip placement and polymer underfill processes using a Compression or squeeze Flow technique. It results in significantly lower assembly costs and reduced cycle time. In general, the Compression Flow of the underfill material governs assembly yield and reliability. This paper focuses on Flow simulation studies of the Compression Flow chip placement process. It represents a fundamental advancement in Compression Flow simulation of polymers in its successful application to the complex geometries and surface topologies demanded by miniaturized flip-chip assembly. Here a simulation methodology is developed and simulation studies are conducted to characterize the Compression Flow of the underfill, estimate required chip placement forces, evaluate the effect of underfill geometry, and assess the potential formation of voids. Results yield design guidelines that give insight into process parameters such as the limits on underfill deposition geometry and underfill viscosity, and provided an initial process window.
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Compression Flow modeling of underfill encapsulants for low cost flip chip assembly
International Symposium on Advanced Packaging Materials. Processes Properties and Interfaces, 1998Co-Authors: Nathan W. Pascarella, Daniel F AldwiAbstract:Currently, underfill dispense processing is achieved through capillary action, making it a costly and time consuming process particularly as device size increases and standoff gaps decrease. As part of the Low Cost Next Generation Flip Chip Processing Program at Georgia Tech, an advanced flip chip assembly process is being developed. This process eliminates the need for time consuming capillary Flow processing, and integrates the simultaneous reFlow and cure of the solder interconnect and polymer underfill. The advanced process results in a significantly lower assembly cost combined with reduced throughput time. Reduced throughput time and cost are achieved through the Compression Flow of the underfill material. Since the Flow of the material governs assembly yield and reliability, this work focused on Flow simulation studies of the placement process. Here a simulation methodology and simulation studies were conducted to characterize the Compression Flow of the underfill and predict void formation. Results yielded design guidelines that gave insight into process parameters such as the limits on underfill deposition geometry and underfill viscosity. The results indicated the initial limits of an overall process window for Compression Flow chip placement.
Behzad Fallah - One of the best experts on this subject based on the ideXlab platform.
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prediction of hot Compression Flow curves of ti 6al 4v alloy in α β phase region
Materials & Design, 2011Co-Authors: Mohammad Amin Shafaat, Hamid Omidvar, Behzad FallahAbstract:Abstract Prediction of material Flow behavior is essential for designing the forming process of any material. In this research, experimental Flow curves of Ti–6Al–4 V alloy were obtained using the isothermal hot Compression test done at 750–950 °C with 50 °C intervals and constant strain rates of 0.001, 0.005 and 0.01 s−1. For prediction of hot deformation Flow curves two methods of modeling were applied. In the first method, an entire Flow curve was modeled using Sellars equation. In the second one, modeling of a Flow curve up to the peak point was carried out with Cingara model, and modeling beyond that was performed with a model developed based on the Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. The accuracy of each model was examined through a statistical method. Results showed that Flow curve modeling using Cingara model and JMAK theory leads to results that are more consistent with the experimental data.
M H Parsa - One of the best experts on this subject based on the ideXlab platform.
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hot deformation and dynamic recrystallization of niti intermetallic compound
Journal of Alloys and Compounds, 2014Co-Authors: Hamed Mirzadeh, M H ParsaAbstract:Abstract The hot deformation behavior of a binary nitinol alloy with chemical composition of 50.5 at.% Ni–49.5 at.% Ti was studied using the hot Compression Flow curves corresponding to the temperature range of 700–1000 °C under strain rate of 0.1 s −1 . The typical single-peak dynamic recrystallization (DRX) behavior was seen in the resultant Flow curves. The strain hardening rate analysis was used to reveal if DRX occurred. The effect of the Zener–Hollomon parameter ( Z ) on the characteristic points of Flow curves was studied using the power law relations. The normalized critical stress and strain for initiation of DRX were respectively found to be 0.98 and 0.73. A power law constitutive equation, which relates the peak stress to Z with a Z exponent of 0.15, was proposed to characterize the hot working response of the investigated material.