• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.102-110
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• 2001

In this paper, methods to analyze wire sweep and paddle shift during the semiconductor ship-encapsulation process have been studied. The analysis of wire sweep includes flow-field analysis in a complicated geometry, drag-force calculation for given flow of fluid, and wire-deformation calculation for given loads. The paddle-shift analysis is used to analyze the deformation of the paddle due to the pressure difference in two cavities. the analysis is done using either analytical solutions or numerical simulation. The analytical solution is used for rough but fast calculation of wire sweep. The numerical solution is used for more accurate calculation of wire-sweep. The numerical results of wire sweep show good agreements with the experimental ones.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.17-22
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• 2000

In this paper, methods to analyze wire sweep during the semiconductor chip encapsulation have been studied. The wire sweep analysis is used to analyze the deformation of bonding wires that connect the chip to the leadframe during encapsulation. The analysis is done using either analytical solutions or numerical simulation. The analytical solution is used for rough but fast calculation of wire sweep. The results from the numerical simulation are closest to the experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.13-21
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• 1996

In this paper, methods to reduce wire sweep during the chip-encapsulation process have been studide. Two methods have been tried for this purpose, namely runner balancing and ram velocity control. Runner balancing has been achieved automatically by using a computer program. Ram-velocity control has been achieved using empirical rules and results from a flow simulation of the encapsulation process. A mold which has 12 cavities for chip has been used as a case study. The simulation results show that the wire sweep obtained from the optimal process condition is about 1/5 of that from initial, unoptimized condition.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.10a
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• pp.64-67
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• 1995

Transfer Molding is currently the most widely used process for encapsulation integrated circuits(;IC). Although the process has been introduced over 20 years ago, generating billions of parts each year, it is far from being optimized. With each new mold, epoxy mold, epoxy mold compound, and lead-frame, lengthy period and expensive qualification runs have to be performed to minimized defects ranging from wire sweep, incomplete fill, and internal voids etc. This studies describes how simulation can be applied to transfer molding to yield acceptable design and processing parameter. The non-isothermal filling of non-newtonian reactive epoxy molding compound(;EMC) in a multi-cavity mold is analyzed. Sensitivity analysis is conducted to investigate the influence of process deviations on the final molded profile. This study trend is carried out by following some heuristic process guidelines.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.17-20
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• 2003

The EMC's rheological effects on molding process are evaluated in this study. When considering mold processing for IC packages, the major concerning items in current studies are incomplete fill, severe wire sweeping and paddle shifts etc. To simulate EMC's fast curing rheokinetics with 3D mold flow behavior, one should select appropriate rheometry which characterize each EMC's rheological motion and finding empirical parameters for numerical analysis current studies present the new rheometry with parallel plate rheometry for reactive rheokinetic experiments, the experiment and numerical analysis is done with the commercial higher filler loaded EMC for the case of Thin Quad Plant Packages (TQFP) with package thickness below 1.0 mm. The experimental results and simulation results based on new rheometry matches well in point of the prediction of wire sweep, filling behavior of melt front advancement and void trapping position.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.99-106
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• 1998

In this paper, we have constructed an expert system for semiconductor chip encapsulation which combines a knowledge-based system with CAE software. The knowledge-base module includes heuristic and pre analysis knowledge for evaluation and redesign. Evaluation of the initial design and generation of redesign recommendations can be developed from the rules as applied to a given chip package. The CAE programs can be used for simulating the filling and packing stage of encapsulation process. The expert system is a new tool which enables package design or process conditions with high yields and high productivity.

• Journal of Biosystems Engineering
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• v.27 no.5
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• pp.391-398
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• 2002

During handling unitized products, they are subjected to a variety of environmental hazards. Shock and vibration hazards are generally considered the most damaging of the environmental hazards on a product and it may encounter while passing through the distribution environment. A major cause of shock damage to products is drops during manual handling. The increasing use of unitization of pallets has been resulted in a reduction of the shock hazards. This has caused an increasing interest in research focused on vibration caused dam age. Damage to the product by the vibration most often occurs when a product or a product component has a natural frequency that falls within the range of the forcing frequencies of the particular mode of transportation being used. Transportation vibration is also a major cause of fruit and vegetable quality loss due to mechanical damage. This study was conducted to determine the vibration characteristics of the corrugated fiberboard bones for packages of pears, and to investigate the degree of vibration injury of the pears in the boxes during the simulated transportation environment. The vibration tests were performed on an electrohydraulic vibration exciter. The input acceleration to exciter was fixed at 0.25 G for a single container resonance test and 0.5 G for the vertical stacked container over the frequency range from 3 to 100 Hz. Function generator (HP-33120A) was connected by wire to the vibration exciter for controlling the input acceleration at a continuous logarithmic sweep rate of 1.0 octave per min. The peak frequency and acceleration on the single box test were 22.02 Hz, 1.5425 G respectively, and these values on the vertical stacked boxes were observed from the bottom box 19.02, 18.14, 16.62 and 15.40 Hz and 2.2987, 3.7654. 5.6087, and 7.9582 G, respectively. The pear in the bottom box had a slightly higher damage level than the fruit packed in the other stacked boxes. It is desirable that the package and transportation system has to be so designed that 15∼20 Hz frequency will not occur during the transportation environment.

• Progress in Superconductivity and Cryogenics
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• v.22 no.1
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• pp.12-16
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• 2020

As high homogeneity in magnetic field is required to increase the resolution of MRI magnets, various shimming methods have been researched. Using one of them, the design of the superconducting active zonal shim coil for MRI magnets is discussed in this paper. The magnetic field of the MRI magnet is expressed as the sum of spherical harmonic terms, and the optimized current density of shim coils capable of removing higher-order terms is calculated by the Tikhonov regularization method. To investigate all potential designs derived from calculated current density, 4 sweeping parameters are selected: (1) axial length of shim coil zone; (2) radius of shim coils; (3) exact axial position of shim coils; and (4) operating current. After adequate designs are determined with constraints of critical current margin and homogeneity criterion, the total wire length required for each is calculated and the design with a minimum of them is chosen. Using the superconducting wire length of 9.77 km, the field homogeneity over 50 cm DSV is improved from 24 ppm to 1.87 ppm in the case study for 9.4 T whole-body MRI shimming. Finally, the results are compared with the finite element method (FEM) simulation results to validate the feasibility and accuracy of the design.