Topology Optimization on Targeting Frequency and Mode of Ultrasonic Bonding Tool for Microchip Packaging

2011 ◽  
Author(s):  
Chang Yong Ha ◽  
Soo Il Lee
Keyword(s):  
Topology Optimization ◽  
Flip Chip ◽  
Longitudinal Mode ◽  
Practical Aspect ◽  
Laser Vibrometer ◽  
Modal Assurance Criterion ◽  
Semiconductor Chip ◽  
Ultrasonic Bonding ◽  
2D And 3D ◽  
Microsystem Packaging

Ultrasonic flip chip bonding is one of the widely used methods in semiconductor chip or microsystem packaging and ultrasonic (US) bonding tool is important part for the bonding machine. To perform the proper operation of US bonding, the adequate vibration frequency and mode of US tool is required and the vibration design of the tool is very important. Until recent days, however, the most of practical aspect of the tool design follows the trial-and-error approach. In this study, we introduce the method of topology optimization for US bonding tools. The solid isotropic material with penalization (SIMP) method is used to formulate topology optimization and optimal criteria (OC) method is introduced for the update scheme. The objective resonance frequency and longitudinal mode is tracked using Modal Assurance Criterion (MAC). We compare between 2D and 3D finite element models, and realize two types of US tools which are based on 3D optimization results. To ensure the validity of topology optimization applied to the high frequency and tough devices such as US bonding tools, the vibration displacements at anti-nodal points of the optimized US tools are measured by laser vibrometer.

Research on Evolutionary Topology Optimization in ANSYS

2013 ◽  
Vol 572 ◽  
pp. 547-550 ◽  
Author(s):  
Dong Yan Shi ◽  
Jia Shan Han ◽  
Ling Cheng Kong ◽  
Lin Lin
Keyword(s):  
Topology Optimization ◽  
Optimization Method ◽  
Secondary Development ◽  
Filter Method ◽  
Ansys Software ◽  
Evolutionary Structural Optimization ◽  
Elemental Sensitivity ◽  
Beso Method ◽  
Optimization Function ◽  
2D And 3D

Topology optimization function in ANSYS software is inefficient with the limitation of element types. By using the secondary developing language APDL and UIDL, the secondary development of bi-directional evolutionary structural optimization (BESO) method with volume constraint and stiffness maximization is completed in ANSYS. To suppress the checkerboard patterns, the elemental sensitivity numbers are recalculated by a filter method. To ensure the convergence of the optimization method in ANSYS, the elemental sensitivity numbers are updated by adding in their historical information. Two classic numerical examples are calculated to obtain the best topology structure. The numerical results indicate that the secondary method can solve the 2D and 3D problems effectively, which makes up for the deficiency of topology optimization part in ANSYS and broadens the application scope of the evolutionary optimization method.

scholarly journals Level set band method: A combination of density-based and level set methods for the topology optimization of continuums

2020 ◽  
Vol 15 (3) ◽  
pp. 390-405
Author(s):  
Peng Wei ◽  
Wenwen Wang ◽  
Yang Yang ◽  
Michael Yu Wang
Keyword(s):  
Topology Optimization ◽  
Level Set ◽  
Level Set Methods ◽  
Boundary Representation ◽  
Structural Topology ◽  
Topology Changes ◽  
Practical Engineering ◽  
Band Method ◽  
2D And 3D ◽  
Level Set Framework

Abstract The level set method (LSM), which is transplanted from the computer graphics field, has been successfully introduced into the structural topology optimization field for about two decades, but it still has not been widely applied to practical engineering problems as density-based methods do. One of the reasons is that it acts as a boundary evolution algorithm, which is not as flexible as density-based methods at controlling topology changes. In this study, a level set band method is proposed to overcome this drawback in handling topology changes in the level set framework. This scheme is proposed to improve the continuity of objective and constraint functions by incorporating one parameter, namely, level set band, to seamlessly combine LSM and density-based method to utilize their advantages. The proposed method demonstrates a flexible topology change by applying a certain size of the level set band and can converge to a clear boundary representation methodology. The method is easy to implement for improving existing LSMs and does not require the introduction of penalization or filtering factors that are prone to numerical issues. Several 2D and 3D numerical examples of compliance minimization problems are studied to illustrate the effects of the proposed method.

Mechanism and Model of Bond Formation in Ultrasonic Wire Bonding

2015 ◽  
Author(s):  
T. Calvin Tszeng
Keyword(s):  
Flip Chip ◽  
Critical Phenomenon ◽  
Bond Formation ◽  
Interfacial Shear Stress ◽  
Wire Bonding ◽  
Micromechanics Model ◽  
Ultrasonic Bonding ◽  
Microelectronic Devices ◽  
Ultrasonic Wire Bonding ◽  
Technological Significance

Despite being a critical phenomenon of tremendous technological significance in ultrasonic flip-chip and wire bonding processes of today’s microelectronic devices, interfacial bond formation still calls for better understanding at a fundamental level. The goal of the research is to improve these processes through better understanding and modeling of bond formation. This paper presents a micromechanics model that addresses increasing contact area during ultrasonic cyclic loading cycle. The micromechanics model provides interfacial shear stress as boundary condition to FEM simulations of ultrasonic bonding processes. Comparison between preliminary results and experimental data is conducted.

Topology Optimization for Design of Origami-Based Active Mechanisms

2014 ◽  
Author(s):  
Kazuko Fuchi ◽  
Philip R. Buskohl ◽  
James J. Joo ◽  
Gregory W. Reich ◽  
Richard A. Vaia
Keyword(s):  
Topology Optimization ◽  
Mechanism Design ◽  
Design Method ◽  
Truss Structures ◽  
Systematic Design ◽  
Design Strategies ◽  
Foldable Structures ◽  
And Performance ◽  
2D And 3D ◽  
Additional Constraints

Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form of the structure and show potential for many engineering applications. However, the enormity of the design space and the complex relationship between origami-based geometries and engineering metrics place a severe limitation on design strategies based on intuition. The presented work proposes a systematic design method using topology optimization to distribute foldline properties within a reference crease pattern, adding or removing folds through optimization, for a mechanism design. Following the work of Schenk and Guest, foldable structures are modeled as pin-joint truss structures with additional constraints on fold, or dihedral, angles. The performance of a designed origami mechanism is evaluated in 3D by applying prescribed forces and finding displacements at set locations. The integration of the concept of origami in mechanism design thus allows for the description of designs in 2D and performance in 3D. Numerical examples indicate that origami mechanisms with desired deformations can be obtained using the proposed method. A constraint on the number of foldlines is used to simplify a design.

A Study on Basis Functions of the Parameterized Level Set Method for Topology Optimization of Continuums

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Peng Wei ◽  
Yang Yang ◽  
Shikui Chen ◽  
Michael Yu Wang
Keyword(s):  
Topology Optimization ◽  
Radial Basis Functions ◽  
Level Set Method ◽  
Level Set ◽  
Computational Efficiency ◽  
Basis Functions ◽  
The Finite Element Method ◽  
Radial Basis ◽  
Commercial Applications ◽  
2D And 3D

Abstract In recent years, the parameterized level set method (PLSM), which rests on radial basis functions in most early work, has gained growing attention in structural optimization. However, little work has been carried out to investigate the effect of the basis functions in the parameterized level set method. This paper examines the basis functions of the parameterized level set method, including radial basis functions, B-spline functions, and shape functions in the finite element method (FEM) for topology optimization of continuums. The effects of different basis functions in the PLSM are examined by analyzing and comparing the required storage, convergence speed, computational efficiency, and optimization results, with the benchmark minimum compliance problems subject to a volume constraint. The linear basis functions show relatively satisfactory overall performance. Besides, several schemes to boost computational efficiency are proposed. The study on examples with unstructured 2D and 3D meshes can also be considered as a tentative investigation of prospective possible commercial applications of this method.

Laddered-UBM Structure: Bump Reliability Improvement through Distribution of Load Concentration Points

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 001827-001839
Author(s):  
Roden Topacio
Keyword(s):  
Load Distribution ◽  
Flip Chip ◽  
Solder Bump ◽  
Dielectric Film ◽  
Coefficient Of Thermal Expansion ◽  
Circuit Board ◽  
Bending Moments ◽  
Semiconductor Chip ◽  
Semiconductor Chips ◽  
Solidification Stage

Flip-chip mounting schemes have been used for decades to mount semiconductor chips to substrates. In flip-chip process, a solder bump is metallurgically bonded to the under-bump-metallurgy, also known as UBM, on a given pad of the semiconductor chip and a pre-solder is metallurgically bonded to a corresponding pad of the substrate. Thereafter the solder bump and the pre-solder are brought into proximity and metallurgically bonded using reflow. Flip-chip solder joints are subjected to mechanical stresses from a variety of sources, such as coefficient of thermal expansion mismatches, ductility differences and circuit board warping. Such stresses can subject the conventional UBM structure to bending moments specially during the flip-chip reflow solder solidification stage where the bump is still unprotected by the underfill. The effect is somewhat directional in that the stresses tend to be greatest nearer the die edges and corners and fall off with increasing proximity to the die center. The bending moments associated with this so-called edge effect can impose stresses on the dielectric film beneath the UBM structure that, if large enough, can produce fracture. This paper will discuss the load distribution on a conventional UBM structure due to the bending moments and how the Laddered-UBM structure attempts to overcome or reduce the effects of these bending moments. Contrary to conventional methods where stress concentration points are eliminated, the Laddered-UBM is designed to strategically increase the number of load concentration points along the UBM structure. With the increased number of load concentration points, the stress along the UBM is distributed more evenly which effectively reduces the stress at any given point thus preventing a single large enough stress to cause dielectric fracture. Theoretical analysis and experimental data including reliability results on both the conventional UBM structure and the Laddered-UBM structure will be presented and discussed in this paper.

Ultrasonic Bonding Using Anisotropic Conductive Films (ACFs) for Flip Chip Interconnection

2009 ◽  
Vol 32 (4) ◽  
pp. 241-247 ◽  
Author(s):  
Kiwon Lee ◽  
Hyoung-Joon Kim ◽  
Myung-Jin Yim ◽  
Kyung-Wook Paik
Keyword(s):  
Flip Chip ◽  
Conductive Films ◽  
Ultrasonic Bonding
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