Microvia Formation for Multi-Layer PWB by Laser Direct Drilling: Improvement of Hole Quality by Silica Fillers in Build-Up Layer

2011 ◽  
Author(s):  
Keiji Ogawa ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Kuniyoshi Obata ◽  
Tsukasa Ayuzawa
Keyword(s):  
Copper Foil ◽  
Fem Analysis ◽  
Printed Wiring Boards ◽  
The Finite Element Method ◽  
Silica Filler ◽  
Silica Fillers ◽  
Via Holes ◽  
Overhang Length ◽  
Novel Method ◽  
Direct Drilling

Microvia formation technology using lasers has become the dominant method for drilling microvia called blind via-holes (BVHs) in printed wiring boards (PWBs). Laser direct drilling (LDD), drilling directly outer copper foil by laser, has attracted attention as a novel method. In particular, when copper and resin with different processing thresholds are drilled at the same time, an overhang defect occurs on the drilled hole. However, the overhang generation mechanism has not been clarified. Therefore, we investigated it by detailed observation of the drilled-hole section. Moreover, the overhang length was estimated using the finite element method (FEM). Influences of surface treatment of outer copper foil and thermal properties of the build-up layer were evaluated experimentally and analytically. Consequently, an experiment with a prototype PWB with silica filler added in the build-up layer was carried out. Using the prototype PWBs, the overhang was reduced as shown in FEM analysis results.

Cu-Direct Laser Drilling of Blind Via-Hole in Multi-Layer PWBs: Influence of Surface Treatment on Drilled Hole Quality

2009 ◽  
Author(s):  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa ◽  
Tsukasa Ayuzawa
Keyword(s):  
Surface Treatment ◽  
Co2 Laser ◽  
Copper Foil ◽  
Laser Energy ◽  
Copper Surface ◽  
Laser Drilling ◽  
Hole Quality ◽  
Direct Laser ◽  
Overhang Length ◽  
Direct Drilling

This report describes the quality assessment of Blind Via Holes (BVHs) of Printed Wiring Boards (PWBs) drilled by a CO2 laser using Cu-direct drilling. In the Cu-direct drilling method, the copper foil and the build-up layer are melted at the same time, and the surface is treated to increase the laser energy absorbed by the copper foil since an untreated copper surface reflects most of the 10.6-μm-wavelength CO2 laser beam. However, there are few reports dealing with Cu-direct laser drilling of PWBs. In addition, when copper and resin with different processing thresholds are drilled at the same time, occurrences of a defect called overhang have been observed. So, in this report, first we propose a new method using thermography to measure the absorptance of a PWB surface for a CO2 laser. Moreover, we investigate how surface treatment of the outer copper foil influences the quality of a laser-drilled hole. Then, we observe the circumference of a point irradiated with the CO2 laser and explain how melting processes are different from surface treatment. Finally, based on the research we establish a method in order to cut down the overhang length as a parameter of drilled-hole quality. We also show that a high absorptance improves BVH quality.

Microvia Formation for Multi-Layer PWB by Laser Direct Drilling: Improvement of Drilled Hole Quality of GFRP Plates

2012 ◽  
Author(s):  
Keiji Ogawa ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Tsukasa Ayuzawa
Keyword(s):  
High Speed ◽  
Fiber Reinforced ◽  
Hole Quality ◽  
Reinforced Plastics ◽  
Glass Fiber Reinforced ◽  
Via Holes ◽  
Overhang Length ◽  
Fiber Reinforced Plastics ◽  
Direct Drilling

Microvia formation technology using lasers has become the dominant method for drilling microvia that are called blind via-holes (BVHs) in printed wiring boards (PWBs). Laser direct drilling (LDD), which is direct drilling of the outer copper foil by laser, has attracted attention as a novel method. In particular, when copper and resin with different processing thresholds are simultaneously drilled, an overhang defect occurs on the drilled hole. On the other hand, aramid fiber reinforced plastics (AFRP) have been replaced by glass fiber reinforced plastics (GFRP) as the material used for the build-up layer because of its cost performance. Moreover, the PWB quality of the particle incrustations around the drilled holes has problems in the manufacturing process. However, the LDD process of such a composite has not been clarified. Therefore, we investigated it by detailed observation using a high-speed camera. We estimated the overhang length using the finite element method (FEM) and experimentally and analytically evaluated the effects of filler contented build-up layers. As a result, we improved drilled-hole quality by using prototype PWBs made of GFRP with filler in the build-up layer.

scholarly journals A Metawindow with Optimised Acoustic and Ventilation Performance

2021 ◽  
Vol 11 (7) ◽  
pp. 3168
Author(s):  
Gioia Fusaro ◽  
Xiang Yu ◽  
Zhenbo Lu ◽  
Fangsen Cui ◽  
Jian Kang
Keyword(s):  
Natural Ventilation ◽  
Noise Control ◽  
Fem Analysis ◽  
The Finite Element Method ◽  
Noise Mitigation ◽  
Acoustic Performance ◽  
Potential Applications ◽  
Ventilation Performance ◽  
Sound Reduction ◽  
Window Design

Crucial factors in window performance, such as natural ventilation and noise control, are generally conceived separately, forcing users to choose one over the other. To solve this dualism, this study aimed to develop an acoustic metamaterial (AMM) ergonomic window design to allow noise control without dependence on the natural ventilation duration and vice versa. First, the finite element method (FEM) was used to investigate the noise control performance of the acoustic metawindow (AMW) unit, followed by anechoic chamber testing, which also served as the validation of the FEM models. Furthermore, FEM analysis was used to optimise the acoustic performance and assess the ventilation potential. The numerical and experimental results exhibited an overall mean sound reduction of 15 dB within a bandwidth of 380 to 5000 Hz. A good agreement between the measured and numerical results was obtained, with a mean variation of 30%. Therefore, the AMW unit optimised acoustic performance, resulting in a higher noise reduction, especially from 50 to 500 Hz. Finally, most of the AMW unit configurations are suitable for natural ventilation, and a dynamic tuned ventilation capacity can be achieved for particular ranges by adjusting the window’s ventilation opening. The proposed designs have potential applications in building acoustics and engineering where natural ventilation and noise mitigation are required to meet regulations simultaneously.

Elastic-Plastic FEM Analysis of Deformations of a Cylinder Subjected to Severe Uniaxial and Bilateral Compression by Flat Plates

1991 ◽  
Author(s):  
M. Gotoh ◽  
Y. Shibata
Keyword(s):  
Compressive Force ◽  
Fem Analysis ◽  
Plane Stress State ◽  
Deformation Pattern ◽  
Lateral Compression ◽  
The Finite Element Method ◽  
Ring Plane ◽  
Flat Plates ◽  
Elastic Plastic ◽  
Plastic Forming

Abstract Uni-lateral and bi-lateral elastic-plastic compressions of a circular cylinder with three different wall thicknesses by flat plates are numerically analysed by the Finite Element Method (FEM). J2-flow theory (J2F), and J2-Gotoh’s corner theory (J2G) which was previously proposed by one of the authors are used as the constitutive equations. In the case of uni-lateral compression, the cylinder is compressed up to a completely flattened shape, which is considered a kind of plastic forming processes. The deformed shapes and the compressive force are predicted better by J2G than by J2F. The spring-back behaviours are also analysed by imposing unloading process during deformation. The deformation process in the compression of a ring (plane stress state) and a spherical shell (axi-symmetric state) is also analysed. In the case of bi-lateral compression, the process is considered a kind of square-tube forming. In its final stage, the cylinder deforms into a completely unexpected shape which could be thought of as a square tube reinforced with ribs. The J2G allows the process to proceed at a lower compressive force than that for J2F. The effect of n-value (the strain-hardedning exponent) on the deformation pattern is also discussed.

scholarly journals Research of the Design Feasibility of a 3-Wheel Electric Vehicle with a Simplified Control System

2020 ◽  
Vol 14 (1) ◽  
pp. 32-35
Author(s):  
Srđan Medić ◽  
Veljko Kondić ◽  
Tihomir Mihalić ◽  
Vedran Runje
Keyword(s):  
Control System ◽  
Electric Vehicle ◽  
Fem Analysis ◽  
Steering Wheel ◽  
Circular Path ◽  
Main Concern ◽  
The Finite Element Method ◽  
Vehicle Aerodynamics ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

The need for a simple, customised electric vehicle (EV) has inspired the research of the possibility to build a simple EV tailored for the specific needs of the buyer. This paper is focused on the concept of an EV with no conventional control mechanism. In this paper, a research of user needs, vehicle dynamics, vehicle aerodynamics, type of drive and batteries was carried out. EV aerodynamics characteristics were simulated by using the Computational Fluid Dynamics (CFD) software. The control system was designed in correlations with the maximal safe velocity and the radius of EV turning on a circular path. The stability of the EV, concerning the vehicle turning over and wheels slipping while driving in the curves, was the main concern of this paper. The steering wheel and brake pad were replaced with a control stick. Using the Finite Element Method (FEM) analysis, key parts of the construction were constructed.

Application Study on a Detecting Tube for Deformation Settlement Monitoring for Earth Dike Based on Distributed Optical Fiber Sensors

2011 ◽  
Vol 103 ◽  
pp. 327-331
Author(s):  
Ping Yu Zhu ◽  
Hua Lei ◽  
Yuan Bao Leng
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Fem Analysis ◽  
Optical Fiber Sensors ◽  
Earth Dam ◽  
The Finite Element Method ◽  
Fiber Sensors ◽  
Application Study ◽  
Distributed Optical Fiber ◽  
Settlement Monitoring

A monitoring structure has been designed to detect settlement using a tube with distributed optical fiber sensors inside. The strain of the optical fibers inside the detecting tube was calculated to estimate the settlement degree of earth dam. The Finite Element Method (FEM) analysis of the tube interaction with the earth dam by ANSYS software is applied to find the best installation location of the detecting tube.

Semi-Analytic Solution of Multiple Inhomogeneous Inclusions and Cracks in an Infinite Space

2015 ◽  
Vol 12 (01) ◽  
pp. 1550002 ◽  
Author(s):  
Kun Zhou ◽  
Rongbing Wei ◽  
Guijun Bi ◽  
Xu Wang ◽  
Bin Song ◽  
...  
Keyword(s):  
Analytic Solution ◽  
The Finite Element Method ◽  
Infinite Space ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Dislocation Densities ◽  
Distributed Dislocation ◽  
Potential Applications ◽  
Novel Method ◽  
Dislocation Technique

This work develops a semi-analytic solution for multiple inhomogeneous inclusions of arbitrary shape and cracks in an isotropic infinite space. The solution is capable of fully taking into account the interactions among any number of inhomogeneous inclusions and cracks which no reported analytic or semi-analytic solution can handle. In the solution development, a novel method combining the equivalent inclusion method (EIM) and the distributed dislocation technique (DDT) is proposed. Each inhomogeneous inclusion is modeled as a homogenous inclusion with initial eigenstrain plus unknown equivalent eigenstrain using the EIM, and each crack of mixed modes I and II is modeled as a distribution of edge climb and glide dislocations with unknown densities. All the unknown equivalent eigenstrains and dislocation densities are solved simultaneously by means of iteration using the conjugate gradient method (CGM). The fast Fourier transform algorithm is also employed to greatly improve computational efficiency. The solution is verified by the finite element method (FEM) and its capability and generality are demonstrated through the study of a few sample cases. This work has potential applications in reliability analysis of heterogeneous materials.

Design of the Interval between Reaction Mass and Foundation in Vibration Test System

2013 ◽  
Vol 321-324 ◽  
pp. 17-22
Author(s):  
Lu Tao Yan ◽  
Zhi Peng Yang ◽  
Hong Li
Keyword(s):  
Large Scale ◽  
Maximum Amplitude ◽  
Fem Analysis ◽  
Test System ◽  
Reaction Mass ◽  
Vibration Test ◽  
The Finite Element Method ◽  
Mass System ◽  
Design And Optimization ◽  
Set Up

The dynamic model of the reaction mass system in the large-scale vibration test system is set up, and the crossover frequencies are calculated in order to determine the operation capability and the interval between reaction mass and foundation. On the basis of the finite element method (FEM) analysis and theory of analysis mechanics, the dynamic response of the reaction mass is studied. The results show that the maximum amplitude of the dynamical system is obtained at the natural frequency of the system. The results of theoretical and FEM calculations indicate that the maximum displacements responses are all much lower than the design of the interval, which means the design is satisfied and reasonable. This method can calculate the operation capability of the reaction mass effectively and can be used for vibration test system design and optimization.

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