Modeling Melting Solder in System-in-Package Assembly

2005 ◽  
Author(s):  
J. F. Zhao ◽  
J. F. Wang ◽  
C. Yang
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Solder Joint ◽  
Printed Circuit Boards ◽  
Element Model ◽  
System Level ◽  
Electrical Performance ◽  
Superposition Method ◽  
Circuit Boards ◽  
Passive Components

System-in-package (SiP) technologies typically demand an increasing number of passive components assembled into a single package to achieve system level electrical performance. Traditionally, these passive components and their assembly technologies are designed for printed circuit boards and are now integrated at the package level. However, problems may arise when solder joints are used as interconnects between the passive components and the substrate in SiP system. The solder joint may melt during the surface mounting process. Since the size of the solder joint is comparable to that of the passive components, the melting may significantly alter the stress field in the package. Consequent failure may occur if the interconnect structure is not properly designed. It is a challenge to simulate solder melting with commercial finite element codes. In this paper, the interaction between the melting solder and the surrounding structures is investigated. The stress superposition method is used in the finite element model, in which the melting solder is removed from the package and a void with identical geometry was analyzed in its place. The overall stress field is the superposition of the stress field due to temperature change and the stress field caused by the uniform pressure acting on the void surface. This method greatly simplifies the mechanical modeling.

A Fundamental Study of the Interaction of Residual Stress and Applied Loading on Fracture

2010 ◽  
Author(s):  
C. J. Aird ◽  
M. J. Pavier ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Crack Closure ◽  
Applied Load ◽  
Element Model ◽  
Residual Stress Field ◽  
Fundamental Study ◽  
Analytical Expression ◽  
Applied Loading

This paper presents the results of a fundamental finite-element based study of the crack-closure effects associated with combined residual and applied loading. First, an analytical expression for a representative two-dimensional residual stress field is derived. This residual stress field contains a central compressive region surrounded by an equilibrating tensile region. The analytical expression allows the size and shape of the field to be varied along with the magnitude of the residual stress. The residual stress field is then used as a prescribed initial stress field in a finite element model, in addition to a far field applied load. By introducing cracks of increasing length into these models, charts of stress-intensity-factor versus crack length are produced for different relative magnitudes of residual stress and applied load and for different sizes and shape of the residual stress field. These charts provide insight into the way in which crack-tip conditions evolve with crack growth under conditions of combined residual and applied loading and also enable conditions of crack closure and partial closure to be identified.

3D Back Analysis of Initial Stress Field Based on Neural Network RBF Model

2011 ◽  
Vol 243-249 ◽  
pp. 3223-3228
Author(s):  
Zhong Fu Wang ◽  
Han Dong Liu ◽  
Tong Jiang ◽  
Si Wei Wan
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Initial Stress ◽  
Linear Regression Analysis ◽  
Back Analysis ◽  
Element Model ◽  
Training Sample ◽  
Geological Condition ◽  
Initial Stress Field ◽  
Factory Building

Based on geological condition of underground factory building in Hohhot pumped storage power station, research and analysis are taken for the fundamental element which affect initial stress field, 3D finite element model of underground factory building is build for the analysis. Beigin with regrssion analysis, adopt linear elasticity caculation of finite element method to take linear regression analysis, and obtain range of optimized parameters. Adopt homogeneous design to definite various assemblies of optimized parameters at different levels. Obtain training sample by elasto plastic caculation of finite element, train for RBF model in oder to get inverse model of ground stress field. The calculation result shown that: RBF model overcome the disadvantages such as slow calculating speed and overfitting of BP model, and it could obtain distrubution rule of initial stress filed by inverse analysis in a reasonable way.

scholarly journals Reduced-Reflection Multilayer PCB Microstrip with Discontinuity Characterization

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1473
Author(s):  
Aleksandr Vasjanov ◽  
Vaidotas Barzdenas
Keyword(s):  
Printed Circuit Boards ◽  
Dielectric Material ◽  
Academic Research ◽  
System Level ◽  
Reference Plane ◽  
Impedance Change ◽  
Circuit Boards ◽  
Impedance Mismatch ◽  
The Difference ◽  
Technology And Communication

In the era of technology and communication, printed circuit boards (PCBs) can be found in a myriad of devices—from ordinary household items, to state of the art custom metrology equipment. Different types of component for wireless communications are available and come in various packages, supplied by multiple manufacturers. The signal landpads for some high-frequency connectors and components, encapsulated in larger packages, are usually wider than the controlled impedance trace, thereby introducing unwanted impedance mismatch and resulting in signal reflections. The component land pad and microstrip width a discrepancy issue can be found in both complex high-density industrial devices and system-level academic research papers. This paper addresses the topic of compensating discontinuities, introduced by signal pads, which are wider than the target impedance microstrip, characterizes the difference between the compensated and uncompensated microstrip with discontinuity, and proposes a generalized guideline on compensating for the introduced impedance change in multilayer PCBs. The compensation method is based upon carefully designing the stackup of the PCB allowing for a reference plane cutout under the discontinuity to even out the impedance mismatch. A 6-layer PCB with IT180A dielectric material containing three structures has been manufactured and characterized using an Agilent E8363B vector network analyzer (VNA). A 4–12 dB improvement in S11 response in the whole frequency range up to 10 GHz, compared to that when no compensation has been applied, was observed.

Modeling and Simulation of High Speed Intermittent Cutting Based on the Finite Element Method

2013 ◽  
Vol 683 ◽  
pp. 556-559
Author(s):  
Bin Bin Jiao ◽  
Fu Sheng Yu ◽  
Yun Jiang Li ◽  
Rong Lu Zhang ◽  
Gui Lin Du ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Field ◽  
Cutting Force ◽  
High Speed ◽  
Element Model ◽  
Periodic Variation ◽  
Element Analysis ◽  
Intermittent Cutting ◽  
Element Method

In order to study the distribution of the stress field in the high-speed intermittent cutting process, finite element model of high-speed intermittent cutting is established. Exponential material model of the constitutive equation and adaptive grid technology are applied in the finite element analysis software AdvantEdge. The material processing is simulated under certain cutting conditions with FEM ( Finite Element Method ) and the distribution of cutting force, stress field, and temperature field are received. A periodic variation to the cutting force and temperature is showed in the simulation of high-speed intermittent cutting. Highest value of the milling temperature appears in front contacting area of the knife -the chip.and maximum stress occurs at the tip of tool or the vicinity of the main cutting edge. The analysis of stress and strain fields in-depth is of great significance to improve tool design and durability of tool.

Sign in / Sign up

Export Citation Format

Share Document