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barcode reading in c#.net COMPONENTTOPWB RELIABILITY in Software
COMPONENTTOPWB RELIABILITY QR Code Decoder In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Quick Response Code Encoder In None Using Barcode generator for Software Control to generate, create QR Code ISO/IEC18004 image in Software applications. FINITE ELEMENT ANALYSIS (FEA) Decode QR Code In None Using Barcode reader for Software Control to read, scan read, scan image in Software applications. QR Code Generator In Visual C#.NET Using Barcode creator for .NET Control to generate, create QRCode image in .NET framework applications. FEA is a numerical technique used to solve complex boundary value problems. It involves discretizing a complex geometry into smaller simpler geometries that can be represented by a set of differential equations. These equations can then be solved numerically to determine the deformation of the overall structure subjected to structural, thermal, or other loading conditions. FEA is a powerful numerical tool that has been used to assess the reliability of solder joints. FEA can be employed to: Encoding Quick Response Code In .NET Framework Using Barcode creator for ASP.NET Control to generate, create QRCode image in ASP.NET applications. Generate QR Code ISO/IEC18004 In VS .NET Using Barcode maker for .NET Control to generate, create QR Code image in VS .NET applications. Estimate the fatigue life of a new package Compare reliabilities of different packaging options Assess impact on reliability due to material and design changes to the package Assess impact on reliability due to PWB material and design changes Determine changes in warpage due to package density and location Denso QR Bar Code Encoder In Visual Basic .NET Using Barcode drawer for VS .NET Control to generate, create Quick Response Code image in .NET framework applications. Draw EAN / UCC  14 In None Using Barcode encoder for Software Control to generate, create UCC128 image in Software applications. FEA has been used effectively in simulating thermomechanical, bending, and shock conditions. This section focuses on the use of FEA to determine the lifetime of packages subjected to thermomechanical strains, and the use of bend test simulations to determine the factors that influence the bend strength of a package. 59.4.1 FEA for Thermomechanical Lifetime Assessment FEA lifetime assessments are typically broken down into four phases: USS Code 128 Encoder In None Using Barcode creation for Software Control to generate, create Code128 image in Software applications. Create Barcode In None Using Barcode generation for Software Control to generate, create barcode image in Software applications. Phase 1: global model Phase 2: local model Phase 3: singlejoint lifetime assessment Phase 4: statisticsbased package reliability estimate Figure 59.15 shows the interrelationships between these four phases. Printing Data Matrix 2d Barcode In None Using Barcode generation for Software Control to generate, create DataMatrix image in Software applications. EAN13 Supplement 5 Encoder In None Using Barcode drawer for Software Control to generate, create UPC  13 image in Software applications. 59.4.1.1 Phase 1: Global Model. Phase 1 involves building a global geometric model of the package. Models in FEA can be twodimensional, 2.5dimensional (strip), or threedimensional. Twodimensional models (plane strain or plane stress) are computationally very efficient as only a twodimensional cross section of the assembled package is modeled. However, they are based on the assumption that the outofplane deformation and stresses in the assembly are negligible, which is not the case with discrete solder joints. Thus, although they are useful for providing qualitative deformation and stress comparisons, they are not useful for quantitative fatiguelife estimates. A 2.5dimensional or strip model has a thickness, but it is very small just enough to capture the round shape of the solder joints.While it is an improvement over a twodimensional model, it does not capture the increased stress concentration at package corners. A threedimensional model is a much closer representation of an assembled package. Although it is computationally challenging, it is the best way to estimate the deformation and stresses induced in an assembled package. A global model of oneeighth of a BGA package can be found in Figs. 59.16. Note that only oneeighth of the package is modeled (Fig. 59.16).This is due to the fact that the package is octant symmetric, and thus symmetry boundary conditions can be employed to reduce the model size, which in turn increases the speed at which a solution can be obtained.46 Wherever possible, the deformation results of the global FEA model should be verified with experimental warpage measurement (using tools like Shadow Moir 45). A unit temperature rise is applied to the global model, the worstcase joint is determined, and the displacements of the worstcase joints are calculated. Worstcase joint determination Make EAN / UCC  8 In None Using Barcode creator for Software Control to generate, create UPC  8 image in Software applications. Barcode Drawer In Visual Studio .NET Using Barcode creation for ASP.NET Control to generate, create bar code image in ASP.NET applications. PRINTED CIRCUITS HANDBOOK
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Identify worst case joint and develop zoomedin model.
Apply thermal cycling loads on local model. Analyze joint and determine its fatigue life using a damage parameter. Phase 3 Single Joint Lifetime Assessment Based on probability of individual joint failure, determine the reliability of the entire package. Phase 4 Statisticsbased Package Reliability Estimate Phase 2 Local Model
FIGURE 59.15 FEA flowchart. Phase 1 involves creating the global model to determine global strains and displacements across the entire package. The global model also helps identify the locations of maximum stress. Phase 2 entails zooming into the location with the maximum strain. The boundary conditions applied around the local model are extracted from the global model. Phase 3 involves applying thermal cycling loads on the local model and determining the fatigue life of the worstcase solder joint in the local model. Phase 4 entails the use of statistical assessment tools to determine the reliability of the other solder joints relative to the worst case and thus estimating the solder joint reliability of the entire package. is typically based on a maximum stress or strain in the solder joints. It is essential to obtain the displacements of the worstcase joint because those displacements can now be incorporated in a local model that will simulate multiple thermal cycles on a worstcase joint. Only a unit temperature rise is applied to the global model to reduce the computational run time. An additional assumption employed in global models to reduce run time is that all materials are linearelastic and temperatureindependent. Because the goal of the global model is to determine the worstcase joint and the corresponding displacement, this approach is typically valid. Reference 46 contains a series of experimental cases and corresponding FEA predictions that validate the global/local approach and the linear elastic, temperatureindependent unit temperature rise technique for the packages studied. 59.4.1.2 Phase 2: Local Model. A local model of the worstcase joint is created and subjected to simultaneous temperature cycle and temperaturescaled displacementloading conditions obtained from the global model. The displacement field of the worstcase joint obtained

