Solder joint attachment reliability and assembly quality of a molded ball grid array socket

Author(s):  
R.J. Coyle ◽  
A. Holliday ◽  
P.P. Solan ◽  
C. Yao ◽  
H.A. Cyker ◽  
...  
2010 ◽  
Vol 118-120 ◽  
pp. 70-74
Author(s):  
Yu Liu ◽  
Jian Xin Liu ◽  
Shu Yi Yan ◽  
Zhi Min Wang ◽  
Bing Zhang

Welding process of automobile panels is a key process in the manufacturing of automobile body and its quality directly impact on the appearance and quality of automobile. The causes of dimensional deviation of welded assembly could be workpieces variation, assembly tooling variation, and welding distortion. As a major source of assembly deviation, dimensional variations of workpieces have important effects on the assembly quality of automobile body. In this paper, pre-stressing was used to reflect the workpieces’ variation and the node coupling method was used in the numerical simulation to predict the deformation of assembly caused by the welding process of automobile panels. And further the computation results were listed and compared with the measured ones.


Author(s):  
James P. Hofmeister ◽  
Pradeep Lall ◽  
Dhananjay Panchagade ◽  
Norman N. Roth ◽  
Terry A. Tracy ◽  
...  
Keyword(s):  

2021 ◽  
Author(s):  
Romain Feron ◽  
Robert Michael Waterhouse

Ambitious initiatives to coordinate genome sequencing of Earth's biodiversity mean that the accumulation of genomic data is growing rapidly. In addition to cataloguing biodiversity, these data provide the basis for understanding biological function and evolution. Accurate and complete genome assemblies offer a comprehensive and reliable foundation upon which to advance our understanding of organismal biology at genetic, species, and ecosystem levels. However, ever-changing sequencing technologies and analysis methods mean that available data are often heterogeneous in quality. In order to guide forthcoming genome generation efforts and promote efficient prioritisation of resources, it is thus essential to define and monitor taxonomic coverage and quality of the data. Here we present an automated analysis workflow that surveys genome assemblies from the United States National Center for Biotechnology Information (NCBI), assesses their completeness using the relevant Benchmarking Universal Single-Copy Orthologue (BUSCO) datasets, and collates the results into an interactively browsable resource. We apply our workflow to produce a community resource of available assemblies from the phylum Arthropoda, the Arthropoda Assembly Assessment Catalogue. Using this resource, we survey current taxonomic coverage and assembly quality at the NCBI, we examine how key assembly metrics relate to gene content completeness, and we compare results from using different BUSCO lineage datasets. These results demonstrate how the workflow can be used to build a community resource that enables large-scale assessments to survey species coverage and data quality of available genome assemblies, and to guide prioritisations for ongoing and future sampling, sequencing, and genome generation initiatives.


Gene ◽  
2012 ◽  
Vol 505 (2) ◽  
pp. 365-367 ◽  
Author(s):  
Adriana R. Carneiro ◽  
Rommel Thiago Jucá Ramos ◽  
Hivana Patricia Melo Barbosa ◽  
Maria Paula C. Schneider ◽  
Debmalya Barh ◽  
...  

2015 ◽  
Vol 1105 ◽  
pp. 159-163
Author(s):  
Manit Timata ◽  
Charnnarong Saikaew

In the drilling of forging materials, exit burrs are produced on the end of hole and had some undesirable characters leading to assembly quality problem. Deburring is one of the practical techniques used to solve this problem. However, this technique is a time consuming and causes high operation cost. Hence this work presented an experimental study in drilling forging brass using special tungsten carbide drilling tools. The exit burr size was evaluated at various spindle speeds and lot size. Effect of spindle speed on exit burr height was investigated using analysis of variance (ANOVA). The results of ANOVA indicated that the spindle speed of 415 rpm gave lowest exit burr height and produced higher quantity and quality of products.


2018 ◽  
Vol 2018 (1) ◽  
pp. 000534-000542
Author(s):  
Ephraim Suhir ◽  
Sung Yi ◽  
Jennie S. Hwang ◽  
R. Ghaffarian

Abstract The “head-in-pillow” (HnP) defects in lead-free solder joint interconnections of IC packages with conventional (small) stand-off heights of the solder joints, and particularly in packages with fine pitches, are attributed by many electronic material scientists to the three major causes: 1) attributes of the manufacturing process, 2) solder material properties and 3)design-related issues. The latter are thought to be caused primarily by elevated stresses in the solder material, as well as by the excessive warpage of the PCB-package assembly and particularly to the differences in the thermally induced curvatures of the PCB and the package. In this analysis the stress-and-warpage issue is addressed using an analytical predictive stress model. This model is a modification and an extension of the model developed back in 1980-s by the first author. It is assumed that it is the difference in the post-fabrication deflections of the PCB-package assembly that is the root cause of the solder materials failures and particularly and perhaps the HnP defects. The calculated data based on the developed analytical thermal stress model suggest that the replacement of the conventional ball-grid-array (BGA) designs with designs characterized by elevated stand-off heights of the solder joints could result in significant stress and warpage relief and, hopefully, in a lower propensity of the IC package to HnP defects as well. The general concepts are illustrated by a numerical example, in which the responses to the change in temperature of a conventional design referred to as ball-grid-array (BGA) and a design with solder joints with elevated stand-off heights referred to as column-grid-array (CGA) are compared. The computed data indicated that the effective stress in the solder material is relieved by about 40% and the difference between the maximum deflections of the PCB and the package is reduced by about 60%, when the BGA design is replaced by a CGA system. Although no proof that the use of solder joints with elevated stand-off heights will lessen the package propensity to the HnP defects is provided, the authors think that there is a reason to believe that the application of solder joints with elevated stand-off heights could result in a substantial improvement in the general IC package performance, including, perhaps, its propensity to HnP defects.


Author(s):  
Krishna Tunga ◽  
James Pyland ◽  
Raghuram V. Pucha ◽  
Suresh K. Sitaraman

Various constitutive and fatigue-life predictive models for lead-tin solders in SBGA (Super Ball Grid Array) packages are studied and compared with the results from experimental data. Two solder compositions, 62Sn/36Pb/2Ag and 63Sn/37Pb are studied in this work. The fatigue life of 62Sn/36Pb/2Ag solder is studied using different constitutive models that take into consideration both the time-independent and time-dependent behavior of the solder. The fatigue life of 62Sn/36Pb/2Ag solder is predicted using an energy-based predictive model and compared with the experimental data. The choice of various predictive models on the solder joint life is studied using 63Sn/37Pb solder. Various predictive models, available in the literature, for eutectic and near eutectic solder compositions are studied to predict the fatigue life. Guidelines are provided for selecting constitutive and predictive models with appropriate damage metrics.


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