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This paper focuses on the design of an inexpensive and accurate range scanner for automatic acquisition of a CAD model of a manufactured part by using two‐dimensional images to determine a digitized three‐dimensional shape. In the developed approach, the object is passed at a speed of 4 cm/s through a single linear laser stripe and forty continuous images are captured into the frame memory of the host computer for subsequent processing. A major problem that is encountered in the design of laser stripe scanner is the specula reflection, which can be mitigated by the developed approach. Six center‐locating algorithms are described, which are central to the developed approach. These algorithms are able to achieve sub‐pixel accuracy. The center of mass algorithm that uses three points, gives the best repeatability over the other algorithms. The center of mass algorithm that uses intensity threshold, provides the best linearity over the other algorithms.

A computational parametric study on the solder joint reliability of a plastic ball grid array (PBGA) with solder bumped flip chip (FC) is presented. The basic configuration of the PBGA is 27mm package‐size and 1.27mm ball‐pitch. There were three kinds of ball population: four‐row perimeter grid array with/without thermal balls, and full grid array. A total number of 24 cases, involving various chip sizes, chip thicknesses and substrate thicknesses, were studied. The diagonal cross‐section of the PBGA‐printed circuit board (PCB) assembly was modeled by plane‐strain elements and was subjected to uniform thermal loading. Through mismatch of coefficient of thermal expansion (CTE), and lack of structural compliance, the solder joints were stressed to produce inelastic deformation. The accumulated effective plastic strain was evaluated as an index for the reliability of solder joints. The present study revealed the effects of aforementioned design parameters on the solder joint reliability of FC‐PBGA assemblies. Some peculiar phenomena were identified.

Evaluates the board level reliability of plastic ball grid array (PBGA) assemblies under thermal and mechanical loading, with the objective of characterizing the reliability of lead‐free solder joints for various assembly conditions. A five‐leg experiment was designed which included various combinations of solder materials and peak reflow temperatures. It was found that the lead‐free solder joints have a much longer thermal fatigue life than the 63Sn–37Pb solder. The 63Sn–37Pb solder joints seem to perform slightly better than the lead‐free solder under mechanical loading.

In this paper, a computational analysis is presented for the comparison of wafer level chip scale package‐on‐build‐up PCB assemblies with various solders and microvia configurations. The printed circuit board of the assembly has one build‐up layer on one side. For comparison, the board with two build‐up layers on the same side is studied as well. Furthermore, two solder joint materials, namely, 62Sn–2Ag–36Pb and 96.5Sn–3.5Ag are studied for comparison. The assembly is simulated by a finite element model and the model is analyzed under thermal cyclic loading. A comprehensive stress analysis is performed and comparisons are made for assembly deformation, stress/strain ranges, and creep responses.

This paper introduces a simple computational model for the analysis on the solder ball shear testing conditions. Both two‐dimensional (2‐D) and three‐dimensional (3‐D) finite element models are used to investigate the effect of shear ram speed on the solder ball shear strength of plastic ball grid array (PBGA) packages. An effective thickness is identified for the 2‐D finite element analysis. By using this effective thickness as a scale factor, it is shown that the 2D model is feasible for the study of 3‐D problems. The computational model is validated by experimental data in terms of load‐displacement curves. The results from both testing and modeling indicate that the shear ram speed has a substantial effect on the solder ball shear strength. In general, faster ram speed can result in higher ball shear strength. Therefore, the characterization of solder ball shear strength is loading rate‐dependent.

The purpose of this paper is to evaluate the lead‐free solder joint reliability of a variety of surface mount components assembled onto printed circuit boards (PCBs) under a number of different tests.

Lead‐free solder with a composition of Sn96.5‐Ag3.0‐Cu0.5 was used in a surface mount reflow process. Different types of surface mount dummy components with a daisy chain, such as CBGAs, BGAs, PLCCs, CSPs, and QFNs, were assembled onto PCBs. Both the mechanical and thermo‐mechanical reliability of the solder joints were evaluated by several tests. The experiments included package shear, package pull, three‐point bending and accelerated thermal cycling testing for 2,000 cycles. The packages were examined by X‐ray and C‐SAM before the reliability tests were carried out. The maximum load and the corresponding load‐displacement curve were recorded in the mechanical test.

The results from the mechanical tests show the major failure mode is on the copper pad. Weibull analysis shows that the characteristic lives of most packages are between 1,100 and 2,400 cycles. For the CBGA, the characteristic life of 96 cycles is relatively short, due to the serious CTE mismatch. Cross‐section inspection shows failures occur at the solder joint. Copper pad failure is also observed.

This paper provides both the mechanical and thermal‐mechanical reliability of lead‐free solder joints. The experimental data are very useful in the lead‐free SMT industries.