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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.

Computational stress analysis was performed in this study to investigate the solder joint reliability of plastic ball grid array (PBGA) packages with various configurations. The packages under investigation were 27 mm body‐size, 1.27 mm ball‐pitch, perimeter PBGAs with and without thermal balls at the centre. The diagonal cross‐section of the PBGA‐printed circuit board (PCB) assembly was modelled by plane‐strain elements. The model was subjected to a uniform thermal loading and the solder joints were stressed due to the mismatch of coefficient of thermal expansion (CTE). A total number of 24 cases, involving different solder ball populations, chip sizes, and substrate thicknesses, were studied. The accumulated effective plastic strain was evaluated as an index for the reliability of solder joints. The results of this study revealed the effects of the aforementioned parameters on the solder joint reliability of perimeter PBGA assemblies. The findings are very useful for the design of plastic ball grid array packages.

This paper presents a non‐linear numerical study to investigate the effect of chip dimension and substrate thickness on the solder joint reliability of plastic ball grid array (PBGA) packages. The package under investigation was a 225‐pin full‐grid PBGA assembly. The diagonal cross‐section of the PBGA together with the printed circuit board (PCB) was modelled by plane‐strain elements. A uniform thermal loading was applied and the solder joints were stressed due to the mismatch of coefficient of thermal expansion (CTE) and constructions of the PCB assembly. The effective stress and accumulated plastic strain of solder balls against various chip dimensions and substrate thicknesses were evaluated as an index for the reliability of solder joints. The results of this study are helpful for electronics packaging engineers to optimise the geometry of plastic ball grid array packages.

A no‐clean mass reflow process for 396‐pin, 324‐pin and 225‐pin over moulded plastic pad array carriers (OMPACs) or plastic ball grid array (BGA) is presented. Emphasis is placed on the OMPAC assembly parameters such as the design, material and process of the packages and printed circuit board (PCB), solder paste, stencil design, printing technology, pick and place, mass re‐flow and inspection. Furthermore, cross‐sections and the ‘popcorn’ effect of the OMPAC assembly are provided and discussed.

A computational model was established in this study to simulate cavity‐down plastic ball grid array (PBGA) assemblies. Stress analysis was performed to investigate the solder joint reliability of a PBGA‐PCB (printed circuit board) assembly. The packages under investigation had two different body sizes and two kinds of ball population. The diagonal cross‐section of the assembly was modeled by plane‐strain elements and was subjected to a uniform thermal loading. The solder joints were stressed due to the mismatch of the assembly’s coefficient of thermal expansion (CTE). The accumulated effective plastic strain was evaluated as an index for the reliability of solder joints. Effects on solder joint reliability such as package size and ball population were identified. Furthermore, it was found that, unlike conventional PBGA assemblies, the outermost solder ball has the highest plastic strain for all cases in the present study. This peculiar phenomenon was further discussed with the consideration of package deformation.

Plastic ball grid arrays (PBGAs) have begun to gain popularity in the electronic packaging market because of their advantages over peripheral leaded devices. In addition to good electrical performance, the PBGAs offer advantages to the assembler. The development of a successful assembly process for PBGAs requires an understanding of the PBGA itself and the assembly process. The key attributes required for high yield manufacturing of PBGAs are discussed. The emphasis is placed on the PBGA assembly parameters including proper PBGA handling, printing , stencil design, placement, reflow and inspection. This paper is intended to increase the understanding of the plastic ball grid array manufacturing process.

Two types of Plastic ball Grid array packages, a 225‐lead full matrix array and a 256‐lead perimeter array, were subjected to 168 hours of moisture preconditioning at 85°C and 30% relative humidity followed by simulated infra‐red reflow at temperature ramp rates of 1°C/s and 0.67°C/s. The packages were subsequently examined for delamination and cracking using scanning acoustic microscopy and environmental scanning electron microscopy. At the higher ramp rate, delamination and cracking were observed in both package types, originating in the die attach and propagating along the weakest interfaces. At the lower ramp rate, a small amount of delamination was observed. This suggests that there is a critical ramp rate below which popcorn cracking does not occur.

Plastic ball grid arrays (PBGAs) have been gaining increasing industry acceptance as potentially the lowest cost packages for high pin count applications. The main factors for their success include the inherent low cost of plastic packages, the high yields achievable with existing assembly equipment, the density advantages of an area array and, in many cases, superior electrical performance. The reliability of these packages with respect to solder joint fatigue has been extensively studied; however, little has been published on their reliability with respect to moisture‐related failure mechanisms during assembly, such as popcorning. In this study, two types of plastic ball grid array packages, a 225‐lead full matrix array and a 256‐lead perimeter array, which were preconditioned by baking at 125°C for 24 hours followed by exposure to 85°C and 30% relative humidity for 168 hours, were then subjected to three passes of simulated infra‐red reflow at 1°C/s and 0.67°C/s. Subsequent examination using scanning acoustic microscopy and environmental scanning electron microscopy revealed considerable delamination and cracking in both package types reflowed at the higher ramp rate. This damage originated in the die attach and propagated along the weakest interfaces in the package. At the lower ramp rate, a much smaller amount of delamination was observed. This suggests that there is a critical ramp rate below which popcorn cracking can be inhibited.

The effect of heat‐spreader sizes on the temperature distribution, thermal resistance, and cooling power of a set of cost‐effective cavity‐down plastic ball grid array (PBGA) packages assembled on an FR‐4 epoxy glass printed circuit board (PCB) is presented. The sizes of these packages are 35 × 35mm and 40 × 40mm and with four and five rows of solder balls.

NuBGA is a low‐cost, single‐core, two‐metal layer, cavity‐down plastic ball grid array package. With special design concepts, NuBGA provides electrical and thermal enhancements for electronic packaging applications. The concepts of these innovative designs are briefly described. Thermal resistance of junction to air is investigated first by finite element simulations, and the results are then compared to experimental measurements. Also, thermal measurements are carried out for both with, and without, heat sink attachment. Geometric dependence of thermal resistance on structural parameters such as thickness of the copper heat spreader and organic substrate, power and ground planes in printed circuit board (PCB), and the size of PCB are also discussed.