In a typical electronic assembly, many of the solder joints undergo multiple reflow cycles during the course of a complete manufacturing process from wafer bumping to the board level assembly. Effect of these reflows on the solder joint formation and its evolution during these cycles was investigated. In the first part of the study, small size BGA’s were assembled with 12mil spheres of a number...

In this study, microstructure evolution at intermetallic interfaces in SnAgCu solder joints of an area array component was investigated at various stages of a thermal cycling test. Failure modes of solder joints were analyzed to determine the effects of process conditions on crack propagation. Lead-free printed-circuit-board (PCB) assemblies were carried out using different foot print designs o...

Miniaturisation of electronic equipment, such as those found in a notebook computer, palm held devices, cell phones etc., requires high-density packing of electronic components onto printed circuit boards (PCB). To join the interconnections, solder materials are used to bond microprocessor chips and board during assembly. In the Reflow process case, the board assembly passes through a furnace w...

Purpose: Computer vision has been widely used in the inspection of electronic components. This paper proposes a computer vision system for the automatic detection, localisation, and segmentation of solder joints on Printed Circuit Boards (PCBs) under different illumination conditions. Design/methodology/approach: An illumination normalization approach is applied to an image, which can effective...

Three kinds of Bi-based solder powders with different chemical compositions of binary Bi–Sn, ternary Bi–Sn–In, and quaternary Bi–Sn–In–Ga were prepared using a gas atomization process and subsequently ball-milled for smaller-size fabrication. In particular, only the quaternary Bi–Sn–In–Ga solder powders were severely broken to the size of less than 10 μm in a polyhedral shape due to the presenc...

Skin effect of lead-free solder joints is investigated over a wide frequency band. Contrary to common believe that ‘effective impedance of solder alloys increases with frequency’, resistance tends to saturate when frequency reaches a critical value, 10 MHz for SAC solder alloys. Negative surface impedance growth rate is observed when employs square waveform AC current loading at high current de...

Machine vision has been widely used in various industrial productions. However, the study for solder joints detection is not enough. This paper presents a solder joints detection method based on surface recovery. For a single gray-scale image, using shape-from-shading (SFS) technology, the surface of the solder joints is recovered. According to the shape distribution, the quality of solder join...

Increasing environmental concerns and pending government regulations have pressured microelectronic manufacturers to find suitable alternatives to Pb-bearing solders traditionally used in electronics packaging. Over recent years, Sn-rich solders have received significant attention as suitable replacements for Pbbearing solders. Understanding the behavior of intermetallics in Sn-rich solders is ...

Plastic-ball-grid-array (PBGA) packages were assembled onto FR-4 printed-circuit-boards (PCBs) using lead-free SnAgCu solder, different solder pad diameters, stencil thicknesses and reflow peak temperatures, and the effects of the design and assembly process conditions on the dimensions and reliability of the solder joints were investigated. The assembled microelectronic devices were subjected ...

One of the challenges in an experimental study of solder joint reliability is to determine when cracks occur in a solder joint or when a solder joint fails. Cracks in a real solder joint are difficult to identify using an X-Ray system. Cross-sectioning and scanning electron microscopy (SEM) is a destructive method. A common non-destructive test method is to monitor resistance increase in a sold...