A new wettability evaluating system was developed by combining a contact angle measurement instrument, which optically and insitu measures the contact angle of molten solder, with a conventional wettability tester (meniscograph). Using this new evaluation system, a well-known experiential knowledge that the wettability for Sn-3.5Ag, a typical Pbfree solder, is inferior to that for Sn-37Pb is qu...

Article history: Received: 14.3.2013. Received in revised form: 23.12.2013. Accepted: 23.12.2013. This paper presents the microstructure, hardness and elastic modulus of Sn58Bi, Sn57Bi1Ag and Ag nanopowders reinforced Sn58Bi composite solders. Microstructural observations reveal that the Ag nanopowders reinforced Sn58Bi composite solders have smaller grains of Ag3Sn and a more uniform Ag3Sn dis...

We report that individual metallic nanowires and nanoobjects can be assembled and welded together into complex nanostructures and conductive circuits by a new nanoscale electrical welding technique using nanovolumes of metal solder. At the weld sites, nanoscale volumes of a chosen metal are deposited using a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their stru...

The reliability of solder joints in electronic packaging is becoming more important as the ball grid array (BGA) develops rapidly into the most popular packaging technology. Thermal fatigue of solder joints has been a reliability concern in the electronic packaging industry since the introduction of surface mount technology (SMT). Microstructural coarsening (phase growth) is considered to be cl...

Article history: Received 4 July 2009 Received in revised form 16 November 2009 Available online 29 January 2010 0026-2714/$ see front matter 2009 Elsevier Ltd. A doi:10.1016/j.microrel.2009.11.010 * Corresponding author. Address: Department of M University, P.O. Box 10028, Beaumont, TX 77710, USA +1 409 880 8121. E-mail address: [email protected] (X.J. Fan). In this paper, a variety of wafe...

For companies that choose to take the Pb-free exemption under the European Union’s RoHS Directive and continue to manufacture tin-lead (Sn-Pb) electronic products, there is a growing concern about the lack of Sn-Pb ball grid array (BGA) components. Many companies are compelled to use the Pb-free Sn-Ag-Cu (SAC) BGA components in a Sn-Pb process, for which the assembly process and solder joint re...

The casting of lead-free solder bulk samples has been investigated by varying the conditions of solidification. Two sets of samples were generated, one water-quenched and the other air-cooled. From these cast samples, tensile testing specimens were produced for the investigation of their mechanical properties. Cooling rate effects were specifically analyzed using small solder droplets. Excellen...

Fatigue damage of solder joints is a serious reliability concern in electronic packaging. In this study, a flip chip package was modeled to investigate the effects of underfill material properties and BT substrate thickness on solder joint reliability. The CTE was found to have the main effect and matching CTE between underfill and solder joint is the most important consideration in the selecti...

In this paper, efficient techniques for solder joint inspection have been described. Using three layers of ring shaped LED's with different illumination angles, three frames of images are sequentially obtained. From these images the regions of interest (soldered regions) are segmented, and their characteristic features including the average gray level and the percentage of highlights referred t...

This paper explores the behaviour of a copper test vehicle with multiple reflowed solder joints, which has direct relevance to ball grid arrays (BGA) and high density interconnect structures. The paper explores the relative stress conditions on the distributed joints and the sensitivity to ball joint shape. The joints were exposed to isothermal fatigue, which was produced by a mechanical load t...