Lead‐free PCB assembly and effects of process conditions on the profile and reliability of solder joints

Abstract

Purpose -To study the effects of design and assembly process conditions on lead-free solder joints for an area array component. Design/methodology/approach -Experiments using SnAgCu solder for assembling plastic ball grid array components on printed circuit boards (PCBs) were carried out to investigate the reliability of the solder joints made under various conditions. The process variables studied include solder pad diameters, solder paste volume and reflow peak temperatures. Findings -The average joint diameter increased with the peak reflow temperature, stencil thickness and pad diameter. The average joint height decreased with the increasing peak reflow temperature and pad diameter. However, increased stencil thickness would lead to increased solder paste volume and therefore increases both joint diameter and height. The assembled boards were subjected to a temperature cycling test (2 40 to þ1258C) for 5,700 cycles and no failures of the daisy chained resistance loops were found, indicating that the thermal fatigue resistance of the SnAgCu solder joints was good. Originality/value -The findings provide greater confidence to implement a lead-free soldering process without compromising reliability. Reliable lead free soldering can be made over a wide process window allowing flexibility in design and manufacturing.

A grey-ANN approach for optimizing the QFN component assembly process for smart phone application

“…Lee et al (2011) used DOE to improve the height of solder paste deposition, tombstoning, solder bridging and placement errors. Zhong et al (2005) investigated solder joint reliability when SnAgCu solder was used for assembling plastic ball grid array components. The process variables studied included pad diameters, solder volume and peak temperatures during reflow soldering.…”

Temperature cycling with Peltier elements of boards with SMD components and failure evaluation

“…This topic has been well researched in the scientific literature and related articles. The following topics have been studied: temperature cycling of FCOB assembly with underfill (Lu et al, 2000), thermo-mechanical reliability of SMD chip components on FR4 substrate (Russkikh and Sandera, 2008), reliability during PCB bending (Kü hl, 1999), optimisation of the design and reliability prediction with the help of computer simulation for wafer level packaging (Fan et al, 2009) and testing of the reliability of BGA packaging (Nurmi and Ristolainen, 2002;Li et al, 2011;Zhong et al, 2005).…”