KOKI Company Ltd. - Providing Soldering Materials and Solutions Worldwide

Abstract

Over the last few years, there has been an increase in the rate of Head-in-Pillow component soldering defects which interrupts the merger of the BGA/CSP component solder spheres with the molten solder paste during reflow. The issue has occurred across a broad segment of industries including consumer, telecom, and military.

There are many reasons for this issue such as warpage issues of the component or board, ball co-planarity issues for BGA/CSP components, and non-wetting of the component based on contamination or excessive oxidation of the component coating. The issue has been found to occur not only on lead-free soldered assemblies where the increased soldering temperatures may give rise to increase component/board warpage but also on tin-lead soldered assemblies.

In order to reduce this affect, work was done on a set of tin-lead and lead-free solder pastes which were developed with flux formulations in the solder paste having higher heat resistance which did not lose their flux activation properties as quickly and quicker wetting which helped to reduce the head-in-pillow defect. The results of the evaluation are presented with test methods to analyze the head in pillow defect not only on BGA components.