A STUDY OF THE THERMAL CYCLING PERFORMANCE OF SOLDER JOINTS IN AREA ARRAY PACKAGING

Abstract

For both the electronics manufacturer and consumer, reliability is an essential characteristic defining the quality of the electronic component and system. Gradual degradation of the electronic components decreases efficiency of the system, and lack of reliability can lead to a significant loss. Efforts at achieving better quality and reliability of electronic components involve the inspection of solder joints in area array packaging. It is of note that solder interconnections are the vulnerable parts of circuit board assemblies (CBA), because they are mainly subjected to various assembly process during electronic manufacturing as well as environmental exposure failures during service. Therefore, the reliability of solder joints is a major concern during the entire life of an area array packaging in order to minimize the electronic failure rate that may lead to large losses. This thesis aims to provide a solution that helps to overcome some of the challenges that can occur during the reliability inspection of solder joints in area array packaging. Firstly, by successfully developing a non-destructive monitoring methodology to study the performance of solder joints under thermal cycling test. The quality of the solder joints in this research work from growth to failure was monitored by using a type of ultrasonic inspection called acoustic micro imaging (AMI). Results indicate that provided a suitable AMI parameters is applied, one can generate a 3D reconstruction of the solder joints images to allow and assess the solder joints’ behaviour in flip chip packages. AMI inspection of solder joints show good agreement with the results obtained that was used to examine how the reliability was affected by the geometry and position of the joints. An automatic segmentation technique was developed that allow to characterize and extract distinctive features of solder joints on different area array packages; such features include mean intensity, structural similarities model and histogram intensity of the region of interest of solder joints. The validation experimental results have been statistically implemented using novel geometrical and time domain features extraction methods like area, form factor and standard deviation. The result from these methods were used to extrapolate the solder joint’s fatigue life at normal operating conditions. Moreover, the analysis of variance (ANOVA) was employed to determine the percentage contribution of solder joints parameters on the acquired images. The results indicated that the thickness of the printed circuit board can affect solder joint reliability.