Failure Analysis of High Density Printed Circuit Board Assembly Inside Smartphone
Authors: David Edwards-Schofield, Anil Kurella Ph.D., Choon Kheam Lim, Yi Yun Chua and Binh T Nguyen Company: Intel Corporation Date Published: 4/8/2014
Abstract: The advent of High Density Printed Circuit Board (HD PCB) into electronic assemblies has enabled the evolution of mobile computing devices like smartphones and tablets. System level failure analysis to understand quality and reliability issues of such products is challenging. The presence of blind and buried vias stacked in a multi-layer Printed Circuit Board (PCB) coupled with double sided assemblies without test or probe points for electrical continuity access adds to the complexity. This paper presents one such case study where a detailed failure analysis approach was adopted to identify the root cause of failures. Coupling software and complimentary electrical techniques the problem was isolated to the PCB part of the system assembly. Deep dive material analysis of the fault isolated signals revealed cracks in inner layers of the PCB.
The study also highlighted the fact that marginal PCB manufacturing issues could worsen during the thermal exposures associated with motherboard assembly and product usage.