Spectral-Based Fatigue Assessment of Ball Grid Arrays under Aerospace Vibratory Environment

Abstract

Ball grid arrays (BGAs) embedded in aerospace devices should satisfy strict standards in the purpose to ensure their mechanical safety, particularly in fatigue. In fact, critical phases of BGAs service life such as launch lead to high cycle fatigue (HCF) failure due to severe random accelerations.To face this problem, designers are still using experimental qualifications based on deterministic time-domain fatigue methods. This work is motivated principally to study the applicability of the principal spectral fatigue models as cost effective alternative to assess BGA HCF. The study includes an assembly made up of a BGA chip and a support board. Finite element spectrum analysis brings out that the fatigue failure is expected to occur at different interconnect locations like for instance a critical solder joint made of a ductile tin-lead alloy. Among all the studied spectral models, it emerges that the Dirlik’s fatigue prediction is the most relevant in the typical range of the solder fatigue coefficients.

Dirlik and Tovo-Benasciutti Spectral Methods in Vibration Fatigue: A Review with a Historical Perspective

“…The literature also offers examples of use of spectral methods in engineering sectors such as aerospace and electronics, or with composite materials. In the former cases, for example, spectral methods combined with finite element analysis are employed for the virtual qualification of electronic assemblies subjected to aerospace vibratory environment [60]. Other examples with electronic devices [61,62] are discussed in the following section.…”

Robustness Evaluation of Adhesively Bonded Ceramic Quad Flat Chips for Space Applications

“…7). Quantitatively, a standardized rainflow counting method is carried out [11]. The application of this method requires on the one hand a stress or strain history and on the other hand the knowledge of the high cycle fatigue (HCF) properties of the solder material.…”