Pure nickel lidded TO style packages are a common packaging type for active microelectronics with application in various fields including commercial, aerospace and defense. This paper will focus on the history of nickel flakes in the industry, current trends and failure analysis findings, and future considerations for this potential failure mechanism.
In 2004 Hi-Rel Laboratories became involved in an important nickel flake study which led to further inspections to document and evaluate nickel flakes in TO style lids from various customers and manufacturers. Through 2015 these inspections also assisted manufacturers to evaluate the effectiveness of their lid preparation and various cleaning methods for this package style, resulting in a substantial reduction in total number of nickel flakes greater than the specified critical dimension.
In 2019 investigations were rekindled after the discovery of a suspected nickel flake-induced failure in transistors from a manufacturer not involved in prior analyses. As part of the investigation, which included nickel flake inspection of 38 total transistors from 1992, 2010, 2011 and 2017 lot date codes, the components were subjected to various environmental conditions including vibration, mechanical shock, mild thermal cycling, ionized airflow and degaussing. It was discovered that degaussing alone greatly affected the adhesion of the nickel flakes to the internal surfaces, causing the majority of the flakes to break free. The methodology, findings and implications of this analysis will be discussed.