Exploration of an adhesive peel test for failure and crack analysis of overmoulded MEMS packages

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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu | Master's thesis
Date
2021-01-25
Department
Major/Subject
Mechanical Engineering
Mcode
Degree programme
Master's Programme in Mechanical Engineering (MEC)
Language
en
Pages
107
Series
Abstract
The proliferation of inertial MEMS sensors into automotive safety systems has contributed to annually declining road accidents and deaths. Being the integral sensing components for vehicular safety, the reliability of inertial MEMS is stringently tested in a wide range of thermal conditions, pushing the boundaries of the designs and materials. For this reason, die attach mediums are often subject to cracking or delamination during development qualification. Fully understanding the mechanisms behind these defects is essential in preventing and fixing them. This research set out to develop an adhesive peel test method for identifying and studying die attach adhesive cracks in over-moulded lead frame-based packages. This presented two main challenges, how to expose the die pad for peeling, and how to perform the peel test itself. Various de-capsulation methods were explored, resulting in the samples being ground to the die pad backside and die pad edge to allow access for peeling. Several peel methods were trialled with different levels of success. A manual peel test was successfully implemented, which effectively revealed the die attach surfaces for analysis. The peeled surfaces clearly revealed cracked adhesive surface morphology in three dimensions, which could be studied in detail with a SEM. The peels also revealed other die pad surface artefacts, the relevance of which could be investigated further in future research. All cracks and surface artefacts were clear and could be successfully measured using software tools.
Description
Supervisor
Bossuyt, Sven
Thesis advisor
Nurmi, Sami
Keywords
adhesive peel test, die attach, electronics packages, temperature cycling, cracking, inertial MEMS
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