ISBN 9783843952750

978-3-8439-5275-0, Reihe Ingenieurwissenschaften

Romit Kulkarni
Reliability Study of Electronic Components on Board-Level Packages Encapsulated by Thermoset Injection Molding

179 Seiten, Dissertation Universität Stuttgart (2022), Softcover, A5

Zusammenfassung / Abstract

The aim of this work is to investigate the reliability of microelectronic assemblies encapsulated by thermoset injection molding. One part of this work was to build up an improved understanding of the process simulation. Research was conducted in order to build up a knowledge base of the material parameters required for injection molding simulations of thermosets as well as their underlying measurement methods. In addition, the effect of simulation parameters on the error of predicting filling behavior was studied. The goal was to develop an understanding of which simulation parameters are particularly relevant and which model simplifications can be made since this is directly related to the measurement effort of material data and computing time. A further question is which minimum wall thickness (< 500 μm) can be achieved during encapsulation, which modes of stress are generated in the assembly, and how exactly this can be represented by the simulation. Established simulation software providers have no information about the minimum achievable wall thickness. The manufactured test assemblies were further used for reliability tests, whereby the service life of the assemblies was determined by means of an online resistance measurement. From the tests, the failure causes of encapsulated microsystem assemblies can be identified. Parallel to the reliability tests, numerical simulations mirroring the thermo-mechanical effects subjected to boundary conditions taken from the temperature cycling tests were carried out. Lifetime models were derived from the experimental results and the simulations. The derived lifetime models were further put through validation by means of a different package layout with the help of numerical simulations and experimental tests. Finally, design rules for reliable microsystem assemblies with regard to sprue planning, component alignment, component type, etc. were deduced from the investigations based on simulation and life cycle models.