A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Advanced Adhesion Strength Testing Methods of Thin Film Multilayers in Electronic Packaging Systems(2016) Mahan, Kenneth Howard; Han, Bongtae; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)With the continued miniaturization and increasing performance of electronic devices, new technical challenges have arisen. One such issue is delamination occurring at critical interfaces inside the device. This major reliability issue can occur during the manufacturing process or during normal use of the device. Proper evaluation of the adhesion strength of critical interfaces early in the product development cycle can help reduce reliability issues and time-to-market of the product. However, conventional adhesion strength testing is inherently limited in the face of package miniaturization, which brings about further technical challenges to quantify design integrity and reliability. Although there are many different interfaces in today's advanced electronic packages, they can be generalized into two main categories: 1) rigid to rigid connections with a thin flexible polymeric layer in between, or 2) a thin film membrane on a rigid structure. Knowing that every technique has its own advantages and disadvantages, multiple testing methods must be enhanced and developed to be able to accommodate all the interfaces encountered for emerging electronic packaging technologies. For evaluating the adhesion strength of high adhesion strength interfaces in thin multilayer structures a novel adhesion test configuration called “single cantilever adhesion test (SCAT)” is proposed and implemented for an epoxy molding compound (EMC) and photo solder resist (PSR) interface. The test method is then shown to be capable of comparing and selecting the stronger of two potential EMC/PSR material sets. Additionally, a theoretical approach for establishing the applicable testing domain for a four-point bending test method was presented. For evaluating polymeric films on rigid substrates, major testing challenges are encountered for reducing testing scatter and for factoring in the potentially degrading effect of environmental conditioning on the material properties of the film. An advanced blister test with predefined area test method was developed that considers an elasto-plastic analytical solution and implemented for a conformal coating used to prevent tin whisker growth. The advanced blister testing with predefined area test method was then extended by employing a numerical method for evaluating the adhesion strength when the polymer’s film properties are unknown.Item Development of an Advanced Adhesion Test for Polymer Interfaces(2007-11-19) Vickey, Nathan Andrew; Han, Bongtae; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The bond strength of polymer interfaces within packaged microelectronic devices significantly influences their reliability. In the interest of predictive modeling and to facilitate materials selection during the design process, it is highly desirable to be able to distinguish between the adhesive performances of multiple polymer interfaces. However, typical adhesion testing is normally plagued by large deviations in its test results which make drawing statistical conclusions from adhesion strength data difficult. To remedy this, an investigation into the primary sources of variance associated with the pull test was performed. Four primary factors were identified, load alignment, loading rate, bond thickness, and the edge condition. The control of each of these four parameters was targeted during the development of an improved adhesion test technique. The results are an adhesion measurement method which has successfully reduced the scatter in test results from a standard deviation of 50% to approximately 10%.