The long-term goal of this research is to assist in the development of a fast, accurate, and low-cost nondestructive inspection prototype for solder joints in integrated circuits (IC). The goal of the work described in this thesis is to develop a fully automated system to maintain the signal strength of the vibrometer that would reduce the testing time while maintaining or improving the quality of the defect detection results. The ability to perform the inspections in an automated manner is very important in order to demonstrate the ability of the defect detection system to be used for online inspection without the need of an operator. The system was able to find the maximum signal strength (at a single point on the surface of a flip chip) nearly five times faster than Polytec's commercial system with a search time of approximately 2.1 sec. When integrated into the nondestructive inspection prototype, the system described in this work was found to approximately reduce the data acquisition time per test location by four times, with a minimum data acquisition time of 8.5 sec and an average time of 15.4 sec, while maintaining the same level of quality of results obtained by a skilled operator when manually maintaining the signal strength of the vibrometer. Hardware was developed that retrofitted a vibrometer's focusing head at the end of a fiber optic cable to a motorized linear stage. This stage controlled the standoff distance between the focusing head and the IC's surface with a fixed focal length, which allowed the spot size of the laser to be adjusted while searching for a desired signal strength. Numerous tests were conducted to determine the search parameters, which led to a search time of approximately 2.1 sec. This time was found to be dependent on the surface finish of the IC being inspected. It was also found that to achieve a desired signal intensity strength, not only does the standoff height of the focusing head, which determines the laser spot size, need to be controlled, but also the exact location on which the laser is reflecting off the IC.

Flip Chip in Package (FCIP) has been developed to achieve the assembly process with area array interconnects. Particularly, a high I/O count coupled with finer pitch area array interconnects structured FCIP can be achieved using no-flow underfill assembly process. Using the assembly process, a high, stable yield assembly process recently reported with eutectic lead-tin solder interconnections, 150 µm pitch, and I/O counts in excess of 3000. The assembly process reported created a large number of voids among solder interconnects in FCIP. The voids formed among solder interconnections can propagate, grow, and produce defects such as solder joint cracking and solder bridging. Moreover, these voids can severely reduce reliability performance. Indeed, many studies were conducted to examine the void formation in FCIP. Based on the studies, flip chip geometric design, process conditions, and material formulation have been considered as the potential causes of void formation. However, the present research won't be able to identify the mechanism of void formation, causing a lot of voids in assembly process without consideration of chemical reaction in the assembly process with a fine-pitch, high I/O density FCIP. Therefore, this research will present process technology necessary to achieve high yields in FCIP assemblies using no-flow underfills and investigate the underlying problem of underfill void formation in these assemblies. The plausible causes of void formation will be investigated using experimental techniques. The techniques will identify the primary source of the void formation. Besides, theoretical models will be established to predict the number of voids and to explain the growth behavior of voids in the FCIP. The established theoretical models will be verified by experiments. These models will validate with respect to the relationship between process parameters to achieve a high yield and to minimize voids in FCIP assemblies using no-flow underfill materials regarding process as well as material stand points. Eventually, this research provides design guideline achieving a high, stable yield and void-free assembly process.

Soldering results from the interfacial interactions between the die and the casting alloy during high pressure die casting and is one of the major die failure modes. To prevent this occurring, lubricant layers and surface coatings are used to act as a barrier between the die and the casting alloy. The microstructures of a series of soldered layers on H13 tool steel core pins were examined after conducting high pressure die casting experiments with a specially designed die using removable core pins and Al-11Si-3Cu casting alloy. This showed that first, a casting alloy build-up layer formed, and then intermetallic phases nucleated at the die steel interface and grew to cover the entire surface in subsequent casting cycles. The structures of intermetallic layers formed during immersion of H13 tool steel into an Al-11Si-3Cu casting alloy melt were studied by X-ray diffraction and energy dispersive spectroscopy (EDS). A thick composite layer away from the H13 steel substrate consisted of irregular intermetallic phases and solidified casting alloy. A thin intermetallic layer was present between the composite layer and an inner compact layer next to the steel substrate. The irregular intermetallic phase in the thick composite layer away from the H13 steel substrate was identified to have a body centre cubic (bcc) structure, abcc-( FeSiAlCrMnCu). The thin and continuous intermetallic layer between the composite layer and the inner compact layer was found to be structurally isomorphous with aH-Fe2SiAl8. The compositional differences observed between aH and abcc phases indicated that the latter consisted of a higher amount of chromium, manganese, copper, and a lower amount of iron. It was likely that the presence of chromium, manganese and copper in the H13 tool steel caused the transformation of aH®abcc. The inner compact layer next to the steel substrate was identified to be orthorhombic h-Fe2Al5 containing silicon and chromium. An examination of lubricants to prevent soldering in high pressure die casting in conjunction with Nissan Casting Australia Pty Ltd. found that soldering was reduced by using a suitable lubricant. The chemistry of the lubricant, spray parameters, and die surface temperature were important factors in producing a protective lubricant layer. It was found that lubricant containing polypropylene waxes prevented soldering significantly better than lubricant containing polyethylene waxes. It was also found that the lubricant containing polypropylene waxes had lower surface tension. An examination of the use of iron oxide layers to prevent soldering in high pressure die casting was performed. H13 tool steel was oxidised in air and produced porous iron oxide with a mixture of haematite (Fe2O3) and magnetite (Fe3O4). These porous iron oxides did not completely prevent the H13 steel from soldering in immersion tests as intermetallic cones formed at the surface of the steel. Commercial steam tempering of H13 steel produced more compact iron oxide layers with magnetite (Fe3O4) and haematite (Fe2O3) structures. It was found that these compact iron oxide layers offered better protection against soldering than the porous layers created in air. Pure iron oxidised in a CO2/H2 gas mixture at a ratio of 95:5 at 550°C produced structurally pure, compact magnetite (Fe3O4) layers. H13 steel oxidised in a CO2/H2 gas mixture at a ratio of 95:5 at 550°C produced compact iron oxide layers that showed only magnetite (Fe3O4) structure. The magnetite (Fe3O4) layer containing chromium, manganese, silicon and vanadium formed next to the H13 substrate was found to be a very adherent layer and protected H13 steel from soldering in high pressure die casting experiments with a specially designed die using removable core pins and Al-11Si-3Cu casting alloy. An examination of aluminium oxide layers to prevent soldering in high pressure die casting was performed. Incoloy MA956 containing 4.5 wt.% aluminium, oxidised in air at 1100°C, produced a single, compact, adherent oxide layer with a-alumina (Al2O3) structure, that prevented the formation of intermetallic phases between aluminium alloy and Incoloy MA956 during high pressure die casting. However, non-reactive casting alloy build-up formed on the oxide coatings, similarly to physical vapour deposition (PVD) and vanadium carbide coatings. It was found that the thickness of the non-reactive casting alloy build-up was reduced by decreasing the roughness of the oxide coatings by lightly grinding of the surface of the coatings. The industrial application of these findings are discussed and directions for further research are presented.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--State University of New York at Binghamton, Mechanical Engineering Department, 2005. / Includes bibliographical references (leaves 149-155).

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 175-)

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008. / Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2007. / Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008. / Includes bibliographical references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 100-111).