Development and reliability of a direct access sensor using flip chip on flex technology with anisotropic conductive adhesive

Technological developments in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic sensing capsules are an example of these. In none of the diagnostic sensing capsules, is the sensor’s first level packaging achieved via Flip Chip Over Hole (FCOH) method using Anisotropic Conductive Adhesive (ACA). In a capsule application with direct access sensor (DAS), ACA not only provides the electrical interconnection but simultaneously seals the interconnect area and the underlying electronics. The development showed that the ACA FCOH was a viable option for the DAS interconnection. Adequate adhesive formed a strong joint that withstood a shear stress of 120N/mm2 and a compressive stress of 6N required to secure the final sensor assembly in place before encapsulation. Electrical characterization of the ACA joint in a fluid environment showed that the ACA was saturated with moisture and that the ions in the solution actively contributed to the leakage current, characterized by the varying rate of change of conductance. Long term hygrothermal aging of the ACA joint showed that a thermal strain of 0.004 and a hygroscopic strain of 0.0052 were present and resulted in a fatigue like process. In-vitro tests showed that high temperature and acidity had a deleterious effect of the ACA and its joint. It also showed that the ACA contact joints positioned at around or over 1mm would survive the gastrointestinal (GI) fluids and would be able to provide a reliable contact during the entire 72hr of the GI transit time. A final capsule demonstrator was achieved by successfully integrating the DAS, the battery and the final foldable circuitry into a glycerine capsule. Final capsule soak tests suggested that the silicone encapsulated system could survive the 72hr gut transition.

System packaging & integration for a swallowable capsule using a direct access sensor

Technological developments in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic capsules are an example of this. In this paper, a diagnostic capsule technology is described based on direct-access sensing of the Gastro Intestinal (GI) fluids throughout the GI tract. The objective of this paper is two-fold: i) develop a packaging method for a direct access sensor, ii) develop an encapsulation method to protect the system electronics. The integrity of the interconnection after sensor packaging and encapsulation is correlated to its reliability and thus of importance. The zero level packaging of the sensor was achieved by using a so called Flip Chip Over Hole (FCOH) method. This allowed the fluidic sensing media to interface with the sensor, while the rest of the chip including the electrical connections can be insulated effectively. Initial tests using Anisotropic Conductive Adhesive (ACA) interconnect for the FCOH demonstrated good electrical connections and functionality of the sensor chip. Also a preliminary encapsulation trial of the flip chipped sensor on a flexible test substrate has been carried out and showed that silicone encapsulation of the system is a viable option.

A parametric study of flip-chip reliability via computer simulation

Abstract not available

Large scale parallel simulations for the assembly of a flip-chip component to a printed circuit

Abstract not available

Optimisation tools for flip-chip design

Abstract not available

(Table 1) Composite surface scraping samples and Coscinodiscus nodulifer abundance from DSDP Hole 64-480

Analysis of individual laminae in Recent sediments from the slopes of the Guaymas Basin indicates an increased abundance of the larger sizes (>60 µm) of Coscinodiscus nodulifer when upwelling conditions persist over the depositional site and an increase of the smaller sizes (<60 µm) when nonupwelling conditions exist. The size distributions of C. nodulifer in 10-cm composite samples from Hole 480 show a greater abundance of the large sizes (>60 µm) associated with well-laminated sections and more of the smaller sizes (<60 µm) in samples from the homogeneous sections. We have tentatively correlated the pronounced homogeneous zones with late Pleistocene glacial periods. These results indicate a persistence of nonupwelling conditions over Hole 480 during glacial periods (homogeneous zones) and a predominance of upwelling conditions during interglacial periods (laminated zones). Other evidence from diatom and silicoflagellate floral analysis seems to support these preliminary conclusions.

(Table 1) Magnetic susceptibility, lithologic composition and stable isotope record for ODP Hole 132-810C

Site 810 was drilled atop Shatsky Rise during Ocean Drilling Program (ODP) Leg 132. The principal objective at Site 810 was to drill interbedded cherts and chalks of Mesozoic age using the diamond coring system (DCS). The objective was not achieved because of difficulties in setting up the reentry cone on the seafloor; however, a shortened section of Cretaceous-Cenozoic nannofossil ooze was recovered with the advanced piston corer (APC). Although the section is interrupted by hiatuses, the upper 50 m carry detailed information relating to biogenic productivity, water chemistry, and eolian input during the Pliocene and Pleistocene. Four holes were drilled at Site 810. Hole 810A consists of a single mud-line core for an ongoing ODP geriatric study. The second hole (Hole 810B) was washed to 60 mbsf (without core recovery) to provide information required for setting the 16-in. casing attached to the reentry cone. Hole 810C penetrated 136.1 mbsf, mostly with the APC, with a total recovery of 143.81 m of nannofossil ooze. A reentry cone was placed over Hole 810D but no casing was successfully suspended in the hole and no sediment was cored. This data report presents the results of shore-based high-resolution analyses of carbonate and oxygen isotopic variations in the upper 50 m of the section at Site 810 and compares these variations with the shipboard determinations of magnetic susceptibility and GRAPE bulk density from the multisensor track.

Integració 3D de detectors de píxels híbrids

La miniaturització de la industria microelectrònica és un fet del tot inqüestionables i la tecnologia CMOS no n'és una excepció. En conseqüència la comunitat científica s'ha plantejat dos grans reptes: En primer lloc portar la tecnologia CMOS el més lluny possible ('Beyond CMOS') tot desenvolupant sistemes d'altes prestacions com microprocessadors, micro - nanosistemes o bé sistemes de píxels. I en segon lloc encetar una nova generació electrònica basada en tecnologies totalment diferents dins l'àmbit de les Nanotecnologies. Tots aquests avanços exigeixen una recerca i innovació constant en la resta d'àrees complementaries com són les d'encapsulat. L'encapsulat ha de satisfer bàsicament tres funcions: Interfície elèctrica del sistema amb l'exterior, Proporcionar un suport mecànic al sistema i Proporcionar un camí de dissipació de calor. Per tant, si tenim en compte que la majoria d'aquests dispositius d'altes prestacions demanden un alt nombre d'entrades i sortides, els mòduls multixip (MCMs) i la tecnologia flip chip es presenten com una solució molt interessant per aquests tipus de dispositiu. L'objectiu d'aquesta tesi és la de desenvolupar una tecnologia de mòduls multixip basada en interconnexions flip chip per a la integració de detectors de píxels híbrids, que inclou: 1) El desenvolupament d'una tecnologia de bumping basada en bumps de soldadura Sn/Ag eutèctics dipositats per electrodeposició amb un pitch de 50µm, i 2) El desenvolupament d'una tecnologia de vies d'or en silici que permet interconnectar i apilar xips verticalment (3D packaging) amb un pitch de 100µm. Finalment aquesta alta capacitat d'interconnexió dels encapsulats flip chip ha permès que sistemes de píxels tradicionalment monolítics puguin evolucionar cap a sistemes híbrids més compactes i complexes, i que en aquesta tesi s'ha vist reflectit transferint la tecnologia desenvolupada al camp de la física d'altes energies, en concret implantant el sistema de bump bonding d'un mamògraf digital. Addicionalment s'ha implantat també un dispositiu detector híbrid modular per a la reconstrucció d'imatges 3D en temps real, que ha donat lloc a una patent.

Superior color rendering with a phosphor-converted blue-cyan monolithic light-emitting diode

The future generation of modern illumination should not only be cheap and highly efficient, but also demonstrate high quality of light, light which allows better color differentiation and fidelity. Here we are presenting a novel approach to create a white solid-state light source providing ultimate color rendition necessary for a number of applications. The proposed semi-hybrid device combines a monolithic blue-cyan light emitting diode (MBC LED) with a green-red phosphor mixture. It has shown a superior color rendering index (CRI), 98.6, at correlated color temperature of around 3400 K. The MBC LED epi-structure did not suffer from the efficiency reduction typical for monolithic multi-color emitters and was implemented in the two most popular chip designs: “epi-up” and “flip-chip”. Redistribution of the blue and cyan band amplitudes in the white-light emission spectrum, using the operating current, is found to be an effective tool for fine tuning the color characteristics. (Figure presented.).

Black Hole and Galaxy Growth over Cosmic Time: the Chandra COSMOS Legacy Survey

The study of supermassive black hole (SMBH) accretion during their phase of activity (hence becoming active galactic nuclei, AGN), and its relation to the host-galaxy growth, requires large datasets of AGN, including a significant fraction of obscured sources. X-ray data are strategic in AGN selection, because at X-ray energies the contamination from non-active galaxies is far less significant than in optical/infrared surveys, and the selection of obscured AGN, including also a fraction of heavily obscured AGN, is much more effective. In this thesis, I present the results of the Chandra COSMOS Legacy survey, a 4.6 Ms X-ray survey covering the equatorial COSMOS area. The COSMOS Legacy depth (flux limit f=2x10^(-16) erg/s/cm^(-2) in the 0.5-2 keV band) is significantly better than that of other X-ray surveys on similar area, and represents the path for surveys with future facilities, like Athena and X-ray Surveyor. The final Chandra COSMOS Legacy catalog contains 4016 point-like sources, 97% of which with redshift. 65% of the sources are optically obscured and potentially caught in the phase of main BH growth. We used the sample of 174 Chandra COSMOS Legacy at z>3 to place constraints on the BH formation scenario. We found a significant disagreement between our space density and the predictions of a physical model of AGN activation through major-merger. This suggests that in our luminosity range the BH triggering through secular accretion is likely preferred to a major-merger triggering scenario. Thanks to its large statistics, the Chandra COSMOS Legacy dataset, combined with the other multiwavelength COSMOS catalogs, will be used to answer questions related to a large number of astrophysical topics, with particular focus on the SMBH accretion in different luminosity and redshift regimes.