5,267 research outputs found
Adhesion strength of leadframe/EMC interfaces
No full textCu-based leadframe sheets were oxidized in alkaline solutions to produce brown and/or black oxide on the surfaces, and molded with epoxy molding compound (EMC). The adhesion strength of leadframe/EMC interface was measured using sandwiched double-cantilever beam (SDCB) specimens and pull-out specimens. Results showed that the adhesion strength of leadframe/EMC interface was inherently very poor but could be increased drastically with the nucleation of acicular CuO precipitates. The presence of smooth-faceted Cu(2)O on the surface of the leadframe gave close to zero fracture toughness (G(C)) and suitable pull strength (PS). A direct correlation between G(C) and PS showed that PS can be a measure of G(C) only in a limited range
Effects of chemical oxidations on the fracture toughness of leadframe/EMC interfaces
No full textCu-based leadframe sheets were oxidized by a chemical oxidation method, which formed two kinds of oxides on its surface, a brown one and a black one. The oxidation characteristics of each oxide were studied and then to measure the adhesion strength of the leadframe/EMC interface as a function of fracture toughness, the oxidized leadframe samples were molded with an epoxy molding compound (EMC) and machined to form sandwiched double-cantilever beam (SDCB) specimens. SEM and XRD studies on the surfaces of the oxidized leadframe as well as the measurement of fracture toughness showed that the interfacial fracture toughness is directly related to the formation of acicular CuO precipitates on the surface of the leadframe. However, once a continuous layer of CuO precipitates formed on the surface of the leadframe (brown oxide) or on the Cu2O layer (black oxide), the interfacial fracture toughness is found to saturate regardless of a further oxide thickening. The size of the acicular precipitates seems to have a secondary effect on the interfacial Fracture toughness
Selective alkylation of naphthalene with tert-butyl alcohol over HY zeolites modified with acid and alkali
No full textLiquid phase alkylation of naphthalene with tert-butyl alcohol over HY zeolites modified with acid and alkali had been studied. A highest naphthalene conversion of more than 90 mol% was achieved over HY zeolites modified with hydrochloric acid (HY-H). 2,6-di-tert-butylnaphthalene(DTBN) was synthesized selectively over HY zeolites modified with oxalic acid (OY) and with stepwise acid and alkali (OSY-BS-H), with 2,6-/2,7-DTBN ratios of 5.93 and 6.11, respectively. Correlations between 2,6-selectivity and zeolite structures, catalysts acidity, products properties were obtained. (C) 2008 Elsevier B.V. All rights reserved
Finding Hy-Brasil: The Gateway Between Reality And Unreality
No full textThrough Irish history, different spiritual demands in specific historical moments impacts on the legends of Hy-Brasil. In turn, the stories of Hy-Brasil reflects the history of Ireland through its possible position, appearances, items events, viewpoints gateways and monuments. The project is to use the history of Hy-Brasil, a mystical island of Ireland, to explore the architecture of myth, which are expected to be triggered and formed by the current situation of Ireland. It looks to design a pragmatic space by providing a gateway to the mythic island of Hy-Brasil. Siting on the north end the Ireland, the Lough Foyle in Donegal, the project constructs an architectural artifact out of a particular strata of Ireland’s specific geology and monumental landscape to take people into the imagination and expectation of perceive the Irish mythology.The Berlage Post-MSc in Architecture and Urban Desig
Cohesive failure of the Cu/polyimide system
No full textThe cohesive failure which occurs in the inside of the polymer near the metal/polymer interface was studied in the Cu:Cr/polyimide and Cu/CuCr/polyimide systems. The interface energy was varied by pretreating the polyimide surface by varying rf plasma power density, or by varying the Cr content in the CuCr alloy layer, respectively, and peel tests were conducted. Then, peeled metal strips were analyzed by AES and XPS, and correlations were made among the peel strength, the amount of carbide-like Cr-C bonds near the interface, and the polyimide thickness on peeled metal films inferred from the AES depth profiling. Results indicate that the peel strength increased with the rf power density at a constant metal thickness and that the thickness of polyimide adhering to peeled metal films increased with the peel strength, which was related to the amount of carbide-like Cr-C bond near the interface affecting the interface energy. In the case of specimens with the same plasma treatment but various metal layer thickness, the thickness of polyimide on peeled metal films remained constant even though the peel strength increased with the metal layer thickness. (C) 2000 Elsevier Science S.A. All rights reserved
Quantification of the pulse wave velocity of the descending aorta using axial velocity profiles from phase-contrast magnetic resonance imaging.
No full textOptimal steady-state design of reactive distillation processes using simulated annealing
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