Tracing water paths through small catchments under a tropical montane rain forest in south Ecuador by an oxygen isotope approach

In three steep microcatchments under tropical montane forest, samples of rainfall, throughfall, organic layer solution (lateral flow), mineral soil solution, and stream water were collected between 23 August 2000 and 15 August 2001. Water samples were analysed for O and partly H isotopes to elucidate the preferential directions — vertical versus lateral — of water flow paths in soils and how they are linked to the precipitation and soil water regime. Additional soil moisture measurements were conducted to support the isotope study. The δ18O of rainfall shows large variations (−12.6 to +2.1‰) related to different air-masses. There is no correlation between δ18O values in rainfall, temperature, and rainfall amount. Local meteoric water lines for rainfall and throughfall suggested that evaporation was minimal. The δ18O values of throughfall and lateral flow are similar to those in rainfall. Variations in δ18O values of the soil solution and the stream water are smaller (−9.1 to −3.0 and −8.7 to −5.8‰) than those of rainfall, throughfall, and lateral flow. The δ18O values in stream water increased immediately after an intense rainstorm event to isotope values similar to those of rainfall and lateral flow indicating that during elevated rainfall the water flows rapidly in the organic layers to the stream channel paralleling the surface. This finding was confirmed by the higher volume of water in the organic layer than in the upper mineral soil during the rainstorm event. Our findings suggest that water flow paths through the ecosystem are dominated by vertical directions through the soil profile to the stream channels during normal wet conditions, interrupted by short-term flow direction changes to lateral pathways mainly in the organic layers during rainstorm events. Results from an isotope two-component hydrograph separation for the three microcatchments showed that new rain water (‘event water’) contributed 81, 44, and 78% to the total stormflow runoff during peak discharge of a studied rainstorm event, respectively

Ball Grid Array Gehaeusetechnologie fuer Multi-Chip-Module Abschlussbericht

Evaluation of organic multilayer MCM-substrate materials of projekt partner STP in terms of dimension stability at thermal and mechanical treatment during assembly processes. Compatibility of organic and metallic substrate surfaces (by STP and atotech) with contact materials for assembly is evaluated. Analysis of surface tension, performance of adhesion test and wirebond test. Definition of suitable materials and topography. Description of the suitable assembly processes diebonding, wirebonding, molding, ball apply and evaluation with special testvehicles. Selection of mold compounds with respect to influence on package dimension stability and optimal processability. Describing the limits of unreinforced dielectrica materials. Evaluation and description of a flexible ball apply equipment for low volume production. Deduction of design rules for manufacturing of substrate. For essential reliability evaluations as well as for the thermal characterization of MCMs (with SMD, Flip chip, and Die- and wirebond chips) special testvehicles are used. The testvehicles have meandering structures at the innerlayers and are mounted with individual testable chips. Pick and place technology of MCM-package and Flip chips to board level is evaluated and the requirements for measuring, recognition and placing are evaluated and defined. Evaluation results of testvehicles lead to general recommendations of suitable materials for manufacturing of substrate and assembly processes of MCM-BGA package. They are completely used for the design of two demonstrators for automotive (BMW) and telecomunication (Blaupunkt). (orig.)SIGLEAvailable from TIB Hannover: F00B616+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman