Advantages of the New Generation Quasi-Monolithic Integration Technology (QMIT)

Fabrication process and advantages of the new generation quasi-monolithic integration technology are presented. The novel fabrication process gives excellent advantages such as extremely low thermal resistance, and a much lower thermal stress than the earlier QMIT concept [1]. This highly improves the packaging lifetime and electrical characteristics of the active devices. The fabrication process is simple and compatible with fabrication of high-Q passive elements. In comparison to the old concept of QMIT, elimination of air-bridges in this technology not only reduces the parasitics but also enables the fabrication of the rest of the circuit after measuring the microwave characteristics of the embedded active devices. This makes very accurate microwave and millimetrewave designs possible. Using the new fabrication process, microwave and millimetrewave circuits (with both coplanar and microstrip lines) containing power devices have for the first time been realised

Quasi-Monolithic integration technology (QMIT) for power applications

In this paper, we address the most important issues related to realisation of µ-wave and mm-wave circuits containing power devices in the novel technology of Quasi-Monolithic Integration Technology (QMIT). A finite element simulator (2D and 3D), a scanning probe microscopy (SPM), a nanometer surface profiler (DEKTAK) and a Peltier element (PE) have been used to optimise the standard structure of QMIT with respect to these issues and limitations in fabrication process. The first important issue is the thermal resistance of QMIT structure. Using a 2D finite element method, the effects of the most important parameters on thermal resistance such as the distance between active device and substrate (W), the thermal conductivity of glue (kepoxy) and use of a heat spreader to decrease thermal resistance have been investigated in detail. The second important issue is the induced thermal stress in QMIT structure which results from differences in thermal expansion coefficient of materials involved. A 3D finite element simulator, a scanning probe microscopy (SPM) measurements and a nanometer surface profiler (DEKTAK) accompanied with a Peltier element (PE) have been used to simulate and measure the thermal stress distribution in QMIT standard structure. Then, the effect of the most important parameters such as W, baking temperature of epoxy and material properties of epoxy have been described in detail

Improvements of Thermal Resistance and Thermal Stress in Quasi-Monolithic Integration Technology (QMIT) with a New Fabrication Process

Static heat transfer and thermal stress analysis for the new generation quasi-monolithic integration technology (NGQMIT) is presented using a three-dimensional finite element simulator. Effects of different factors and parameters such as the gap between the silicon sidewalls and GaAs-chip (Wg), temperature dependent materials properties, isotropic material properties and backside gold metallization thickness or diamond-filled polyimide are described. It is shown that thermal resistances of 11 °C/W and 8.5 °C/W are possible using 200 µm electroplated gold heat-spreader and diamond-filled polyimide on the backside of the active device, respectively. This promises successful realization of the high frequency circuits containing power active devices using the novel QMIT. In comparison to the earlier fabrication process [1-2], eight times improvement in thermal stress is achieved. This extremely improves lifetime of the packaging. The results of thermal stress simulation are compared with white-light interferomety measurement

Next-Generation Morphometry for pathomics-data mining in histopathology

Pathology diagnostics relies on the assessment of morphology by trained experts, which remains subjective and qualitative. Here we developed a framework for large-scale histomorphometry (FLASH) performing deep learning-based semantic segmentation and subsequent large-scale extraction of interpretable, quantitative, morphometric features in non-tumour kidney histology. We use two internal and three external, multi-centre cohorts to analyse over 1000 kidney biopsies and nephrectomies. By associating morphometric features with clinical parameters, we confirm previous concepts and reveal unexpected relations. We show that the extracted features are independent predictors of long-term clinical outcomes in IgA-nephropathy. We introduce single-structure morphometric analysis by applying techniques from single-cell transcriptomics, identifying distinct glomerular populations and morphometric phenotypes along a trajectory of disease progression. Our study provides a concept for Next-generation Morphometry (NGM), enabling comprehensive quantitative pathology data mining, i.e., pathomics

Groundwater Storage Changes: Present Status from GRACE Observations

Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) provide quantitative measurement of terrestrial water storage (TWS) changes with unprecedented accuracy. Combining GRACE-observed TWS changes and independent estimates of water change in soil and snow and surface reservoirs offers a means for estimating groundwater storage change. Since its launch in March 2002, GRACE time-variable gravity data have been successfully used to quantify long-term groundwater storage changes in different regions over the world, including northwest India, the High Plains Aquifer and the Central Valley in the USA, the North China Plain, Middle East, and southern Murray-Darling Basin in Australia, where groundwater storage has been significantly depleted in recent years (or decades). It is difficult to rely on in situ groundwater measurements for accurate quantification of large, regional-scale groundwater storage changes, especially at long timescales due to inadequate spatial and temporal coverage of in situ data and uncertainties in storage coefficients. The now nearly 13 years of GRACE gravity data provide a successful and unique complementary tool for monitoring and measuring groundwater changes on a global and regional basis. Despite the successful applications of GRACE in studying global groundwater storage change, there are still some major challenges limiting the application and interpretation of GRACE data. In this paper, we present an overview of GRACE applications in groundwater studies and discuss if and how the main challenges to using GRACE data can be addressed