Embedding and assembly of ultrathin chips in multilayer flex boards

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Purpose – The purpose of this paper is to present results from the EC funded project SHIFT (Smart High Integration Flex Technologies) on the embedding in and the assembly on flex substrates of ultrathin chips. Design/methodology/approach – Methods to embed chips in flex include flip-chip assembly and subsequent lamination, or the construction of a separate ultra-thin chip package (UTCP) using spin-on polyimides and thin-film metallisation technology. Thinning and separation of the chips is done using a “dicing-by-thinning” method. Findings – The feasibility of both chip embedding methods has been demonstrated, as well as that of the chip thinning method. Lamination of four layers of flex with ultrathin chips could be achieved without chip breakage. The UTCP technology results in a 60 mm package where also the 20mm thick chip is bendable. Research limitations/implications – Further development work includes reliability testing, embedding of the UTCP in conventional flex, and construction of functional demonstrators using the developed technologies. Originality/value – Thinning down silicon chips to thicknesses of 25mm and lower is an innovative technology, as well as assembly and embedding of these chips in flexible substrates.EC/FP6/EU/507745/Smart high-integration flex technologies/SHIF

Design of a Low-Capacitance Planar Transformer for a 4 kW/500 kHz DAB Converter

International audienceIncreasing electrification in transport sectors, from automotive to aerospace, highlights the need for low size and high power density components. The recent advent of planar technology theoretically allows to reduce considerably the size of the magnetic components. This article focuses on the design of a high frequency planar transformer intended to be used in a 4 kW 500 kHz DAB converter. In particular, the inter-winding capacitances are assessed, as they have a strong influence on the behaviour of the DAB, and in some extreme cases may impede operation entirely. Analytical and finite element models are used to evaluate the stray elements of the transformer (resistance of the conductors, inter-winding capacitance and leakage inductance), and the resulting circuit model is compared with experimental measurements. This work focuses on influences of design parameters on the transformer stray elements

Exploitation of the Timing Capabilities of Metallic Magnetic Calorimeters for a Coincidence Measurement Scheme

In this report, we compare two filter algorithms for extracting timing information using novel metallic magnetic calorimeter detectors, applied to the precision X-ray spectroscopy of highly charged ions in a storage ring. Accurate timing information is crucial when exploiting coincidence conditions for background suppression to obtain clean spectra. For X-rays emitted by charge-changing interactions between ions and a target, this is a well-established technique when relying on conventional semiconductor detectors that offer a good temporal resolution. However, until recently, such a coincidence scheme had never been realized with metallic magnetic calorimeters, which typically feature much longer signal rise times. In this report, we present optimized timing filter algorithms for this type of detector. Their application to experimental data recently obtained at the electron cooler of CRYRING@ESR at GSI, Darmstadt is discussed

Approaching the Gamow Window with Stored Ions : Direct Measurement of Xe 124 (p,γ) in the ESR Storage Ring

© 2019 American Physical Society. All rights reserved.We report the first measurement of low-energy proton-capture cross sections of Xe124 in a heavy-ion storage ring. Xe12454+ ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. The Cs125 reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.Peer reviewedFinal Published versio

Towards an Intrinsic Doppler Correction for X-ray Spectroscopy of Stored Ions at CRYRING@ESR

We report on a new experimental approach for the Doppler correction of X-rays emitted by heavy ions, using novel metallic magnetic calorimeter detectors which uniquely combine a high spectral resolution with a broad bandwidth acceptance. The measurement was carried out at the electron cooler of CRYRING@ESR at GSI, Darmstadt, Germany. The X-ray emission associated with the radiative recombination of cooler electrons and stored hydrogen-like uranium ions was investigated using two novel microcalorimeter detectors positioned under 0∘ and 180∘ with respect to the ion beam axis. This new experimental setup allowed the investigation of the region of the N, M → L transitions in helium-like uranium with a spectral resolution unmatched by previous studies using conventional semiconductor X-ray detectors. When assuming that the rest-frame energy of at least a few of the recorded transitions is well-known from theory or experiments, a precise measurement of the Doppler shifted line positions in the laboratory system can be used to determine the ion beam velocity using only spectral information. The spectral resolution achievable with microcalorimeter detectors should, for the first time, allow intrinsic Doppler correction to be performed for the precision X-ray spectroscopy of stored heavy ions. A comparison with data from a previous experiment at the ESR electron cooler, as well as the conventional method of conducting Doppler correction using electron cooler parameters, will be discussed

The decay pattern of the Pygmy Dipole Resonance of ¹⁴⁰Ce

The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N=82 nucleus ¹⁴⁰Ce using a novel combination of nuclear resonance fluorescence and γ–γcoincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR and the [2+1×PDR]is extracted

Nuclear astrophysics with radioactive ions at FAIR

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process, β-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Chemical interaction of Na with cleaved (011) surfaces of CuInSe₂

To study the beneficial effect of sodium‐containing substrate material on the photovoltaic properties of thin‐film CuInSe₂ solar cells the chemical interaction of Na with CuInSe₂ has been investigated by synchrotron excited photoelectron spectroscopy. A clean CuInSe₂ (011) surface was prepared by cleaving an oriented single crystal in UHV. The cleaved surface exhibits an electron affinity of χ≊4.6 eV. The Se 3d level shows a surface core level shift of −0.4 eV. Na was sequentially deposited in UHV in small steps from a commercial dispenser source. Initially ionized Na adsorbs on the surface leading to a shift of the surface Fermi level by 0.3 eV closer to the conduction band. Removal of Cu from the surface is observed. For higher Na deposition a chemical reaction of Na with the CuInSe₂ surface occurs leading to the formation of metallic indium and Na₂Se

Elektronisches Modul und Verfahren zu seiner Herstellung

Die Erfindung bezieht sich auf ein elektronisches, insbesondere leistungselektronisches Modul (28) mit einem ersten Schichtverbund (1), der eine innere, elektrisch isolierende Schicht (4) aufweist, in die ein oder mehrere Halbleiterelemente (2, 3) derart eingebettet sind, dass sie wenigstens auf ihrer Ober und Unterseite von dem Material der inneren Schicht (4) abgedeckt sind, wobei der erste Schichtverbund (1) auf der Unterseite und/oder der Oberseite eine Metallisierung aufweist, und mit einem zweiten Schichtverbund (9), der einerseits sowohl eine dem ersten Schichtverbund zugewandte, elektrisch isolierende Schicht als auch eine dem ersten Schichtverbund abgewandte Schicht mit einer hohen thermischen Leitfähigkeit, insbesondere einer höheren thermischen Leitfähigkeit als derjenigen der dem ersten Schichtverbund zugewandten elektrisch isolierenden Schicht, aufweist oder andererseits eine Schicht aufweist, deren Material elektrisch isoliert und eine hohe thermische Leitfähigkeit, insbesondere eine höhere thermische Leitfähigkeit als das einbettende, ungefüllte Material der inneren Schicht des ersten Schichtverbunds, aufweist, wobei der erste Schichtverbund (1) mit dem zweiten Schichtverbund (9) flächig entlang einer Fügefläche (32) zusammengefügt und verbunden ist. Durch das Vermeiden einer integrierten Herstellung des ersten und zweiten Substrats und stattdessen durch die Zusammenfügung einzelner Substratabschnitte lassen sich bei der Herstellung der elektronischen Module mechanische Probleme durch unterschiedliche thermische Ausdehnungen des ersten und zweiten Substrats (1, 9) vermeiden