Integrated Electronics Module Research Articles

Shrinkage controlled pastes for bulky silver and copper thick films in power electronics

Harvesting green energy and sustainable, effective use of it is based on efficient, cost-effective power electronics. To build robust, multi-functional and highly integrated electronic modules, metallizations with low resistances and the capability to carry high current loads for inner and top layer thick-films are needed. Additionally, these layers have to be interconnectable by metallized vias, soldering and bonding. A major challenge in realization of bulky silver and copper thick-films is to allow sufficient evaporation of the gaseous products during the interface reaction. Various ways to attain evaporation possibilities via controlled shrinkage retardation of the thick metal film are examined. The influence of composition of the used solids, their grain size distributions and the use of miscellenaous organic vehicles were examined in several research projects by variation of glass amount, particle size, shrinkage measurements as well as microstructure and film properties. Through partial retardation, a thick printing copper paste for 300 μm and a pure silver paste for 100 μm metallizations could be realized. By use of suited additives, the film shrinkage could be almost completely constrained which allowed the development of non-shrinking via-fill pastes.

Novel PCM-based coating for thermal management of high temperature electronic assemblies

The electronic components are exposed nowadays increasingly higher temperatures. On one site the power density is increasing and on the other site the electronic appliances are used in more and more harsh environments with high temperature loads. In worst case the combination of both can quickly lead to exceeding the critical temperature resulting in damage and total failure. There are a lot of investigations to increase the robustness of certain elements, like semiconductor and packaging materials, interconnections and PCB. Another approach for increasing the reliability of power electronic modules is the development of sophisticated thermal management system. Traditional cooling methods are coming up to their limits in high integrated electronic modules. A possible solution is the use of latent heat storage materials (PCM - phase change materials), which can be fully integrated into a compliant selective coating of critical electronic components [1], [2]. During phase change process the temperature peaks can be effectively smoothed by adsorbing and releasing the heat. This results directly in increasing of number of cycles until end of life.

Neutron detector array at IUAC: Design features and instrumentation developments

The characteristics and performance of the newly commissioned neutron detector array at IUAC are described. The array consists of 100 BC501 liquid scintillators mounted in a semi-spherical geometry and are kept at a distance of 175 cm from the reaction point. Each detector is a 5″ × 5″ cylindrical cell coupled to 5″ diameter photomultiplier tube (PMT). Signal processing is realized using custom-designed home-made integrated electronic modules which perform neutron – gamma discrimination using zero cross timing and time-of-flight (TOF) technique. Compact custom built high voltage power supply developed using DC–DC converters are used to bias the detector. The neutrons are recorded in coincidence with fission fragments which are detected using multi-wire proportional counters mounted inside a 1 m diameter SS target chamber. The detectors and electronics have been tested off-line using radioactive sources and the results are presented.

The New Horizons mission to Pluto: Advances in telecommunications system design

This paper presents the RF telecommunications system designed for the New Horizons mission, NASA's planned mission to Pluto, with focus on new technologies developed to meet mission requirements. These technologies include an advanced digital receiver—a mission-enabler for its low DC power consumption at 2.6 W secondary power. The receiver is one-half of a card-based transceiver that is incorporated with other spacecraft functions into an integrated electronics module, providing further reductions in mass and power. Other developments include extending APL's long and successful flight history in ultrastable oscillators (USOs) with an updated design for lower DC power. These USOs offer frequency stabilities to 1 part in 10 13, stabilities necessary to support New Horizons’ uplink radio science experiment. In antennas, the 2.1 m high-gain antenna makes use of shaped sub- and main reflectors to improve system performance and achieve a gain approaching 44 dBic. New Horizons would also be the first deep-space mission to fly a regenerative ranging system, offering up to a 30 dB performance improvement over sequential ranging, especially at long ranges. The paper will provide an overview of the current system design and development and performance details on the new technologies mentioned above. Other elements of the telecommunications system will also be discussed. Note: New Horizons is NASA's planned mission to Pluto, and has not been approved for launch. All representations made in this paper are contingent on a decision by NASA to go forward with the preparation for and launch of the mission.

Transceiver-based spacecraft telecommunication systems with two-way doppler tracking capability

Recent developments in transceiver-based telecommunication systems at The Johns Hopkins University Applied Physics Laboratory (APL) are described. The transceiver architecture provides inherent flexibility and a cost-efficient way of reducing mass relative to existing coherent transponder systems. The simplified architecture permits ready incorporation of the RF electronics into an integrated electronics module (IEM) along with other core spacecraft electronics. The development of a set of highly integrated S-band transceiver cards for the TIMED spacecraft and the development of an X-band command receiver suitable for deep space missions are described. A unique and very useful feature of the APL transceiver approach is its ability to perform highly accurate, two-way Doppler tracking. This tracking technique is designed to be compatible with existing assets of the Deep Space Network and provides the high accuracy (0.1 mm/s) required for deep space missions.