Automotive under-the-hood electronics often have to withstand temperatures up to 175 °C in combination with harsh environment conditions. This paper gives an overview about the reliability potential ...of epoxy based encapsulants for automotive applications. Therefore the resistance of epoxy molding compound against typical automotive fluids at temperature of use is analyzed. Six epoxy molding compounds available on the market, showing high temperature automotive potential have been carefully selected to undergo a media resistance testing. For this purpose a dedicated mold tool has been designed and manufactured to prepare these encapsulants for material testing. Thermo-mechanical, mechanical and thermal properties had been determined in initial state directly after molding and after storage in aggressive fluids typical for automotive applications as e.g. gas oil, automatic transmission fluid (ATF), brake fluid or accumulator acid at the respective temperature of use.
In recent years, within power electronics packaging, there has been a trend toward compact power electronics modules for automotive and industrial applications, where a smart integrated control unit ...for motor drives is replacing bulky substrates with discrete control logic and power electronics. Most recent modules combine control and power electronics, yielding maximum miniaturization. Transfer molding is the method of choice for cost-effective encapsulation of such modules due to robustness of the molded modules and moderate cost of packaging. But there are challenges with this type of package.
Typically, these packages are asymmetric, and thus a substrate with single sided assembly is overmolded on the component side and the substrate backside is exposed, providing a heat path for optimized cooling. This asymmetric geometry is prone to yielding warped substrates, preventing optimum thermal contact to the heat sink and also putting thermomechanical stress on the encapsulated components, possibly reducing reliability.
Such packages are truly heterogeneous, combining power ICs, wire bonds, SMDs, control ICs, substrate, and lead frame surfaces. As a result, the encapsulant used needs to adhere sufficiently to all surfaces present.
Additionally, those packages need to operate at elevated temperatures for extended time periods, for example, at 150°C for 2000 h and more, so high thermal stability is of prime importance.
Within this paper, a reference application is described integrating power and control logic inside a lead frame based molded package. Taking into account the challenges mentioned above, a detailed description of material selection for this module will be given, including material analysis, such as rheology, reactivity, and change in εr; and thermomechanical properties, in initial stage as f(t,T) and after media storage. Process development tools for module molding are used to ensure manufacturability and usability. Concluding rules for encapsulant material selection and package setup are provided.
The calcium isotopes have emerged as an important testing ground for new microscopically derived shell-model interactions, and a great deal of focus has been directed toward this region. We ...investigate the relative spectroscopic strengths associated with 1f7/2 neutron hole states in 47,49Ca following one-neutron knockout reactions from 48,50Ca. The observed reduction of strength populating the lowest 7/2- 1 state in 49Ca, as compared to 47Ca, is consistent with the description given by shell-model calculations based on two- and three-nucleon forces in the neutron pf model space, implying a fragmentation of the l=3 strength to higher-lying states. The experimental result is inconsistent with both the GXPF1 interaction routinely used in this region of the nuclear chart and with microscopic calculations in an extended model space including the ν1g9/2 orbital.
Rotational band structure in Mg 32 Crawford, H. L.; Fallon, P.; Macchiavelli, A. O. ...
Physical review. C,
03/2016, Letnik:
93, Številka:
3
Journal Article
Previous experiments observed a 4 super(+) state in the N=28 nucleus super(44)S and suggested that this state may exhibit a hindered E2-decay rate, inconsistent with being a member of the collective ...ground state band. We populate this state via two-proton knockout from a beam of exotic super(46)Ar projectiles and measure its lifetime using the recoil distance method with the GRETINA gamma-ray spectrometer. The result, 76(14) sub(stat)(20) sub(syst)ps, implies a hindered transition of ProQuest: Formulae and/or non-USASCII text omitted single-particle or Weisskopf units strength and supports the interpretation of the 4 super(+) state as a K=4 isomer, the first example of a high-K isomer in a nucleus of such low mass.
Situated in the so-called "island of inversion," the nucleus \(^{32}\)Mg is considered as an archetypal example of the disappearance of magicity at \(N=20\). We report on high statistics in-beam ...spectroscopy of \(^{32}\)Mg with a unique approach, in that two direct reaction probes with different sensitivities to the underlying nuclear structure are employed at the same time. More specifically, states in \(^{32}\)Mg were populated by knockout reactions starting from \(^{33}\)Mg and \(^{34}\)Si, lying inside and outside the island of inversion, respectively. The momentum distributions of the reaction residues and the cross sections leading to the individual final states were confronted with eikonal-based reaction calculations, yielding a significantly updated level scheme for \(^{32}\)Mg and spin-parity assignments. By fully exploiting observables obtained in this measurement, a variety of structures coexisting in 32Mg was unraveled. Comparisons with theoretical predictions based on shell-model overlaps allowed for clear discrimination between different structural models, revealing that the complete theoretical description of this key nucleus is yet to be achieved.
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