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The wire-bonded version of the quad flat non-lead with 64 leads (QFN64b) is increasingly integrated in modern arrangements, given its thermal and electrical…
The wire-bonded version of the quad flat non-lead with 64 leads (QFN64b) is increasingly integrated in modern arrangements, given its thermal and electrical characteristics suited for specific applications. Temperature control is thus essential for its proper operation, particularly when the heat exchange with the environment is done by natural convection. This work aims to consider a conventional assembly consisting of a large printed circuit board (PCB) on which is welded a QFN64b generating a power in the range 0.01-0.1 W. The PCB could be inclined at an angle varying between 0° and 90° (horizontal and vertical positions, respectively) according to the intended application.
The 3D numerical approach done by means of the finite volume method is complemented by thermal and electrical measurements for all the configurations numerically processed. The low deviations obtained between the calculations and the measurements validate the adopted model. These results complement recent work that considers the same assembly equipped with a tilted and low-powered QFN64 basic model subjected to free convection.
The surface temperature in any part of the assembly has been determined. The influence of the power generated by the device and the PCB’s inclination angle relative to the gravity field have been quantified. The work shows that the radiative heat transfer is negligible given the temperatures reached and that the thermal state of the considered assembly is different from the one equipped with the QFN64 basic model. The QFN’s temperature is lowered, while that of the PCB is increased. The temperature distribution is also different from that of assemblies equipped with other QFN models with and without wire-bonding.
The correlations proposed in this survey help optimize the thermal design of the QFN64b electronic package used in many engineering fields.
The purpose of this paper is to explore how workers experience planned and unplanned change(s), how the effects of change endure in organizations and the entanglement…
The purpose of this paper is to explore how workers experience planned and unplanned change(s), how the effects of change endure in organizations and the entanglement (Gherardi, 2015) of materiality, affect and learning.
Research design is ethnographic in nature and draws from 30 semi-structured interviews of workers in an Australian organization. Interviews were designed to elicit narrative accounts (stories) of challenges and change faced by the workers. Desktop research of organizational documents and material artefacts complemented interview data. Analysis is informed by socio-material understandings and, in particular, the ideas of materiality, affect and learning.
Change, in the form of a fire, triggered spontaneous and surprisingly positive affectual and organizational outcomes that exceeded earlier attempts at restructuring work. In the wake of the material tragedy of the fire in one organization, what emerged was a shift in the workers and the practices of the organization. Their accounts emphasized challenges, excitement and renewal, which prompt reconsideration of learning at work, in particular the entanglement of affect, materiality and learning in times of change.
Much workplace learning research identifies change as conducive to learning. This paper builds on this research by providing new understandings of, and insights into, the enduring effects of change.