Abstract
The depression of the order parameter at grain boundaries in high critical temperature superconducting oxides is determined using two formulations. First, we use the Bardeen-Cooper-Schrieffer formulation and assume formation of Cooper pairs by an attractive interaction potential. The spatial variation of the density of energy states at the Fermi level near the boundary, estimated as a function of hydrostatic stress field, is used to determine the depression of the order parameter. Second, the proximity-effect formulation is used in the form of a boundary condition on the order parameter at the interface. The boundary conditions are solved taking into account the spatial variation of the density of energy states. The depression of the order parameter from the two formulations is used in conjunction with atomic modeling to determine the critical current density associated with the grain boundaries. The model correctly predicts dependence of the critical current density across grain boundaries on the misorientation angle and temperature, in good agreement with experimental observations.
Highlights
Users of hybrid circuits expect some degree of quality from their suppliers, but how do they quantify their requirements and how do they go about obtaining them? I suspect there are as many views on this subject as there are users.Quality, is not something that can be added to the component at will
It is shown that the capability approval approach developed within the BS9000/CECC systems is appropriate to hybrid circuits where only small quantities of each circuit are produced and the steps involved in obtaining capability approval are discussed
If we wish to influence the quality of components we must attempt to do it at the manufacturing stage and if we wish to have confidence that the required quality is being achieved, it must be demonstrated that the manufacturing environment is capable of producing it before we commit components to expensive quality assurance testing
Summary
Ministry ofDefence, EQD., GolfRd., Bromley, Kent, U.K. The quality and reliability of hybrid circuits is examined, with particular reference to the BS9000/CECC systems. It is shown that the capability approval approach developed within the BS9000/CECC systems is appropriate to hybrid circuits where only small quantities of each circuit are produced and the steps involved in obtaining capability approval are discussed
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