Breakthrough In Superconducting Materials

EE May 1988 The advantages that come from such a clearance are that they ease the clearing of flux residues from under the compo- nents and make possible the close in- spection of solder joints by either nor- mal visual means or new techniques such as X-ray microfocus. This type of inspec- tion is not possible without stand-off height. The complete clearance of flux residues is highly desirable since the presence of such contaminants can pose a serious risk to long-term reliability. External connections to the circuit board are made by a surface-mounted connec- tor with soldered joints formed by reflow soldering. There are essentially two methods of as- sembly adopted by the Micro-electronics Technology Centre. The first makes use of a single sided board fitted with metal edge supports so that the ceramic board can be inserted directly into a standard Eurocard rack. The second method takes advantage of the good thermal conduc- tivity of the aluminium oxide ceramic substrate and us...