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Soldering of electronic components on printed boards generally takes place at temperatures of between 240 and 250°C. During soldering, the components and printed boards are exposed to thermal shock that affects their long‐term reliability. A reduction in the soldering temperature to about 180°C using low melting point solders is expected to decrease component failures. The authors describe tests on a number of possible solders and the development of a suitable low temperature flux.

Polyester connector strips were joined to polyimide substrates with anisotropic electrically conductive adhesives. Copper conductors as well as Au/Ni‐coated copper conductors were used on flexible circuits. The adhesives were composite materials consisting of heat curing, one‐component epoxy resin and powdered ternary solder alloys: tin‐bismuth‐zinc, tin‐indium‐zinc and tin‐zinc‐aluminium. An adhesive filled with eutectic tin‐bismuth alloy powder was used as reference. The effect of bonding parameters (e.g., temperature, dwell time and pressure) on contact resistance values was evaluated. The contact resistance values were measured for evaluating the reliability of adhesive joints during a 60°C/95%RH test. Furthermore, the joint microstructures were examined with optical and scanning electron microscopy. The results showed that with the copper conductors the initial contact resistance values were lower than with the Au/Ni‐coated copper conductors. The most reliable joints were produced with low melting filler alloys (with respect to bonding temperature) on bare copper metallisation. The most likely reason for failure of the Au/Ni‐coated circuits was strong oxidation of locally exposed nickel in the presence of moisture.

In view of the increasing interest in low temperature and lead‐free solder alloys, a review was made of existing information on the physical properties of bismuth alloys suitable for electronic bonding applications, by reflow and wave soldering. A comparison was made, where possible, with existing tin‐lead alloys already in widespread use, with new information experimentally derived where none was currently available.

The members of the chapter at the annual meeting held on 27 November 1992 in Brno decided not to split after the separation of Czechoslovakia. It was suggested to organise a larger chapter from the Central European States to provide greater co‐operation and better functioning of the smaller chapters. A new name for the chapter was proposed — Central European Chapter (CEC) — to express neutrality and to point out that the chapter is open to other neighbouring chapters and to new members from the states where no national chapter yet exists.

An empirical study was conducted to determine the thermal fatigue behaviour of 1.27 mm pitch, J‐bend and gullwing surface mount solder joints, manufactured with four low‐temperature solders. Selected solder alloys were: 58Bi‐42Sn (wt %), 43Sn‐43Pb‐14Bi, 52ln‐48Sn and 40ln‐40Sn‐20Pb. Accelerated thermal cycling was used in conjunction with metallographic analysis and mechanical (pull) strength measurement to test their behaviour. The relative merit of each solder composition was determined by comparing it with 63Sn‐37Pb solder, subjected to identical testing conditions. The strength decreased linearly with increased number of thermal cycles for gullwing solder joints of all four solder alloys. The fatigue lifetime was relatively longer for 58Bi‐42Sn and 40ln‐40Sn‐20Pb than for other alloys, but significantly lower than that obtained with 63Sn‐37Pb solder. No discernible degradation of strength was observed with the J‐bend solder joints of any solder alloy, even after the completion of 6000 thermal cycles. Thermal fatigue resistance of the latter joints was attributed to a more favourable coefficient of thermal expansion (CTE) mismatch. Solder joint cracking occurred only in gullwing components soldered with 52ln‐48Sn, 40ln‐40Sn‐20Pb and 43Sn‐43Pb‐14Bi alloys, after 1000 or 2000 thermal cycles. The crack initiated on the outside surface of the solder fillet, and appeared to propagate through both phases of the microstructure. The stress‐induced heterogeneous coarsening of the microstructure was evident only with 43Sn‐43Pb‐14Bi solder, although not as prevalent as that usually observed with eutectic Sn‐Pb solder. Fatigue cracks were absent from solder joints of 58Bi‐42Sn and 63Sn‐37Pb alloys.

The Deutscher Verband für Schweisstechnik (German Welding Society) made a very judicious and much appreciated choice of venue for its Third International Conference on 18–20 February, 1986, on Interconnection Technology in Electronics. Fellbach, less than 10 km from the Schlossplatz in Stuttgart, and whose past profile was shaped almost entirely by winegrowing, has become since the opening in 1976 of the Schwabenlandhalle a town renowned equally for its significance as a conference centre. With the vine‐crowned Kappelberg hill dominating the town and commanding views to the Neckar Valley, Swabian hospitality and friendliness at its best, and a most impressive congress hall with excellent facilities in picturesque snow‐clad surroundings, the ingredients for providing a conference venue conducive to an optimum interchange of technological information were certainly present.

As a result of reorganisation within the Company, AVX Limited have appointed Keith France as General Manager, Sales and Marketing. Previously General Manager, Sales, Europe, Mr France now assumes the added responsibility for the marketing of AVX products throughout Europe.