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A model SMD test‐piece has been developed which permits mechanical stressing of a solder joint in a similar mode to that occurring in the process of thermal fatigue. The failure mechanisms in the 60Sn40Pb alloy studied have been in agreement with those frequently observed in thermal fatigue. Further, the fatigue life of model joints was found to increase with increasing solder volume whilst, upon ageing at room temperature, fatigue resistance decreased. These effects were attributed to microstructural changes occurring within the solder.

Studies have been made of ageing effects, both at room temperature and at 125°C, on the microstructure of 60:40 tin‐lead solders. A comparison was made of the effect of ageing on slow and rapidly cooled matrices. Precipitation of tin within lead dendrites was observed to occur very rapidly after solidification of the alloy. Subsequently the precipitates coarsened markedly over a period of a few weeks. The matrix of the alloy also coarsened at room temperature over this period. At elevated temperatures a similar sequence of events occurred, but substantially faster. The microstructural origins of the known loss in mechanical strength of solders with ageing are discussed.

This is the second of two papers reporting work carried out under a programme sponsored by the Department of Trade and Industry (DTI), involving collaboration between the above companies and research centres. The objectives of the programme are to identify/develop lead‐free alternatives to Sn‐40Pb solder, progress towards the development of which is described in this paper. A number of promising alloys have been selected for trial in a further round of experimentation.

This is the first of two papers reporting work carried out under a programme sponsored by the Department of Trade and Industry (DTI), involving collaboration between the International Tin Research Institute, GEC‐Marconi Ltd, BNR (Europe) Ltd and Multicore Solders Ltd. Part 1 describes the methodology used to select a number of candidate alloys as possible suitable lead‐free alternatives to tin‐lead solder.

Electronic materials, particularly tin‐lead coated component leads, may degrade and acquire a poor solderability as a result of long‐term storage or prolonged periods at elevated temperatures (during burn‐in). This paper presents the results of studies on the surface chemistry and microstructure of such coatings together with a technique for stripping degraded coatings and replacing them with pristine finishes having excellent solderability.

This, the first BABS meeting to be held at the Institute of Metals was well supported with over 60 delegates in attendance. The seminar Chairman, Dr Hector Steen of Multicore Solders Ltd, is to be congratulated on putting together such an excellent programme which I am certain helped ensure the success of the event. I hope that all future BABS seminars will be as well supported.

The annual Autumn Conference of the British Association for Brazing and Soldering offers a forum for discussions between scientists and engineers involved with two technologies which, because of their obvious similarities, would be expected to be of mutual benefit and learning. In reality both the science and the practice of brazing and soldering are quite different. I suspect, with some regret, the BABS Management Committee decided that for the first time this division be formally recognised by offering soldering as the subject of the first day and brazing and diffusion bonding the subjects of the second. This report covers the soldering day only, during which seven papers were presented:

The following is an annotated list of materials dealing with information literacy including instruction in the use of information resources, research, and computer skills related to retrieving, using, and evaluating information. This review, the nineteenth to be published in Reference Services Review, includes items in English published in 1992. A few are not annotated because the compiler could not obtain copies of them for this review.

Establishes a quantitative evaluation method on solder bridging in microsoldering using a printed wiring board with comb pattern conductors. Bridge tests were conducted by immersing the comb pattern board into a molten solder bath. The total length of solder bridge between conductors against the total length between conductors was measured as a measure of the occurrence of solder bridging. The occurrence of bridging depended on the number of immersions, flux activity including solid content, conductor spacing, solder bath temperature and solder composition. The increase in number of immersion enhanced bridging. The rosin flux without activators showed higher bridging than the activated flux. Sn‐37Pb solder showed lower bridging than Sn‐3.5Ag‐5Bi solder. Solder bridging was found to be closely correlated with wettability, therefore, the improvement of wettability could be effective to suppress solder bridging. The proposed method is believed to be suitable for the quantitative evaluation of solder bridging.