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The recently developed Reduced Oxide Soldering Activation (ROSA™) method is shown to be compatible with long‐term use with mass soldering processes. Prototype regeneration cells operated for as long as six months with minimal maintenance retained their effectiveness for providing short wetting times under a variety of perturbations. The operating window for the process is wide and component degradation caused by exposure to the fully charged solution is minimal. The ROSA treatment provides soldering performance comparable to that attainable with a fully activated rosin flux and offers the promise of providing low soldering defect rates without the use of CFC solvents.

Fluxless wave soldering in a nitrogen atmosphere was investigated for epoxy‐fibreglass circuit board coupons having bare copper and solder‐coated through‐holes. The Reduced Oxide Soldering Activation (ROSA™) pretreatment was found to consistently provide good hole filling and through‐hole solder joints of excellent appearance. For preheated coupons, low levels of residual oxygen and short exposure to air after the ROSA treatment were found to have no effect

The kinetics of wetting were studied on several different prepared surfaces of copper (Cu) to simulate the microstructure observed in pre‐tinned Cu‐clad printed circuit boards. The results illustrate the effectiveness of pre‐tinning in maintaining the solderability of Cu surfaces. Pre‐tinning with Pb‐rich solder (95Pb‐5Sn) is particularly effective since solderability is preserved even after a relatively long ageing treatment. On the other hand, pre‐tinning with eutectic solder risks the loss of solderability during ageing or baking due to surface exposure of an ε‐phase intermetallic with poor wetting properties. The results also confirm the presence of carbon in pre‐tinned specimens due to the use of flux. The effect of carbon on solderability is not yet known.

The sequential electrochemical reduction analysis (SERA) method was evaluated in production and demonstrated to provide a non‐destructive, objective measure of the solderability of production printed wiring boards. Approximately 1000 boards were analysed just before wave soldering and the SERA parameters were correlated with the soldering defect occurrence rates. The data show that PWB solderability is determined primarily by the nature of the surface tin oxide, as reflected in the corresponding SERA plateau voltage, rather than by the oxide thickness. By proper choice of the value of the plateau voltage used as the criterion for solderability, the most advantageous trade‐off between the costs of rejected boards and the rework of defects can be made.

The unique advantages of confocal microscopy are used to explore four cases of interest: (i) voids in solder (depth and surface texture determined), (ii) steam vs ambient aged solder coupons (significant differences detected), (iii) integrated circuit construction (sub‐surface contamination by µm‐size particles observed) and (iv) circuit boards and solder pads (non‐destructive optical sectioning through no‐wash flux layers). It is shown that confocal microscopy strongly complements SEM (scanning electron microscopy); SEM alone presents an incomplete description of a solder surface and in fact can sometimes produce misleading results.

In [ancient moral] philosophy the duties of human life were treated of as subservient to the happiness and perfection of human life. … In the ancient philosophy the perfection of virtue was represented as necessarily productive to the person who possessed it, of the most perfect happiness in this life. In the modern philosophy it was frequently represented as almost always inconsistent with any degree of happiness in this life, and heaven was to be earned by penance and mortification…not by the liberal, generous, and spirited conduct of a man. …By far the most important of all the different branches of philosophy became in this manner by far the most corrupted. (Adam Smith, The Wealth of Nations)

A significant number of integrated circuit (IC) package leads failing solderability tests also had a very thin eutectic solder coating. Poor solderability is attributed to degradation of this coating during various burn‐in times and temperatures. Techniques were developed to pre‐tin IC leads with lead‐rich solder (95Pb‐5Sn) as this finish had been reported in the literature to be particularly effective and superior to the eutectic composition in preserving solderability even after long ageing treatments. The present work has not confirmed those recommendations. In fact, surface analyses and various solderability tests performed on steam‐aged finishes demonstrate that 95Pb‐5Sn is not a viable alternative to 63Sn‐37Pb if standard spacecraft soldering practices are to be followed. Good solder wetting was always achieved if the artifically aged leads had a minimum eutectic coating thickness of 5–7 micrometres.

Gives a bibliographical review of the finite element meshing and remeshing from the theoretical as well as practical points of view. Topics such as adaptive techniques for meshing and remeshing, parallel processing in the finite element modelling, etc. are also included. The bibliography at the end of this paper contains 1,727 references to papers, conference proceedings and theses/dissertations dealing with presented subjects that were published between 1990 and 2001.

Composite solders were prepared by mechanically dispersing 15v% of Cu or Ag particles into the eutectic Sn‐3.5Ag solder. The average sizes for the nominally spherical Cu and Ag particles were 6 and 4 microns, respectively. Two different processing methods were used to prepare the composite solders: blending the powdered particles with solder paste, and adding particles to the molten solder at 2808C. The composite solders were characterised by studying the morphology, size and distribution of the reinforcing phase. Particular interest and emphasis are given towards the modifications of the reinforcements during the reflow process. Microstructural features and chemical analysis of the composite solders were studied using optical and scanning electron microscopy (SEM), and energy dispersive x‐ray (EDX) analysis. The effect of reflow and isothermal ageing on the microstructure as well as the morphological changes in the interfacial IM layer of the composite solders were extensively analysed. A mechanism for IM layer growth is proposed for solid state isothermal ageing.

A series of composite solders in 63/37 Sn/Pb was prepared: Cu₆ Sn₅ (10, 20, 30 wt%); Cu₃ Sn (10, 20, 30 wt%); Cu (7.6 wt%); Ag (4 wt%); and Ni (4 wt%). These composite solders were prepared by two procedures: (A) admixture with solder paste; and (B) admixture with molten solder. The original particulates and the final composite solders were analysed and characterised by SEM (scanning electron microscopy) EDX (energy dispersive X‐ray), and ESCA (electron spectroscopy for chemicals analysis); or XPS (X‐ray photoelectron spectroscopy). A variety of morphological characterisations, intermetallics and porosities were noted. Good wetting was noted in all cases, and porosity was greater for method (A). The particulates all exhibited excellent binding to the solder matrix.