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A combination of analytical methods was used on printed circuit board coupons to conclude the following: (1) while steam ageing deteriorates solderability of tinned…
A combination of analytical methods was used on printed circuit board coupons to conclude the following: (1) while steam ageing deteriorates solderability of tinned coupons, it does not increase the oxide thickness or tin‐lead ratio of the surface (top 50 Angstroms) of tinned coupons; (2) therefore, some other factor, probably oxidation of the copper or tin/copper intermetallic substrate, determines solderability of the coupons.
Because of recent interest in nickel silver (copper‐zinc‐nickel alloy) in electronic applications, this alloy was chosen for an ageing‐solderability study. An Auger/ESCA…
Because of recent interest in nickel silver (copper‐zinc‐nickel alloy) in electronic applications, this alloy was chosen for an ageing‐solderability study. An Auger/ESCA study was performed on the surface of samples of nickel silver to determine the chemical nanostructure at various degrees of ageing (0–2 years). During this time a redistribution of the three constituent metals occurred, with migration of copper to the surface. All three metal constituents oxidised at different rates. Additionally, the thickness of the surface carbon layer increased with time. The effect of physical abrading (cleaning by erasing) of the samples on solderability, ageing, and chemical surface was also studied. After erasure, all samples appeared similar to one another and close to the original composition, and the copper oxide layer was completely removed. All the cleaned surfaces, when returned to the atmosphere, experienced air oxidation of copper to copper oxide in less than two days. Angle‐resolved ESCA studies were performed to determine the concentration gradient close to the surface. Nickel was not evenly distributed with depth, but was more concentrated on the surface of the cleaned samples. Solderability studies on nickel silver samples showed no improvement with chemical treatment, attesting to the creation of a resistant passivation layer.
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…
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.
The purpose of this paper is to develop a new ionic compound free soldering process.
The ability of hydrocarbons including 9,10‐dihydroanthracene, eicosane, 2,6,10,14‐tetramethylpentadecane, cyclooctane, and dicyclopentadiene to reduce cuprous or cupric oxide was investigated. The applicability of hydrocarbons as ion free flux reagents was experimentally examined. The hydrocarbons were applied to the soldering of pre‐oxidized copper electrodes under practical conditions.
A 9,10‐dihydroanthracene was found to be efficient at reducing cuprous or cupric oxide powder under an argon atmosphere at 300°C for 2 min. The high‐reducing ability of the hydrocarbon is in agreement with the low‐homolytical C−H bond dissociation energy calculated based on the density functional theory. A 9,10‐dihydroanthracene was shown, by the highest soldering efficiency and sufficient reliability in the environmental testing, to be applicable as an ion‐free soldering flux.
The findings of this paper suggest a new method for an ionic compound free soldering process.
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…
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.
This paper presents the result of a document review on leisure and travel developments in mature Central European markets. Based on an extensive analysis of (1…
This paper presents the result of a document review on leisure and travel developments in mature Central European markets. Based on an extensive analysis of (1) socio‐demographic developments, (2) developments with regard to changing values, (3) developments with regard to the economic framework, (4) the future role of work, leisure and allocation of time here fore, (5) consumption trends, and (6) a number of singular other issues, implications for the tourism industry are drawn: (1) There is an increasing international standardisation (homogenisation) of basic service factors in terms of infrastructure and key service elements functionality, coupled with differentiating efforts in terms of specific service elements and experiences provided. (2) Due to and based on network advantages, future quantitative growth is basically triggered by large supply networks and travel corporations. (3) Growth will further take place at best suitable destinations in terms of securing time efficiency of travel experience, multi optionality of supply and international level of quality.