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Substitution of lead‐free solders in electronic assemblies requires changes in the conventional Sn:Pb finishes on substrates and component leads to prevent contamination of the candidate solder. Options for solderability preservative coatings on the printed wiring board include organic (azole or rosin/resin based) films and tin‐based plated metallic coatings. This paper compares the solderability performance of electroless tin coatings versus organic azole films after exposure to a series of humidity and thermal cycling conditions. It is shown that the solderability of immersion tin is directly related to the tin oxide growth on the surface and is not affected by the formation of Sn‐Cu intermetallic phases as long as the intermetallic phase is protected by a surface Sn layer. For a nominal tin thickness of 60 ?inches, the typical thermal excursions associated with assembly were not sufficient to cause the intermetallic phase to consume the entire tin layer. Exposure to elevated temperatures, in the presence of humidity, promoted heavy tin oxide formation which led to solderability loss. In contrast, thin azole films were shown to be more robust to humidity exposure; however, upon heating in the presence of oxygen, they decomposed and led to severe solderability degradation. Evaluations of lead‐free solder pastes for surface mount assembly applications indicated that immersion tin significantly improved the spreading of Sn:Ag and Sn:Bi alloys compared with azole surface finishes.

Terpene based cleaning agents, such as Petroferm Inc.'s EC‐7,® are currently being used successfully for cleaning rosin based fluxes from a variety of electronics substrates. However, if rosin undergoes any thermal degradation during the various soldering operations, the effectiveness of the cleaning process becomes acutely dependent on the condition and control of the terpene bath. One of the problems associated with controlling the cleaning process is an ‘ageing’ effect of the cleaning solution as evidenced by a noticeable colour change, substantial increase in viscosity and decrease in cleaning effectiveness. There is, therefore, a critical need for accurately monitoring EC‐7 chemical composition during normal process use. FT‐IR was identified as a suitable analytical technique for convenient and accurate monitoring of the EC‐7 composition. The terpene and surfactant components of EC‐7 have characteristic fingerprints in the IR spectrum. Calibration curves were generated and used to determine the composition of ‘aged’ EC‐7 solutions. As rosin has its own unique IR absorption band, rosin contamination (bath loading) can also be easily determined. These studies demonstrated that the ageing process is governed by both the volatilisation and the oxidation of the terpene component in EC‐7, the relative rates being determined by the specific configuration of the cleaning equipment used.

The purpose of this paper is to experimentally investigate the capability of four non-destructive testing (NDT) techniques to detect the layer orientation in textile composite laminates. The aerospace industry has been the primary driving force in the use of textile composites.

Woven glass fiber composite samples were inspected using C-scan ultrasonic, vibration analyzer, X-ray micro-tomography and ultraviolet technique. In a complementary study, mechanical testing was carried out to investigate the effect of mid-layer orientation on in-plane tensile strength and their failure modes using microscopic imagining.

During C-scan ultrasonic, the high attenuation and scattering of ultrasonic waves caused by the textile fabric layers limited its application to only detect the first layer of samples. Frequency response tests of composite samples were also conducted to investigate the effect of mid-layer orientation on dynamic responses. The same trend was observed in the finite element modeling results with a clear effect of the fiber orientation defect seen in frequency response function response and higher mode shapes. Moreover, the results of micro computed tomography demonstrate that this technique could definitely detect the orientation of each layer; however, X-ray imaging at small scales introduced some challenges. Images obtained from ultraviolet technique did not reveal mid-layer orientation.

In this paper, the application of different NDT techniques along with finite element modeling to inspect two-dimensional textile composites was presented. Hopefully, the research results presented here will lead to much published papers in inspection of textile composites.

Without aspiring to emulate Robert Browning's song thrush, we venture to repeat an admonition on smoking in the food trade of almost a decade ago. (The Smoking Habit, 1962, BFJ, 64, 79). The first time it coincided with a little research we had undertaken, which later saw the light of day epitomized in article form and was enthusiastically (sic) commented upon in sections of the press and then died as if it had never been born. (Tobacco and Lung Cancer, 1965, Med. Offr., 2955, 148). Now, it coincides with the most concentrated, officially inspired, campaign, so far, mounted against the evils of smoking. The most striking fact about all these national efforts every few years is the lack of success in real terms. A marketing organization achieving such poor results would count it a costly failure. It would be unfair to say that none have given up, but with a habit so ingrained, determination is required and in many, if not most, of those able to refrain, the craving is so great that they are smoking again within a week or so. Overall, the smoking population is enormous, including, as it does, girls and women‐folk. Once, it was undignified for a woman to be seen smoking. We recall a visit by Queen Mary to the village Manor House, just after the First War; she was an expert in antique furniture and came to see the manor's collection. When Her Majesty asked for a cigarette, the village rang with astonishment for days. Nothing as amazing had happened since Cavaliers and Roundheads tethered their horses beneath the three great poplars which stood on the green. “Queen Mary! 'er smokes!”

In the vibration reduction field, constrained stand-off layer damping cylindrical shell plays an important role. However, due to the lack of accurate analysis of its damping characteristics, this hinders its further research and application. Therefore, the purpose of this paper is concerned with an accurate solution for the vibration-damping characteristics of a constrained stand-off-layer damping cylindrical shell (CSDCS) under various classical boundary conditions and conducts a further analysis.

Based on the Rayleigh–Ritz method and the Hamilton principle, a dynamic model of CSDCS is established. Then the loss factor and the frequency of CSDCS are obtained. The correctness and convergence behavior of the present model are verified by comparing the calculation results with the literature. By using for various classical boundary conditions without any special modifications in the solution procedure, the characteristics of CSDCS with S-S, C-C, C-S, C-F and S-F boundaries are discussed.

The Rayleigh–Ritz method is effective in handling the problem of CSDCS with different boundaries and an accurate solution is obtained. The boundary conditions have an important influence on the vibration and damping behavior of the CSDCS.

Based on the Rayleigh–Ritz method and Hamilton principle, a dynamic model of CSDCS is established for the first time, and then the loss factor and frequency of CSDCS are obtained. In addition, the effectiveness of adding the stand-off layer between the base shell and the viscoelastic layer is confirmed by discussing the characteristics of CSDCS with S-S, C-C, C-S, C-F and S-F boundaries.

From earliest times the land and all it produced to feed and sustain those who dwelt on it was mankind's greatest asset. From the Biblical “land of milk and honey”, down through history to the “country of farmers” visualised by the American colonists when they severed the links with the mother country, those who had all their needs met by the land were blessed — they still are! The inevitable change brought about by the fast‐growing populations caused them to turn to industry; Britain introduced the “machine age” to the world; the USA the concept of mass production — and the troubles and problems of man increased to the present chaos of to‐day. There remained areas which depended on an agri‐economy — the granary countries, as the vast open spaces of pre‐War Russia; now the great plains of North America, to supply grain for the bread of the peoples of the dense industrial conurbations, which no longer produced anything like enough to feed themselves.

The emergence of new interconnection technologies involving double‐sided surface mounted components has put stronger restrictions on the method of preserving the solderable finish on printed circuit (PC) boards. The popular Sn/Pb coatings have come under strong scrutiny due to environmental hazards of lead and also because they do not provide flat, planar surfaces for SM assembly. Organic solderability preservative coatings (OSP) are emerging as strong contenders for replacing Sn/Pb surface finishes. Benzotriazole based organic coatings have been successfully used in the past by several electronics manufacturers. However, assembly technologies involving multiple thermal operations have necessitated a fundamental understanding of the thermal stabilities and the mechanism of corrosion protection provided by the OSPs. This paper reports the results of an investigation of the thermal stabilities of two organic corrosion protection coatings. Although both are organic azole based, they operate in two distinct regimes: one forming thin films (∼100 Å) and the other forming thick films (∼5000 Å). The mechanism of surface protection has been studied using direct surface analytical techniques such as X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), scanning transmission electron microscopy (SEM/TEM) and Fourier transform infrared spectroscopy (FT‐IR). The solderability of the copper was measured by wetting balance techniques and correlated to the amount of copper oxidation. The results indicate that, although the thin films provide excellent protection for storage and handling operations, they decompose under heat, thereby causing oxidation of the copper. The thick films appear to withstand multiple thermal cycling. However, the underlying copper substrate can still be oxidised by oxygen diffusion through pores or cracks, or the film may undergo chemical changes that render the copper unsolderable.

The use of U‐V technology in conformal coating applications has come of age. This paper discusses the material, process, and equipment which recently have been utilised for the conformal coating of printed wiring boards. First is presented a description of the coating material properties, both uncured and in the cured state. Next follows a discussion of the processing scheme, parameters such as time, speed, and U‐V light source requirement. Hardware to enable the coating operation to fit into an automated assembly line is also described. Of special interest will be the employment of masking techniques to prevent coating of certain critical areas. Lastly, typical performance data on the actual product having the U‐V coating are presented. An overall appraisal of the entire U‐V system is included.

On June 27,1950 President Truman ordered American air and naval forces to South Korea to provide support in that country's defense against the North Koreans. By June 30 U.S. ground forces had entered the battle. On July 7 the United Nations agreed to send troops to S. Korea, the UN's first armed response to aggression. General Douglas MacArthur was named commander of both the troops of the United States and the United Nations. Three years later, July 27, 1953, an armistice agreement was signed and the Korean War drew to a close.

OUR theme in general this month is the personality of the librarian. One may say that librarians have a habit of discussing the recruitment of the profession, its pay and other factors in the personnel. And it is natural that they should have, because after all it is their life. The librarian as a man rarely figures at any length or in any detail in the books or magazines that we usually read. Lately, it is true, Mr. L. Stanley Jast has been contributing to a contemporary, The Library Review, some admirable all‐too‐brief articles on his memories of personalities and doings mainly in connection with the Library Association thirty or more years since. It is a pity that Mr. Jast cannot be persuaded to give these reminiscences at much greater length, and although it is possible that their main appeal is to the born librarian, yet for those who read as they run, they possess many things of quite living interest. In short, the librarian is bound to be interested in the librarian himself; that is human nature.