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The purpose of this paper is to carry out a comprehensive experimental investigation into the role of screen and conductive carbon material formulation on line conductivity and printing capability in the screen printing process, to provide design knowledge and further understanding of the screen printing for printed carbon.

A full factorial experiment was carried out where six carbon materials were printed through ten screens to a polyester substrate under a set of standard conditions.

Material characterization showed that viscosity and the corresponding viscous and elastic material modulli increased with solids content and that the elastic properties at low shear are significant. The solids carbon content materials were unable to produce the minimum printable line features possible with the low carbon materials. Increasing the solids contents reduced the final cured line resistance, reduced the printed line width, increased the film thickness, increased the cross sectional area and reduced the material resistivity. Material resistivities were around 700 to 950 μΩcm were obtained in the printed lines.

Lower material resistivities were obtained with higher solids materials and it is postulated that the increased visco‐elastic nature of the solids content materials, play a role in determining the microscopic structure of the cured film through alignment of the carbon graphite platelets.

A dataset which allows material, screen and print characteristics has been created allowing process optimization and formulation development to be accelerated.

The work provides insight into the role of material properties and process settings on the electrical and physical characteristics of printed carbon.

THIS month usually sees the estimates adopted that must govern public library spending for the year to come. It is likely to be a testing time for many librarians and we look forward with much interest to their experiences this year. The international rearmament programme, which authority has told us will not radically change our economic position, must have its repercussions on all municipal activities; expansion, so badly needed and so often deferred, is not likely to come immediately. However, as we remarked last month, dismal prophecies have so often been confounded by the subsequent facts that we hope 1951 will not be an exception. The defence programme may have some Staff effects, especially if the Z reserves are called again to the Colours. There is much that we may hope and much we should plan for in the months immediately ahead.

The purpose of this paper is to optimize the key parameters (mesh count, paper type and ink type) in screen printing, which are affecting the printed ink volume. The objective of the optimization was to maximize the color reliability by decreasing the color difference (ΔE value) of the prints while minimizing the ink consumption. Screen printing is still dominating the printing industry to make cost-effective production when high volumes are needed.

The experiment was designed using the Taguchi method, and the samples were prepared with screen-printing by using the standard squeegee angle and pressure. The effect of mesh count, ink type and paper type on ink consumption was evaluated with using analysis of variances and main effects plots of S/N ratio and standard deviation.

The factors ink type, paper type and mesh count were found significant for ink consumption due to their Probability (P) values which were lower than 0.05. It was determined that the mesh count was the most critical variable with the analysis of variance. The analysis showed that the selection of an optimum mesh count was the key to controlling the amount of the deposited ink. Although mesh counts were inversely proportional with the ink consumptions, they did not affect the color differences as expected.

The optimization of process parameters, that are most effective on the print quality, is necessary to minimize the ink usage and lower the costs and environmental impact without exceeding the desired ΔE value limits.

Printed flexible circuits that combined conventional silicon technology will enable the realisation of many value added products such as smart packaging for the fast moving consumer goods (FMCG) industry. This paper aims to describe an investigation into integrating silicon and printable circuits for the FMCG packaging industry and this would allow products with features such as brand protection, time temperature indicators, customer feedback and visual product enhancement. Responding to interest from the FMCG packaging industry, an investigation was carried out which investigated the printing conductive silver ink on common packaging substrates.

Standard IC mounting patterns were screen printed using two conductive silver materials (one high silver content traditional paste and one lower silver content gel polymer) to four plastic and three paper substrates which represent common FMCG substrates (HDPE, BOPP, PET and three paper substrates). Materials were characterised in terms of material rheology whereas prints were characterised through electrical performance and printed film topology.

There was a significant interaction between the substrate, silver ink formulation and the resultant line quality, line topology and conductivity. On paper substrates, the absorption of binder into the substrate resulted in denser silver packing and higher conductivity for the paste material. Higher conductivities were obtained on the substrates capable of withstanding higher curing temperatures. On the polymer substrates higher conductivity could be obtained by lower content silver materials due to the denser particle packing in the cured ink film as a result of its higher solvent/lower solids components.

Further work should examine the interactions for other printing processes commonly used in the FMCG industry such as rotogravure of flexography and should also examine nano particle materials. Further work should also address the mechanical adhesion of silicon logic on the substrates and bottlenecks in processing.

The lower silver content gel material potentially provides material cost reduction by a factor of between 4 and 7 for the same conductivity. The gel material also has potential for more uniform performance across all substrate types. Typically 3.1 Ω/cm resistance values are achieved on all substrates for 300 micron lines.

For those in the field of smart packaging the work has highlighted the interaction between silver materials and non PET/PEN substrates in flexible printed circuits. It has demonstrated the implications of rheology, substrate absorbency and materials processing temperature on circuit design. For those seeking printing process understanding it has provided further validation to support material transfer mechanisms in the screen printing process.

The resistivity of cured conductive ink films are dependent on a wide range of process parameters. An early indication of the resistivity that is likely to result following curing can enable these parameters to be optimised and, therefore, improve product quality. This paper aims to report on the use of alternating current (AC) impedance measurement techniques on curing printed ink films as a means of assessing the resistivity likely to be attained following the curing process.

Impedance measurements (100 Hz-10 MHz) were performed on curing conductive carbon ink films printed on polyethylene terephthalate substrates during convective heat curing. A jig was designed to incorporate the test structure in an convection oven such that the effect of cure on the structure impedance could be investigated.

The initial impedance was found to decrease with an increase in the measurement frequency. As the ink films were cured, the impedance magnitude across the 100 Hz-10 MHz range converged with the direct current (DC) resistance value. For a given ink, the ratio of initial AC impedance at 10 MHz to final cured resistance was found to be consistent, thus giving a method where final conductivity can be estimated before cure.

Data from printed ink resistance measurements are required to ensure the optimal conductivity of printed devices. However, after the printed structures are fabricated and cured, it is too late to optimise process parameters, leading to significant wastage. AC impedance measurement can give an indication of the final cured resistivity whilst the structure is freshly printed and still in its curing phase, enabling the printing process parameters to be adjusted to improve the resistivity of subsequently printed devices. Measuring AC impedance of printed ink structures in a production environment can, therefore, improve output.

THE old trouble caused by local authorities levying rates on Public Libraries has been coming to the fore in several places lately. There is usually a great deal of discussion, but little is done to clear the ground. It has been decided that Public Libraries are liable to be assessed for local rates, and no amount of talking will alter that position at present. But something can be done to try to induce the local authorities to abandon their present endeavour to “bring everything into line” (as some of them have it) by making Public Libraries pay full rates. While it is perfectly legal to make Public Libraries pay these rates, yet it does not seem to be understood clearly that the local assessment committees have full discretion in the application of this legal power. They have the power to assess fully, nominally, or not at all. We put this emphatically because some of the statements we have seen indicate that there is a belief in certain districts that the rates must be levied. Now the payment of full or any large proportion of local rates is a serious item in the limited expenditure of a Public Library; and at the same time it is a negligible addition to the general income of a locality. In other words, this sum of money is a mere drop in the bucket to the locality as a whole, while it may mean all the difference between efficiency and stagnation to the Public Library. From a purely business point of view it seems somewhat futile to levy a certain limited amount of money for the maintenance of a Public Library, and then to cripple that institution by diverting a portion of that money in the direction of sewers, roads, or any of the other departments of municipal activity, none of which is similarly limited in its expenditure. What has to be done therefore, is to emphasize the permissive nature of powers of the local assessment committees, and to try and obtain either exemption from rates, or at most a nominal assessment.

The ways communities have regarded disasters and natural hazards in the cultural sphere can provide a lens to inform the understanding of their ability to withstand shocks and the factors that led to such conditions. Only by tracing the complexities of creating, transmitting and preserving a culture of preparedness among disaster-vulnerable communities can researchers and practitioners claim to be working toward policy that is informed by the communities’ own experience and design policy or programming on their behalf.

In efforts to prevent, respond to and recover from disasters, what alternatives are available to top-down strategies for imposing expert knowledge on lay publics? How is the context of communities’ socioecological context understood in the development of programs and policy on their behalf? What can be learned from community narratives and cultural practices to inform disaster risk reduction?

I collected examples of how different communities perceive, prevent and respond to disaster through art, music and literature and analyzed how these were embedded into local narratives and how historical context influenced such approaches. My findings show that communities use cultural practices to contextualize experiences of hazards into their collective narrative; that is, storytelling and commemoration make disasters comprehensible. By incorporating such findings into existing policies and programs, institutions may be able to more effectively apply them to affected communities or build new ones around their actual needs and experiences.

By framing disasters as an anthropological inquiry, practitioners can better recognize the influence of a place’s nuance in the disaster management canon–guided by these details, not despite them.

Our readers are now preparing for the Southport Conference, which, offers an opportunity for reviewing the present curious position of the library profession. We have had crises in the past, but none perhaps quite so acute as the present, because no one knows where we are drifting. We understand that Mr. Fisher has invited the Library Association to submit our views on the proposed legislative (or other) changes, and possibly the Association will now express itself. Our past experience of educationists leads us to think that it will be unwise to oppose close co‐operation, or even coalescence, with education authorities—that, in short, they “will absorb us whether we like it or not—at least in some way. If we can preserve a certain independence of action and of status we shall perhaps not suffer to much as will be the case if we are placed entirely under the local education committees, and if the library committees become merely sub‐committees of the larger bodies.

Signs are not wanting that the policy we have so often urged in these pages, that the present is the appropriate time for all public libraries to pay strict and systematic attention to their collections upon science and its technological and industrial applications, is being adopted by several libraries. An interesting example is that of Richmond, where a special “trades” section is to be formed having as its purpose the collecting and segregating of industrial literature, and Aberdeen has formed a sub‐committee to revise its collections similarly. No librarian believes there is anything novel in either case, since the competent librarian is continually reviewing his collections with the object of replacing obsolete works; but the public particularising of the technology sections is at the moment a policy the wisdom of which cannot be gainsaid. Moreover, numbers of books on important, but little understood, industries are coming from the press at present, and an unusual alertness is necessary to prevent them passing out of notice. Further, definite advertising of the books was never more desirable. In this connexion we have not seen any recent lists more calculated to serve the purpose than those issued by the Coventry Public Libraries, and not their least virtue is their unpretentious character— they are single leaflets with brief library information, a carefully selected set of titles, and an invitation to manufacturers, artisans and other readers to use the telephone in their search for information. We do not suppose that a very great number will avail themselves of the privileges these collections and bulletins offer; but it is all‐important that they should exist. A keen publicity spirit, which is not ashamed of or deterred by lack of visible results, is required now in order to reach the employer and the young worker in particular. Many methods suggest themselves: Lists posted at workshops, special catalogues such as that issued by Gateshead, bulletins such as those at Coventry, even visits from the librarian to the various factories, workshops, business houses and schools. Some of these have been tried, we know, but the circumstances of two years ago are not those of to‐day; and, if results were discouraging in the past, they need not be so now; and, in any case, new efforts should be made.

DURING the three years I have attended the meetings of this branch association, papers of so interesting a character have been read that I am well aware of the difficulty each paper reader must have in keeping up the standard. But as my subject seems a good one, you may be inclined to overlook an indifferent treatment of it.