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Uniformly thick, conductive, tin oxide thin films ranging in thickness from 3 to 85 nm were deposited by reactive evaporation of tin, in the presence of oxygen, onto heated glass substrates. The conductivity of the films could be increased by doping with molybdenum using a simple, novel technique which is described.Film resistivity was found to increase with the time of exposure to laboratory ambients subsequent to deposition. Mobility and carrier density data for the more conductive films are presented. An approximately constant sheet resistance was found for the undoped films from which it is inferred that conduction is probably dominated by a highly conductive surface layer. The sheet resistance of the doped films increased with decreasing thickness.The films produced consisted entirely of tin oxide phases as Indicated by x-ray diffraction results and were highly transparent ( T > 85%). There was no significant difference between the optical absorption edge (3.6-3.9 eV) for doped and undoped films. A direct optical transition was found to be the dominant absorption process. The direct bandgap was found to lie in the region 4.1 L 0.1 eV.

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Experimental design has proved to be a useful statistical tool in reducing process variation. The technique has been applied to a wide range of processes, including electronics assembly and soldering processes. For effective SMT assembly the screen printing of solder paste requires tight process control, especially as pad geometries become ever smaller. However, printing of solder paste is a rather complex process which is affected by machine, material, environmental and human factors, which make it difficult to characterise effectively. This paper examines the practical application of experimental design to solder paste printing for SMT and also the results from a number of experiments carried out on a semi‐automatic ‘clamshell’ type screen printer. The experimentation concentrates on the important printer and squeegee parameters and their effect on paste deposition, with measured solder paste height and ‘measle’ diagrams used as process outputs. The usefulness of the experimental results in determining the best printer settings, as well as the problems encountered during the experimentation, are highlighted.

States that the time taken to deliver a product to the market determines a company’s success, and that research has shown that a delay of six months leads to 33 per cent of its potential profit being lost. Explores the existing method of assessing new product reliability, namely reliability demonstrating testing, and presents its numerous shortcomings and deficiencies. Analyses the results of performing reliability demonstration testing on eight products which support the viewpoint that it is no longer appropriate. Proposes a SURGE (stress unveiled reliability growth enhancement) process, leading to significant saving in development time and thereby time‐to‐market while providing a more reliable product and process. Places emphasis on the control of all of the development processes, design, manufacturing, and materials procurement and producing prototype units via the intended volume process. Performs monitoring by appropriate stress testing designed to precipitate all potential defects and involves testing beyond design specification. By correcting defects on the product, and ultimately on the processes which produced them, develops more reliable products. Concludes that the results of the SURGE process have led to a reduction in development times of 14 per cent while also reducing the time taken to ramp up to full volume production by 50 per cent.

The effects of dye coatings upon the transport properties of tin oxide thin films are studied. Conductivity enhancement factors ranging in magnitude from 2 to 20 were observed in fully characterized films painted with a crystal violet dye derivative. The conductivity enhancement is shown to be due to a combination of mobility and carrier density increase. Both of these effects are attributed to a reduction in surface scattering within a highly conductive surface layer rather than to more exotic models such as exciton coupling of conduction electrons. Preliminary studies using Langmuir-Blodgett films of the crystal violet dye did not, however, produce an increase in the tin oxide film conductivity.

Argues that in the coming years the present methods of demonstrating reliability will no longer be feasible and alternative methods must be found. Deals with building‐in reliability (BIR) and the necessity to change from the standard end‐of‐line‐measurement technique of life test to a more proactive in‐line approach, where reliability can be measured by process parameters and reaction time is immediate, resulting in a continuous flow of reliable product to the end user. This approach will not eliminate the use of end‐of‐line monitoring, but will reduce the amount which needs to be carried out. Suggests that it will only be done to demonstrate that processes are operating to certain maximum failure rates, where the online controls will in fact guarantee that the reliability is much greater than that being demonstrated. Examines the customers’ attitude towards reliability, and points out that sharing of data will be essential if the BIR approach is to be successful. Outllines two examples which demonstrate the effectiveness of a BIR program and explains how, if implemented, it can be used to prevent the manufacture of potentially unreliable product.

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