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This paper presents an experience in designing a printed circuit board prototype as part of a general surface mount investigation for commercial electronics application. The point of view is that of a low volume assembler of relatively large, complex PC boards which use standard components. Three prototype versions were designed using different criteria. FR‐4 substrate was used for all of the designs. A comparison of the three designs with the through‐hole version indicates that the economic success of surface mounted printed circuit assemblies is heavily dependent on the physical design of the printed circuit board. Some of the aspects of a surface mounted circuit assembly that are discussed include design philosophy and tools, printed circuit board fabrication and bare board test. Design practices that would ideally utilise the small size of surface mount components are contrasted with those practices necessary to provide low cost and manufacturability of the printed circuit board.

Surface Mounting is shown to be the fourth generation of electronic interconnection technology. It has several facets and is seen differently from various viewpoints in the assembly industry. A review of published papers shows that the subject grew during the 1970s with no single inventor and as a result of numerous developments which are now combining into a coherent technology with important compatibility with other recent innovations.

An overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot‐dipped, plated, and plated‐and‐fused 100Sn and Sn‐Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all‐around best options in terms of solderability protection and wire bondability. Nickel/Pd finishes offer a slightly reduced level of performance in these areas which is most likely due to variable Pd surface conditions. It is necessary to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that include thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non‐Pb bearing solders are discussed.

The need for high packing density has led to a requirement for photo‐imageable solder masks, and the increase in surface mount technology is rapidly expanding the use of these systems into consumer electronics in addition to the traditional high‐technology outlets. This paper compares the properties and performance of the two broad types of photo‐imageable systems—dry film solder masks and liquid systems. The manufacturing and coating requirements are outlined. Dry film solder masks are supplied by major chemical companies as high‐quality pre‐formed films while producing coatings from liquid systems is the responsibility of the printed circuit board producer. The process for producing solder masked boards from the two systems is outlined. The relative performance of the systems is compared in detail. Resolution, encapsulation, topography and reliability are considered and these are discussed as well as the requirements for fluxing and defluxing and formation of tented via holes, a highly desirable feature for SMT. Finally, the attractiveness of the more established dry film technology for surface mount boards is summarised, with a request that designers consider the features available and build these into their designs for new circuit boards. Provided the appropriate application system is used and the thickness of dry film solder mask is matched to the requirement, cost advantages can be derived from their use.

Testing has become one of the dominant costs in the process of bringing a product from initial conception to the market place. Because of this, it is now imperative that the impact of any technology change on the test process is considered at an early stage. In this light, the increasing trend towards the use of surface‐mounting techniques in the fabrication of electronic systems is examined, with particular emphasis on the consequences on product testing during design validation, manufacture and repair. The aim is to highlight areas in which new attitudes and replacements for traditional solutions will be needed if surface‐mounting techniques are to be as cost‐effective as possible.

A general introduction is given to surface mounted devices, processes and machinery, followed by Mullard Electronic Assemblies Division's experience and a description of practical assemblies using surface mounted devices. Thoughts of future possibilities and requirements of substrate systems for the advancement of surface mounted assemblies are also presented.

This paper describes some recent innovations in design, process and materials in printed circuit laminate technology, which can lead to significant paradigm shifts in the design and application of electronic products. The traditional roles for printed circuit cards and boards have been to provide wiring interconnection capacity, and a robust mechanical structure for the more delicate and costly chips and modules. The advent of surface mount technology eliminated the need for plated‐through holes as anchors for pinned components. The proliferation of light, high performance, multifunction electronic products will lead to light weight, small, low profile printed circuit assemblies. Adding a redistribution layer to the traditional card surface allows flip‐chip‐on‐board and MCM‐L packages as a low‐cost alternative to traditional high density MCM packages, particularly in applications where size, shape and weight are as important as density and performance. Concurrent with the deliberate evolution of traditional printed circuit technology, some important new materials and process innovations have brought about a new generation of laminate capabilities that are particularly important for the future high I/O requirements predicted for the second part of this decade.

This paper describes how PCB designers must adjust their approach to take into account the new requirements for the production of high technology printed circuit boards using the latest plated‐through hole and surface mounting techniques. It also describes how the correct use of dry film solder masks is contributing towards the achievement of zero‐defect soldering.

Printed (circuit) boards have been used in the electronics industry for the past 25 years and more. The technology used to design and manufacture PCBs is well known and accepted. Recently, however, designers of electronic equipment have shown that the use of newer materials and systems, such as flexible and moulded circuits, hybrid circuits, or a combination of these, can significantly improve the cost/performance ratio for electronic interconnects. This paper examines some of the many possibilities open to electronics designers and how these new opportunities can improve the economics and performance of electronic equipment.

A wire matrix has been developed for mounting LED dot matrix displays whereby insulated wires are ‘woven’ to produce a matrix that is fixed on an aluminium board with epoxy adhesive. This monolayer woven wire board simplifies the fabrication process of the display board while at the same time showing more than double the heat dissipation of conventional insulated aluminium printed circuit boards and five times that of conventional glass epoxy printed circuit boards when mounted with bare LED chips. In addition, it is suitable for high‐density and high‐brightness LED dot matrix displays.