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The popular reflow day was repeated at Henley and commenced with Mike Judd giving an overview of current reflow techniques.

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.

In the last decade through‐hole mounting to printed wiring boards has matured and people now have the tools to diagnose and correct any solderability problems which might arise. Such is not the case with surface mount soldering technology. In surface mount the connections are smaller and are often hidden from view. Therefore when a solderability problem does occur it may never be known until the assembly fails. The solution to the situation is to understand the nature of the problems and provide assurance that they will not occur during assembly soldering. This paper is structured in two parts. The first details the types of solderability problems unique to surface mounting. Examples of these problems will be shown and discussed with reference to solder joint life. The second part of the paper discusses the solderability testing of surface mount devices and printed wiring boards intended for surface mounting. This discussion will concentrate on the new quantitative solderability test methods being developed in this company's laboratory for leadless devices and printed wiring boards. As part of this development, new solderability criteria have been defined which reflect the unique problems associated with surface mounting.

As guest editor, I was asked to view Surface Mount Technology (SMT) in the U.S. through the eyes of a member of the Surface Mount Council. As such, my observations are interwoven with the work of the Surface Mount Council.

Alpha Metals Ltd (UK) have announced the appointment of David Crimp to the position of General Manager. Having served the company for four years as Sales Manager, Mr Crimp now assumes complete responsibility for Alpha's entire UK operation. Prior to his appointment with Alpha Metals, he was employed by AMAX in both the UK and France.

The International Electronic Components Show in Paris in November, 1983, provided the occasion for a very successful meeting of ISHM‐France which attracted 170 attendees. The following presentations were given:

The UK is a leader in the implementation of surface mount technology, and SMARTEX '91 sponsored by the SMART Group is one of only a few shows organised worldwide which is dedicated solely to this field. Perhaps it was not surprising then that this year's three‐day event proved a great success.

ISHM invites papers for the above Conference, to be held on 29–31 May 1991 in Rotterdam, The Netherlands. Papers should cover areas such as: design, manufacturing, packaging and interconnection, materials and processing, applications, reliability, components, new technologies, marketing and economics, optoelectronics. Summaries should be in English, length 200–300 words. The deadline for receipt of summaries is 30 September 1990. (For full details, see announcement on pp. 54–55.)

Earl Moon of Viking Interconnect Systems addressed those present at the 21 May meeting on the subject of ‘Characterisation of Military SMT/MLB Requirements as a Function of the Total Package Concept’.

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.