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To investigate the influences of environmental stresses on board‐embedded polymeric waveguides.

Optical multimode waveguides were embedded on printed circuit boards using commercial polymers. The optical‐PCBs varying in board structure and in optical build‐up materials were exposed to heat, moisture and ionic‐contaminants in accelerated reliability tests. The influence of stress factors on the structural integrity and functional parameters, namely the refractive index and optical transmissivity, was investigated at the key communication wavelengths.

Isothermal annealing reduced the refractive index to the greatest extent. The optical‐PCB structure with an optical surface build‐up layer was observed to be more vulnerable under temperature shock when compared with the optical‐PCB with optical inner layer. The buffer layer beneath the optical build‐up was found to improve the stability of the optical waveguides significantly. The results indicated of wavelength dependence to the aging factor with a failure mechanism. The factors affecting the performance and reliability of polymer‐based optical waveguides on PCBs were discussed.

More experimental data and investigations of failure mechanisms are required to ultimately obtain sufficient reliability statistics for accurate life‐time prediction models.

Optical interconnects are seen as a promising solution to overcome performance limitations encountered with high‐frequency electrical interconnections. As an emerging technology, only a limited amount of reliability data on optical/electrical packages is available. The paper investigates the influences of environmental stresses on board‐embedded polymeric waveguides.

High density interconnect (HDI) printed circuits are now being designed in ever‐increasing quantities for very high‐speed applications. The challenge of opto‐electronics and integration of photonics into the printed circuit has started to take off. In the next 7 years, expectations are that photonic printed circuit boards will grow to a $2.5 billion industry. This paper looks at the issues, materials and current processes being researched by European, Japanese and North American organizations to create this integrated opto‐electronic circuit board. In addition to reviewing the global players in polymer photonics, this paper will review the current programs of four of the six groups globally, namely EOBC‐OptoFoil (University of Ulm, Fraunhafer Inst., Daimler‐Chrysler, Siemens), PolyGuide (Dupont, HP), TOPCat (NIST, 3M, Goodyear), Truemode™ (Terahertz), NTT and JIEP.

Eighty‐five participants attended the 4th ISHM Display meeting at the Jaarbeurs Congress Centre in Utrecht on 16 October, 1986. The programme of the day started with the annual general membership meeting of the Benelux Chapter. The chairman, Mr T. Kwikkers, gave a short review of the state of affairs of ISHM‐Benelux and of the activities of the last year. He mentioned the temporary enlargement of the executive committee to give a new generation a chance to gain experience in the ISHM organisation and to take up some new activities. In order to raise publicity for ISHM and Hybrid Circuits a new brochure has been designed and a set of material for demonstration purposes was collected. With the material every member of the chapter can easily set up a presentation for schools or customers. This year ISHM‐Benelux has grown from 85 to 100 members and enjoys a healthy financial situation. Next year again emphasis will be put on public relations. Professor R. Govaerts signified that he was no longer available for a position in the executive committee. As Prof. Govaerts has been very active and stimulating for the ISHM‐Benelux Chapter from its foundation in 1976 up to now, the general membership meeting decided to appoint him as (the first) honorary member of this chapter. Except for Professor Govaerts, the sitting executive committee, consisting of 15 members, was re‐elected for another year. After the European conferences in Bournemouth and Hamburg the ISHM‐Benelux chapter is asked to organise the 1991 Conference. The executive committee is already looking out for candidates for a function in the organising committee, which must be formed in the coming year.

The purpose of this paper is to study high-voltage interactions in polymer thick-film resistors, namely, polyvinyl chloride (PVC)-graphite thick-film resistors, and their applications in universal trimming of these resistors.

The authors applied high voltages in the form of pulses and impulses of various pulse durations and with different amplitudes to polymer thick-film resistors and observed the variation of resistance of these resistors with high voltages.

The paper finds that high voltages can be used for trimming of polymer thick-film resistors in both directions, i.e. upwards and downwards.

The research implication of this paper is that polymer thick-film resistors can be trimmed downwards or upwards practically using this method.

The practical implications of this paper is that one can trim the polymer thick-film resistors, namely, PVC–graphite thick-film resistors, in both directions, i.e. upwards and downwards, by using this method.

The value of the paper is in showing that high voltages can be used to trim downwards and also upwards in the case of polymer thick-film resistors. This type of trimming is called universal trimming, developed first time for polymer thick-film resistors.

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

The paper describes a new electro‐optical board technology, based on the discrete wiring principle. Isolated copper wires are embedded in the circuit board to realise the electrical interconnections. Glass optical fibres are embedded to obtain optical interconnections. The technology allows for crossovers and for electrical and optical interconnections on one layer of interconnection. As the technology can be applied on the level of package or multichip module, circuit board and backpanel, it has the ability to offer a complete solution for chip to chip electrical and optical interconnections. The paper will describe the basic manufacturing technology of the boards. The benefits of the technology from a system designer's viewpoint will be addressed. The problem of coupling light in and out of the embedded optical fibres will be discussed and the realisation of a first on‐board optical link via embedded optical fibres will be described.

The drive towards low unit cost in optoelectronic packaging is assisted by avoiding the need for hermeticity and by the use of simple assembly techniques. Silicone gels can solve this problem, provided the reliability meets the application requirements. Extensive lifetest data for semiconductor lasers and PIN photodiodes coated in silicone gels are reported in this paper. Results to date show great promise and promote confidence in the use of these materials for the environmental protection of optoelectronic devices. Apart from silicone gels, light cured resin materials can also offer benefits towards lower cost assembly processes. Tests are reported of the degradation in optical transmission of these resins and also bulk degradation under differing environmental conditions. The use of these polymer materials can play an integral part in low‐cost optoelectronic packaging developments, two specific designs of which — a silicon laser optical bench and a ceramic ferrule co‐axial structure — will be described. Both of these packages take advantage of a passive fibre/device alignment allowed by the use of an expanded beam laser design.