A prototype system utilizing a vision technique to monitor the parameters of adhesive beads or sealants is presented. The system uses a structured light technique to investigate adhesive beads and extract information about the shape of the bead from binary images. The geometrical model of the bead, the relationship between this model and the shape of a line of light on the image are investigated. The models for calculating the parameters of the bead and the height of the camera are analyzed. Control strategies are suggested.

Non-conductive adhesive (NCA) flip chip interconnects are emerging as attractive alternatives to lead or lead-free solder interconnects due to their environmental friendliness, lower processing temperatures, and extendability to fine pitch applications. The electrical connectivity of a NCA interconnect relies solely on the pure mechanical contact between the integrated circuit bump and the substrate pad; the electrical conductivity of the contact depends on the mechanical contact pressure, which in turns depends to a large extend on cure shrinkage characteristic of the NCA. In addition, to reduce the cost and increase the output, NCA is usually ramped up to 200 °C and cured for 1 min during the assembly process. However, fast cure reaction poses a great challenge for the accurate measurement of cure shrinkage. In this paper, to precisely determine the cure shrinkage at high temperature, cure shrinkage was first measured at lower temperatures with slow reaction rate by means of thermomechanical analyzer and then extrapolated to high temperatures. With the increase of cure temperature, the maximum of degree of cure will increase, but the maximum cure shrinkage reduces due to the expansion of materials at higher cure temperature. Furthermore, the slopes of the linear relationship between the cure shrinkage and the degree of cure at different cure temperatures after gelation were found to be similar and independent of the cure temperature. The cure shrinkage from gel-point to complete curing was determined to be 4.275%.

Although adhesives, particularly those based on epoxy resins, are finding increasing use in structural applications, their utilization at elevated temperature (>150°C) has been limited by their relatively poor thermal and thermo-oxidative stability. As a result, significant effort has been directed in recent years toward the development of polymers exhibiting increased thermal resistance. Although a wealth of research conducted over several decades has resulted in a myriad of polymer types exhibiting, in some cases, impressive high-temperature performance, many systems have demonstrated poor processability Thus, much emphasis has been placed on developing high-temperature performance while providing processability characteristics that are similar, if not identical, to epoxies. This article considers the various approaches that have been shown to offer such dual capabilities. In addition, the results of various studies undertaken to investigate the effects of elevated temperature on the strength and fatigue resistance of bonded joints are reported.

This issue of MRS Bulletin provides an overview of the state of the art and emerging trends in the area of adhesives. An adhesive is basically defined by its function, which is to assemble two surfaces together. In order to fulfill this function, the properties of an adhesive must include easy positioning at the interface, rapid and complete bond formation and subsequent hardening, and a bond strength adapted to the specific application (structural, permanent, removable, rigid, or soft). A variety of solutions exist in practice, and their application requires an understanding both of polymer chemistry and materials science. The main families of adhesives, their properties, and their basic design principles will be discussed in the articles in this issue, while this introductory article presents an overview of the functions required of adhesives and future trends.

A number of different types of adhesives are used in the assembly of electronic components and devices. This article provides an overview of such adhesives that also have another job–they work at conducting electricity or heat. The resins or binders in these adhesives range from thermosetting to pressure-sensitive. Conductivity is obtained by the judicious choice of filler. For electrically conducting adhesives, the fillers range from silver flake to silver-coated fibers. For thermally conducting adhesives, the fillers range from aluminum oxide to boron nitride. We also discuss a specific type of electrically conducting adhesive–the z-axis film adhesive. In these adhesives, particles are oriented in such a fashion that allows conduction in the direction perpendicular to the adhesive, but not in the plane of the adhesive.

Endaural incisions provide a cosmetic approach to the middle-ear cleft, tympanic membrane for myringoplasty, and attic and antrum for small cavity mastoidectomy. These wounds have traditionally been closed with sutures, but platelet or fibrin adhesives provide an alternative. However, discomfort at the time of suture removal, particularly in children, and the risk of transmission of blood-borne infections in gels are limitations to these wound closure techniques. This paper describes our experience with Histoacryl® glue (butyl-2-cyanoacrylate) in closing endaural incisions.

Adhesive bonding/joining through microwave radiation curing has been evaluated as an alternative processing technology. This technique significantly reduces the required curing time for the adhesive while maintaining equivalent physical characteristics as the adhesive material is polymerized (crosslinked). This results in an improvement in the economics of the process. Testing of samples cured via microwave radiation for evaluation of mechanical properties indicated that the obtained values from the single lap-shear test are in the range of the conventionally cured samples. In general, the ultimate tensile strength, OB, for the microwave processed samples subjected to this single lap-shear test was slightly higher than for conventionally cured samples. This technology shows promise for being applicable to a wide range of high volume, consumer goods industries, where plastics and polymer composites will be processed.

Non-setting adhesives available were assessed for catching insects of medical and veterinary importance. Physical, chemical and handling properties are described. The results of tests are given using the most suitable adhesives against Glossina spp. (tsetse), Aedes aegypti (mosquito), Lutzomyia longipalpis (sandfly), triatomid bugs and cockroaches. Details are given of a formulation suitable for the capture of most insects in a variety of climatic conditions. The manufacturer's addresses are given to prevent difficulties in ordering and obtaining these products.