Ultraviolet-curing anaerobic adhesives

FIGURE 8.3 Examples of monomers used in acrylic reaction adhesives, e.g. anaerobic and ultraviolet curing types. 

Instead of directly curing an adhesive, ultraviolet light can replace chemical primers for anaerobic formulations under certain conditions. This technique involves applying the formulation to a substrate and irradiating the coated substrate for a prescribed length of time. Although the adhesive remains liquid, it has become susceptible to anaerobic polymerization and assembly leads to bond formation. 

While the overall rate of increase of adhesive consumption since 1950 has been high, the growth of certain types of products has been especially dramatic. Pressure sensitive and hot melt formulations have been very rapid gainers and anaerobic adhesives too have been strong performers in recent years. Specialty adhesives, including cyanoacrylates (the so-called instant glues) and ultraviolet radiation cured products have also been favorably received. 

Another bonding method which allows rapid assembly and gradual development of bond strength hinges on a combination of anaerobic and ultraviolet light curing.In the attachment of small electronic components to printed circuit boards, drops of adhesive are dispensed onto the board. Each component is then placed on top of the drops so as to form a fillet around... 

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