EXFO is a global leader in the design, manufacture, and marketing of light-based delivery systems. Our focus is within the following market applications:

Applications

UV Curing of Adhesives

The benefits of UV curing materials are fast cure times, low temperature requirements, and low out gassing compared to solvent-based thermal cure materials. UV cure materials are especially useful for the assembly of heat-sensitive devices. The majority of UV cure materials are acrylate or epoxy based. Acrylate-based materials exhibit fast curing characteristics with a radical photopolymerization mechanism; epoxy-based materials normally exhibit prolonged photopolymerization reactions after exposure to UV light. [insert multimedia or cartoon sequence of PI process from 2001 presentation]

The efficiency of the photopolymerization process is strongly dependent upon the overlap of the spectral power density of the curing system and the photoinitiator's absorption spectrum. The standard HBO or mercury lamp offers multiple wavelengths with peak emissions that may be of benefit for curing numerous materials using a single type of lamp system. For example, the standard UV curing system offers versatile curing for both UV acrylate and epoxy materials. [insert spectrum of Hg lamps and typical photoinitiator absorption spectra] However, the broad range of wavelengths may also cause excessive heating, uncontrolled reaction rates and shrinkage. In some special cases, photon bleaching may also occur, such as in the case of ink or DVD writable organic dye. Filters may have to be used to eliminate the IR and/or UVB and UVC spectral components to prevent the detrimental effects of the multi-wavelength curing. Alternatively, UV LEDs may be used if the adhesive and curing configuration allow.