Experimental evaluation method of curing condition and shrinkage for UV curing adhesive

The application of optical products using Laser or LED (Light Emitting Diode) spreads through industry and other fields, and the precise adhesive bonding technology becomes more important. In this paper, for the optimization of UV (Ultra Violet) curing adhesive bonding using UV Lamp or UV LED irradiation, two evaluation methods of UV curing condition were investigated. One is UV curing speed measurement by peak temperature time using thermography, and the other is UV curing end time estimation by adhesive transmittance change. Furthermore assuming 3D position jointing for small Laser Diode optical system, the relationship between adhesive thickness and UV cure depth was optimized. To observe UV curing shrinkage, the visualization of shrinkage part using image processing was tried, and the real time shrinkage measurement using displacement meter was demonstrated. The required UV irradiation energy can be estimated and the UV curing shrinkage about micro meter level can be measured. By applying these evaluation methods for acrylic and epoxy type UV curing adhesives, the comparison of UV irradiation energy and UV curing shrinkage becomes easier, and it is useful to optimize the irradiation condition in the viewpoint of high precision UV adhesive productivity.