Jan 22, 2020 ACW Dual-Cure epoxy adhesives are cured by either UV light or heat, and it sounds as if a light-blocking Dual-Cure epoxy might not be possible. But, that’s not the case. A1708-FT is a Dual-Cure epoxy adhesive that blocks almost all light, even into the near IR. If you are trying to cure your adhesive with UV and still filter ambient visible or Near IR light in your device, then A1708-FT might be just what you want.
A1708-FT is based on ACW’s popular Dual-Cure epoxy adhesives A1708-TX and A1708-TX2. It is a thixotropic resin that can be cured to a depth of about 300 microns with UV, and UV plus heat gives a cured resin with excellent adhesion and environmental properties. The UV-vis-Near IR spectra of 30 micron and 300 micron films of A1708-FT are shown in the figure below. Look closely. The % transmission axis is for 0-10%. The 30 micron film blocks 99+% of light all the way to 1,200 nm, and the 300 micron film blocks just about everything from 250 nm to 1,650 nm.
But how does A1708-FT differ from an adhesive containing carbon black? If we added carbon black to A1708-TX, the UV cure would be reduced to a few microns depth. In many cases, that would not work for active alignment applications or even simple alignment tasks where the adhesive is thick and the components must be set in position by UV.
Figure. UV-vis-Near IR spectra of 30 micron and 300 micron films of A1708-FT.