Advanced light curing practices for electronic and optoelectronic assembly

Previous research and ongoing materials evaluation continue to demonstrate that the developed properties of light curing adhesives are directly affected by their conditions of cure. The use of ultraviolet light to cure adhesives is a well established method for the assembly of small components. Advanced curing practices have been shown to improve developed material properties, evidenced by Differential Scanning Calorimetry and Shore Microhardness testing, as well as actual device performance data. Such curing techniques can include multiple phase light exposure and component preheating. More recently, controlled delivery of light in the infrared spectrum has been shown suitable for initiating heat cured adhesives. Contemporary experience with small electronic components suggests that targeting partial cure of catalytic adhesives can improve process yield, when compared with processing to full cure in a conventional oven. This paper reviews newly developed applications and processes based on a-priori characterization of the adhesive products involved. We further demonstrate cases where the adhesive manufacturer's published curing recommendations may be insufficient to generate best results.