Assessment of Low Cost, Sustainable, Reflective Layers for Optical Mixing

Abstract:

The reflective properties of white solder masks are subject to this investigation. Selected materials were used to fabricate test boards with increasing solder resist thickness, ranging from 1 to 4 layers. Reflectivity and reflectivity loss were measured, and some visual and mechanical properties. Our main conclusion is that high reflective white solder masks appear suitable for optical mixing design-in for lighting systems. The main route seems to be to print a first layer of a white photosensitive solder resist, which will define the component footprint for soldering; followed by multiple layers of a screen printed, thermal curable white resist, with slightly bigger opening, which will give the needed reflectivity and stability. Reflectivity increases with increasing layer thickness from 87-90% for one layer of 20µm to 95% for four layers or 80µm. Reflectivity loss up to 10% is observed in the blue spectrum after heat treatment for 1000hrs at 100°C.

• Periodical: Key Engineering Materials (Volume 572)
• Pages: 62-65
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.572.62
• Online since: September 2013
• Authors: Wil Peels, Kevin Cheng, Jonathan Hu, Joe Jiao, Ding Jin, Hans Rebergen, Pauline Sun, Rob van Wijk
• Keywords: Diffuse Reflectivity, Mixing Optics, Reflectivity Loss, Solder Mask, White Solder Resist

References

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