Authored By:
Dr. Aysegul Kascatan Nebioglu, Chris Morrissey
Dymax Corporation, Torrington, CT
Summary
Light-curable materials can provide significant benefits over conventional technologies, including very fast tack free curing, lower operating costs driven by lower labor needs, space savings, lower energy demand, and higher throughput. Encapsulants are often required to protect PCB components against moisture, chemicals, and rapid and extreme temperature changes while providing mechanical support and electrical insulation. We have developed a light and moisture dual curable 100% solids encapsulant that exhibits an excellent balance of properties.
While the key advantage to light-curable encapsulant is the ability to use a non-solvated “green” (100% solids) material, secondary moisture curing allows curing of the material in shadow areas – areas not available to UV light. And, the secondary moisture curing material can be shipped and stored at ambient conditions, does not requiring cold shipping/storage. We will discuss the performance of this material against other light-curable materials as well as other types of encapsulants in reliability tests such as heat and humidity resistance (85 oC / 85 % RH), thermal shock resistance (-55oC to +125oC) and corrosion resistance against salt spray and chemicals.
Conclusions
Encapsulants are used to protect PCB components against mechanically induced damages and environmental effects such as heat, humidity and chemicals. The new light and moisture curing encapsulant (LME1), provided an excellent balance of properties when compared with other commercially available encapsulants. LME1 cures tack-free in seconds with UV light which allows faster processing of the parts. Additionally, it cures tack-free in shadow areas relatively fast and it does not require cold or frozen storage and shipping. This material does not require heating to cure which makes it ideal choice for heat sensitive substrates. LME1 demonstrated excellent performance when tested against high temperature and humidity, thermal shock and salt spray corrosion.
Initially Published in the SMTA Proceedings
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