SMTA International Conference Proceedings

Non-Isocyanate, Non-Mercury Polyurethane Encapsulation Resins

Authors: Xiaoping Lei, Ph.D., and Darren Hodson
Company: Electrolube Ltd.
Date Published: 10/14/2012   Conference: SMTA International

Abstract: Polyurethane is a unique material that offers the elasticity of rubber combined with the toughness and durability of metal. Because it is available in a very broad hardness range it allows people to replace rubber, plastic and metal with the ultimate in physical properties. For electronic applications the advantages of polyurethane material over other polymers include excellent resistance to abrasion, tear and chemicals such as oil and various solvents, outstanding resistance to oxygen, ozone, sunlight and general weather conditions. Polyurethane also has excellent electrical insulating properties and resistance to low temperatures, remaining flexible down to -30°C. For these reasons polyurethane has found wide applications in the electronics industry as encapsulation/potting resins and conformal coatings, even being mixed/synthesised with other polymers to produce hybrid conformal coatings such as urethane acrylics, urethane alkyds etc.

However, there are two major issues with production of polyurethane polymers. One is obviously the toxicity of the isocyanate and the other is the fact that the most effective catalyst used for the polymerisation contains mercury. These issues become even more pronounced with its use in the electronics industry because the polymerization process normally takes place in situ where the operators have to be exposed to such conditions. To overcome these drawbacks the R&D group in HK Wentworth Limited have carried out intensive research and have now developed a novel system to produce polyurethane polymer without using isocyanate and mercury catalyst. This paper will compare the properties of the polyurethane material cured using the novel non-toxic system and that made from the conventional cure chemistry.

Key Words: 

Non-isocyanate, Urethane linkage, Carbamate groups, Mercury free, Encapsulation resin

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