19 November 2018
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UL 94 – why the fuss?

Underwriters Laboratories is an independent, product safety testing and certification organisation. Its evaluation and approval can make a huge difference to a manufacturer.

UL (Underwriters Laboratories) was founded in 1894 and, over the last century, has become the world’s best-known independent product safety certification organisation.

More than 19,000 types of products, components and materials systems are now rigorously evaluated each year and, with 20 billion UL marks appearing on 66,000 manufacturers’ products, more and more consumers are looking for products displaying this mark. UL marks are incredibly beneficial, as it shows that manufacturers are meeting the standardised minimum requirements for safe operation and have invested in increased product safety.

Why is UL Classification useful? When you see UL approval, you can be confident in the products safety – there is a decreased risk when using UL approval products, compared to those without. Utilising Underwriters Laboratories standards aids manufacturers to stand out from competitors, as all possible measures have been taken to meet and/or exceed industry standards. UL approval can verify this and allows manufacturers to benefit from a greater reputation.

A growing number of products have been classified with UL 94 Safety Standard – and many of these are available from Ellsworth Adhesives, including:

Robnor ResinLab HX439N, a thermally conductive flame-retardant potting and encapsulating compound. Approved to UL94-V0 Standard, this material offers high adhesion, low shrinkage, and good chemical and water resistance. HX439N is particularly suited for transformers, PCB, control modules and general potting and encapsulation applications.

DOWSIL (Formerly Dow Corning) HC 1100, a one-part RTV solventless silicone conformal coating. Grey in colour, HC 1100 is said to offer fast, tack-free, controlled volatility and low viscosity cure. Thanks to its UL94 V-0 approval, HC 1100 is best suited for electrical applications.

Dymax E-MAX 903-E, a UV/moisture-cure conformal coating engineered for superior circuit protection in thin coating applications requiring less than 0.127 mm (0.005 in) thickness and an ambient shadowed area cure. The product offers a quick cure, high chemical resistance, and is tack free immediately after cooling. E-MAX 903-E is certified to UL94 V-0.

Robnor ResinLab PX700K-1 is a general-purpose flame-retardant potting and encapsulating compound. Approved to UL94 V-0, this material has good thermal conductivity, high electrical insulating characteristics and high adhesion. PX700K-1 is said to work well in high voltage transformer, circuit board and high voltage capacitor applications.

Henkel Loctite Stycast 2850 FT is a two-component, room temperature curing, epoxy encapsulant that is used for components that are exposed to thermal shock and require heat dissipation. It offers a low coefficient of thermal expansion, electrical insulative and thermally conductive properties. UL94 V-0 approved Stycast 2850 FT can be used for PCB protection encapsulants, epoxy potting encapsulants and general epoxy-based applications.

So, how is the UL 94 Safety Standard achieved? Plastic material testing is undertaken with either a Horizontal Burn (HB) test or Vertical Burn (VB) test, determined by the materials application requirements. During all tests, the materials are subject to a flame source for a set duration of time.

Brian Wall

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