By David Reed, UT EditorCuyahoga Falls, Ohio-An agreement between Isotherm AG of Uetendorf, Switzerland, and Ohio-based Linden Industries, will see the latter introducing the Swiss firm's encapsulation technology to American makers of electrical products. This will make items such as chargers for electric toothbrushes or cell phones safe for use in areas where they may encounter water, including bathrooms and kitchens as well as various industrial environments.The technology was developed jointly by Isotherm, Salcomp Oy of Finland, and Bayer MaterialScience AG for the European market, and the Finnish firm is already using it to make chargers for companies including Motorola, SONY-Ericsson, Braun, and Remington, according to an announcement from Linden.The new process encapsulates the electronics in a solid, lightweight, seamless casing made of the polyurethane Baydur E from Bayer MaterialScience, replacing the two conventional thermoplastic shells, Linden explains. In addition to providing a watertight seal, the good thermal properties of the polyurethane allow the product to be much smaller, roughly 20 to 30 percent smaller than thermoplastic housings. The encapsulation of the electronics is so thorough that they are completely protected from moisture or dust, the US firm says.Manufacture is also simplified, Linden claims, since the power supply units are made in an efficient single-step process. Liquid polyurethane is injected using Isotherm high-pressure RIM equipment into a closed mould containing the electronic components. The material surrounds the components and cures in less than three minutes and, because this is a chemical reaction, with a low processing temperature and mould temperature of just 50°C, it will not harm electronics during encapsulation.This means that the cord and components are completely encapsulated and cannot be pulled out or loosened. In addition, Linden points out, the flexible and intrinsically flame retardant material provides the electronics with added protection."
