Published 8/1/2003

Molded-In Fabrics Give New Look and Feel To Electronic Enclosures

Robert D. Leaversuch

Executive Editor

Inclosia Solutions, a unit of Dow Chemical Co., claims to have found a better way to integrate denim, suede, leather, fur, lace, velvet and other fabrics into the surfaces of enclosures for portable devices like cell phones, laptop computers, and pocket calculators. The product-development company says its EXO system, a variant of two-shot overmolding, is more efficient and cost-effective than conventional one-shot insert molding for mating fabrics to enclosures molded of polycarbonate, ABS, and PC/ABS.

“Performance features are no longer the sole differentiator in electronics purchasing,” says Tom Tarnowski, Inclosia Solutions’ global business manager. He argues that the visual and tactile appeal, enhanced by molded-in fabrics, is increasingly important to marketing of consumer electronics. OEMs can exploit fabric decoration to define and strengthen the brand identity of their newest products. Costs are relatively low, since the same tool can be used to incorporate many fabric and color combinations.

The first commercial use of the EXO overmolding system was recently announced by computer maker Hewlett-Packard and Targus Inc., a supplier of electronic accessories. The new HP1000 professional case for the iPAQ pocket computer features a black synthetic-leather panel embedded in a two-shot, hard-soft case of ABS and TPU.

Meanwhile, an effort to capture the aesthetics of natural materials is also under way at Bayer USA in Pittsburgh. Its focus is to exploit natural fibers in film insert molding. Bayer has partnered with a film extruder that has a process for implanting natural fibers in the surface of films made of Bayer’s PC or TPU materials. The resulting films have a fabric feel and are marketed by Bayer as Faria decorative film inserts. These are initially offered in denim and red velvet and are aimed at auto interiors and consumer products.

Overmolding refined

Fabrics have long been insert molded into parts such as automotive floor panels, door liners, and seat components. The usual approach is to insert fabric or carpet in the tool and then back it up by injecting plastic behind it. But fabric-plastic moldings generally don’t achieve quality standards required for consumer enclosures, often showing wear and fraying at the edges. Also, it is critical in electronic enclosures that the fabric be isolated from the interior, since encroachment can cause short-circuits or compromise compliance with UL flame-resistance requirements.

Tarnowski says the EXO process addresses those deficits. It begins by creating fabric blanks or preforms. These are reinforced with laminated film and adhesive backings that minimize fabric degradation, wrinkling, or misalignment during overmolding. The fabric blanks can be used either as flat inserts or can be thermoformed into 3D shapes for more complex applications.

Next, the preforms are loaded robotically into a standard two-shot molding system. The first shot is typically a rigid material that provides a solid backing for the fabric. The second shot overmolds the edges of the preform to seal the perimeter of the fabric (preventing wear at exposed points) and to incorporate molded-in anchors that more firmly fix the fabric in place. This second shot can be of a different (softer) material and/or color. It also opens the door to improved functionality, says Tarnowski. For example, overmolded layers can act as gaskets to provide a water-tight seal.

Inclosia Solutions has set up design and engineering bureaus in the U.S. and the Netherlands, and it plans to add a third in Asia shortly. The company offers electronics OEMs a one-stop source for design, material selection, tooling, prototyping, assembly, and production. For this purpose, Inclosia Solutions has formed a collaborative alliance with Eimo Oyj in Lahti, Finland, a designer and molder of enclosures for telecommunications.