Apple has filed a patent (number 8,372,495) with the U.S. Patent & Trademark Office for an electronic device enclosure using a sandwich construction.
The layer or sandwich construction imparts strength and rigidity while decreasing the overall weight to the housing. The case/housing may have a first layer and a second layer formed from a first material. The case may also include a core formed from a second material. Where the first layer may be bonded to a top surface of the core and the second layer may be bonded to a bottom surface of the core.
Here’s Apple’s background on the invention: “Many electronic devices, including portable devices, have housings made of plastic. Plastic enclosures tend to be relatively inexpensive and simple to manufacture but may be brittle and crack under relatively low stresses or impacts. Other electronic devices have metal housings. Metal casings are durable but may be heavier and/or more expensive to manufacture than an equivalently-sized plastic casing.
“Some electronic devices use a reinforced plastic housing. For example, certain devices may have a housing formed from carbon fiber reinforced plastic (CFRP). A standard CFRP may be made of multiple layers, each of which typically has carbon fibers aligned in a plastic matrix such that the fibers all extend in substantially the same direction within that layer. The carbon fibers impart structural strength and resistance to bending and breaking against force applied transversely to the length of the fibers.
“CFRP materials generally have a high strength to weight ratio and weight to stiffness ratio. However, CFRP materials generally do not resist bending or stresses applied in a direction transverse to the length of the carbon fibers. Further, CFRP may be thicker than a corresponding plastic or metal electronics enclosure having similar weight and/or stiffness.
“It is desirable in many instances for portable electronics to be light weight and be as thin as possible. Therefore, the materials currently used for portable electronics (including CFRP, metal and plastic) may not be desirable for every application, as they may be too heavy, too thick or they may not provide enough structural support.”
Kevin M. Kenney is the inventor.