Apple is studying the potential for use of insert injection molding to create smaller and more secure frames (also known as ground rings) for plug connectors used on iPads, iPhones and other electronic devices.
In a U.S. patent awarded this month, Apple said the frames “include features to support contacts, house circuitry for coupling with the contacts, facilitate the flow of molten material during the molding of the frame, and allow for ease of insertion and removal of the plug connector to and from a corresponding receptacle connector. For example, a frame may include ledges, interlocks, and rounded and tapered openings.”
Several potential manufacturing methods are covered by the patent. In three of the methods, insert injection molding is used to form part of the plug. In two of the embodiments, a formed metal component is inserted in the mold cavity.
The invention could indicate a potential breakthrough application for the liquid amorphous metal molding process that Apple has licensed through Liquidmetal, a Cal Tech spin off.
“Methods are provided for metal injection molding processes for forming a plug connector frame that includes some or all of the features described above,” the patent states. “Some of these methods may result in a plug connector frame having distinctive physical characteristics, including an outer layer with increased density, surface hardness and/or reduced porosity as compared to a remainder of the plug connector frame.”
In the third embodiment of the invention, thermoplastic insert molding is used to embed contacts within the first and second openings and a printed circuit board within the cavity. Polyoxymethylene (POM, also called polyacetal) would be “formed around the contacts to provide smooth and substantially flat upper and lower surfaces of the tab or insertion end of plug connector and provide a finished look”.
The patent also disclosed the potential use of powdered metal injection molding (MIM) to make parts. Atomized steel 630 powder would be used in a conventional MIM process.