Last September Patently Apple posted a report titled "Revealing Apple Patent Covers Ceramic Apple Watch and All-New Ceramic iPhone" Today the US Patent & Trademark Office published a patent application from Apple that reveals the first ever industrial process for 'Laser Polishing Ceramic Material' on a future iPhone. Technically speaking, the crystallinity of ceramic materials ranges from highly oriented to semi-crystalline, and often completely amorphous (e.g., glasses). The minute you talk about amorphous/glass, you're also entering the realm of liquid metal. As Liquidmetal Technologies explains it "Liquidmetal® alloys belong to a class of highly engineered materials called Bulk Metallic Glasses (BMG), which have been developed with the goal of advancing physical material properties to their theoretical limits." Patently Apple posted a report in November titled "Rumor Claims Apple will Shift to Glass iPhone in 2017 to Accommodate Wireless Charging." It's very possible that the "glass" iPhone will be using materials noted in Apple's latest patent filing revealed today by the U.S. Patent Office.
Technically speaking, corundum is a crystalline form of aluminum oxide and may be found in various colors, many of which are generally referred to as sapphire. In general, sapphire is a hard and strong material with a hardness of 9.0 on the Mohs scale, and, as such, is capable of scratching nearly all other minerals. Because of its hardness and strength, sapphire may be an attractive alternative to other translucent materials like polycarbonate. However, due in part to its inherent properties, manufacturing components out of sapphire may be difficult in high-volume manufacturing conditions. In particular, sapphire's hardness makes polishing the material both difficult and time consuming particularly if the component includes contoured surfaces or features.
Apple's invention relates to techniques for polishing a portion of a surface of a ceramic component. The ceramic component may be formed from a transparent ceramic material, such as sapphire, zirconia, or other similar material.
Numerous consumer and non-consumer devices utilize protective coverings, windows, and/or surfaces formed from hard materials, including various transparent ceramic materials. Compared to other optically clear materials, such as polycarbonate, hard ceramic materials like sapphire offer improved scratch resistance and strength. However, as previously mentioned, sapphire may be difficult to polish using traditional techniques. In particular, portions of a sapphire component that have contoured, curved, or otherwise non-planar surfaces may be difficult to polish using abrasive polishing techniques.
High-temperature annealing may be used to polish a surface of a ceramic component made from materials including sapphire or zirconia. Localized high-temperature annealing may promote movement and/or flow within the material near the surface, which may reduce the roughness and/or irregularities on the surface of the component while maintaining the structural integrity of the core or remainder of the component.
For ceramics that are formed from a crystalline structure, a high-temperature annealing process may allow for realignment of the crystalline structure into a lower-energy state, which may improve the smoothness of the surface and/or increase the strength of the component by removing micro-cracks or other surface defects.
Using a laser, high-temperature annealing may be well controlled over a localized region, which may be advantageous when polishing a contoured feature or non-planar surface, particularly if the feature or surface is located within a flat sheet component that has already been polished.
In some embodiments a localized region of the surface of a ceramic component may be polished using a laser-based annealing process. To reduce thermally induced stress, the laser-based process may be controlled to minimize thermal gradients within the material. For example, the size of the heated region, the duration of the heating, the depth of the heating, and other similar factors may be controlled to reduce thermally induced stress as a result of the laser-based annealing process. In some implementations, short pulses of the laser are used to ablate or otherwise remove small portions of the ceramic component and polish the surface of the ceramic component while minimizing thermally induced stress. Additionally or alternatively, the component may be heated by a furnace or other laser-based process to reduce the thermal gradient between the polished region and other regions of the ceramic component.
Apple's patent FIG. 6 below depicts a schematic view of an exemplary system for polishing a sapphire component.
Apple notes in their patent filing that "a sapphire component is described as an example ceramic component. However, processes may also be applied to other types of ceramics having various form factors. In the following examples, the sapphire component may include a sheet of sapphire material less than 3 mm thick and may be obtained from a variety of sources, natural and/or synthetic.
As one non-limiting example, the sapphire component may be a sheet between approximately 1 mm in thickness cut from a cylindrical boule of sapphire material. In some cases, the sapphire component may be a laminate composite having multiple layers and at least one layer made from a sapphire material. Other layers in the sapphire laminate may include, for example, silicate glass, a polymer sheet, or additional layers of sapphire material.
Apple's patent application 20170029327 was filed back in Q3 2015, well after the debacle relating to their GT Advanced partnership. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
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