Apple's fingerprint sensor encapsulation tech could be headed for future iPhone
The U.S. Patent and Trademark Office on Thursday published an Apple filing for a unique encapsulation structure which holds both a fingerprint sensor and its conductive bezel, allowing for a smaller, more protective final component suitable for a mobile device.
Apple's patent application, filed in February and titled "Integrally molded die and bezel structure for fingerprint sensors and the like," describes a unitary encapsulation structure that protects a delicate biometric array, while still allowing for a portion of the sensor and bezel to be exposed or thinly coated with a protective seal. While the filing is for a "strip" type sensor, the technology can feasibly be applied to other fingerprinting methods.
As noted in the filing, current electrical-based sensors are formed in a package containing the die, which holds a semiconductor and said sensors along with related circuitry. Because of the small die size, secondary structures like a lead frame and wires are needed to make an electrical connection between the die and the printed circuit board on which it is situated. These structures are then encased in an encapsulation material to protect the intricate wirebonding and other internal components from damage.
Because such sensors can only operate within a certain threshold distance between a user's fingerprint and the die, many encapsulation methods leave the package uncovered.
In one embodiment, the sensor assembly includes a substrate like a PCB or ceramic structure with a region specifically designed to receive a die assembly, as well as regions for holding bezels. The encapsulation structure is molded from a resin or plastic and is injected in such a way as to leave the top portion of the die and bezel parallel or nearly coplanar. These structures can be either partially exposed, or covered with a thin layer of material to protect it from the elements.
In addition to the above embodiments, the filing notes that the bezels can be provided with visual indicators and possibly a light source.
The invention would prove to be of substantial value if Apple were to deploy a fingerprint reader in a future iteration of the iPhone, as the tech would allow for a small, reasonably durable component that can withstand everyday wear and tear.
Apple is widely rumored to be incorporating fingerprint scanning technology into its next-generation iOS devices, with the forthcoming "iPhone 5" being a prime candidate. Rumors and speculation were sparked by the company's 2012 acquisition of biometrics firm Authentec.
Interestingly, Apple's filing cites multiple patents and patent applications on fingerprint biometrics owned by STMicroelectronics, one of the world's largest semiconductor companies. Besides sensors and embedded processing solutions, the firm also supplied Apple with the three-axis gyroscope found in the iPhone 5.