Palo Alto Research Center Inc.

Scott J H Limb

Gregory Lewis Whiting

Sean Roark Garner

Jengping Lu

Dirk De Bruyker

Dirk DeBruyker

William S Wong

Steven E Ready

Erica Ronchetto

Robert D Fosdyck

A stressed substrate for transient electronic systems (i.e., electronic systems that visually disappear when triggered to do so) that includes one or more stress-engineered layers that store potential energy in the form of a significant internal stress. An associated trigger mechanism is also provided that, when triggered, causes an initial fracture in the stressed substrate, whereby the fracture energy nearly instantaneously travels throughout the stressed substrate, causing the stressed substrate to shatter into multiple small (e.g., micron-sized) pieces that are difficult to detect. The internal stress is incorporated into the stressed substrate through strategies similar to glass tempering (for example through heat or chemical treatment), or by depositing thin-film layers with large amounts of stress. Patterned fracture features are optionally provided to control the final fractured particle size. Electronic systems built on the substrate are entirely destroyed and dispersed during the transience event.

Stressed substrates for transient electronic systems

A stress-engineered frangible structure includes multiple discrete glass members interconnected by inter-structure bonds to form a complex structural shape. Each glass member includes strengthened (i.e., by way of stress-engineering) glass material portions that are configured to transmit propagating fracture forces throughout the glass member. Each inter-structure bond includes a bonding member (e.g., glass-frit or adhesive) connected to weaker (e.g., untreated, unstrengthened, etched, or thinner) glass member region(s) disposed on one or both interconnected glass members that function to reliably transfer propagating fracture forces from one glass member to other glass member. An optional trigger mechanism generates an initial fracture force in a first (most-upstream) glass member, and the resulting propagating fracture forces are transferred by way of inter-structure bonds to all downstream glass members. One-way crack propagation is achieved by providing a weaker member region only on the downstream side of each inter-structure bond.

Complex stress-engineered frangible structures

A method of masking glass in an ion exchange bath includes applying a dissolvable sealant to a cover material, adhering the cover material to a glass part to form a mask on the glass part, immersing the glass part into an ion exchange bath. removing the glass part from the ion exchange bath, and using a solvent to dissolve the sealant and the cover material from the glass part. A mask on glass having a piece of glass, and a dissolvable sealant on a cover material, the dissolvable sealant comprising an inorganic material and a silicate, the dissolvable sealant between the cover material and the piece of glass.

Dissolvable sealant for masking glass in high temperature ion exchange baths

A transient electronic device utilizes a glass-based interposer that is treated using ion-exchange processing to increase its fragility, and includes a trigger device operably mounted on a surface thereof. An integrated circuit (IC) die is then bonded to the interposer, and the interposer is mounted to a package structure where it serves, under normal operating conditions, to operably connect the IC die to the package I/O pins/balls. During a transient event (e.g., when unauthorized tampering is detected), a trigger signal is transmitted to the trigger device, causing the trigger device to generate an initial fracture force that is applied onto the glass-based interposer substrate. The interposer is configured such that the initial fracture force propagates through the glass-based interposer substrate with sufficient energy to both entirely powderize the interposer, and to transfer to the IC die, whereby the IC die also powderizes (i.e., visually disappears).

Transient electronic device with ion-exchanged glass treated interposer

Stress-engineered frangible structures

A thermally tempered glass substrate for transient electronic systems (i.e., including electronic devices that visually disappear when triggered to do so) including two or more fused-together glass structures having different coefficient of thermal expansion (CTE) values disposed in an intermixed arrangement manner that generates and stores potential energy in the form of residual, self-equilibrating internal stresses. In alternative embodiments the substrate includes laminated glass sheets, or glass elements (e.g., beads or cylinders) disposed in a glass layer. A trigger device causes an initial fracture in the thermally tempered glass substrate, whereby the fracture energy nearly instantaneously travels throughout the thermally tempered glass substrate, causing the thermally tempered glass substrate to shatter into multiple small (e.g., micron-sized) pieces that are difficult to detect. Patterned fracture features are optionally provided to control the final fractured particle size. Electronic systems built on the substrate are entirely destroyed and dispersed during the transience event.

Thermally tempered glass substrate using CTE mismatched layers and paste mixtures for transient electronic systems

Multicrystalline silicon (mc-Si) solar cells having patterned light trapping structures (e.g., pyramid or trough features) are generated by printing a liquid mask material from an array of closely-spaced parallel elongated conduits such that portions of the mc-Si wafer are exposed through openings defined between the printed mask features. Closely spaced mask pattern features are achieved using an array of conduits (e.g., micro-springs or straight polyimide cantilevers), where each conduit includes a slit-type, tube-type or ridge/valley-type liquid guiding channel that extends between a fixed base end and a tip end of the conduit such that mask material supplied from a reservoir is precisely ejected from the tip onto the mc-Si wafer. The exposed planar surface portions are then etched to form the desired patterned light trapping structures (e.g., trough structures).

Solar cell texturing

A digital lithography system including a droplet source (printhead) for selectively ejecting liquid droplets of a phase-change masking material, and an imaging system for capturing (generating) image data representing printed features formed by the ejected liquid droplets. The system also includes a digital control system that detects defects in the printed features, for example, by comparing the image data with stored image data. The digital control system then modifies the printed feature to correct the defect, for example, by moving the printhead over the defect and causing the printhead to eject droplets onto the defect's location. In one embodiment, a single-printhead secondary printer operates in conjunction with a multi-printhead main printer to correct defects.

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Palo Alto, CA, United States of America

Scott J H Limb