Palo Alto Research Center Inc.

Xerox Corporation

Dirk DeBruyker

Eugene Michael Chow

Eric Peeters

Armin R Volkel

Thomas Hantschel

Michel A Rosa

John Dunec

Sean Roark Garner

Bowen Cheng

Scott J H Limb

Gregory Lewis Whiting

David Eric Schwartz

Jengping Lu

An ionic wind engine unit for cooling semiconductor circuit assemblies includes a curved micro-spring and an associated electrode that are maintained apart at an appropriate gap distance such that, when subjected to a sufficiently high voltage potential (i.e., as determined by Peek's Law), current crowding at the spring's tip portion creates an electrical field that sufficiently ionizes neutral molecules in a portion of the air-filled region surrounding the tip portion to generate a micro-plasma event. In one engine type the electrode is a metal pad, and in a second engine type the electrode is a second micro-spring. Ionic wind cooling is generated, for example, between an IC die and a base substrate in a flip-chip arrangement, by controlling multiple engines disposed on the facing surfaces to produce an air current in the air gap region separating the IC device and base substrate.

Micro-plasma generation using micro-springs

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

System and methods are disclosed for controlled thermal energy transfer. The system includes a thermal energy source, a thermal energy sink, spaced apart from the thermal energy source, an electrocaloric structure carried by a suspension and configured for alternating physical movement between thermal communication with the thermal energy source and thermal communication with the thermal energy sink, and a control signal source simultaneously providing both a temperature control signal for controlling the temperature of the electrocaloric structure and a movement control signal for controlling the alternating physical movement of the electrocaloric structure between thermal communication with the thermal energy source and thermal communication with the heat sink. Heating or cooling of a desired element may be provided. Movement control may be electrostatic, magnetic, mechanical, etc., and is self-synchronizing with the field employed for temperature control in the electrocaloric structure.

Electrocaloric cooler and heat pump

A flexible metal interconnect structure for transmitting signals between IC devices in flexible electronic devices is formed between two compliant flexible material layers that are laminated together form a multi-layer flexible substrate. The interconnect structure is formed by two rows of spaced-apart conductive pads (metal islands) attached to the inside (facing) surfaces of the flexible material layers. Compliant micro-contact elements such as micro-springs provide sliding metal pressure contacts that maintain electrical connections between the islands during stretching of the composite sheet. Specifically, at least two micro-contact elements are attached to each metal island in one of the rows, with one element in sliding pressure contact with an associated first metal island in the opposing row and the second element in sliding pressure contact with an associated second metal island. The islands and sliding contacts can be patterned into high density traces that accommodate large strains.

Flexible metal interconnect structure

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

Micro-plasma is generated at the tip of a micro-spring by applying a positive voltage to the spring's anchor portion and a negative voltage to an electrode maintained a fixed gap distance from the spring's tip portion. By generating a sufficiently large voltage potential (i.e., as determined by Peek's Law), current crowding at the tip portion of the micro-spring creates an electrical field that sufficiently ionizes neutral molecules in a portion of the air-filled region surrounding the tip portion to generate a micro-plasma event. Ionic wind air currents are generated by producing multiple micro-plasma events using micro-springs disposed in a pattern to produce a pressure differential that causes air movement over the micro-springs. Ionic wind cooling is produced by generating such ionic wind air currents, for example, in the gap region between an IC die and a base substrate disposed in a flip-chip arrangement.

A stacked-die electronic package assembly includes IC chips connected to a base substrate in a flip-chip, offset (e.g., pyramid-type) stacked arrangement by way of single-curved interconnect springs. Each interconnect spring is patterned from a spring metal film that bends to form a cantilevered structure having an anchor portion secured to the base substrate, a body portion that curves upward from the base substrate, and a tip disposed at the free end of the body portion. The IC chips are mounted onto interconnect springs such that contact pads on the chips contact the spring tips, causing the springs to slightly compress. Optional solder is utilized to secure the connection of the spring tips to the contact pads. Optional spacers and adhesive are utilized to maintain proper spacing between the IC chips and the base substrate. The springs are formed with different tip heights to facilitate connection to the stacked IC chips.

Multilevel IC package using interconnect springs

A curved spring structure includes a base (anchor) section extending parallel to a planar substrate surface, a cantilever section extending away from the substrate surface, and an optional elongated section extending from the base section along the substrate surface under the cantilevered section. The cantilever section includes a body portion integrally attached at a lower end to the anchor section and extending at an acute angle relative to the planar surface, and a curved portion integrally attached to an upper end of the body portion and including a downturned tip. A middle section of the curved portion is disposed a first distance away from the planar surface of the substrate, and the downturned tip is disposed a second distance away from the planar surface of the substrate, the first distance being greater than the second distance.

Curved spring structure with downturned tip

A MEMS system including a fixed electrode and a suspended moveable electrode that is controllable over a wide range of motion. In traditional systems where an fixed electrode is positioned under the moveable electrode, the range of motion is limited because the support structure supporting the moveable electrode becomes unstable when the moveable electrode moves too close to the fixed electrode. By repositioning the fixed electrode from being directly underneath the moving electrode, a much wider range of controllable motion is achievable. Wide ranges of controllable motion are particularly important in optical switching applications.

Growing community of inventors

San Jose, CA, United States of America

Dirk DeBruyker