Technology you can use 1555

LCP STANDS UP TO RF PACKAGING DEMANDS

The proprietary LCP (liquid crystal polymer) formulation developed by Quantum Leap Packaging allows the hermetic sealing of plastic air cavity packages. Where previously used biphenol or specialized epoxies proved too permeable, the LCP features low permeability and moisture absorption, and high temperature strength.

Typical LCPs melt at 280C, good enough for reflow solder fabrication around 260C, but direct die-attach processes are more demanding. Gold-tin attachment takes place around 320C and gold silicon works at 400C. In contrast, the LCP used in the Quantum RF packages can withstand 350C, and by year end, gold-silicon compatible material will be available.

The LCP's coefficient of thermal expansion (CTE) can be tailored in both degree and direction for compatibility with various package materials, which lowers mean time between failures. These characteristics allow use of a proprietary, less expensive but thermally efficient conducting copper alloy for both the lead frame and base (flange), which are separated by the LCP dielectric ring, for a net 30 percent improvement in heat dissipation. Previous packages used a less thermally efficient copper tungsten flange to ensure CTE compatibility with ceramic dielectric rings and nickel alloy lead frames.

Contact:Michael Zimmerman, Quantum Leap Packaging; Tel (978) 253-6101 e-mail: [email protected]; http://rbi.ims.ca/3849-500

SENSOR SHEET DETECTS MINUTE PRESSURE SIGNALS

Squeezing these sensor sheets produces a charge and resulting voltage on the electrodes similar to piezoelectric materials. But the less expensive "quasi piezoelectric" Emfit sensor is based on a ferro-electret film, which responds to thickness change rather than strain. A permanent charge on the internal "bubbles" within the gas-expanded plastic film between electrodes causes this transducer to work like an active capacitor. As the sheet is compressed, the charges on opposite sides of the bubbles come closer, and a mirror charge is generated on the electrode layers. An additional conductive layer electrically shields the sensor layer and is topped with a PET layer for protection against wear and abrasion.

With appropriate signal processing using a Microchip Technology PIC microcontroller, the sensor mats can detect not only the presence of a patient in a hospital bed, but also whether that person is experiencing tremors typical of seizures. The sensor mats are sensitive enough that they are placed below the mattress, where they can last for years.

Emfit sensors are available in mats or ribbons and can be used for safety mats, switches, and vehicle and pedestrian counting.

Contact:Heikki Raisanen, Emfit Ltd. Tel (358) 14-332-9000; Fax (358) 14-332-9001 e-mail: [email protected]; http://rbi.ims.ca/3849-501

SPRINGS GIVE COMPRESSOR LONG LIFE

A patented magnetic circuit, along with a spring-suspension compliant bearing system, helps provide long life for this reluctance drive linear compressor. The magnetic drive does not use permanent magnets but adapts solenoid technology-with electromagnets driving a sintered iron, pressed-core plunger. The circular leaf springs supporting the plunger have special cutout patterns that tailor force and deflection to the application. These stamped spring-steel disks provide radial stiffness and tight radial airgap tolerances for the plunger in its bore while being axially flexible for plunger compression motion. The arrangement eases assembly but provides the close tolerances needed.

To further adjust the force/deflection characteristics of the compressor, disks can be attached to each plunger end. The multiple disks allow tuning the pump to run at its natural frequency for minimal energy use. Using several disks also reduces the fatigue-inducing stresses in individual springs for longer life.

Contact:Paul Thomas, Rietschle Thomas Sheboygan, Tel (920) 457-4891; Fax (920) 451-4276; e-mail: [email protected]http://rbi.ims.ca/3849-502

DISPLAY FURNISHES A LOOK WITHIN

The basic idea of the DepthCube^TM 3D display seems simple enough-20 color liquid-crystal light-scattering shutters stacked one behind the other can form an image having physical depth. But such a display, even with its 15-micron-thick layers spaced 5 mm apart, would still produce an image that appears as separate layers stacked with jagged edges.

As a demonstration in the Design News office showed, what makes the 1,000-frames/sec rear-projected display useful is the patented algorithm that linearly interpolates RGB (red, green, blue) color values between shutter planes for seamless images. This processing effectively produces 608-layer (19 gaps x 32 vertical points) images. The display thus provides physical depth cues and psychological ones, such as shading, forced perspective, and foreshortening.

The fast-acting shutters are based on technology for welding helmet eyepieces that protect the user's vision. Applications include medical imaging, CAD, CFD, security screening, and complex molecule drug design.

Contact:Alan Sullivan, LightSpace Technologies Tel (203) 846-0033; Fax (203) 846-6655, e-mail: [email protected]; http://rbi.ims.ca/3849-503