Designer's Corner 23393

DN Staff

April 21, 1997

2 Min Read
Designer's Corner

No-drip pump

Tangency between auger's ball point and seat's flat, angled sides eliminates drip. Rotary pump can deliver 10-200 milligrams of materila with a volumetric accuracy of +/- 3% at volumes to 100 milligrams per second.

When dispensing encapsulation or flip chip underfill materials, volumetric accuracy is critical. The 680 Series Rotary Positive Displacement Pump ensures accurate delivery via:

  1. Positive material shut-off valve. An air cylinder lifts the dispensing auger out of its seat for unobstructed flow.

  2. Closed-loop motor control. The rotary encoder adjusts motor speed in 1 rpm increments to compensate for viscosity changes.

  3. Heating cartridge. Exiting warm air pre-heats material in the feed tube for proper viscosity.

Craig Lazinsky, Camelot Systems, Inc., 145 Ward Hill Ave., Haverhill, MA 01835, 508-373-3742.

Silicon relay

Faster response in a smaller package; silicon micro-machined relays combine the isolating benefits and low leakage of electromagnetic relays with the speed/size advantages of solid-state relays.

Microelectromechanical system (MEMS) is small enough that a multiplexing relay can be put directly on a probe card.

Bonded silicon and glass chips form the relay building blocks. A cavity, etched into the silicon side, houses the deflecting paddle, while the glass side supports an actuator plate.

Applying a voltage to the actuator plate initiates switch action. Electrostatic attraction pulls the paddle towards the glass until the shunt bar closes the circuit.

Designed for automated test equipment, the prototype relay offers millisecond response, high reliability, and low power dissipation.

Harold Joseph, EG&G IC Sensors, 1701 McCarthy Blvd., Milpitas, CA 95035, 408-432-1800.

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