Electronic Design


Cooler Chills Air To 20°F While Purging Contaminants
The Non-Hazardous Purge (NHP) Cabinet Coolers use a vortex tube to chill an ordinary supply of compressed air to 20°F without the help of any refrigerants or environmentally harmful CFCs. Under normal conditions, the system passes 1 SCFM of air through the cooler to maintain a slight positive pressure inside the electrical enclosure. Once the thermostat detects a high temperature, it energizes the solenoid to pass line pressure to the cooler, producing full cooling capacity.

This process also keeps the inside of the panel clean and free of contaminants like dirt, smoke, and water. These coolers have capacities up to 2800 Btu/h. They're suited for NEMA 12, 4, and 4X enclosures. Corrosion-resistant stainless steel construction is available. All models are UL listed as well. They can be used to cool microprocessors, PLCs, motor drives, and robotic controls. They are not suitable for explosive or flammable environments.

Prices start at $450.

EXAIR Corp., 1250 Century Circle N, Cincinnati, OH 45246-3309; (800) 903-9247; fax (513) 671-3363; www.exair.com.

Series Of Heatsinks Designed For 486 And Pentium Processors
A series of super-cooling, fan-enhanced heatsinks for heat-generating workstations and servers can be used to optimize CPU speed and stability. For example, the A10 provides a chilly thermal resistance of 1.14°C/W \[Tj−Ta/W (T-junction)\] for 733 MHz, where Tj = 72.36 and Ta = 45°C. Designed for use in 486 and newer processors, these heatsinks specifically target P5 and P60 Pentium, Pentium Pro, Pentium II, and Pentium III machines. They're made out of extruded aluminum, and their assembly is a combination of a heatsink and stainless steel mounting clip and a Furon C1055 thermal pad or Dow Corning thermal compound SC102. All of the members of the series exceed the relevant UL/CSA, VDE, and CE requirements. The fans themselves are rated at 50,000 hours strong.

Pricing ranges from $2.90 to $3.99 each in 10,000-piece quantities.

Jaro Components Inc., 6600 Park of Commerce Blvd., Boca Raton, FL 33487; (561) 241-6700, ext. 328; www.jaro1.com.

Heatsink System Uses Clips To Cool Power Semiconductor Devices
The Max Clip System is a line of extruded fin heatsinks and clips for power semiconductor devices. It supports increased mounting force and thermal connectivity to heatsinks for reduced thermal resistance. It also provides flexibility in moving or changing devices and in mounting discrete power devices that have no through-holes. Exerting a constant pressure, the clips improve thermal contact and component reliability by applying the right amount of force over the device's center.

The attachment method is very flexible. It increases thermal performance, and it reduces assembly costs as well as future retrofits. Additionally, the system supports rapid automated or manual assembly without the problems associated with the torque control of screws, from over-tightening to component lifting. With higher-volume production, it even supports the use of jigs and high-speed automated equipment in component assembly.

Volume pricing ranges from $1.50 for solutions that cool 15 W, to $3.50 for solutions that cool up to 50 W, to about $7.00 for fan-cooled heatsink solutions that remove up to 300 W. Prototype quantities and pricing also are available.

Aavid Thermalloy, 143 N. Main St., Ste. 206, Concord, NH 03301; (603) 223-9988; fax (603) 223-1738; www.aavid.com.

Thermal Interface Materials Supply Low Thermal Resistance Paths
Thermflow T725 phase-change thermal interface materials provide low thermal resistance paths between semiconductor components and their heatsinks. They have a thermal impedance of 0.03°C-in2/W. Their tacky nature permits fast, accurate positioning without thermal performance degradation. Solid at room temperature, these materials soften at component operating temperatures. Once heated, they conform to fill air gaps and form a very thin bond line. The subsequent low thermal resistance path maximizes the heatsink performance and improves the device's reliability.

The T725 pads are provided in roll form on a carrier liner for convenient manual or automated assembly. Standard pads are supplied kiss-cut in continuous roll form in 100-ft. lengths. They include a pull tab for easy removal of the protective top liner prior to heatsink installation. Roll stock also is available. T725 material can be custom pre-cut for specific power module shapes as well. Prices start at about $0.10/in.2 for kiss-cut pads with a standard release liner pull tab.

Chomerics, 77 Dragon Ct., Woburn, MA 01888-4014; (781) 935-4850; fax (781) 935-4318; www.chomerics.com.

Heatsinks Use Radial Folded Fin Design For Volumetric Efficiency
The Radial Fin line of heatsinks utilize a radial folded fin design to enable a 360° air flow, providing higher volumetric efficiency than traditional extruded heatsinks. Consequently, designers can achieve comparable microprocessor cooling with less air flow, thereby reducing fan noise in quieter PCs. These heatsinks also weigh as little as 50% less than traditional models. They don't require heatsink supports to meet mechanical and vibration requirements. Their CPU diode chassis ambient thermal resistance can reach as low as 0.64°C/W. Additionally, a hand-attachable spring clip lets designers easily mount them on the microprocessor socket.

Prices depend on the model and quantity ordered. In 5000-unit quantities, for instance, the Radial Fin Heat Sink for PGA microprocessors costs $4.89 each.

Molex Inc., 2222 Wellington Ct., Lisle, IL 60532; (800) 78-MOLEX; fax (630) 969-1352; www.molex.com.

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