Volume 7 | Issue 4 | Year 2004

As expansion takes place across the globe, some manufacturers are finding big things come in small packages. This is the case with Aavid Thermalloy, a company that provides thermal solutions and assemblies for everything from personal computers, medical instrumentation, and telecommunications equipment to power supplies, industrial machinery, and even trains. And in the current drive toward miniaturization, in which powerful things are increasingly being contained in smaller packages, Aavid Thermalloy sees itself well positioned to supply the market.

The company was founded in 1964 as Aavid Engineering, a machine shop that worked with metals and machined these into varying shapes; the core capability, however, was the company’s manufacture of heat sinks, devices that divert damaging heat away from machines such as personal computers. Aavid Thermalloy today is part of Aavid Thermal Technologies, a thermal engineering company specializing in system, board, and component level design and analysis using CFD (conceptual fluid dynamics) software and experimental techniques. The company also offers a unique software package called Icepak, touted as fully interactive, object-based thermal management software for optimizing design at every phase of the development cycle.

Says Vice President of Sales and Marketing George Davison, Aavid Thermalloy enables Aavid Thermal Technologies to offer a complete spectrum of services, from concept to final product, with Aavid Thermalloy representing the “execution arm” of the business. This ability has been particularly potent with the trend toward miniaturization as smaller components are embedded with greater functionality, requiring higher performance devices; in short, says Davison, “More heat is required in smaller packages.”

Davison also stresses that Aavid Thermalloy is “a custom product business. Generally we’re more involved in applying our technology to specific applications. Our main value add is that we can solve thermal problems at the front end of the design cycle because of the company’s software and mechanical aspects.”

Heating up the market
With its niche in heat sinks, Aavid Thermalloy is the company with whom businesses consult to find the best solutions, especially in view of the fact that thermal management has become a more important element of electronic product design because of the increase in heat dissipation from microelectronic devices and the reduction in overall form.

According to company literature: “The relationship between the reliability and the operating temperature of a typical silicon semiconductor device shows that a reduction in the temperature corresponds to an exponential increase in the reliability and life expectancy of the device.” Because of this, the durability of a component can be achieved by effectively controlling the device operating temperature within the limits set by the device design engineers.

And this is where heat sinks come in; these devices are specifically engineered to enhance heat dissipation from a hot surface, to a cooler ambient, usually air. The purpose is to maintain the device temperature below the maximum allowable temperature specified by the device manufacturer. In most situations, heat transfer across the interface between the solid surface and the coolant air is the least efficient within the system, and the solid-air interface represents the greatest barrier for heat dissipation. A heat sink lowers this barrier mainly by increasing the surface area that is in direct contact with the coolant.

Aavid Thermalloy has been able to employ its breadth of knowledge and expertise in a number of areas. For example: a power supply customer faced a problem cooling high wattage power semiconductors, which perform crucial switching functions within the power supply circuit. Most power semiconductors are packaged in traditional tab packages such as TO-218, TO-220, and TO-247, which have mounting holes for hardware attachment, while others like TO-252 and TO-262 packages provide no tab or mounting hole. Long standing application methods involve attaching the components to extruded aluminum heat sinks which require that the heat sink have threaded holes and the component have a tab with a mating hole for screw mounting. Mounting semiconductors with loose hardware is labor intensive, creates inconsistent pressure between the device and heat sink, and is obviously impossible with tab-less packages.

To solve all of these problems, Aavid Thermalloy developed a flexible system called MAX CLIP(tm), which allows for quick and easy assembly by integrating a clip mounting feature into extrusion profiles and incorporating a spring clip that contacts the center of the die package. This provides consistent pressure, which improves the thermal performance and increases reliability. In addition, MAX CLIP(tm) is ideal for high volume manufacture because the design allows for automated assembly.

Another problem involved a video graphic array (VGA) customer that experienced a problem cooling increased thermal load for a high performance gaming graphic processor unit (GPU) in a space-confined environment limited especially by its height. As with most standard and aftermarket VGA cards used in personal computers, reducing overall height is critical to preventing encroachment and rendering adjacent industry standard architecture (ISA) slots unusable. Challenged by the heat generated in the latest 128MB and 256MB graphic cards and the lack of sufficient system airflow, a dedicated fan became necessary to dissipate the heat. In most cases, fans would be mounted to the top of a heat sink to blow directly down upon them, but this application involved certain height restrictions. Aavid Thermalloy was able to design and manufacture a heat sink with a recessed fan and mounting system whose total height was no higher than the existing heat sink’s tallest feature. This innovative solution provided superior performance without violating any of the design parameters.

In yet another scenario, this one involving a locomotion/traction customer, Aavid Thermalloy again supplied its unique vision and solution-finding ability. The problem was in cooling next generation traction drives for alternating current (AC) locomotives that generate massive thermal loads. The new power requirement was significantly higher with only a minor increase in airflow. Traditional fin designs could not meet the new goal in the existing space and environmental constraints. Aavid Thermalloy designed an all-copper-augmented fin solution that increased heat transfer by 20 percent. These fins incorporate precisely positioned slots and bends which disrupt the airflow to increase the rate of heat transfer without adding mass or surface area. The new fin geometry was also designed to pass elevated temperature, shock, and vibration testing with a 20-year life requirement.

For a laptop PC customer, Aavid Thermalloy exceeded all of the customer’s complex requirements. This time the problem centered on cooling the central processing unit (CPU), graphic processing unit (GPU), and memory chips in a high performance slim design (15mm) notebook computer with very limited space. Traditional methods of cooling, such as using dedicated fans, were not possible, given the space constraints and the customer’s desire for the solution to have minimum impact on system battery life, acoustic performance, and reliability. In addition, ease of assembly during system manufacture and total cost were major considerations in the design. Aavid Thermalloy designed two heat pipe assembly heat sinks, which cooled all three systems, lowering total system part count and overall cost. In order to do this, Aavid Thermalloy incorporated heat pipe technology, which transported the heat generated by the components away from the source to an area in the system that has access to the airflow required to dissipate the heat.

With three manufacturing sites in North America, which include facilities in New Hampshire, Canada and Mexico; one factory in Asia and two in Europe, Aavid Thermalloy finds itself well positioned to be a leading supplier in its arena. As technology is further developed, the company’s adeptness at engineering complex solutions that fit both large and small packages will prove a boon not only to Aavid Thermalloy but also to the range of companies it can service.