November 29th, 2017
Use of Aluminum and Magnesium Heat Sinks for Cooling Electronic Circuitry
Today, electronic circuitry is used in many industries, including medical, industrial, automotive, and more. Application challenges continue to grow, with the need to pack high processing power in a very limited volume or the need to drive related electronic components such as LEDs. Meeting these electronic requirements, especially in harsh environments or compact space, is challenging. The combination of these high system densities and difficult packaging environments create challenging thermal management conditions for today’s modern circuitry. If not properly managed, the device temperature can reach failure levels. As a result, here at GTV we have seen that thermal management activities have become one of the main engineering priorities for anyone developing circuitry in modern products.
As requirements for thermal capacity continues to increase, keeping electronic circuitry cooled properly becomes an every growing challenge. One of the most common and effective solutions is through the use of aluminum and magnesium heat sinks. The goal is to maintain the temperature of the device, keeping it below critical levels, regardless of the environment.
By using aluminum and magnesium heat sinks, CPU power densities can increase significantly. There are a number of design varieties used, from straight forward cast and machined parts to those which are encapsulated by a structural shell of different materials, including aluminum and magnesium, and potentially other thermally conductive materials such as invar, copper, and nickel. Since the shell fully surrounds and seals the electronic circuitry, the temperature is controlled. The goal is to choose heat sinks made from aluminum and magnesium that have a high thermal conductivity of up to 1,400 W/mK (watts per kelvin per meter), high stiffness up to 50 Msi (thousand square inches), low mass density down to 1.9 g/cm3 (grams per cubic centimeter), and an engineered coefficient of thermal expansion.
One area of significant importance for the use of heat sinks involves applications requiring LED circuits. The newest high-powered LED’s are highly impressive, capable of very high lumen light outputs from very small sized LEDs. In some cases, we can now produce equivalent or greater light output using a single LED than we were able to do using a full string of LEDs in the recent past. The challenge however is in order for these new high powered LED’s to function as intended, heat must be managed and drawn away from the LEDs as they operate. As such, many applications of LEDs requiring high light output today involve an integrated circuit (rigid one-sided, two-side, or flex strip) paired together with a heat sink. These circuits are frequently attached by fastener directly to the heat sinks and utilize thermal paste which helps allow fast and efficient heat transfer directly from the circuit to the heat sink. Heat sinks are typically machined smooth on the side bonded to the circuitry but designed with cooling fins on the opposite side in order to create maximum surface area to dissipate the heat. Good efficient development of compact heat sinks, which need to provide great cooling capacity combined with accurate location of corresponding circuitry, as well as provide excellent mechanical and structural capability, has now become the best prototyping supplier.
To summarize, aluminum and magnesium sinks for the purpose of cooling electronic circuitry are integral to electronic development for both high-powered processors and driver-oriented components like LEDs. Aluminum and magnesium heat sinks allow cost-effective optimization of the overall assembly and safe thermal management of the circuitry when engineered correctly. When aluminum and magnesium are used as the shell in an encapsulated heat sink, they can have very high specific thermal conductivity values. Although magnesium is not quite as good of a thermal conductor as aluminum, its low density makes it a perfect material for applications that are weight-sensitive. Use of magnesium heat sinks as light way thermal management solutions in automotive system design in particular, where weight concerns are paramount, continues to grow strongly.