Photo-Etched Thermal Devices
Photo etching is a very effective means of producing parts with complex topographies such as heat transfer and radiating devices. Surface area is a key aspect of the rate of thermal conductivity for a particular mass. The ability to create etched features such as raised bosses, channels and other surface effects during the etching process has a relatively minor effect on mass, but can have a dramatic impact on surface area.
In the example pictured below, about 2,000 etched bosses increase the effective surface area by nearly 25%. This particular plate, photo-etched in aluminum and used on the space shuttles, has radiating surfaces on both sides.
Although many thermal devices are produced in aluminum due to light weight and cost, copper is a substantially more efficient conductor of heat. The rate of thermal conductivity is expressed in watts/meter*Kelvin (W/m*K). The rate for pure aluminum (1100 series) is 247 and the rate for copper is 398, nearly 60% greater conductivity. Only silver at 428 and diamond at an astounding 2500 watts are more effective than copper.
Many radiating and heat dissipating applications demand the lighter weight of aluminum. All other things being equal, a copper device will be three times heavier than an aluminum one.
Conard photo etches aluminum up to .080” thick. We also routinely etch copper up to .063” thick. Locational tolerances, regardless of material thickness will be +/-.001” to drawing nominal. Dimensional tolerances at .063” will run +/-.012”.
Photo etching in combination with the excellent thermal conductivity of copper has applications in a variety of thermal management applications including cryo-cooling, commercial refrigeration and heat exchangers.
LED lighting, now widely used in applications including vehicles, traffic signals, emergency service light bars, aircraft exterior lamps and a growing number of commercial and residential lighting fixtures, is known to be vulnerable to thermal failure. Photo etching is a cost effective solution for producing heat dissipating lamp base devices.
