alumina PCBs compare to FR4 PCBs
The choice of substrate material in printed circuit boards impacts the performance, durability and cost of electronic devices. PCBs can be made with a range of materials, and each material has specific advantages and limitations. Two commonly considered options are FR4 and aluminum. Both offer a combination of electrical, thermal and mechanical properties that are suitable for many applications. However, which one is right for your device? This primer examines the key differences between these two common PCB types, helping you select the ideal material for your next project.
alumina pcb are fabricated by applying metallized circuit patterns to a sintered alumina base plate with multilayer builds also possible. They typically feature copper layers with 0.7 to over 3 oz thickness that follow circuit patterns etched into pads, traces and planes similar to a standard pcb. The direct alumina-copper interface facilitates efficient heat transfer and maintains structural stability at peak operating temperatures of over 600degC.
The insulating layer of the alumina pcb is a high-density polyimide or epoxy that offers superior resistance to chemical degradation and high temperature strength. It is a good choice for high reliability, hostile environment, and high power electronic devices that require excellent electrical insulation. Alumina pcbs have an impressive ability to dissipate heat, with thermal conductivity about three times that of FR4.
How do alumina PCBs compare to FR4 PCBs?
Unlike FR4, alumina does not shrink and expand during the manufacturing process. This eliminates the need for additional insulating layers such as rubber, mica or paper, and frees up space on the board for more components. Alumina pcbs are also less bulky, with an average density of only 1.25oz per square inch. This reduced footprint allows the addition of more circuits and higher power levels without increasing the overall size of the device.
Another advantage of alumina is its excellent machinability and thermal conductivity, making it a good choice for applications requiring heavy machining or high-speed circuits. Alumina is also resistant to etching and resists corrosion, which makes it suitable for harsh environment applications.
While alumina has an edge over FR4 in terms of thermal and electrical properties, it has some key drawbacks that should be taken into account before selecting it as the substrate material for your next project. These include: Higher costs than FR4 PCBs due to the specialized materials and production processes involved. Prototypes fabricated with alumina will generally run twice as much as standard FR4 PCBs, at minimum.
Depending on your application, this could prove to be a significant financial consideration. Also, alumina pcbs are not as flexible as FR4 PCBs, which limits the number of components that can be used in your design. While technologies that allow for embedded actives, discretes and passives within alumina have been developed, they are still expensive and limited in their availability. However, alumina’s exceptional performance under shock, vibration and extreme temperature conditions validates its role in many specialized military, oil drilling, aerospace and medical electronics projects where reliability is paramount in unforgiving environments.