If the electronic design requires fast removal of heat from its components, the best way to achieve this is to use an Aluminum Printed Circuit Board (PCB).
Consider that an aluminum backed board is ten times more effective in removing heat from circuit components than what can be achieved by a regular fiberglass backed board. Therefore, an aluminum backed PCB allows the implementation of designs of higher power and higher density, as it offers significantly higher levels of thermal dissipation.
Aluminum backed PCBs are popularly used in LED applications. This includes general lighting, traffic lighting, and automotive lighting. The aluminum backing in the design of LED PCBs allows a high density of LEDs in the board design and the mounted LEDs to be driven at higher currents, while the LEDs remain within their temperature tolerances. The aluminum-backed design allows designers to reduce the power ratings of the LEDs without decreasing the safety used with power LEDs, compared to the use of conventional PCB material. As the operating temperature of the LEDs drops, they can operate longer before failing.
Construction of Aluminum PCBs
Traditionally, PCB fabricators have been using fiberglass substrates such as FR-4 for manufacturing their boards. Aluminum backed PCBs consist of a standard circuit layer on an aluminum backing plate, with a highly thermally conductive dielectric layer bonding the two. Incidentally, the circuit layer may be as complex as those on a traditional fiberglass board may be.
Aluminum backed PCBs are also highly stable mechanically, and are useful in applications that are subject to high mechanical stress or require a high level of mechanical stability. Compared to fiberglass-based boards, thermal expansion affects PCBs backed with aluminum to a lesser degree. Use of an aluminum-backed design is desirable for applications where the PCB has to have very tight dimensional tolerances and be subject to a great deal of heat.
Although single-sided designs are more common, it is also possible to have a two-sided design with aluminum backing. Circuit layers can be attached to both sides of the aluminum backing through dielectric layers of highly thermally conductive types. Such a double-sided design may even be connected by way of plated through holes. Regardless of whether it is single or double sided, the aluminum backing offers an excellent thermal pathway to the environment surrounding it. It is usual for the solder mask on aluminum backed PCBs to be black in power designs to enable it to radiate heat better.
Although not very popular, other materials such as copper and copper alloys sometimes replace the aluminum backing, but typically at a higher cost. Compared to aluminum, copper and its alloys offer higher levels of thermal heat dissipation. Therefore, if the standard aluminum backed design fails to meet the demands of thermal heat dissipation, the designer can consider using copper backing for their PCB requirements instead.
Use of aluminum backed PCBs help in increasing the reliability and lifespan of a design, as it offers better temperature control, resulting in low component failure rates. Low levels of thermal expansion and high levels of mechanical stability are also characteristic of such PCBs. For more advice on whether your PCB requirements are suitable for using aluminum, please don’t hesitate to contact the team at Synergy Electronics for more information on the advantages of using aluminum PCB’s.
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