Metal backed PCBs for high power LED applications - IMS
Metal backed PCBs for high power LED applications / IMS
With recent developments in LED technology, a range of high intensity surface mount LEDs has enabled designers from many industries such as traffic signals, concealed lighting, decorative work and many others, to use LEDs where once they may have used conventional bulbs or lamps.
While usage of this technology continues to expand, there is a challenge to counter the heat generated by the new components in normal running, especially when grouped closely together. This can cause burning of standard FR4 laminate and therefore a failure of the circuit. A solution to this problem is to use metal backed PCBs which are, in essence, thin PCBs bonded to an aluminium backplate of varying thickness. The result is LED PCB boards where any excess heat generated can easily pass through the FR4 laminate of the circuit board and then dissipate quickly into the aluminium, thus allowing the PCB to have its own large ‘heat sink’ permanently attached.
Another facility commonly offered in conjunction with the aluminium backing is the use of black solder resist to allow the heat to be removed by radiation. The use of aluminium backed PCBs or LED PCB boards is of course not limited to high power LEDs and can be of use to any product where heat dissipation is important. The simplest type, and hence most cost effective, metal backed PCBs available are single sided surface mount PCB boards. For more complex circuits, both double sided “plated through holes” (PTH) and multi layer (multilayer) PCBs can also be manufactured using this technique. These require a more complicated manufacturing process for the application of aluminium and also the use of standard multi layer (multilayer) registration techniques.
Final profiling of metal backed circuit boards is generally achieved by routing, though on some simpler PCBs guillotining may be acceptable and more cost effective.
What can be achieved using metal backed PCBs or LED PCB boards
- Insulated metal substrate technology utilises the printed circuit board as a key constituent in heat removal from component devices.
- The thermal efficiency gained by using an aluminium backed board allows downsizing of designs and hardware removal.
- Electrical insulation between the copper and base metal is achieved using dielectric layers with high thermal conductivity.
The advantages of using metal backed PCBs and LED PCB boards:
- Power densities can be increased whilst components are kept cool, increasing life and durability.
- Surface mount technology can remove manual assembly from the traditional heat sink, clip, sil-pad arrangement.
- Dielectrics can be tailored to suit your thermal or insulation level requirements.
- The circuits can be shaped, drilled and formed, an advantage when compared to ceramic based products.
- Cooling properties allow devices to be driven harder or de-rated for lower cost components.
