Spotlight on COB

Spotlight on COB


Chances are that you will be presented with a Chip On Board LED light any time now. As a designer you might understandably shrink from yet another wave of semi-conductor technology. After all, your job is to strip bare the rhetoric and specify lights that have both a functional and an aesthetic application.

The good news is that is why we are here – to filter the useful information from the blizzard of less than useful techno-blag. The even better news is that COB technology does offer the designer real advantages!

In the beginning…..

There was the classic LED – with wire leads in a cylindrical reflector package –known as a T-Pack. One LED, one colour – some came with and some without heat dissipation.

Then came SMD LEDs (Surface-Mounted Device). These LEDs hide wire connections.

They are directly soldered on a printed circuit board.

The latest generation of high-power LEDs is characterized by COB (Chip On Board) manufacturing. Numerous tiny semiconductor chips (LEDs) are mounted on a flat circuit board and covered by a common singular phosphor coating – creating an ‘array’.

So what is all the fuss about?

Ppx New COB SlideFinal-918Due to the small size of the LED chip, Chip-on-Board technology allows for a much higher packing density than surface mount technology. This results in higher intensity & greater visual uniformity for the user, no more clusters of dots often seen on early LED lamps.
Benefit: Compactness due to small size of chip High-Intensity, particularly at close distance.

By spreading the smaller LEDs over a wider surface area COB LED lights arguably provide a light that is easier on the eye, as the single point source is broader. A softer radiance is a key consideration for interior design where we find some LEDs are just too stimulating to the eye.

Benefit: Softer radiance.

COB-LED-Packaging-chip-on-board-COB-LED-module-10Watt-LCOB50-BThe mounting of the tiny chips directly on the substrate give added thermal benefits which is good news for longevity and performance. It is a method of LED packaging which has a number of advantages over traditional surface mount technologies such as the use of “T-pack” and Surface mount LEDs.

Benefit: Superior Thermal Performance for better lifetime, stability and reliability.

The figure on the left illustrates the differences in the number of LEDs that can be placed on a 10X10mm square and the resulting power output of the array.

As you can see, by using COB technology, the number of LEDs is 38 times higher than T-Pack technology and 8.5 times higher than surface mount technology, improving the brightness significantly.

Does this replace other technologies – such as remote phosphor? No – it’s another choice that should be weighed up by it’s own merits – including cost. However the new technology is delivered without a significant price disadvantage.

Never forget important issues over quality remain – when choosing all formats of LED, colour consistency, longevity, colour temperature and lumen levels are just as relevant as before. Remember to ask the manufacturer and avoid the bottom of the market!

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