The Changing Landscape that is LED Lighting

By Roger ElliottAugust 29, 2016

If it truly was easy...

In the ever changing landscape that is LED lighting, it can be rather difficult for a company to keep up with all the technological and regulatory changes. Everyone likes an easy solution to a problem and when you look at all the options that are available, it does not appear easy by any stretch of the imagination.

The higher efficiency LEDs in the mid-power segment can show great potential for all types of fixtures; and the high power devices can show lower system cost with a smaller footprint. As with any choice there are a number of tradeoffs to these two types of SMD (surface mount device) solutions.

So how can it be easy with all these options, when you just need a simple, elegant solution? This is when higher density devices like COBs start getting discussed. It is very tempting to consider this type of device for all of your manufacturing and production needs. So why not? They are “easy” to handle, they are “easy” for manufacturing, and they are “easy” to meet regulatory certifications. They just make life “easy”.

You might have someone selling you on this ease of process or how easy LED design can be. The reality is that these components are not “easy”, and there are a number of concerns that should be considered.

If you do choose to look at a COB, you may want to start by looking at thermal performance. Most derating curves for this product show a significant decline in performance once temperatures exceed 85c at 25c ambient. The catch is always the ambient… even in the driver world the ambient rise will cause your Tc to rise thus exceeding your initial calculations for lifetime and performance.

Also, handling these devices might not be so “easy” since most are a ceramic substrate that you are trying to secure to a metal heatsink with or without TIM (thermal Interface material). Any defect induced in the handling or that may be present under that package during your assembly could cause improper thermal transfer or even contribute to the failure of the device. Do you inspect every LED you assemble? The below picture shows a pre-assembly defect that will fail:

There are multiple strings of single LED chips under that big yellow surface. They are in a series parallel configuration, thus allowing for current hogging and thermal imbalance. The arrows are pointing out the multiple strings under the encapsulation which has cracking from thermals correlating to the backside TIM being burnt.  

A COB is not inherently “bad”. In the right design they are easy and they are still a great product for lighting and very efficient, but they are not right for everything.

If you are looking to develop a robust system and you honestly want easy visit and check out the L2 modules. These really do make it easy. Select your lumen range, CRI and CCT, then order. Easy!  They even arrive with the TIM in place and with a Cree LED, this is one product you can trust to be of high quality with great performance and price.

Just as mid-power and high-power have their applications, make sure you evaluate your true cost from a system level and not just on a component cost.  Understand that “easy” comes in different forms. Talk to your WGPA sales person or contact for more information.