What does LED binning mean

LED Binning, in relation to LEDs is a practice designed to maximize effective utilization in the production of LEDs. It is most important for luminaire manufacturers to specify and control since it has serious implications on performance, cost and lead-time.

In LED production, a single round wafer is coated with materials (epitaxial growth) to create a semiconductor which forms the ‘heart’ of the blue LED. This is then sliced into small rectangles, wire bonds ( or other electrical connectors) are inserted and the phosphor is added as a coating within the enclosure. The whole thing is then encapsulated to create a finished white light LED.

Why is binning needed

binning cubicAs the variations between individual LEDs are big, the current needed to power one led, might overload another. For this reason forward voltage is the first selection made to sort LEDs.

Also the color of light might vary drastically per LED, as stated above that the coating process (epitaxial growth and phophors) creates significant inherent variations that impact color temperature.

Binning can be thought of as an “oversized Rubik‟s Cube” LED Corporations produce this myriad of binning combinations, but using all of these many bins together would result in a wide range of performance.

When LEDs are manufactured they are broadly grouped into color categories such as red, red-orange, cyan, cool white, warm white, etc.

For example, cyan LEDs can range from 490nm to 520nm making the light output from cyan LEDs with a 520nm rating very ‘greenish’. Similarly, red LEDs can range from 645nm to 620nm, making some red LEDs appear very ‘orangey’.

For many applications, this is far too wide a color range to be useful.

Below is example table for cyan LEDs which are binned on the basis of dominant wavelength for colour constancy.

Bin code

Cyan LED

Minimum Dominant Wavelength (nm)

Cyan LED

Maximum Dominant Wavelength (nm)

1

490

495

2

495

500

3

500

505

4

505

510

5

510

515

6

515

520

so as part of the manufacturing process every LED is tested to determine their exact color, lumens output and forward voltage and are then assigned a ‘bin’ number. Users can then request a specific bin number if their application requires tighter tolerances. And Omiitek have four performance ranges, which is higher than the average, many manufacturers have only two. Customers buying from manufacturers with more ranges can expect less variation in their products.

Different LED bins

Some bins might consist of LEDs within a certain max. forward voltage that can be applied safely. Another Bin might consist of LEDs that emit light within a certain minimum and maximum wavelength or flux.

Each LED manufacturing brand divides LEDs by different standards and therefor has their own standard set of lumen bins and provide clear information on expected lumen performance for each of their ranges. The larger a bin size – the more variation you can expect around color temperatures and outputs – small bins have tighter control. but because very often product lines are developed for similar purposes, binning of different brands is never far apart.

Binning Codes

Binning is essential for most but not all LED applications. For example, due to binning it is possible to produce a traffic signal with the specific colour needed to meet the European standard (EN12368 – Standard for Traffic control equipment and signal heads). In the case of a high quality LED luminaire product, proper binning will ensure all the LEDs used have no visible differences in flux (brightness) or colour.

White LEDs are binned for Correlated Colour Temperature (CCT) or by x, y coordinates of the LED in the CIE diagram. The binning structure for white LEDs considers both CCT and the x, y coordinates of the LED whilst binning. This is because of the fact that even white LEDs with approximately the same CCT can have different colour appearances. A typical bin for a white LED might look as follows:

 Bin Code

X

Y

Typical CCT (K)

U0

0.362

0.372

4750

0.360

0.357

0.344

0.344

0.346

0.356

In this example, the bin U0 can only contain LEDs having a correlated colour temperature of 4750 K. However, the colour point of the LEDs can be any of the four X, Y coordinates listed above.