1. MCPCB Part Numbering System


Group 1

Shape - dimension - configuration


Group 2

LED designed package and spacing


Group 3

Board feature(s)

E or V prefix.

  • E for newer 2021 Eurekatronix products

  • V for older 2016 – 2020 VirEnce products

a.    Board shape. 

  • R = Round

  • S = Square

  • RT = Rectangular or long strip

  • O = Ring

  • H = Hexagonal

b.    Board dimension. 

  • 10 = 10mm (diameter or width x length)

  • 20 = 20mm (diameter or width x length)

  • 10150 = 10mm (width) x 150mm (length)

  • etc…

c.    Configuration.

Series Only

  • S1 = single LED

  • L2 = two independent LEDs

  • L3 = three independent LEDs

  • etc…

Parallel Only

  • P2 = up to two LEDs in parallel

  • P3 = up to three LEDs in parallel

  • etc…

Series and/or parallel

  • SP2 = up to two LEDs configurable to either series or parallel

  • SP3 = up to three LEDs configurable to either series or parallel,

  • etc…

d.    Designed LED package. 

  • 17 = 1,7mm x 1,7mm

  • 21 = 2,1mm x 2,1mm

  • 2835 = 2,8mm x 3,5mm

  • Etc…​

e.    LED spacing

Apply only for boards with more than one LED (S2, SP2, SP36, etc…)

  • 01 = 0,1mm gap between LEDs

  • 04 = 0,4mm gap between LEDs

  • 025 = 0,25mm gap between LEDs​

f.    Special board features

  • N = Normal

  • DTP = direct thermal path design

  • FX = flexible (continuous)

  • BD = bendable (one time, fixed bent)

  • HV = high voltage

  • ADZ = anodized

  • HE = high emissivity back (coated or finned)

g.    Board’s base material (excludes the copper trace and solder mask thicknesses)

  • A1 = 6061 aluminum

  • A2 = 5052 aluminum

  • A3 = 1010 aluminum

  • C = Copper

  • AN = Aluminum Nitride

  • P = Polyimide

h.    Board thickness

  • 15 = 1,5mm

  • 20 = 2mm

  • Etc…

i.    Board dielectric layer thickness

  • 30 = 30μm = 0,03mm

  • 100 = 100μm = 0,1mm

  • Etc…

j.    Copper circuit layer thickness

  • 35 = 0,035mm (1 Oz)

  • 70 = 0,07mm (2 Oz)

  • 105 = 0,105mm (3 Oz)

  • Etc...


Group 4

Additional board information

Example 1: "VR21SP4-21.025-N-A1.20.30.35"

Group 1: VR21SP4

-    VirEnce product prior to 2021. 
-    Round shaped
-    21mm diameter
-    Up to 4 LEDs in parallel or series configuration

Group 2: 21.025 

-    Designed for 2,1mm x 2,1mm LEDs
-    0,25mm spacing between the four LEDs

Group 3:

-    No special features

Group 3: A1.20.30.35 
-    Base metal made from 2mm thick 6061 aluminum
-    30μm dielectric thickness 

-    35μm copper layer thickness

Example 2: "ER16L4-17.01-N-C.15.40.105" 


Group 1: ER16L4

-    Eurekatronix product. 
-    Round shaped
-    16mm diameter
-    Up to 4 independent LEDs configuration

Group 2: 17.01
-    Designed for 1,7mm x 1,7mm LEDs
-    0,1mm spacing between the four LEDs

Group 3: N

-    No special feature

Group 4: C.15.40.105
-    Base metal made from 1,5mm copper
-    40μm dielectric thickness

-    105μm copper layer thickness

Example 3: "VS35SP36-30.04-MV-A2.20.100.70"

Group 1: VS35SP36

-    VirEnce product prior to 2021. 

-    Square shaped

-    35mm x 35mm

-    Up to 36 LEDs in either series or parallel configuration

Group 2: 30.04

-    Designed for 3mm x 3mm LEDs

-    0,4mm spacing between the LEDs

Group 3: MV

-    Designed for medium voltage application

Group 4: A2.20.100.70

-    Base metal made from 2mm thick 5052 aluminum

-    100μm dielectric thickness

-    70μm copper layer thickness

Example 4: "ER20S1-35-DTP-C.15.40.105"

Group 1: ER20S1

-    Eurekatronix product. 

-    Round shaped

-    20mm diameter

-    Single LED configuration

Group 2: 35

-    Designed for 3,5mm x 3,5mm packaged LED

Group 3: DTP

-    Featured a direct thermal path design.

Group 4: C.15.40.105

-    Base metal made from 1,5mm thick copper

-    40μm dielectric thickness

-    105μm copper layer thickness

In the picture are two Nichia E21A reels. There are lots of internal codes there, but let's focus only on the two strings:

From top reel: sm453D220R9080. 

From bottom reel: sm503D240M1R9080


Put some dashes to isolate the important information. Thus,

Top reel: sm453-D220-R9080. 

Bottom reel: sm503-D240-M1-R9080

The voltage bin information (M1) isn't always included in every reel label, but can be seen in the Inspection chart sheet. According to the datasheet above, the breakdown of above information means:

Top reel: sm453-D220-R9080

CCT of 4500K within 3 steps Macadam ellipse, 220 - 240lm minimum, 90CRI and R9 of 80 points minimum. All measured at 700mA test current

Bottom reel: sm503-D240-M1-R9080

CCT of 5000K within 3 steps Macadam ellipse, 240 - 260lm minimum, 3 - 3,2Volts, 90CRI and R9 of 80 points minimum. All measured at 700mA test current

Now, let's check below screenshots taken from the datasheet:

According to the table on the left, E21A sm453 variant has three flux ranks: D200, D220, and D240. It's easy to pick D240 since it's the brightest of them all, or is it not? This is not the problem if you only care for maximum brightness with the least power input. But why would you use a very high CRI LED in the first place if you only care about the output? Low CRI variant at R70 has the D340 which is super efficient.

Now check another datasheet screenshot at top right. As you can see, the chromaticity point changes depending on the current applied and operational LED die junction temperature. This is the nature of LED which is a big problem if consistent chromaticity is one of the most important aspect in your lighting such as in photography, movie making, and color printing laboratories. For general uses, our eyes adapt very well to small changes given enough time. Within 3 steps Macadam ellipse, only those with super sensitive eyes able to instantly detects the changes.

This apply to almost any LED: brighter flux bin within the same CCT and CRI class will have chromaticity point higher than those with dimmer flux bin. In this case, the D240 chromaticity point will be located above the D200. What does this mean in real world applications? Now check the diagram on the right...

Neutral chromaticity refers to any points which track closely to the Blackbody locus (BBL). Using our example above, assuming the D220 measured right on the BBL, then the D240 flux bin will almost always located above the BBL (positive duv). The opposite is true for the D200 flux bin which will be located lower than BBL (negative duv).

Let's say an LED with neutral chromaticity measured at 700mA, it will cast more green or yellow color (CCT dependent) at lower current and/or colder temperature. At higher current and/or hotter temperature, it will also cast more red or magenta color (again, CCT dependent). This all means, that if your application requires a very consistent chromaticity, selecting the right flux bin in the first place will make a big difference. Choose specific flux bin for specific current application or when the system spends more time working at that particular current range. You can get the information by carefully check the product page. I always include Maukka's spectrum test in almost all of the LED I sell. Check for the chromaticity point (Duv).  A very high CRI LED with overly positive or negative chromaticity looks worse than a low CRI LED with a well balanced chromaticity. A slightly negative duv (approximately down to -0,005) for CCT 4000K - 5000K is desireable by most people for it's rosy appearance which effectively boost healthy skin tone complexion. On the other hand, a slightly positive duv has far fewer fans, although the sun as the ultimate comparator is just like that!

Below images are digitally altered very close to what they would look like in the real world to better illustrate how either extremely positive and negative duv are a bad thing.

To overcome this problem, PWM (Pulsed Width Modulation) controlled lighting system solved most of the problem when consistent chromaticity is needed in a dimmable system. PWM works by fixing the operating current fed to the LED and adjusting the on and off time of the LED at high frequency to alter perceived brightness. Longer total off time will produce dimmer perceived brightness and the opposite is true with more on time. Temperature compensation/regulation can be added to further refine the system.

But for portable lighting applications where efficiency is very important, PWM is less desired. Unlike LASER diode, LED works more efficient at lower current. Designers have to choose at what operating current and temperature the chosen LED work mostly. Otherwise, the lighting system will have too wide chromaticity swings. Another option is to use multiple LEDs to narrow down the operating current range. Or as simple as a combination of fixed current controlled system with multiple LED chips switched on/off for desired output - more output = more LED switched on. The latter assuming that creating a driver with ultra wide voltage output is not a problem.

Chromaticity shift or widely known as "tint shift" is more prominent in high power LEDs with their extremely wide usable operating current. In our example, a single Nichia E21A can be driven from as low as 0,01A all the way up to 2000mA. Or much wider for higher power LED such as 149AM with max rated current of 4500mA. On the other hand, low and mid power LEDs such as Nichia 757 series working current is only up to 400mA for 757GR-V3 and mostly 150mA for the rest, resulting in an almost unnoticeable tint shifting even in maximum brightness down to off dimming operation.

2. Nichia LED part numbering system

As the biggest LED manufacturer, Nichia is best known for its color quality and reliability. At first, LED always associated with highly efficient light source compared to old incandescent or CFL. But as the technology matured, most of us reached to a point that using the brightest and most efficient LED is not the most pleasant experience, especially in general lighting. This is the area where Nichia excels - creating very high quality LED light source for almost every situations. Nichia LED binning system revolved around factors which determines specific light parameters for optimal desired lighting quality. 

So, if you're new to LED color system, then it's best to check and study below topics before proceeding further:


In general, Nichia part numbering goes as follow:

But outside the standard part number, there are other codes which are very useful for determining the best LED for particular application such as color temperature, output rank, and CRI rank. Below is an examples of how to make the most of the codes to your advantage.


For this exercise, you will need to download these two files:

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