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Understanding LED components - LED Packages

Posted: 2013/07/08

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The individual light sources in this LED light strip are SMD LED packages.

LED packages are assemblies that house the LED chip. There are many types of LED packages in use today, each with particular applications and advantages. The purposes of LED packages include:

  1. Protecting the LED chip and welded lead wires from direct contact with the environment.
  2. Securing and encapsulating the chip with LED phosphors and epoxy silicone resin
  3. Allowing for versatility and standardization in LED lighting applications

LED packages are crucial LED components that allow the lighting unit to link up the light emitting LED source. When you're looking to source or purchase LED lights, be sure to ask your representative what kinds of LED packaging (and how many packages) are used in the product.

What are the main types of LED packages?

F5 Lamp

These LED packages are the most traditional types, commonly seen in indicator lamps. Recently, the development of white LEDs has allowed for these to be used in lighting applications such as in signs and also in standard commercial and residential lighting applications. They are composed of a double-pronged aluminum frame with the LED chip sitting in a small depression on one of the ends of the prongs. The gold wires are welded , connecting the terminals to the two parts of the frames. The outside is made up of epoxy encapsulation to protect the entire component. They consume relatively low power, rated at about 0.1 W, releasing about 10 lumens each (for comparison, an incandescent 60W light bulb emits about 800 lumens).

This 3W spotlight uses F5 lamp packages as its light source.

SMDs (Surface Mount Devices)

SMD, short for "Surface Mount Device," describes LED packages that can be mounted onto a (typically PCB) surface via welding. SMDs come in all shapes and sizes, and are typically described with a four digit number. 3528 SMDs and 5050 SMDs are presently some of the most commonly used SMDs. The four digit numbers refer to the length and width dimensions of the SMD, in this case, 3.5 x 2.8 mm and 5.0 x 5.0 mm, respectively.

This lamp uses three SMDs to emit light.

After being welded onto circuit boards, these are typically used in LED lights or backlighting for computer monitor or TV screens. The output light and consumed power depends on the LED chip, chips used in 3528 are typically in line with the F5 lamp types, at about 0.1 W and up to 10 lumens output. For larger packages which have effective heat dissipation methods, higher power and light output is possible. The packaging material is typically made of ceramic, or plastics, though many plastics cannot withstand the high LED junction temperature.

SMDs are a very popular packaging method because of their excellent versatility. They are often used in LED light strips and can be installed in a variety of places. For example, take a look at this lighting display in Beijing.

High Power

High power LEDs are typically suitable for powering about 1 to 3 W chips. They can release a couple hundred lumens each and are most commonly used in spotlights, bulb lights and reading lamps. For example, a 1W or 3W spotlight typically uses just one high power LED package as its light source. For higher wattages, more of these high power LEDs are used.

This 5W bulb light uses 5 1W high power LED packages.

This is a 3W LED spotlight as seen from the outside. The lens piece is fastened by a screw-in ring.

We see inside a single 3W high-power LED package mounted unto the circuit board, which is in turn connected to a driver and the MR-16 fixture.

COB Modules

COB (chip on board) LED modules have multiple LED chips mounted onto a single PCB, encapsulated in a phosphor epoxy mix. These modules can reach many hundreds watts, delivering over 10000 lumens. They can often be used in high-bay or exterior lighting.

The 10x10 array of LED chips (1W each) are visible in this 100W LED COB Array Module.

How does packaging affect the LED light?

When manufacturers decide which package type to use, various factors are considered. The main factors are the footprint (size of the package and how much space it will consume), heat dissipation ability and emission angle. For example, an LED tube is better equipped with SMDs because if high power LEDs are used, the space between the LEDs will be far too great, creating a tube that emits light from perhaps only 20 points along a 1.2 m tube. Whereas SMDs (as used in our products) allows the light to be evenly spread throughout up to about 270 different light source points, creating a much more even tube light. Each application has its different requirements and requires a thorough analysis of determining the appropriate package type.

LED tube lights typically use SMDs instead of high power lights so that the output light is more evenly distributed.
Author: Alex

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