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With the increase in popularity of LED lighting, many people are confused when it comes to choosing an LED lamp.
First we should understand that the quality and price of lamps are determined by four components: LED chip, LED driver, Heat Sink and Printed Circuit Board (PCB).
1. LED Chip
One of the two most important components of an LED lamp, chips come in a wide range of performance standards and consequently the price will vary depending upon the brand of chip used by the manufacturer. While high performance lamps use CREE or OSRAM; the price may be a little rich for most consumers. Instead, you may want to opt for a lamp with a chip from Bridgelux, Samsung or Epistar to name but three affordable, quality chips.Use of a good quality chip results in beautiful color, (as gauged by its color temperature and color rendering index – CRI), as well as high luminous efficacy (a measure of how well a light source produces visible light).
Chip lengths are measured in millimeters (mil) and one millimeter equals one thousandth of an inch. Generally, the larger the chip the better the performance. As specifications and claims by manufacturers tend to be over-stated, it is prudent to compare one lamp with another by determining which components are used in the manufacture of the products in question.
Many manufactures use SMD LED chips in indoor lighting, such as SMD 2835 in LED tubes, and SMD 3014 in LED panel lights. These low power LEDs produce fewer lumens resulting in a light that is easy on the human eye. Simply put, a lumen is a measurement of the amount of light emitted per second. High power LEDs are used in industrial lamps due to their small size and the result is a concentrated light that does an excellent job. Many LED high bay lamps are fitted with 45×45 mil chips and are used and packaged with a chips on board (COB) light source.
For your information, the numbers 2835, 3014, 3528, 5050, 5630 are the names of packaging process models. Another process with a very promising future is the previously mentioned COB light source, where chips are mounted directly on the printed circuit boards (PCB) as opposed to surfaced mount devices (SMD). As these light sources have a variety of features, it's recommended you take a few minutes to familiarize yourself with them in order to best satisfy your requirements.
As you have seen, LED packaging is closely related to its performance and manages a number of functions including heat dissipation, light distribution and varying the color temperature and CRI of the chip.It is interesting to note that a chip that produces white light has yellow phosphor added to it to change the original blue light it initially produces to white.
2. LED Driver
The second key component is the power system, commonly referred to as the driver. It is the limiting factor in the longevity of the LED lamp – while there is an urban myth that alleges the life span of a lamp is as much as 30 years; the driver might only last 1000 to 2000 hours. So ignore manufacturer claims of 50,000 hour of LED lamp life.
A reputable driver, such as Meanwell, can be expected to have 15,000 hours of life. However, the cost would be 80% higher than the average driver manfactured in China. Most manufacturers use their own driver. In these cases it is wise to ask if the capacitor comes from a reputable maker.
Another indication of the life is the warranty offered.
3. Heat Sink
LEDs are temperature sensitive making the heat sink an important concern. Most products use an aluminum alloy heat sink for its cost efficiency and while the specifications don't really tell us much, there are three items we should look at.
A. Thermal conductivity: die-cast 6063 aluminum is the most common material used. The better ones have anodized coating. B. Quantity and size of fins: the more and the bigger the better. C. Heat pipe is used in some high power LED lamps.
4. Printed Circuit Board
The material used and the design of a PCB is important as it connects the chip to the heat sink. A PCB with low thermal conductivity results in a hot lamp. Metal and ceramic core PCBs have a good heat transfer coefficient but most manufacturers choose fiberglass to save money.
