How to judge the Heat sink Performance of a LED lamps

How to judge the Heat sink Performance of a LED lamps?

inspect illumination changes within 30 minutes. (An illumination measurement in 30 minute)

To judge whether heat sink performance of a LED lamp is good or not, the most direct method is to measure the temperature of led chips when the lamp is on whose technical term is “junction temperature”, and obviously it is only a theory.

Maybe someone says advanced technology for heat sink performance analysis through numerical technique is a good method. But for the junction temperature is hidden when the finished lamp was made. That is why we have to collect so many measurements to help judge the heatsink quality of lamps.


As we cannot directly measure the junction temperature, is there an indirect methods which can tell the junction temperature?Fortunately, when LED junction temperature rise, the luminous flux will decline.So, if we can measure the flux of the lamp in the same location, we can know the change of the junction temperature.

The particular instruction is:

  1. Choose a place which without external light interference, had better be in the evening, turn off the other lights.
  2. Measure the illumination lux in a location, write down the reading as the “cold illumination”.
  3. Keep the position of lamps and illuminometer unchanged, lamps keep on working too.
  4. Write down the data of the illuminometer after half an hour, as the “Hot illumination”
  5. If the two numbers are near, in a range about 10 ~ 15%, then the heat sink of lamp is good.
  6. If the two Numbers are far greater than 20%, then the heat sink of this lamp should be improved.
Pic 1. The difference of the junction temperature by the indirect measurement of “An illumination measurement in 30 minute.”

Pic. The difference of the junction temperature by the indirect measurement of “An illumination measurement in 30 minute.”

But what is the reasonable range of an illumination decline? That could only be depends on the performance of the LED chips.

A scope of application in “An illumination measurement in 30 minute.”

We enumerate the “luminous flux vs junction temperature” change curve of several commonly used chip, and from the curve, we can know how many lumen flux decline, and indirectly know junction temperature rose to how many degrees Celsius.

Pic 2. OSRAM S5(3030) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 120°C

pic. OSRAM S5(3030) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 120°C

Pic 3. OSRAM S8(5050) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 120 ℃

Pic. OSRAM S8(5050) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 120 °C

OSRAM E5(5630) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 140 °C

Pic 4. OSRAM E5(5630) chip, Luminous flux decreased by 20% when at 25 °C, junction temperature has more than 140 °C

Pic. LuminusSensus Serieschiip, Luminous flux decreased by 15% when at 25 °C, junction temperature has more than 105°C

Pic.5. LuminusSensus Serieschiip, Luminous flux decreased by 15% when at 25 °C, junction temperature has more than 105°C


From the pictures above, it can tel, if the Luminous Flux decrease by 20%, the junction temperature was already over the tolerate range. And the heatsink system is definitely unqualified.

OSLON SSL 80 chip

Pic. 6 OSLON SSL 80 chip

OSLON Square 1-5w chip [PDF], when the junction temperature was raised from 25℃ to 45℃, the illumination flux was raised. And then reached to 120℃, the heatsink performance only declined about 10%. So to this chip, when adopt this measurement way, the change rate should be only 5~8%.

Summary for performance judgement of  the heatsink of led lamps:

  • Thermal conductivity, heat dissipation are very important to LED
  • The key point is junction temperature
  • Suggest to  “An illumination measurement in 30 minute.”
  • The reasonable change scope is based on the temperature curve of the chip
what is G9 bulb

What Is a G9 Bulb?

G9 Light bulbs for home pageWith the passage of time, every aspect of our life has improved, thanks in large to newer technologies. Appliances, gadgets and other devices have made life more convenient and much more efficient. There are devices that have been largely neglected in this rapid progress; one of them is the bulb. They have remained the same throughout the decades, their shapes and functions have remained similar for all these years; this was true, until G9 bulbs were introduced.

G9 Bulbs

You may be wondering ‘what is a G9 bulb?’ the right answer to this question would be, ‘G9s are the bulbs of the future’. When you first look at a G9’s design, you may immediately think that it is something right out of science fiction as it does not look like any kind of light source at all. These halogen creations are completely different than traditional lights, both in looks and in functionality. They do not have the common screw-in base; instead, the G9s have two looped metal prongs for accessing electricity.

There is one similarity that G9s have with classic lights; they are available in different wattage options, just like the bulbs of old. G9s can easily be recognized because of their out-of-the-box shapes and the lack of ‘Edison’ sockets. The prongs of a G9 halogen bulb can only be fixed in a standard halogen fixture. The investment you make in swapping the traditional sockets to halogen sockets will eventually help you cut your electricity bill significantly.

The Advantages

The most prominent benefit of using G9s is that they are highly energy efficient. They utilize a mix of processes that consume very little electricity, but deliver the same amount of light. Another benefit of using G9s is their longevity; a G9 can last much longer than a traditional bulb. They come in varying sizes, so they can be used in any kind of setting. They can be used in lamps and wall sockets in your home, and the larger G9s can be used in industrial settings as well.

Inner Workings

G9 bulbs are commonly made up of a tungsten filament and a halogen based fill gas. The tungsten in them lasts longer because of the presence of halogen gases. G9s are also available in LED alternatives; these are even more energy efficient and cost effective than their halogen counterparts.


The whole process of halogen cycle requires G9s to reach the temperature of 121 centigrade. So, they are very hot and must not be touched after being used. But this risk is mitigated when you buy a LED version of a G9 instead.


The G9 halogen bulbs are most commonly used in consumer appliances, which require smaller lights. They are also ideal for accent lighting and are often used in lamps and desk lights.

Whether you select a halogen G9 or a LED G9, you will be getting an energy efficient, long lasting and affordable alternative to traditional light sources. Now that you know what a G9 bulb is, you may be thinking about switching to it; all you have to do is find the right place to buy G9 bulbs.

The halogen bulbs like led g4 12v are an excellent option for people who are looking to cut down their electricity bills. Before replacing your bulbs, it is highly advisable to consult the right vendors through online forums and sites.

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4 Suggestions For Improving Performance of Heat Radiation for LED Lighting

The lifespan of a LED lighting depends greatly on the amount of heat level, by virtue making of advancement of the heat level is one the vital technologies. However there are complex issues when it comes to solving of problems related to heat generated by the cheap over the heat sink, and that of cooling the entire body. The issues should be addressed in a proper way to increase the performance and efficiency of the LED lighting.

For this case the power of the LED lamp is necessary to consider the heat problem and on the other hand the power LED is needed for cooling purpose. Power LED therefore means an operating current which is greater than 100mA. According to the United States ASSIST Union, there are two types of LED; 2.1V and 3.3V with 210mw and 330mw respectively. By considering the thermal problems of the LED lighting, we are able to increase its lifespan. This therefore calls for a device that is able to spread the heat experienced. In trying to handle this issue of thermal problem, certain parameters have been designed in order to reduce heat resistance and the temperature rise at the junction. This parameters include the thermal parameters and the heat dissipation parameters.

10w g4 halogen replacements-2Thermal resistance is a way of controlling the temperature difference between two state points on an external device in order to produce a steady flow of power across it. As reported by China technologies, the best thermal resistors at the moment for LED power is 10W followed by 5W and lastly 3W in that order. These thermal resistors helps to increase the life reliability.

Junction temperatures is the temperature between the semiconductors found on the LED device. It is normally reflected when the  device is able to withstand the temperature. Improving the heat resistance has created plans targeting the United States SSL. Introducing Chip and Phosphor resistors to the temperature junction will basically increase the reliability of a device. The resistors comes in two i.e. phosphor 150 and phosphor 130. These helps to reduce the requirements needed for heat dissipation.

We have various types of temperature rise. These include the shell-environmental temperature which refers to a device set of temperature (it allows the LED lighting to be measured in terms of hot spot) and the environment temperature difference (it is done on the luminaire level from a distance of 5m from the source of light). This is a direct measurement of temperature difference and the cooling degree between the LED devices. Experimentally, it has been found that if the ambient temperature of the device is 30 and the bulb is 60 then the temperature should remain the same. Raising too high the temperature of the devices will reduce the functionality of the light source therefore reducing it lifespan.

There are two technologies which came into existence due to the development of the LED lighting products. First, the single-tube flux is needed to be increased to a higher current density. This process causes the chip to generate a lot of heat which requires cooling to be done on the LED device. Second, this concerns the structure of the package, when the power of the light source is increasing then it requires more power on the LED chip which is mounted together. The types of structures include the COB structure and the modular lamps. These therefore produce more heat which require more effective devices for cooling and the necessity to handle the new matters which give rise to dissipation of much heat. If not considered very carefully it may greatly affect the performance of the LED lamps hence reducing its life. This therefore means that when a new structure is introduced a perfect set of package should be used together for effective performance to be attained. Considering this precaution will help to increase the functionality of the lamp.

Delivery by airCurrently, in accordance to various types of lamps, research shows that the overall efficiency of lamps is only 50 percent. The reason for the low percentage in efficiency is because of lack of proper devices to reduce the amount of heat produced by the lamps. A lot of power is produced which in turn produce a lot of heat thus lowering the effectiveness of the lamp. These therefore means that more sophisticated technology on led performance should be put in place to handle this issue. Another cause affecting the performance of the lamp is the modular lighting and high current density. These will create points with higher concentration of heat and to avoid this requires proper dissipation of heat.

Consider the following suggestions for heat level improvement

  1. Embrace the new technologies and new structures by use of  chips. At the temperature junction, the LED chips will resist the temperature hence less heat is dissipated.
  2. Consider using the new technology and new package of structures for  devices. This comes with high thermal conductivity, high resistance of heat, phosphor blend, and has new material which comprises of an adhesive between the metal. To meet the above features you have to use a thermal resistance of 10/ W or less.
  3. Use a material with good thermal conductivity to reduce heat up. In this way the ventilation channels should be designed and spread as soon as possible so that the heat required for heat up should not exceed 30. Also consider the use of modular lighting as it helps in reducing the level of heat dissipated.
  4. Use heat pipes to drive away the excess heat dissipated. This means you should put into consideration the cost of designing it.

Furthermore, the design of LED lighting should be made using good thermal conductivity materials with good lighting requirements. This helps the LED lighting to be more efficient, improve the heat level, and have good appearance. Some reports shows that using nanomaterials coated radiator, can improve the thermal performance by 30 percent. In the design of LED lighting, good mechanical properties and tightness should be considered for better results. The required temperature for dust radiator should be relatively small and should be around 30 for  lamps.