LEDinside recently conducted an in-depth interview with Liquidleds Lighting Corp (Liquidleds) CEO, Mr. Kun-Yuan Chiang (Chiang), in relation to the industry of LED.

Liquidleds has been awarded the “golden medal” for its invention of “High Power LED Light Bulbs Packaging with Liquid Immersed Heat Management Solution”, which not only enhances LED illumination, but also improves the LED heat dissipation, adjusts the LED light direction and reduces the LED cost by “Moscow International Salon of Industrial Property Archimedes”.

Chiang, the inventor of “disposable heat pad”, specializes in LED heat dissipation design including its newly creative solution associated with heat management of which are combined with the use of “liquid” and “thermal pad”, and also holds many KSFs (Key Successful Factors) and patents.

AC LED which is suitable for interior light is needed

”When Liquidleds was established, it tried many ways to develop new technologies of LED heat dissipation and accumulated many design knowhow”, said Chiang.

Liquidleds had its first contact with high power LED in 2001, and obtained “LUXEON LED”, which is formed by LED lenser, reflective cup, and glass glue, from Lumileds US. The heat dissipation of “LUXEON LED” is designed with a high conduction substrate and is packaged with integrated thermoelectrical module. Later, Liquidleds had continued to use a variety of high power LED, and still tried to find a good heat dissipation material.

Chiang had tried and tested almost 2,000 types of materials and completed the method of heat dissipation of LED lamp by using special liquid and thermal pad, also providing a high luminous efficiency to this lamp. For now is to wait for a proper AC LED. However, Seoul Semiconductor launched its new product of AC LED in 2007 just in the wake of related studies on AC LED being published. Liquidleds has immediately contacted and cooperated with them; thus, a brand new AC LED lamp integrated with the heat dissipation solution provided by Liquidleds being formed. At that day, we saw 2W and 4W LED lamps associate with good light shapes and luminous efficiencies. The temperature difference between lamp temperature and room temperature is around 20 degrees centigrade.

Advantages and disadvantages of AC LED

But why is the AC LED? “Because AC LED is workable for household electricity without installing the AC to DC converter”, said Chiang. So, it can save the cost of converters. Also, since the life span of converter is shorter than that of LED components; therefore, it is possible that a LED lamp should malfunction only because of a broken converter, but not of its ended product life. Another distinctive feature of AC LED is its manufacturing has been processed by the area-array pad, which will take 60 turns / s with a 60Hz alternating current, and also makes the life span of AC LED longer than that of DC LED.

The DC LED has been commonly used as the flashlight which is a battery-powered device; therefore, it is quite suitable for the feature of DC LED since no additional converter being required.

However, there are two disadvantages of AC LED. One is that its luminous efficiency is not higher than DC LED’s. It is because that DC LED is still the mainstream product. It is possible that the luminous efficiency of AC LED will catch up with or even exceed that of DC LED in the future. And the second one is the electric shock of AC LED. Therefore, when designing the heat dissipation of AC LED lamps, the thermal pad can not be exposed and should be placed somewhere inside the LED lamps. By doing so, the heat of the thermal pads will be released by liquids. That is also the core design value of Liquidleds.

Mr. Chiang also mentioned that when he contacted Seoul Semiconductor, they did not notice that this LED heat dissipation solution can benefit LED light bulbs. They used to say the application range of AC LED could be wide. However, Chiang still believes that AC LED is suitable, applicable for interior lights, and LED street lamps.

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Liquid Immersed Heat Management Solution solves the problems of “Light Loss”, “Heat Dissipation”, and “Light Shape”.

Since the weakness of the LED luminary is the “light-loss”. Its luminous efficiency will be getting weak after being used for a period of time. The degree of loss depends on different products. Yet, the critical point of solving that problem will rely on the “heat dissipation”. If the heat dissipation is not good, the light dissipation of LEDs will worsen.

“The heat dissipation solution is combined with the use of special liquid and thermal pads, which transfers the heat of LED to metals by means of thermal pads. The metal is a heat retaining material; it can transfer the heat of LED out of the chip very fast. When thermal pads are immersed in the liquid, the heat will be conducted into the liquid”, said Chiang.

The liquid is hard to retain heat, if you want to increase the temperature of the liquid by one degree, then you have to provide a lot of heat. Also, the heat will be diffused and mixed evenly in the liquid by its own convection. In simple terms, its design concept is similar to that of “immersion heater” of which the liquid is surrounded by a glass shell that exposes to air. The heat of the liquid can be conducted outward by the air-convection. By dosing so, it forms a complete heat dissipation convection system.

Chiang also believes that if LED luminaries want to become the main light sources, the best way is to unify the specifications of lamp-holders for favoring customers in relation to their replacing the LED light bulbs. Moreover, the market LED light bulbs are either big or too long (its size will depend on the types of heat dissipation). If AC LED light bulbs have adopted a conventional heat dissipation method such as back heat dissipation, it probably will not meet the needs from customers.

Besides, the use of some DC LED light bulbs will be subject to the environmental constraints. In terms of AC LED light bulbs manufactured by Liquidleds, in addition to no environmental constraints being concerned when using them, since they are vacuum-packaged, the entry of dust will not be allowed.

In terms of luminous efficiency of AC LED light bulbs, since they are designed by special liquid, during the LED light output, an internal reflection will be conducted. Together with the consideration of the proportion of the liquid, the light output efficiency of these LED light bulbs will reach over 65%, and could be better than that of other LED light bulbs of which the light output efficiency is less than 50%. Also, its light-shape can be modified including wide light in addition to the narrow light (or the spot light); furthermore, to broaden its application range.

”The solution of LED street lamps has been developed by Liquidleds and its cooperative firms. This street lamp can be formed by arraying 40 small AC LED light bulbs. Its light-shapes can support each other, and will not affect the mutual heat dissipation. If one light bulb is broken, all you have to do is to replace that one without sending entire lamp for repairing. It will dramatically reduce the cost of repair, maintenance and replacement of the lamp”, said Chiang.

LED luminary, which has already acquired safety certifications and patents, should be popularized in order to save global energy before its price decreased. 

Will AC LED light bulb combined with special liquid be applicable for standard lamp-holder(E27 or E26)?  In terms of this question, Chiang said the max weight is 2 kilos according to the weight regulation of the energy saving light. The weight of their 4W Led light bulb is only 95 grams, 2W LED light buld is only 65 grams, and is in compliance with the regulation. If the power of the LED light bulb is expanded, its weight will still be within the range of the regulated weight.

“Under the environment where heat dissipation is required and luminous angle should be enlarged, to obtain related safety certification is relatively easier, and the Liquidleds has already obtained lots of certifications including UL”, said Chiang. 

“I think the advantages of the AC LED lamp can be classified including lower price, lower heat dissipation cost, zero risk of electric shock, similar to the use of candescent lamp, easy to be mass produced, possess with a great compatibility of the environment and also cost saving. It is just like the candescent lamp invented by Edison, it is a durable product”, said Chiang.

Chiang also reinforces that they have applied for many patents including the structures of heat dissipation, special condiments of liquid, special packaging ways, unique process of production of AC LED light bulbs, and also includes lots of patents approved by G8 which really contributes to the future development of Liquidleds.

So far, Liquidleds has contacted many companies, and still hopes that the price of household AC LED light bulbs could be in compliance with the market price standard which not only popularizes the AC LED light bulbs but also saves global energy. 

Biography of Kun-Yuan Chiang

Kun-Yuan Chiang is General Manager and President of Liquidleds Lighting Corp. Prior to founding Liquidleds Lighting Corp , Kun-Yuan Chiang was Products Manager, Color Star Inc., Taiwan , responsible for the new product development program of next generation LED solution . During the period at Color Star Inc, he works with an excellent RD and product team to finish many innovative projects and new LED product solution. In this role, his RD team got many patterns and awards in LED field.

Previous positions held by Kun-Yuan Chiang include Hsin-Tao Power Station Project Senior Field Superintendent, Taiwan, and later Start-up Engineer, Bechtel Overseas Corp., Kun-Yuan Chiang is a graduate of the Long-Far Technology University of Taiwan where he received a BS in Mechanic in 1981 and 1983 respectively. He spent his early years in LED RD research and got many internal awards& patterns at past 10 years. His unique insight of the technology, combined with his strategic thinking and new product development experience, will ensure that Liquidleds Lighting Corp increases its worldwide reputation for delivering high power AC LED lighting solution to LED industry.

Media contact:
   - Name : Michael Yu
   - Title :  Vice President
   - Mail :  miyu@liquidleds.com.tw
   - office phone : 886-2-2834-6227