Method for solving the problem of temperature rise of the white light LED
The release date：2014-09-13 00:00 source：http://www.amlifecn.com Click on the：
OFweek semiconductor lighting network past the LED industry in order to obtain white light LED beam fully, have developed large size LED chip to take the way to achieve the expected goal. However, in fact, white LED applied power lasts more than 1W above the beam may decline, the luminous efficiency decreases 20~30%. in other words, brightness white LED if LED is several times larger than the traditional fluorescent lamp, power consumption characteristics beyond words, it must overcome the following four major issues: inhibition of temperature rise, to ensure that the service life, improve the light efficiency, and luminescent characteristics of equalization.
Solution temperature rise problem is to reduce the package thermal impedance; method to maintain the LED lifetime is improved using a small chip, chip shape; method of luminous efficiency improvement is to improve the structure of LED chip, using a small chip; as for the light emitting characteristics of homogenization method is packaging method for improving LED, these methods have gradually been in the development of.
To solve the problem of heat dissipation package is the fundamental methodDue to the thermal impedance increase power but will cause package dropped sharply to below 10K/W, therefore the overseas industry had developed high temperature resistant white LED, trying to improve the above problems. However, in fact, high-power LED heat quantity than the small power LED high more than ten times, and the temperature rise will make the luminous efficiency sharply. Even if the packaging technology allows high calories, but engage LED chip temperature is likely to exceed the allowable value, finally the industry finally realized to solve the problem of heat dissipation package is the fundamental method.
LED use the life, such as the use of siliceous packaging materials and ceramic packaging materials, can make the LED to improve service life of a digit, especially white LED luminescence spectrum contains a wavelength below 450nm short wavelength light, the traditional epoxy resin encapsulating material can easily be short wavelength light damage, high power white LED light accelerated the big degradation of packaging materials, according to industry test results show less than ten thousand hours of continuous light, has high brightness power LED decreased more than half, simply can not meet the basic requirements of lighting long-life light source.
The luminous efficiency of about LED, improve the chip structure and package structure, can reach the same level and low power LED. The main reason is the increase of current density is 2 times or more, not easily from large chip out light, the result will cause the luminous efficiency as low power white LED dilemma. If the electrode to improve the structure of the chip, the theory can solve the problem of light.
Try to reduce the thermal impedance, improve heat dissipation problems On Luminescent Properties of uniformity, is generally believed that the phosphor material concentration as long as the LED to improve white uniform manufacturing techniques and phosphor, should can overcome these troubles. As mentioned above, to improve the applied power at the same time, must try to reduce the thermal impedance, improve heat dissipation problems. The specific contents are: to reduce the chip to the package thermal impedance, inhibit the package to a printed circuit substrate thermal impedance, improve the smoothness of chip cooling.
In order to reduce the thermal impedance, many foreign manufacturers LED LED chip is arranged in the radiator made of copper and ceramics (heat sink) surface, and then using the welding mode of printed circuit board and radiating wire connected to the forced air cooling radiator using cooling fan. According to the German OSRAM Opto Semi conductors Gmb the experimental results confirmed, LED chip of the structure to the welding point can reduce the thermal resistance is about 9K/W, the traditional LED about 1/6, after the LED package applied 2W electric power, LED chip junction temperature than welding at 18K, even if the printed circuit board, the temperature rises to 50 C, bonding temperature more than 70 DEG C; compared with previous thermal impedance once reduced, LED chip junction temperature will be printed circuit board, the effect of temperature. Therefore, we must try to reduce the temperature of LED chip, in other words, reducing LED chip to the thermal impedance of the welding points, can effectively reduce the cooling effect of the burden of LED chip. Conversely if white light LED with structure for inhibiting thermal impedance heat conduction, if not from the package to a printed circuit board, the LED temperature rise results will still be the luminous efficiency sharply. Therefore, the integration of technology development Panasonic electrical printed circuit board and packaging, the company will 1mm Affirmative Blu ray LED package to flip chip in the ceramic substrate, and then the ceramic substrate is pasted on the copper surface of a printed circuit board, according to the Panasonic reports including printed circuit board, the overall thermal impedance module is about 15K/W or so.
Solution temperature rise problem is to reduce the package thermal impedance; method to maintain the LED lifetime is improved using a small chip, chip shape; method of luminous efficiency improvement is to improve the structure of LED chip, using a small chip; as for the light emitting characteristics of homogenization method is packaging method for improving LED, these methods have gradually been in the development of.
To solve the problem of heat dissipation package is the fundamental methodDue to the thermal impedance increase power but will cause package dropped sharply to below 10K/W, therefore the overseas industry had developed high temperature resistant white LED, trying to improve the above problems. However, in fact, high-power LED heat quantity than the small power LED high more than ten times, and the temperature rise will make the luminous efficiency sharply. Even if the packaging technology allows high calories, but engage LED chip temperature is likely to exceed the allowable value, finally the industry finally realized to solve the problem of heat dissipation package is the fundamental method.
LED use the life, such as the use of siliceous packaging materials and ceramic packaging materials, can make the LED to improve service life of a digit, especially white LED luminescence spectrum contains a wavelength below 450nm short wavelength light, the traditional epoxy resin encapsulating material can easily be short wavelength light damage, high power white LED light accelerated the big degradation of packaging materials, according to industry test results show less than ten thousand hours of continuous light, has high brightness power LED decreased more than half, simply can not meet the basic requirements of lighting long-life light source.
The luminous efficiency of about LED, improve the chip structure and package structure, can reach the same level and low power LED. The main reason is the increase of current density is 2 times or more, not easily from large chip out light, the result will cause the luminous efficiency as low power white LED dilemma. If the electrode to improve the structure of the chip, the theory can solve the problem of light.
Try to reduce the thermal impedance, improve heat dissipation problems On Luminescent Properties of uniformity, is generally believed that the phosphor material concentration as long as the LED to improve white uniform manufacturing techniques and phosphor, should can overcome these troubles. As mentioned above, to improve the applied power at the same time, must try to reduce the thermal impedance, improve heat dissipation problems. The specific contents are: to reduce the chip to the package thermal impedance, inhibit the package to a printed circuit substrate thermal impedance, improve the smoothness of chip cooling.
In order to reduce the thermal impedance, many foreign manufacturers LED LED chip is arranged in the radiator made of copper and ceramics (heat sink) surface, and then using the welding mode of printed circuit board and radiating wire connected to the forced air cooling radiator using cooling fan. According to the German OSRAM Opto Semi conductors Gmb the experimental results confirmed, LED chip of the structure to the welding point can reduce the thermal resistance is about 9K/W, the traditional LED about 1/6, after the LED package applied 2W electric power, LED chip junction temperature than welding at 18K, even if the printed circuit board, the temperature rises to 50 C, bonding temperature more than 70 DEG C; compared with previous thermal impedance once reduced, LED chip junction temperature will be printed circuit board, the effect of temperature. Therefore, we must try to reduce the temperature of LED chip, in other words, reducing LED chip to the thermal impedance of the welding points, can effectively reduce the cooling effect of the burden of LED chip. Conversely if white light LED with structure for inhibiting thermal impedance heat conduction, if not from the package to a printed circuit board, the LED temperature rise results will still be the luminous efficiency sharply. Therefore, the integration of technology development Panasonic electrical printed circuit board and packaging, the company will 1mm Affirmative Blu ray LED package to flip chip in the ceramic substrate, and then the ceramic substrate is pasted on the copper surface of a printed circuit board, according to the Panasonic reports including printed circuit board, the overall thermal impedance module is about 15K/W or so.
