Effect Of Structure Of Ceramic Eutectic Package LED On Photoelectric Performance

White light emitting diode(LED)devices have been widely used in the field of general lighting.China has become the largest manufacturer,exporter and consumer of LED lighting industry,with an annual output value of nearly one trillion yuan.However,some high power devices still have the problem of relying on imports.The high-power density ceramic eutectic packaged LED is one of the main categories relying on import.The reason is that it involves many scientific and technological problems.Therefore,industry and academic need to conduct in-depth research on it to lay a scientific and technological foundation for its wider application.In this paper,the influence of the number and location of eutectic chips on the luminescent properties of ceramic eutectic packaged led,the influence of eutectic copper layer thickness on the photoelectric performance of ceramic was studied,and the effects of type I and type A,copper metal substrate and ceramic substrate on the photoelectric parameters of LED were analyzed.The main contents and conclusions of this paper are as follows:(1)In order to explore the influence of the number of chips and the position of chips on the luminescent performance of the LED,eight and four 45 × 45 mil flip chip were co crystallized on the 8-core Al N ceramic substrate,and 6 and 3 chips of the same specification were co crystallized on the 6-core Al N ceramic substrate,respectively.The changes of blue light power,white light flux and white light color temperature with forward current are compared.The results show that the blue light power and white light flux of the same size ceramic substrate decrease by half,and the light saturation characteristics of the blue and white light devices are significantly improved,and the change degree of the white light color temperature with the current is also greatly reduced The improvement is more obvious for the 8-core ceramic samples with good matching degree between the metal layer and the eutectic position of the chip.The thermal balance process of blue light power,white light flux and color temperature is compared.The results show that when the number of chips is reduced by half,the blue light power,white light flux and color temperature can reach equilibrium and remain unchanged in a shorter time.After thermal balance,the light flux of white light device decreases more than that of blue light intensity,and the color temperature of each white light sample increases The change range of the product is greater than that of the 4-core and 3-core samples.At the same time,it is also found that a certain amount of optical power will be lost after the flip chip is covered with white glue.(2)The experiment of flip chip blue LED with different thickness of eutectic copper layer was carried out.By taking the independent variable as current and different thickness of eutectic copper layer,the optical properties of the samples were compared and analyzed,and the changes of optical performance parameters caused by different current and different eutectic copper layer were studied.According to the experimental results,we conclude that the peak wavelength of flip-flop blue LED is isotropic in spatial distribution.When the thickness of eutectic copper layer is 40 ? m,the heat dissipation effect is relatively good.The results show that the half wave width of eutectic copper layer with thickness of 40 ? m and 50 ? m is smaller,and the color definition is higher.The corresponding luminous flux and photoelectric conversion efficiency of 40 ? m are the highest.(3)The photoelectric performance of LED with type I and type a EMC package and ceramic package with thermoelectric separation was analyzed.Because the area of copper pad on the back of type I lamp bead is smaller than that of type a lamp bead,the heat can not be dissipated in time under high current,resulting in heat blockage,thus reducing the electro-optic conversion efficiency.Although the thermal power separation of ceramic package LED is realized,its heat dissipation performance is more serious than that of led directly eutectic on copper substrate.Therefore,high power density packaging LED should be selected according to different chip structure.