Optimized heat transfer and homogeneous color converting for ultra high brightness LED package

Jordan, R.; Bauer, Jörg; Oppermann, Hermann

doi:10.1117/12.662976

Cited by 15 publications

(10 citation statements)

References 2 publications

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“…This suggests that the heat inside the conventional package LEDs chips can not be dissipated rapidly to the metal heat sink and lead to the chip fail. We think that the heat of the conventional package LEDs were transferred difficultly to the metal heat sinks, because the heat conductivities of the resins mounting the chip on the heat sink were less than 50C/W [1]. In the other hand, the RGB LEDs chips using novel package are embedded in the metal heat sinks, there is no any thermal interface materials between the RGB LEDs chips and the heat sinks.…”

Section: Resultsmentioning

confidence: 96%

“…Many mediums were used to attach LED chip on lead frame including resin with/without silver particle, tin solder, and indium. The thermal conductivity of epoxy is general less than 5 W/ (miK) [1]. Though tin solder or indium was used to improve the thermal conductivity, it is still not enough for a 40 mils LED to endure high injection current more than 1 A operating under continued mode [2] [3].…”

Section: Introductionmentioning

confidence: 99%

“…Now some applications are not contented with the speed of improvement in external quantum efficiency, therefore thermal management has ramped to be a key issue. In a LEDs module, many interfaces in the path of thermal dissipation are critical to limit the capacity of heat conduction [1], and the interface between LED chip and lead frame is the most important bottleneck of heat conduction. Many mediums were used to attach LED chip on lead frame including resin with/without silver particle, tin solder, and indium.…”

mentioning

confidence: 99%

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High Thermal Dissipation of Ultra High Power Light-Emitting Diodes by Copper Electroplating

Chen

Chuang

et al. 2007

2007 Proceedings 57th Electronic Components and Technology Conference

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The thermal management has become increasingly important when comes to device applications using ultra high power light emitting diodes (UHPLEDs). To thermally manage the devices in a most effective fashion, we report a novel packaging technique in which a copper electroplating process is directly applied over the red, green, and blue LED chips. With the copper-encapsulated layer, the operation current subsequently administered to these LED chips can be increased easily from a conventional 350 mA to more than 1050 mA stable at room temperature. This process can be well adapted to AlInGaP-based red LED when its working current can be driven all the way up to 1650mA. At 350 mA, the relative luminous intensity of these specially packaged red, green, and blue LEDs (RGB LEDs) clearly demonstrate a corresponding enhancement of 53%, 69%, and 23% when compared to those of conventionally packaged LEDs.Furthermore, as the injection current of these LED chips increases to 850mA, the respective improvement in relative luminous intensity of these RGB LEDs chips becomes 4310%, 83%, and 18%, when compared to those of the conventional packaged devices. IntroductionLight emitting diodes (LEDs) are potential candidate for the applications of general lighting, backlight of liquid crystal display (LCD), and headlamp of vehicle. However, lack of good thermal management for the ultra high power LEDs which work over than IA has obstructed the revolution in lighting market. Heat in LEDs was major caused by the high junction temperature, and can be improved by increasing external quantum efficiency. Now some applications are not contented with the speed of improvement in external quantum efficiency, therefore thermal management has ramped to be a key issue. In a LEDs module, many interfaces in the path of thermal dissipation are critical to limit the capacity of heat conduction [1], and the interface between LED chip and lead frame is the most important bottleneck of heat conduction. Many mediums were used to attach LED chip on lead frame including resin with/without silver particle, tin solder, and indium. The thermal conductivity of epoxy is general less

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Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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High Thermal Dissipation of Ultra High Power Light-Emitting Diodes by Copper Electroplating

Chen

Chuang

et al. 2007

2007 Proceedings 57th Electronic Components and Technology Conference

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“…Since the central zone of the phosphor layer is thicker in a freely dispersed coating, there normally is a yellow spot in the illumination map [27]. Seoul Semicon developed an improved method by applying a mold to restrict the flow of phosphor silicone.…”

Section: Phosphor Coatingmentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

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“…Briefly, the conventional fabrication process of LED related lighting apparatus includes: (1) growth of epitaxial layer, (2) chip fabrication, (3) packaging process (adhering the chip on package by Ag glue), and (4) assembling the package products to target appliance. The complex structure results in many interfaces that retard the thermal conduction of LED [4]. To overcome this problem, a brand new technique of LED fabrication and packaging process was developed by our group.…”

Section: Introductionmentioning

confidence: 99%

High thermal dissipation of light emitting diodes by integrating thin film process and packaging technology

Tsai

Hsu

Lin

et al. 2011

2011 6th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)

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We report a brand new technique which is merged thin film fabrication process and packaging technology together to form the shortest thermal dissipation path of LED structure. The effective thermal resistance of the proposed LED was 3.54K/W, which is much better than that of the conventional one 10.8K/W and the operating current can be driven from original 230mA up to 800mA. These results indicate that the LED structure based on our work is useful in improving the performance by enabling great heat dissipation and have higher application potential than conventional one.

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Optimized heat transfer and homogeneous color converting for ultra high brightness LED package

Cited by 15 publications

References 2 publications

High Thermal Dissipation of Ultra High Power Light-Emitting Diodes by Copper Electroplating

High Thermal Dissipation of Ultra High Power Light-Emitting Diodes by Copper Electroplating

Status and prospects for phosphor-based white LED packaging

High thermal dissipation of light emitting diodes by integrating thin film process and packaging technology

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