本申请是申请号为200880131373.5，申请日为2008年10月1日，发明名称为“用于增大的光提取和非黄色的断开状态颜色的在封装剂中具有颗粒的LED”的分案申请。This application is a divisional application with the application number 200880131373.5, the filing date is October 1, 2008, and the title of the invention is "LED with particles in encapsulant for increased light extraction and non-yellow off-state color" Application.
技术领域technical field
本发明涉及发光二极管（LED），并且具体而言涉及用于提高光提取的技术。本发明还涉及形成具有浅黄色磷光体涂层的LED的非黄色的断开状态颜色。The present invention relates to light emitting diodes (LEDs), and in particular to techniques for improving light extraction. The invention also relates to forming a non-yellow off-state color of an LED having a light yellow phosphor coating.
背景技术Background technique
比如GaN LED的半导体LED具有比空气的折射率（n约等于1）高得多的折射率（例如，对于GaN，n=2.2-3.0）。通过将LED封装在具有中间折射率的比如硅树脂（n=1.4-1.76）的透明材料中，光提取显著提高。封装剂还保护半导体LED管芯。进一步增大光提取是期望的。Semiconductor LEDs such as GaN LEDs have a much higher refractive index (eg, n=2.2-3.0 for GaN) than that of air (n = approximately 1). By encapsulating the LED in a transparent material with an intermediate refractive index such as silicone (n=1.4-1.76), light extraction is significantly improved. The encapsulant also protects the semiconductor LED die. It is desirable to further increase light extraction.
高功率LED现在通常用作包含移动电话相机的小型相机中的闪光灯。LED发射白色光。这种用作闪光灯的LED典型地为被一层钇铝氧化物石榴石（YAG）磷光体覆盖的一个或多个GaN LED管芯，该GaN LED管芯发射蓝色光，该磷光体在被蓝色光激励时发射黄色-绿色光。通过YAG磷光体泄漏的蓝色光与黄色-绿色光的组合产生白色光。High power LEDs are now commonly used as flashes in compact cameras including mobile phone cameras. LEDs emit white light. Such LEDs used as flashlights are typically one or more GaN LED dies that emit blue light covered by a layer of yttrium aluminum oxide garnet (YAG) phosphor Emits yellow-green light when excited by chromatic light. The combination of the blue light leaked through the YAG phosphor and the yellow-green light produces white light.
当LED断开时，LED上的YAG磷光体涂层在白色环境光下看上去为黄色-绿色。这种黄色-绿色通常不具备吸引力且典型地不与相机外观很好地匹配。期望以某种方式消除闪光灯在处于其断开状态时的黄色-绿色颜色。When the LED is off, the YAG phosphor coating on the LED appears yellow-green in white ambient light. This yellow-green color is generally unattractive and typically does not match the camera look well. Expect to somehow get rid of the yellow-green color of the flash when it's in its off state.
发明内容Contents of the invention
在一个实施例中，TiOx、ZrOx或其它白色非磷光体的惰性材料的粒子与用于LED的基本上透明封装剂混合。一种合适的封装剂为硅树脂。申请人发现，当惰性材料为封装剂的约2.5-5%（按重量计）时，在封装剂中的惰性材料（比如TiO2）的亚微米尺寸颗粒使GaN LED的亮度（流明）增加超过5%。通常，更高百分比的惰性材料开始使光输出减小。封装剂中的这种少量的颗粒产生令人吃惊的结果，所述结果超越了发明人所预测的任何结果。在封装剂中的TiO2的0.5%-10%的范围通常增大亮度，这取决于所使用的实际LED。更高的百分比开始使通过封装剂的透射显著减小。In one embodiment, particles of TiOx, ZrOx or other white non-phosphor inert material are mixed with a substantially transparent encapsulant for the LED. One suitable encapsulant is silicone. Applicants have found that sub-micron sized particles of an inert material (such as TiO2 ) in the encapsulant increase the brightness (lumens) of GaN LEDs by more than 5%. Generally, higher percentages of inert material start to reduce light output. This small amount of particles in the encapsulant yielded surprising results beyond anything the inventors had predicted. A range of 0.5%-10%Ti02 in the encapsulant generally increases brightness, depending on the actual LED used. Higher percentages start to significantly reduce transmission through the encapsulant.
二氧化钛和氧化锆二者被用作油漆和搪瓷中的白色色素。被认为是白色的颜色具有一系列色温，且该颜色受到检视光的影响。如本公开内容中使用的术语白色在观察者看来在太阳光下为基本上白色。Both titanium dioxide and zirconia are used as white pigments in paints and enamels. A color that is considered white has a range of color temperatures and is affected by the viewing light. The term white, as used in this disclosure, appears to an observer to be substantially white in sunlight.
无论LED涂覆有磷光体还是未涂覆有磷光体，通过将颗粒添加在封装剂中实现的光增强都发生。The light enhancement achieved by adding the particles in the encapsulant occurs regardless of whether the LED is phosphor-coated or not.
在一些实验中，将TiO2添加到封装剂略微减小当LED接通时发射光的色温，这是不明显的。然而，TiO2的添加使在整个180度发射角上的色温变化大幅减小（例如，减小了三分之二）。在摄影中这是重要的，因为整个对象是用基本上均匀的光照射。In some experiments, addingTiO2 to the encapsulant slightly reduced the color temperature of the emitted light when the LED was switched on, which was not noticeable. However, the addition ofTiO2 substantially reduces the color temperature variation over the entire 180-degree emission angle (eg, by two-thirds). This is important in photography because the entire subject is illuminated with substantially uniform light.
此外，将TiO2添加到封装剂也提高了包装各处的色温均匀性。当投影LED的放大图像的光学元件被使用，比如与闪光灯或投影仪一起使用时，这是尤其重要的。Additionally, addingTiO2 to the encapsulant also improves color temperature uniformity throughout the package. This is especially important when optics that project a magnified image of the LED are used, such as with a flash or projector.
由于惰性材料（例如，TiO2或ZrO2）是白色的，具有YAG磷光体涂层的LED的外观在该LED断开时看上去白得多，这比YAG磷光体的黄色-绿色颜色更悦目。Since the inert material (e.g.,TiO2 orZrO2 ) is white, the appearance of an LED with a YAG phosphor coating appears much whiter when the LED is off, which is more pleasing than the yellow-green color of the YAG phosphor .
在一个实施例中，闪光灯LED模块使用具有按重量计约5%的TiO2的硅树脂封装剂，其中封装剂形成为具有平坦表面从而不显著影响LED发射的形状（即，封装剂不形成透镜）。相机包含位于闪光灯上的透镜以控制闪光灯的光发射模式。在另一实施例中，硅树脂封装剂可以成型为透镜从而使光发射模式定形。In one embodiment, the flashlight LED module uses a silicone encapsulant with about 5% by weightTiO2 , wherein the encapsulant is formed into a shape with a flat surface so as not to significantly affect the LED emission (i.e., the encapsulant does not form a lens ). The camera includes a lens on the flash to control the light emission pattern of the flash. In another embodiment, the silicone encapsulant can be molded into a lens to shape the light emission pattern.
附图说明Description of drawings
图1为包含蓝色LED管芯、YAG磷光体涂层、底座和硅树脂封装剂的现有技术闪光灯LED的截面视图。Figure 1 is a cross-sectional view of a prior art flashlight LED comprising a blue LED die, a YAG phosphor coating, a submount, and a silicone encapsulant.
图2为依照本发明实施例的闪光灯LED的截面视图，其中TiO2颗粒与封装剂混合。2 is a cross-sectional view of a flash LED in which TiO2 particles are mixed with an encapsulant in accordance with an embodiment of the present invention.
图3为说明通过在封装剂中添加TiO2，闪光灯在处于其断开状态时的颜色外观从黄色-绿色到白色的变化的曲线图。Figure 3 is a graph illustrating the change in color appearance of the flashlight in its off state from yellow-green to white by addingTiO2 in the encapsulant.
图4为说明通过在封装剂中添加TiO2，闪光灯在处于其接通状态时色温的下降以及在视角上的色温偏差的下降的曲线图。Fig. 4 is a graph illustrating the reduction in color temperature of the flash lamp in its on state and the reduction in color temperature deviation over viewing angle by addingTiO2 in the encapsulant.
图5为说明当TiO2添加到封装剂中时LED包装各处的色温均匀性提高的曲线图。5 is a graph illustrating the improvement in color temperature uniformity across an LED package whenTiO2 is added to the encapsulant.
图6为依照本发明实施例的不具有磷光体涂层的蓝色LED管芯的截面视图，其中TiO2颗粒与封装剂混合。6 is a cross-sectional view of a blue LED die without a phosphor coating in whichTi02 particles are mixed with an encapsulant in accordance with an embodiment of the invention.
图7为图5的LED的光功率输出的曲线图，其示出了随着封装剂中TiO2数量的增大，功率输出提高。7 is a graph of the optical power output of the LED of FIG. 5 showing that the power output increases as the amount ofTi02 in the encapsulant increases.
图8为具有依照本发明一个实施例的闪光灯的相机的正视图，其中TiO2颗粒与封装剂混合。Figure 8 is a front view of a camera with a flash according to one embodiment of the present invention, whereinTi02 particles are mixed with an encapsulant.
在各个图中相似或相同的元件用相同的数字来标记。Similar or identical elements are labeled with the same numerals in the various figures.
具体实施方式Detailed ways
尽管本发明可以应用到任何类型的LED，但是将详细描述在所有实例中使用的一种具体LED。图1为封装在硅树脂中的常规白色光LED 10的截面视图。Although the invention can be applied to any type of LED, a specific LED used in all examples will be described in detail. FIG. 1 is a cross-sectional view of a conventional white light LED 10 encapsulated in silicone.
该实例中LED 10的有源层产生蓝色光。LED 10形成于比如蓝宝石、SiC或GaN的起始生长衬底上。通常，生长n层12，接着是有源层14，接着是p层16。p层16被蚀刻以露出一部分的位于下面的n层12。反射金属电极18（例如，银、铝或合金）接着形成于LED的表面之上从而接触n层和p层。可存在许多分布式电极从而更均匀地扩散电流。当二极管正向偏置时，有源层14发射光，该光的波长是由有源层的成份（例如AlInGaN）确定。形成这种LED是公知的且无需更详细描述。形成LED的附加细节描述于Steigerwald等人的美国专利No. 6,828,596和Bhat等人的美国专利No. 6,876,008，这两个美国专利均转让给本申请的受让人且通过引用结合于此。The active layer of LED 10 in this example produces blue light. LED 10 is formed on a starting growth substrate such as sapphire, SiC or GaN. Typically, n-layer 12 is grown, followed by active layer 14 , followed by p-layer 16 . The p-layer 16 is etched to expose a portion of the underlying n-layer 12 . A reflective metal electrode 18 (eg, silver, aluminum or an alloy) is then formed over the surface of the LED, contacting the n- and p-layers. There may be many distributed electrodes to spread the current more evenly. When the diode is forward biased, the active layer 14 emits light at a wavelength determined by the composition of the active layer (eg AlInGaN). Forming such LEDs is well known and need not be described in more detail. Additional details of forming LEDs are described in US Patent No. 6,828,596 to Steigerwald et al. and US Patent No. 6,876,008 to Bhat et al., both assigned to the assignee of the present application and incorporated herein by reference.
半导体LED接着安装在底座22上成为倒装芯片。底座22的顶表面含有金属电极，该金属电极经由焊料球被焊接或超声焊到LED上的金属电极18。也可以使用其它类型的结合。如果电极本身可以被超声焊到一起，则焊料球可以删去。The semiconductor LEDs are then mounted flip-chip on the submount 22 . The top surface of the submount 22 contains metal electrodes that are soldered or ultrasonically welded to the metal electrodes 18 on the LED via solder balls. Other types of combinations can also be used. If the electrodes themselves can be ultrasonically welded together, the solder balls can be omitted.
底座电极通过通路电连接到底座底部上的阴极和阳极焊盘24，因此底座可以表面安装到印刷电路板上的金属焊盘，该印刷电路板典型地形成用于相机的闪光灯模块的一部分。电路板上的金属迹线将焊盘电耦合到电源。底座22可以由任何合适材料形成，比如陶瓷、硅、铝等。如果底座材料导电，则绝缘层形成于衬底材料之上，且金属电极图案形成于绝缘层之上。底座22充当机械支撑，提供LED芯片上的精巧的n和p电极与电源之间的电学接口，并且提供热沉。底座是公知的。The base electrodes are electrically connected by vias to cathode and anode pads 24 on the bottom of the base so that the base can be surface mounted to metal pads on a printed circuit board typically forming part of a flash module for a camera. Metal traces on the board electrically couple the pads to the power supply. Base 22 may be formed from any suitable material, such as ceramic, silicon, aluminum, and the like. If the base material is conductive, an insulating layer is formed on the substrate material, and a metal electrode pattern is formed on the insulating layer. The base 22 acts as a mechanical support, provides an electrical interface between the delicate n and p electrodes on the LED chip and the power supply, and provides a heat sink. Bases are well known.
为了致使LED 10具有低廓形并防止光被生长衬底吸收，生长衬底被移除，比如通过CMP或者利用激光剥离方法，在激光剥离方法中激光加热GaN和生长衬底的界面以形成高压气体，该高压气体将衬底推离GaN。在一个实施例中，生长衬底的移除是在LED阵列安装在底座晶片上之后且在LED/底座被单体化（例如，通过锯切）之前进行的。半导体层的最终厚度可以约为40微米。LED层加上底座的厚度可以约为0.5mm。To render the LED 10 to have a low profile and prevent light from being absorbed by the growth substrate, the growth substrate is removed, such as by CMP or using a laser lift-off process in which the laser heats the interface of the GaN and growth substrate to create a high voltage gas, which pushes the substrate away from the GaN at high pressure. In one embodiment, the growth substrate is removed after the LED array is mounted on the submount wafer and before the LED/submount is singulated (eg, by sawing). The final thickness of the semiconductor layer may be about 40 microns. The thickness of the LED layer plus the base may be about 0.5mm.
LED半导体层的处理可以在LED安装在底座22上之前或之后进行。The processing of the semiconductor layers of the LED can be done before or after the LED is mounted on the submount 22 .
在生长衬底移除之后，磷光体层30形成于LED顶部上，用于波长转换从有源层14发射的蓝色光。磷光体层30可以喷射沉积、旋涂、通过电泳而薄膜沉积、预形成为陶瓷板并固定到LED层顶部、或者利用任何其它技术形成。磷光体层30可以是透明或半透明结合剂（其可以是有机或无机的）中的磷光体颗粒，或者可以是烧结磷光体颗粒。由磷光体层30发射的光在与蓝色光混合时形成白色光或者另一期望的颜色。在该实例中，磷光体为产生黄色光的钇铝氧化物石榴石（YAG）磷光体（Y+B=白色）。该磷光体可以是任何其它磷光体或者多种磷光体的组合，比如红色磷光体和绿色磷光体（R+G+B=白色），从而形成白色光。在所有实例中，磷光体层30的厚度可以约为20微米。After the growth substrate is removed, a phosphor layer 30 is formed on top of the LED for wavelength conversion of the blue light emitted from the active layer 14 . Phosphor layer 30 can be spray deposited, spin coated, thin film deposited by electrophoresis, preformed as a ceramic plate and affixed on top of the LED layer, or formed using any other technique. Phosphor layer 30 may be phosphor particles in a transparent or translucent binder (which may be organic or inorganic), or may be sintered phosphor particles. The light emitted by the phosphor layer 30 when mixed with blue light forms white light or another desired color. In this example, the phosphor is a yttrium aluminum oxide garnet (YAG) phosphor that produces yellow light (Y+B=white). The phosphor can be any other phosphor or a combination of phosphors, such as a red phosphor and a green phosphor (R+G+B=white), resulting in white light. In all examples, phosphor layer 30 may be approximately 20 microns thick.
利用YAG磷光体（即，Ce:YAG），白色光的色温在很大程度上取决于磷光体中的Ce掺杂以及磷光体层30的厚度。With a YAG phosphor (ie, Ce:YAG), the color temperature of white light largely depends on the Ce doping in the phosphor and the thickness of the phosphor layer 30 .
硅树脂封装剂32接着形成于LED结构之上以保护LED并增大光提取。在一个实施例中，封装剂被旋涂。在另一实施例中，封装剂直接成型在LED和磷光体之上。如果期望使用封装剂作为透镜，封装剂可以利用模具来定形。A silicone encapsulant 32 is then formed over the LED structure to protect the LEDs and increase light extraction. In one embodiment, the encapsulant is spin-coated. In another embodiment, the encapsulant is molded directly over the LED and phosphor. If it is desired to use the encapsulant as a lens, the encapsulant can be shaped using a mold.
图1的现有技术LED结构被用作基线，从而示出当采用本发明时该结构的改进特性。The prior art LED structure of Figure 1 was used as a baseline to show the improved properties of the structure when the present invention is employed.
图2为LED结构的截面视图，该LED结构与图1的LED结构相同，但是其中在封装LED之前，TiO2颗粒34与硅树脂封装剂32混合。取决于LED结构的特性，TiO2的最优数量可以在硅树脂的重量的1-10%之间任意位置变化。在一个实施例中，含有TiO2的封装剂被旋涂。在另一实施例中，含有TiO2的封装剂被直接成型在LED和磷光体之上。如果期望使用封装剂作为透镜，则封装剂可以使用模具来定形。Figure 2 is a cross-sectional view of an LED structure that is the same as that of Figure 1, but whereinTiO2 particles 34 are mixed with a silicone encapsulant 32 prior to encapsulation of the LED. Depending on the characteristics of the LED structure, the optimal amount ofTiO2 can vary anywhere between 1-10% by weight of the silicone. In one embodiment, theTiO2 -containing encapsulant is spin-coated. In another embodiment, theTiO2 containing encapsulant is molded directly over the LED and phosphor. If it is desired to use the encapsulant as a lens, the encapsulant can be set using a mold.
在一个实施例中，平均TiO2颗粒尺寸为0.25微米，且颗粒为随机形状。在典型实施例中，硅树脂的厚度约为100微米。In one embodiment, the averageTiO2 particle size is 0.25 microns and the particles are randomly shaped. In a typical embodiment, the thickness of the silicone is about 100 microns.
当TiO2的重量百分比增大至约5%时，LED结构的光输出增大。在一些实验中，在5%之后光输出减小。在一个实验中，样品的光输出对于0% TiO2为90流明，对于5% TiO2为96流明，以及对于7% TiO2为93流明，随后光输出随着TiO2数量增大而降低。色温（CCT）也随TiO2的百分比变化。在一个实验中，CCT在0% TiO2时为5815K，在5% TiO2时为5332K，以及在7%TiO2时为5486K，证明在TiO2的最高效率百分比处CCT是最低的。When the weight percentage ofTiO2 was increased to about 5%, the light output of the LED structure increased. In some experiments, the light output decreased after 5%. In one experiment, the light output of the samples was 90 lumens for 0%TiO2 , 96 lumens for 5%TiO2 , and93 lumens for 7% TiO2, then the light output decreased with increasing amount ofTiO2 . Color temperature (CCT) also varies with the percentage ofTiO2 . In one experiment, the CCT was 5815K at 0%TiO2 , 5332K at 5%TiO2 , and 5486K at 7%TiO2 , demonstrating that the CCT is lowest at the highest percent efficiency ofTiO2 .
在另一实验中，样品的光输出对于0% TiO2为145流明，对于仅1% TiO2上升到154流明，这在光输出上增大了6%。在另一实验中，仅仅对于0.5% TiO2，看到光输出的显著增大。在另一实验中，对于5% TiO2，光输出增大6%。对于每种类型LED、所使用的材料以及应用，可以凭经验确定TiO2的最优数量。In another experiment, the light output of the sample was 145 lumens for 0%Ti02 , rising to 154 lumens for only 1%Ti02 , which is a 6% increase in light output. In another experiment, a significant increase in light output was seen only for 0.5%Ti02 . In another experiment, the light output increased by 6% for 5%Ti02 . The optimal amount ofTiO2 can be determined empirically for each type of LED, material used, and application.
图3为说明使用CIE xy色度系统（1931版本）绘制的，图2的LED结构在处于其断开状态时的颜色外观变化的曲线图。该磷光体为YAG磷光体。被加热的黑体曲线（也称为普朗克轨迹）也被示出作为参考，其中坐标0.32，0.33对应于约5500-6000K的色温。当x和y值一起朝向0.42，0.54的体磷光体颜色值（未绘出）增大时，LED颜色变得通常更加黄色-绿色。当薄层磷光体（例如，约20微米）形成于LED管芯之上且LED用具有0% TiO2的纯硅树脂（厚约100微米）封装时，如图1中所示，LED（例如，相机中的闪光灯）在处于其断开状态时的外观为黄色-绿色颜色，不过比体磷光体的黄色-绿色浅。当封装剂与5% TiO2混合时，闪光灯为基本上白色。当封装剂与7% TiO2混合时，闪光灯甚至更白（更远离黄色-绿色）。Figure 3 is a graph illustrating the change in color appearance of the LED structure of Figure 2 when in its off state, plotted using the CIE xy colorimetric system (1931 edition). The phosphor is a YAG phosphor. The heated blackbody curve (also known as the Planck locus) is also shown as a reference, where coordinates 0.32, 0.33 correspond to a color temperature of about 5500-6000K. As the x and y values together increase towards 0.42, a bulk phosphor color value of 0.54 (not shown), the LED color becomes generally more yellow-green. When a thin layer of phosphor (e.g., about 20 microns) is formed over the LED die and the LED is encapsulated with pure silicone (about 100 microns thick) with 0%TiO2 , as shown in Figure 1, the LED (e.g. , the flash in a camera) in its off state has a yellow-green color in appearance, though lighter than the yellow-green color of bulk phosphors. When the encapsulant was mixed with 5%Ti02 , the flash was essentially white. When the encapsulant was mixed with 7%TiO2 , the flash was even whiter (further away from yellow-green).
尽管在提交此公开内容的时候，发明人仍在分析性能提高的原因，但是认为：将TiO2添加到封装剂使封装剂的折射率稍微增大，以及TiO2的颜色（白色）致使LED/磷光体的外观更接近纯白色。Although at the time of filing this disclosure, the inventors are still analyzing the reasons for the performance improvement, it is believed that: adding TiO2 to the encapsulant increases the refractive index of the encapsulant slightly, and the color (white) of TiO2 causes the LED/ Phosphors are closer to pure white in appearance.
图4为在-90度至+90度的视角之上，图2的LED结构在该LED接通时的色温的曲线图。该曲线图说明图2的LED结构在其接通状态时的色温（CCT）如何随所添加的TiO2数量而非线性变化。对于5% TiO2，在该视角之上的颜色偏差的期望降低是最小的（约150K）。对于摄影而言这是有利的，因为被拍摄的整个场是用基本上相同颜色闪光灯来照射。0% TiO2曲线具有非常显著的偏差，该偏差约为使用5% TiO2的偏差的三倍。认为TiO2颗粒散射来自LED的光，这帮助混合光输出以形成视场之上更均匀的亮度和颜色。4 is a graph of the color temperature of the LED structure of FIG. 2 when the LED is turned on, over a viewing angle of -90 degrees to +90 degrees. This graph illustrates how the color temperature (CCT) of the LED structure of Figure 2 in its on-state varies linearly with the amount ofTiO2 added. For 5%Ti02 , the expected reduction in color shift above this viewing angle is minimal (about 150K). This is advantageous for photography because the entire field being photographed is illuminated with essentially the same color flash. The 0%TiO2 curve has a very significant deviation, which is about three times the deviation using 5%TiO2 . TheTiO2 particles are thought to scatter light from the LED, which helps mix the light output to create a more uniform brightness and color over the field of view.
替代TiO2，也可以使用比如ZrO2的其它浅白色惰性颗粒。Instead of TiO2 , other off-white inert particles such as ZrO2 can also be used.
尽管本发明特别期望与LED闪光灯一起使用，由于TiO2颗粒的一个效应是使LED管芯之上的黄色-绿色YAG磷光体的外观变白，但是本发明也提高了不使用磷光体涂层的LED的总体光输出。Although the invention is particularly intended for use with LED flashlights, since one effect of theTiO2 particles is to whiten the appearance of the yellow-green YAG phosphor on top of the LED die, the invention also improves performance without the use of phosphor coatings. The overall light output of an LED.
封装剂中的TiO2的效应也有效地过滤掉LED包装各处的显著颜色变化，其中视角垂直于LED表面。图5为近似实际实验结果的曲线图，其中测量了LED包装各处（跨度大约3mm）的色温。对在封装剂中不具有TiO2的LED以及对在封装剂中具有TiO2的类似LED进行该测量。封装剂形成位于LED之上的包覆成型的半球形透镜。该LED为蓝色LED，磷光体板固定到LED芯片的顶部，其中磷光体与泄漏通过的蓝色光组合生成橙色发射。磷光体板不覆盖LED层的边缘。The effect ofTiO2 in the encapsulant also effectively filters out significant color variations across the LED package where the viewing angle is perpendicular to the LED surface. Figure 5 is a graph that approximates the actual experimental results, where the color temperature was measured across the LED package (approximately 3mm across). This measurement was performed on LEDs withoutTiO2 in the encapsulant and on similar LEDs withTiO2 in the encapsulant. The encapsulant forms an overmolded hemispherical lens over the LED. The LED is a blue LED with a phosphor plate affixed to the top of the LED chip, where the phosphor combines with the blue light that leaks through to produce an orange emission. The phosphor plate does not cover the edges of the LED layer.
如在图5的曲线图中所看到，在封装剂中不具有TiO2的LED的左边缘附近存在色温尖峰，这是由于来自LED边缘的未经转换的蓝色光被发射。右边具有在LED边缘附近的较不严重的色温增大。如果该LED用在闪光灯或投影仪中（其中光学元件大幅放大LED图像），边缘附近的蓝色颜色在投影图像中将是可见的。与之对照，如在在封装剂中具有TiO2的LED的色温测量中所看到，在LED边缘附近没有明显的色温尖峰，因为TiO2有效地过滤掉任何尖峰。As seen in the graph of Figure 5, there is a color temperature spike near the left edge of the LED withoutTiO2 in the encapsulant due to unconverted blue light being emitted from the edge of the LED. The right has a less severe increase in color temperature near the edge of the LED. If the LED is used in a flash or projector (where optics greatly magnify the LED image), the blue color near the edges will be visible in the projected image. In contrast, as seen in color temperature measurements of LEDs withTi02 in the encapsulant, there is no noticeable color temperature spike near the edge of the LED because theTi02 effectively filters out any spikes.
图6为不具有磷光体层的LED管芯的截面视图，其中TiO2颗粒34与硅树脂封装剂32混合。LED管芯发射蓝色光。除了磷光体层之外，该LED的所有方面与图2相同。6 is a cross-sectional view of an LED die without a phosphor layer, where TiO2 particles 34 are mixed with a silicone encapsulant 32 . The LED die emits blue light. All aspects of the LED are the same as in Figure 2 except for the phosphor layer.
在图7的曲线图中，方形数据点代表在1000mA驱动电流时，图6的LED结构的光输出功率（单位为mW）与封装剂中TiO2的百分比的关系。圆形为参考数据点，其示出没有封装剂的LED管芯的光输出功率。在0%处的数据点是估计的；其它数据点是测量的。如所见，在裸LED管芯之上的封装剂中包含TiO2颗粒显著增大LED的光输出功率，即使是在TiO2的数量约为0.5%时。In the graph of FIG. 7, the square data points represent the light output power (in mW) of the LED structure of FIG. 6 versus the percentage ofTiO2 in the encapsulant at a drive current of 1000 mA. The circles are reference data points showing the light output power of the LED die without encapsulant. Data points at 0% are estimated; other data points are measured. As can be seen, the inclusion ofTi02 particles in the encapsulant over the bare LED die significantly increases the light output power of the LED, even when the amount ofTi02 is about 0.5%.
图8为利用此处描述的发明的相机40的图示，该相机可以是移动电话相机。闪光灯模块42包含安装在单个底座上的用于增大光功率输出的三个蓝色发射LED 44，该底座安装在电路板上。YAG磷光体层覆盖LED。ESD保护电路也可以安装在底座上且被磷光体覆盖。LED、磷光体和ESD电路利用与TiO2混合的硅树脂来封装，从而实现此处描述的益处。也示出了相机透镜48。Figure 8 is an illustration of a camera 40, which may be a mobile phone camera, utilizing the invention described herein. The flash module 42 contains three blue emitting LEDs 44 for increased light power output mounted on a single base mounted on a circuit board. A layer of YAG phosphor covers the LED. ESD protection circuitry can also be mounted on the chassis and covered with phosphor. LEDs, phosphors, and ESD circuits are encapsulated with silicone mixed withTiO2 to achieve the benefits described here. A camera lens 48 is also shown.
测试表明，在封装剂中添加惰性颗粒的LED结构的可靠性未降低。The tests showed that the reliability of the LED structure was not reduced with the addition of inert particles in the encapsulant.
封装剂中TiO2或ZrO2颗粒的附加用途可以是通过封装剂阻挡或反射光。通过使颗粒的百分比增大为大于10%，通过封装剂的透射率的减小变得非常显著（从具有0% TiO2的90%透射率到具有10% TiO2的25%透射率）。如果颗粒的百分比不断增大，封装剂变得越来越像漫射反射器，将大多数光反射回到LED中且从侧边离开。这种边发射LED在比如LCD背光的某些应用中是有用的。在一个实施例中，颗粒的百分比超过25%从而形成基本上边发射LED。An additional use of theTiO2 orZrO2 particles in the encapsulant can be to block or reflect light through the encapsulant. By increasing the percentage of particles above 10%, the reduction in transmittance through the encapsulant becomes very significant (from 90% transmittance with 0%Ti02 to 25% transmittance with 10%Ti02 ). If the percentage of particles keeps increasing, the encapsulant becomes more and more like a diffuse reflector, reflecting most of the light back into the LED and out the sides. Such edge emitting LEDs are useful in certain applications such as LCD backlighting. In one embodiment, the percentage of particles exceeds 25% to form a substantially edge-emitting LED.
已经详细描述了本发明，本领域技术人员将理解，鉴于本公开内容，可以对本发明进行改动而不背离此处描述的精神和发明构思。因此，不打算将本发明的范围限制为所说明和描述的特定实施例。Having described the invention in detail, those skilled in the art will appreciate that, in light of the present disclosure, modifications may be made to the invention without departing from the spirit and inventive concepts described herein. Therefore, it is not intended that the scope of the invention be limited to the particular embodiments illustrated and described.
| Application Number | Priority Date | Filing Date | Title |
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| CN201610249881.XACN105679922B (en) | 2008-10-01 | 2008-10-01 | The LED with particle in encapsulant for the off-state color of increased light extraction and non-yellow |
| Application Number | Priority Date | Filing Date | Title |
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| CN2008801313735ACN102171844A (en) | 2008-10-01 | 2008-10-01 | LED with particles in encapsulant for increased light extraction and non-yellow off-state color |
| CN201610249881.XACN105679922B (en) | 2008-10-01 | 2008-10-01 | The LED with particle in encapsulant for the off-state color of increased light extraction and non-yellow |
| Application Number | Title | Priority Date | Filing Date |
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| CN2008801313735ADivisionCN102171844A (en) | 2008-10-01 | 2008-10-01 | LED with particles in encapsulant for increased light extraction and non-yellow off-state color |
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| TWI226357B (en)* | 2002-05-06 | 2005-01-11 | Osram Opto Semiconductors Gmbh | Wavelength-converting reaction-resin, its production method, light-radiating optical component and light-radiating semiconductor-body |
| US7847302B2 (en)* | 2005-08-26 | 2010-12-07 | Koninklijke Philips Electronics, N.V. | Blue LED with phosphor layer for producing white light and different phosphor in outer lens for reducing color temperature |
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