Details of LED structure

白光发光二极管可依照其制作所使用的物质分为有机发光二极管、与无机发光二极管。目前市场主要半导体白光光源主要有以下三种方式：

White LED is categorized into organic LED and non-organic LED based on its manufacturing components. Currently, the 3 types of semiconductor white LED in the market are:

以红、蓝、绿三色发光二极管晶粒组成白光发光模块，具有高发光效率、高演色性优点，但同时也因不同颜色晶粒磊晶材料不同，连带使电压特性也随之不同。因此使得成本偏高、控制线路设计复杂且混光不易。

The white LED module that is based on the use of red, blue and green tri-color LED chips has the advantages of high luminous efficacy and high color rendition. However, these chips employed different epitaxial materials to produce different color, resulting in their current-voltage characteristics variant. This leads to high cost, complicates circuit design and also makes color mixing difficult.

而由日亚化学所提出，以蓝光发光二极管激发黄色YAG荧光粉产生白光发光二极管，则为目前市场主流方式。日本日亚化学所研发出的白光发光二极管，其结构为在蓝光发光二极管芯片的外围填充混有黄光YAG荧光粉的光学胶，此蓝光发光二极管芯片所发出蓝光之波长约为400～530nm，利用蓝光发光二极管芯片所发出的光线激发黄光荧光粉产生黄色光。但同时也会有部份的蓝色光发射出来，此部份蓝色光配合上荧光粉所发出之黄色光，即形成蓝黄混合之二波长的白光。然而，此种利用蓝光发光二极管芯片与黄光荧光粉组合而成之白光发光二极管，有下列数种缺点：

However, by Nichia Corporation, using blue LED to stimulate yellow YAG phosphor powder to manufacture white LED is presently the most popular method in the market. The white LED developed by Nichia Corporation is structured by encapsulating blue LED chip within YAG phosphor powder and optical adhesive mixture.The blue LED chip emits blue light at wavelength of 400 ~ 530nm, part of the light stimulates the yellow YAG phosphor and produce yellow light, the other part of blue light transmits out from the phosphor’s yellow light, and the combination of blue light and yellow light forms the white light. However, white LED that makes use of combining blue LED and yellow light phosphor has the following disadvantages:

至于以紫外光发光二极管激发透明光学胶中含均匀混有一定比例之蓝色、绿色、红色荧光粉，激发后可得到三波长之白光。三波长白光发光二极管具有高演色性优点，但却有发光效率不足缺点。

As for using UV LED to stimulate the optical adhesive that contains a certain ratio of blue, green and red phosphor powders, the stimulation generates three wavelengths of white light. This triple wavelengths white LED have the advantage of high color rendering capability, but also have the disadvantage of poor luminous efficacy.

不论白光LED是以紫外光、或蓝光芯片与荧光粉搭配而成，其共同缺点为发光亮度不足与均匀度控制不易。目前工业界以增加透亮度或从晶粒导出更多可用发光量，来解决发光二极管亮度不足之问题。例如使用透明导电材料以增加晶粒的出光量、改变晶粒磊晶或电极结构设计以便汲取出更多可用发光量。另外当使用紫外光LED作激发白光之光源时，因紫外光的波长越短时对人眼的伤害愈大，因此必须将紫外光阻绝于白光LED结构内。要改善以上问题，一方面需提高荧光粉的白光转换效率与阻绝紫外光外漏，另方面是希望在改进荧光发光量的同时亦可改善发光均匀度。

Regardless of whether the phosphor-based white LED uses blue LED chip or UV LED chip as its light source, the disadvantages are insufficient luminous flux and difficulty in controlling uniformity.

Currently, LED industry resolve the luminous flux issue by increasing the transmittance or extracting more luminous flux from the chips. For example, using transparent conductive material to increase the luminous flux that chip generates and changing chip’s epitaxial structure or LED electrode design to gain higher light extraction efficiency. Also, when using UV LED as light source for stimulation, the shorter the UV wavelength, the more harm it causes to the human eye. Hence, the UV has to be detained within the white LED structure. To address the above issues, increasing the UV conversion rate by phosphor powder and blocking the leakage of UV are required. In improving the phosphor's luminous flux, it is also intended that uniformity can be improved at the same time.

《图一 Japan Nichia's patented white LED concept》

Improve LED luminous Efficacy through Packaging

为改善上述缺点，在美国专利第5,962,971号使用紫外光滤波器（UV filter）作为发光二极管荧光粉层光出射面的封装。此方式除可增加荧光粉层的发光均匀度外，并可吸收阻绝发光二极管芯片所发出之紫外光对人眼的伤害。另外在飞利浦所申请的美国专利第5,813,753号，是在紫外光/蓝光发光二极管芯片的发光面上，镀上一层短波穿透滤波器（short wave pass filter），以增加发光芯片之紫外光出射量与发光二极管发光面之可见光(荧光)反射量。另一方面，在紫外光/蓝光发光二极管之前端出射面以可见光穿透滤波器（long wave pass filter）作封装，亦可增加可见光的穿透率。

In order to counter the above deficiency, a UV filter is employed as the packaging of phosphor layer emission exit, as patented in US Patent 5,962,971. This method not only improves the uniformity of phosphors luminosity, it also absorbs and blocks the UV emitted from LED chip which will cause harm to the human eye. Also, in Philips' US Patent 5,813,753, the light emitting surface of UV / blue LED chip is coated with a layer of short wave pass filter to increase the chip’s UV emission and increase chip’s reflectivity of visible light (phosphors). On the other hand, using a long wave pass filter as packaging of UV/blue LED front side emission exit can improve the visible light transmittance.

《图二 Concept of White LED through UV Excitation》

Increase Light Extraction Efficiency and Reduce Heat Resistance

由于高亮度LED的应用面不断扩大，如液晶电视、手机、PDA、以及照明领域等，所以各色LED芯片输入功率的不断提高，对封装技术主要除封装结构要有高的取光效率（extraction efficiency）外，另一重要关键技术是降低热阻，才能使光输出功率稳定、寿命增加和提高可靠性。LED发光层所用的磊晶材料采用MOCVD技术和量子井（Quantum Well；QW）结构，使其提高其内量子效率。但由于内全反射（Total Internal Reflection；TIR）原因，使得芯片的光汲取效率过低并产生发热现象。传统的LED封装结构，一般是用胶或银胶将LED芯片黏贴在导线架的反射杯中或SMD基座上，再由金或铝线焊线机完成LED组件的内外连接正负极后，用环氧树脂封装而成。若采用传统式的LED封装形式其程序虽然简单，但其热阻高达250℃/W～300℃/W。LED将会因为散热不良而导致芯片温度迅速上升和环氧树脂变质，进而造成LED组件的加速老化到失去发光功能，且因为持续的热量累积所产生的发光效率降低，并将加速LED组件本身增温，增温效应形成应力造成结构不良而烧毁。

As the applications of high brightness LED continues expand, such as LCD TV, mobile phones and lighting etc., the input power of various colored LED chips continues to increase. In order to stabilize the power of optical output, increase the life span and improve the reliability, not only does the package structure must have high light extraction efficiency, reducing heat resistance is also an important key technology to package technology.The use of epitaxial material that employed quantum well structure and MOCVD technology for LED light emitting layer increases its internal quantum efficiency. However, due to the total internal reflection, the chip’s light extraction efficiency becomes too low and causes the chip to overheat.In traditional LED packaging, adhesive or silver epoxy is used to mount the LED chip onto the reflection cavity of lead frame or SMD substrate, and then connect the anode and cathode of LED chip to their corresponding leads with gold/aluminum bound wire by using the wire bounder, and finally packaged with epoxy. Though the procedure of traditional LED packaging is simple, the heat resistance can be up to 250℃/W ~ 300℃/W. As such, the bad cooling will cause the temperature of the chip to rise and the epoxy to deteriorate, which accelerates the LED degrading and losing its light emitting ability. The reducing of light luminous efficacy caused by continued accumulation of heat, accelerates the increase of LED temperature and the effect of increasing temperature creates stress to LED structure, causing it to burn.

因此，现有的新型LED的设计采用了覆晶（flip-chip）结构来提高芯片的光汲取效率，并改善芯片的散热特性以降低热阻。另一方面也有利用增大LED芯片面积，提高工作电流来增加LED的光电转换效率，以获得较大的发光量。除了LED芯片外，白光LED的荧光粉材料与微光学设计技术也具举足轻重且关键的封装技术。如何进行整体发光二极管结构的二次光学设计以配合材料特性以提高组件的发光效率为目前热门研究方向，例如晶粒内部结构设计反射功能并配合外加的反射器与特殊微光学透镜结构提升 LED发光效率。另一方面，改进荧光粉的成份以增加荧光转换效率，亦为世界各大光电半导体厂与照明大厂兵家必争的一块大饼。

Hence, the new LED design uses flip-chip packaging to increase the chip's light extraction efficiency, and improves the chip's cooling ability to reduce heat resistance. Other than that, using bigger LED chip surface and increasing working current improve the conversion efficacy, hence gaining higher luminous flux. Besides the LED chip, other key packaging techniques are the materials of the phosphors used in white LED and micro-optic design techniques.

The current popular research direction is how to make a secondary optical design on the overall LED structure, together with the materials' characteristics, to improve the LED's luminous efficacy. For example, by designing the chip internal structure with reflective capability and together with external reflector and special micro-optical lens structure, the LED’s luminous efficacy will be increased. On the other hand, improving the components of the phosphors for higher phosphor conversion efficiency is a competitive market for the optoelectronic semiconductor and lighting manufacturers in the world.

Taiwan's LED Packaging Suppliers' Customer Details

Taiwan's LED Packaging Industry Market Status

LED packaging revenue for August increases by 8.7% which exceeds that of chip industry, which is 5.2%

据产业研究机构LEDinside数据统计，8月台湾上市上柜LED厂商营收总额共新台币64.11亿元，月增率7.2％，其中封装厂月成长8.7％，优于晶粒厂的5.2％。

LED晶粒厂8月营收总额27.57亿元，较7月成长5.2％，年成长达14％；LED封装厂商8月营收约36.54亿元，较7月成长8.7％。

Based on statistics by industry research agency LEDinside, August total revenue for Taiwan's listed LED companies was 64.11 billion NTD, an increase of 7.2% from previous month. Packaging industry rose by 8.7%, which is more than that of the chip industry's 5.2%. LED chip industry's August revenue was 27.57 million NTD, an increase of 5.2% from July's revenue. Its yearly growth is 14%. LED packaging industry's August revenue was 36.54 billion NTD, an increase of 8.7% from July's revenue.

观察下游LED封装部分，8月份整体营收36.54亿元，月增率8.7％，年增率4.4％。封装厂产值超越去年同期水平。如封装厂商亿光8月营收约11.17亿元，创下历史新高。

We can see that LED packaging industry's August total revenue was 36.54 billion NTD, an increase of 8.7% from previous month, and its yearly growth is 4.4%. Packaging industry's output exceeded that of last year's same period. Everlight's August revenue set a record high of about 11.17 billion NTD.

April 2009 LED Packaging Industry's Revenue Ranking

(Domination: NTD million)

Q4 Demand for LED chip is still high, packaging industry suffers

LEDinside调查，由于高亮度蓝光芯片迄今仍供不应求，预估蓝光LED晶粒订单可望旺到10月份，部份厂商接单能见度甚至达年底。至于LED封装厂则因中小尺寸背光需求渐入淡季、大尺寸背光恐面临客户调节库存，第四季业绩动能可能会受到冲击。

From LEDinside's survey, high brightness blue LED chip is in short supply, and it is estimated that the order will continue to increase till October. Some suppliers' orders have even last till year end. As for LED packaging industry, because small and medium size backlight demand decreases due to off season, and adjustment of inventory of large size backlight, Q4's performance may suffer.

LEDinside指出，观察近期LED市场下游LED封装厂，据调查，目前厂商的订单能见度，大多仅达9月底。LEDinside表示，主因是第四季以后传统淡季来临，包括中小尺吋的手机背光源等等应用产品需求，将随着手机的出货淡季来临而逐渐下滑。大尺寸背光部分则因第三季LED供给吃紧，面板厂有超额下单（over booking）的现象。预料在第四季面板需求下滑后，面板厂商也将开始调节手中的LED库存。这些因素都将影响部分LED封装厂今年第四季的营收成长动能。

LEDinside points out with respect to LED's lower stream market, LED packaging industry's order will last till September at most. The main reason is the off-season after the fourth quarter, which includes the lower demand of small and medium size mobile phone backlight due to the off-season of mobile phones. The supply shock of LED in the third quarter causes overbooking of large size backlight by the panel supplier. It is expected that in the fourth quarter when the demand of panel declines, panel supplier may start to adjust their LED inventory. These factors will affect some of the LED packaging suppliers' fourth quarter revenue growth.

个别厂商来看，封装厂亿光8月份营收约11.17亿元，也创历史新高，月增17.2％、年增9.5％。主要系受惠于中大尺寸背光源和智能型手机应用比重提升。东贝由于长期布局于背光领域，直接受惠于中大尺寸背光需求，营收续创历史新高，8月营收达4.24亿元，月增5.5％，相较去年同期成长40％。而手机应用比重较高的宏齐，在白牌手机需求出笼下，8月营收达2.62亿元，月增7.1％，下半年新产品导入下，营收仍有成长空间。佰鸿也因打入中大尺寸背光源供应炼，8月份营收创新高4.33亿元，月增25.7％、年增22％。

Looking at the individual packaging suppliers, Everlight's August revenue set a record high of 11.17 billion NTD, an increase of 17.2% from the previous month, and its yearly growth is 9.5%. This is mainly due to increase in usage of medium and large size backlight and smart phones. Unity Opto's revenue set a record of 4.24 billion NTD in August, an increase of 5.5% from previous month, mainly due the demand in medium and large size backlight. Compared to the same period last year, its growth has increased by 40%. Bright LED, whose market is mainly in the mobile phone, with the increase in white-box cell phone, its August revenue reached 2.62 billion NTD, an increase of 7.1%. With the launch of new products in the second half of the year, there is still room of increase of revenue. Bright, with its market in medium and large size backlight supply, reached a record revenue of 4.33 billion NTD in August, an increase of 25.7% from previous month. Its yearly growth is 22%.

Bright's EPS this year is nearly 1.5 NTD and continues to expand its SMD capacity in the following year.

LED封装厂佰鸿，2009年第三季受惠于红外线产品和SMD型LED封装产品订单显著升温，平均产能利用率提高至近90％水位，不仅营收成长，毛利率和获利也可望大幅好转。法人估佰鸿今年第三季营收将较上季成长25％～30％，毛利率将回升到20％以上。另方面，因应TV背光源业务也逐渐展开，佰鸿也预计，将于明年持续扩充SMD型LED封装产能，明年资本支出可能超过5亿元。

In 2009 third quarter, due to the increase in order of infrared products and SMD LED packaging, Bright's average capacity utilization reached nearly 90%. Not only revenue increased, gross margin and net profit will also significantly improve. It is expected that Bright's revenue will increase by 25% to 30% as compared to the last quarter, and its gross margin will return to above 20%. On the other hand, with the expansion into TV backlight business, Bright expects that next year, with the continued expansion of SMD LED packaging capacity, its capital expenditure may exceed 5 billion NTD.

目前可见光LED产品（包含一般LED产品、各类高亮度LED产品等等）占佰鸿营收比重达55％～60％，不可见光（红外线LED）产品营收占比约40％～45％。受惠于个别客户需求增温，佰鸿今年第三季红外线产品营收，较上季大增70％，红外线产品之产能利用率也达到近乎满载。至于可见光LED方面，SMD型LED产品则因NB背光源和手机背光源出货稳定成长，第三季平均产能利用率也持续升高到90％水位。

Currently, visible LED products (including general LED product and other high brightness LED product, etc.) contributes to 55% to 60% of Bright's revenue while invisible (infrared LED) LED products contributes to 40% to 50% of the revenue. With the increase of customers' demand, Bright's third quarter revenue for infrared products greatly increases by 70%, and its capacity utilization is almost full. As for visible LED, due to the stable growth of NB backlight and mobile phone backlight, third quarter's SMD LED average capacity utilization also reaches a high rate of 90%.

佰鸿预期，9月份营收会比8月份更好。主因是大尺寸背光源业务持续成长，另外中国大陆LED路灯标案也将于近期内加速释出。法人估佰鸿今年9月份营收可望持稳于4亿元高档，第三季合并营收估达12～13亿元，季增25％～30％左右。

Bright expects that September's revenue will be much better than August's, the main reason being the continued growth of large size backlight industry. Also, China's LED street light tender will be released soon. It is expected that Bright's September revenue this year will reach a steady high of 4 billion NTD.

由于佰鸿第三季平均产能利用率大幅提升，毛利率可望回升到20％以上，加上费用支出和业外损失减少，法人估佰鸿第三季单季获利有机会挑战1.8～2亿元。

Because Bright's third quarter average capacity utilization significantly improves, gross profit margin is expected to return to above 20%. Besides, with the decrease in expenses and non-operating loss, there is a chance that Bright's third quarter net profit will reach 1.8 to 2 billion NTD.

由于佰鸿正积极扩张电视背光源产品业务，初步已打入韩系客户电视背光源供应链，接下来佰鸿还会持续开发台湾和中国大陆等地TV系统厂商的订单，未来规划将持续扩充SMD型LED产能，明年资本支出预估将超过5亿元。

As Bright is actively expanding into TV backlight product industry, it has preliminarily penetrated into Korean consumer TV backlight supply chain. Next, Bright will continue to cater to Taiwan's and China's TV system suppliers' order. In the future, it will continue to expand the SMD LED capacity. Next year's capital expenditure is expected to exceed 5 billion NTD.

Taiwan Oasis awarded Hong Kong LED Technology Tender

根据中国东莞市发展利用市场工作领导小组，今年8月份所发布的「2009年粤港关键领域重点突破项目」中的东莞专项招标揭标公告，台湾LED封装厂李洲科技表示，旗下转投资的东莞李洲电子科技，成为这次台资企业中唯一的得标厂商。得标项目包括LED照明灯具散热技术，以及光效能提升研究和产业化计划。东莞市政府不仅将提供经费奖助，未来得标厂商在争取公共部门标案时，也将有优先权。东莞李洲所开发的LED照明产品、LED路灯，也都将于今年第四季陆续上市。

According to the Dongguan tender result announcement in the August issue of “2009 Guangdong-Hongkong Key Domain Breakthrough Project of China” published by China Dongguan City's market leading group, Taiwan's LED packaging supplier Oasis said that its Dongguan Oasistek is the only company among the Taiwan-funded companies awarded the tender. The awarded tender items include LED lighting thermal technology as well as study of optical performance improvement and industrialization project. Not only will Dongguan city government provides grant funding, winning tenderers will be given priority when tendering for public sector's tenders in the future. Dongguan Oasistek's products such as LED lighting fixtures and LED street lights will be launched in the fourth quarter this year.

李洲科技董事长李明顺说，李洲科技在东莞市的电子信息技术投标项目取得第一回合胜利，是通过重重严格的检验。以市场对路灯使用寿命长效期的要求，李洲的产品主要系在亮度、散热及光学设计方面胜出。目前东莞李洲与大陆各省都已展开接洽、合作，其中，东莞和河南地区，可望最先缴出成绩。

Oasistek's chairman, Lee, Ming-Shun said, Oasistek in winning the Dongguan's electronic and information technology tender, went through numerous stringent examinations. Oasis' winning points are on the products' brightness, thermal and optical design, which caters to the market's demand for long operating life street lights. Oasistek has started to contact and cooperate with various Mainland provinces, and the first result is expected to be seen in Dongguan Henan.

李洲近来积极朝照明市场布局。目前在东莞厂区已开始着手建置LED路灯示范工程，除了达到节能目标，同时也供外界进行产品检视。在上游LED晶粒垂直整合部分，李洲转投资的洲磊科技已与旭晶光科技进行整合，未来将加强开发高亮度LED晶粒产品。下游应用则透过转投资的东莞李洲，同步朝LED路灯、崁灯、灯管、台灯、汽车照明及模块等等各项应用发展。

Recently, Oasis has been working towards the lighting fixtures market. Currently, Dongguan plant is working on its LED street lights demonstration project. Besides targeting for energy saving, it also opens its doors to the public for product examination. In terms of upper stream LED chip vertical integration, Oasis' UniLite and LuxtalTek is in the integration process, and will work towards producing high brightness LED chip products. In terms of lower stream supply, Dongguan's Oasis will work towards producing LED street lights, down lights, lamps, table lamps, automotive lighting and modules etc.

尽管目前李洲主要营收来源仍以LED显示广告牌应用为主，占营收比重约达60～70％， SMD表面黏着型LED产品营收占比约10％，灯泡型LED产品营收占比约10％，LED照明系统模块产品，合计营收占比仍低于10％。不过，李洲强调，照明应用是LED业者下一步势必要走的路，明年来自照明应用的营收贡献，就会较显著的增长。

Even though 60% to 70% of Oasis' revenue is from LED display board usage, 10% from SMD surface mount LED products, 10% from bulb-type LED products and 10% from LED lighting module, Oasis emphasizes that lighting applications is the next step for LED industry. In the year to come, revenue from lighting applications will significantly increase.

Conclusion

LED已逐渐普及成为日常生活常用的电子组件。目前全球LED发展趋势以白光LED与高亮度LED为主要发展方向，在环保需求与高价能源时代来临的今天，白光LED因省电与轻薄短小特性，并可应需求制作成大尺寸数组发光模块等而在照明领域成为明日之星。因此若能取代现有照明光源技术，将可为全球能源产业带来新一波产业革命和文明发展。而各种封装技术不断推陈出新，也将为LED提供更好的发光效率。现阶段无论从光、机、电、热等方面探讨白光发光二极管都是可以发挥的领域，其未来发展影响非常深远，值得各界持续投注心力。

LED has gradually become our daily common household electrical components. Currently, the global LED development is heading towards white LED and high-power LED. In today's environment friendly requirements and high cost energy resource environment, white LED with its energy-saving and thin short and small attributes, and its ability to be made into large LED display modules, has made its name as the star of the lighting domain. Hence, if it can replace the current lighting technology, it will bring a new wave of industry revolution and civilization development to the global energy industry. Also, the innovative packaging technology will lead to better LED luminous efficacy. At the present stage, optics, mechanical, electrical science and thermal science are areas to be explored in the study of white LED. It will have a deep influence on the future development; hence the continued effort is much worth.