EEPW论坛

Visible light emitting diodes (LEDs) combine high efficiency and long lifetimes. Today, they’re used in a wide range of applications. Extensive R&D efforts by manufacturers have led to the creation of devices with higher luminous flux, longer lifetimes, greater chromaticity, and more lumens per watt. Accurate and cost-effective testing is critical to ensure device reliability and quality.

可见光发光二极管（LED）兼具高效率和长寿命的特点。目前，它们的应用十分广泛。制造商们通过对LED器件的深入研究已经研制出了具有更高光通量、更长寿命、更多色彩和更高每瓦流明数的新器件。精确而高性价比的测试[1]对于确保器件的可靠性和质量至关重要。

LED testing involves different types of test sequences at various stages of production, such as during design R&D, on-wafer measurements during production, and final tests of packaged parts. Although testing LEDs typically involves both electrical and optical measurements, this article focuses on electrical characterization, including light measurement techniques where appropriate. Figure 1 illustrates the electrical I-V curve of a typical diode. A complete test could include a multitude of voltage values versus current operating points, but a limited sample of points is generally sufficient to probe for the figures of merit.

LED测试在生产的不同阶段具有不同类型的测试序列，例如设计研发阶段的测试、生产过程中的晶圆级测试、以及封装后的最终测试。尽管LED的测试[2]一般包含电气和光学测量，本文着重探讨电气特征分析，只在适当的位置介绍部分光学测量技术[3]。图1给出了典型二极管的电气I-V曲线。完整的测试应该包含大量 的电压值与对应的电流工作点，但是一般情况下有限的采样点就足以测试出器件的品质因数[4]。

Figure 1. Typical LED DC I-V curve and test points (not to scale).

V_f测试、I_L测试、V_R测试

图1. 典型LED的直流I-V曲线和测试点（不可缩放）

[1] LED白皮书http://docs.google.com/viewer?a=v&q=cache:1EIrC4QNgDQJ:www.keithley.com.cn/data%3Fasset%3D55825+LED&hl=zh-CN&pid=bl&srcid=ADGEESgO8XteoWeSHw5lbqPUytkLB4GJcEb3jKBpK_lJyNs4KmFfkqZDurEDAOlE8bqr3PrUXbFPvRpv7honS825N1NM-fhA7-AS6rArXTG0x2Mzeqz4p5lpQyYz0j1ftqjAuiI35VF1&sig=AHIEtbSX8tyKzky4TTz2ikyzG_32i4D_xQ

[2] LED的测试http://www.keithley.com.cn/events/LED

[3] 光学测量技术： http://www.keithley.com.cn/events/LED/2519HBLEDTest.pdf

[4] 在线技术支持：http://www.keithley.com.cn/support/tech_support