Accurate, Cost-Effective High Brightness LED Testing Starts with
Device Fundamentals  Tue, 05/24/2011 - 12:44pm Mark Cejer,
Keithley High brightness light emitting diodes (HBLEDs) combine
high output and high efficiency with long lifetimes.
Manufacturers are developing devices that offer higher luminous
flux, longer lifetimes, greater chromaticity, and more lumens
per Watt. Ensuring their performance and reliability demands
accurate, cost-effective testing at every phase of production.
The electrical I-V curve of a typical diode is illustrated in
Figure 1. Although a complete test sequence could include
hundreds of points, a limited sample is generally sufficient to
probe for the figures of merit. Many HBLED tests require
sourcing a known current and measuring the resulting voltage or
vice-versa. Instruments that combine synchronized sourcing and
measurement can speed system setup and enhance throughput.
Testing can be done at the die level (both wafer and package),
or the module / subassembly level. At the