Throwing light on SSL testing

Increasing demand for high-quality, high-brightness LEDs for use in solid-state lighting (SSL) means that manufacturers have to be able to ramp up production while keeping tight control of device parameters. Since reliable and accurate electrical measurements are vital for the mass production of HB LEDs, it follows that a solid understanding of how to make such measurements is critical.

Fortunately for those involved with SSL, Keithley Instruments is making available a treasure trove of information on how to perform such testing. They are offering a two-part on-line seminar by Applications Engineer David Wyban that examines the requirements for and challenges of testing HB LEDs, along with a technical article on LED fundamentals (“Accurate, Cost-Effective High Brightness LED Testing Starts with Device Fundamentals” by Mark Cejer, Marketing Director), two application notes (“High Speed Testing of High Brightness LEDs” and “Testing High Brightness LEDs under Pulse Width Modulation Using the Model 2651A High Power System SourceMeter Instrument”), and even an introductory YouTube video by Wyban (“How to Overcome Electrical Measurement Challenges of High Brightness LEDs”).

What simplifies the testing of LEDs today is the fact that modern instruments like source/measure units are so much more capable than traditional instruments (for more on this development, see “Taking full advantage of modern bench instruments”, http://www2.electronicproducts.com/T -article-farc_keithley_jul2011-html.aspx). By using SMUs, engineers can rapidly expand the test capabilities of a manufacturing line as demand dictates (see Fig. 1 ).

Fig. 1. SMUs let a single HB LED test system expand rapidly to test multiple devices. (Illustrations from “Accurate, Cost-Effective High Brightness LED Testing Starts with Device Fundamentals” by Mark Cejer, courtesy of Keithley Instruments)

If you’d like to get hold of this information, you can download it from the Web by going to http://gw1.vtrenz.net/?OIQ4NPSWG0:RAVYRL8AE3 and filling out a simple form. I think you’ll find it very useful.