Manual

Cree® XLamp® XR Family LED Reliability
December 2009 This application note describes the types of failures common to high-power LEDs, details Cree’s pre-release qualification testing for XLamp XRFamily LEDs and includes the results of white point stability testing. For information on long-term lumen maintenance testing and projections, please see the XLamp Long-Term Lumen Maintenanceapplication note.

Table of Contents
LED Failure Types .................................................................................................................................... 1 Pre-ReleaseQualification Testing ............................................................................................................... 1 Pre-Release Qualification Test List (Operating Life Tests)............................................................................... 2 Procedures for Operating Life Tests............................................................................................................ 3 Pre-Release Qualification Test List (Non-Operating Life Tests) ........................................................................ 3 White PointStability................................................................................................................................. 4

LED Failure Types
Catastrophic failures are failures that result in the LED emittingno light or very little light at normal current levels (e.g. 350 mA for XLamp XR-E LEDs). Catastrophic failures are not expected for XLamp LEDs that are handled and operated within the limits specifiedin XLamp documentation. Please refer to the product’s datasheet and the application note XLamp Soldering & Handling for more information on design limits. Parametric failures are failures that causekey characteristics to shift outside of acceptable bounds. The most common parametric failure, for a high-power LED, is permanent light output degradation over operating life. Most other light...