This application note provides information about the chemical compatibility of certain substances with LEDs, particularly with regard to some of their basic components. In this context, the main mechanisms of chemical incompatibility are illustrated using examples of blue and white LEDs. In addition, material evaluation results and selection guidelines are provided to support our customers in performing compatibility tests for their specific applications.
Compared to conventional light sources such as incandescent and halogen lamps, LEDs are widely known for their energy efficiency and robustness along with an extremely long operating life. In application, the LEDs are typically subjected to various stresses. Common failure modes include thermal, mechanical or electrical stress, as well as external chemical exposure. In the following document, several main effects of stress and chemical compatibility on LED performance will be illustrated and certain basic guidelines for LED-based applications are provided. Here, the focus will be on compatibility with four key LED packaging components, namely housing materials, lead frame substrates, converter phosphor materials and silicone encapsulations. Moreover, OSRAM Opto Semiconductors describes several procedures to help customers test the chemical compatibility of some potentially critical materials in the application of interest. In the appendices, OSRAM Opto Semiconductors compiles lists of chemical compatibility based on certain material components but not on commercial products, as the chemical components within each commercial product are subject to change without notice. Unfortunately, it would not be possible to include all chemicals, given that LEDs are subjected to very diverse and complex stress challenges in the field. Sufficient customer testing is always necessary as a proper precaution for LED-based applications.