Short for Moisture Sensitivity Level, MSL is a JEDEC (Joint Electron Device Engineering Council) standard established for the purpose of preventing device failure due to volumetric expansion of atmospheric moisture introduced into the resin package of semiconductor devices during reflow. The floor life of IC packages, during which the components must be mounted and reflowed after opening the moisture-resistant packaging, is broken down into 8 MSL levels.
Luminous intensity refers to the overall brightness, from a lamp LED, for example, without regard to the area of the light source. Luminance indicates the degree of brightness over an area, such as from a display device. The greater the source area the higher the luminance. The luminance is normally obtained by dividing the luminous intensity by the light source area.
Reflow soldering is NOT recommended for most LED displays. The only exception is the LF series of surface mount displays. Dip or wave soldering is recommended for all other types (LA/LB/LAP/LBP). Please refer to the respective data sheets for further information.
The reliability of LED displays can be compromised by moisture absorption, which can lead to failures during the soldering process. For this reason humidity control is highly recommended. Please refer to the respective data sheets for additional information.
Although possible, it is not recommended, since directly supplying voltage may, as we have seen above, result in an exponential change in output current, which can cause failure. Therefore, resistors should be connected to limit current.
One of the major factors that influence LED display life is die temperature – the lower the temperature the longer the life. In order to maintain low LED die temperature the following should be heeded: • Keep current flow small • Minimize ambient temperature • Design for sufficient heat dissipation
LED displays in general are not designed to be used outdoors. Adequate moisture treatment, temperature management, UV filtering, salt air protection, and the like should be provided if intended for outdoor use.