Study of light emitting diodes for the application of plant growth in green house

In this paper, the reliability issue of the LED lamp in high temperature and moisture condition was investigated. Thermal stress and hygroscopic stress in the LED package were obtained by coupled-field analysis using Finite element analysis (FEA). The results demonstrate that the temperature of the module can reach saturation in tens of seconds while the moisture field needs longer to reach balance. 85°C/85RH can reach the same distribution of relative humidity with 65°C/65RH, but the time spent is half. So temperature is the important factor to affect the humidity distribution. The moisture concentration is better than the relative humidity response to the material moisture level. So we made further research on hygroscopic stress. Both the thermal stress and hygroscopic stress contributed to the delaminations in LED packages.