Hermetic packaging of the high-speed optoelectronics devices is important not only for robustness but also to protect the device from adverse operational environments and ensure reliable communications. We have developed a complete hermetic packaging assembly process for a photonic Mini-DIL module of 10.0Gbps type. We have developed and simulated the step by step fluxless reflow soldering process (pick and place) of the whole mini-module package and finally, the hermetic sealing by Finite Element Analysis (FEA) simulation. A commercially available, general purpose, finite element program - ABAQUS has been used along with Altair HyperWorks as pre and post processor for this numerical simulation. The actual 3-D model has been simplified to the 2-D model for the hermetic sealing, radiation heat transfer prediction to reduce computational complicacy. During the sealing process at a high temperature, there is a possibility of considerable heat transfer from the module top sealing cap to the high temperature susceptible LD (Laser Diode). In the event of a critical temperature the LD may suffer malfunction and eventual destruction. Radiation along with the conduction heat transfer mechanism has been modeled for this sealing to predict the temperature variation as a result of heat transfer from wledspots to the LD. Various issues with cavity radiations such as, effect of radiation view factor, surface blocking and surface emissivity have been considered and results discussed. The convection mechanism has been neglected considering the hermeticity of the sealing.