Hygro-thermal Analysis of Embedded Device Package in Reflow Process

Embedded packaging technology has become a promising power device packaging technology because of its advantages of light, thin, high density and miniaturization. While polymer materials used in embedded component packages (ECP) such as buildup film, Polyimide(PI), Bismaleimide Triazine(BT), etc. are susceptible to the ingression of moisture during the process of production, storage and transportation. Humidity can pose a significant threat to the integrity and reliability of the microelectronic assemblies. It is because significant amount of vapor pressure during the soldering reflow can cause problems like material hygroscopic swelling and deformation, reduced adhesion, stress concentration, and “popcorn failure”. Long-term exposure to moisture will lead to the interface delaminated and fractured due to the mismatch of the coefficients of hygroscopic swelling after the materials absorb moisture, thereby shortening the service life of the product. In order to investigate the diffusion behavior and mechanism of moisture in these polymer materials, the moisture diffusion coefficient (D), saturated moisture concentration (Csat) and the coefficients of hygroscopic swelling (CHS) were measured by TGA and DMA methods. The distribution of the normalized moisture concentration in the embedded component package (ECP) structure at different time during 30C/60%RH preconditioning(192h) are analyzed based on the finite element method. Then, the hygro-thermal stress distribution in the ECP is calculated. Finally, the simulation results of hygro-thermal stress are loaded into the simulation of reflow stress as initial stress, to investigate the comprehensive effect of the vapor-hygro-thermal-mechanical stress on the reliability during the soldering reflow process.