Pressureless sintering of large dies by infrared radiation

Inhalt:
Silver sinter materials have attracted rising attention to use as interconnect materials in the power electronic devices mainly due to the requirement for devices with longer lifetime, higher efficiency, lower manufacturing cost and the most important is devices that do not contain lead. Silver sintering process are generally classified as pressure and pressure less sintering process based on the presence or absence of applied pressure during the sintering process. The total pressureless sintering process is a function of the die size. The necessary sintering time increases with increasing the chip size. For conventional pressureless sintering in a convection oven, chips with a size of 16 mm² need approximately 4 hours process time. The long process time is one of the reasons that pressureless sintering process is not a favour sintering process. Sintering with IR is an alternative process that enables pressureless sintering performed in significantly shorter times. The influence of the chip sizes on the process time of IR sintering is considerably less than conventional pressureless sintering. In this study, we observed that good sintered joints with no voids and drying channels were obtained for chips with a size of 56 mm² by IR sintering with a total process time of less than 2 hours. Shear strength of above 15 MPa and a die shear failure mode of cohesive break in the sinter layer were obtained.