Method for Bonding Metal Injection Molded Parts to Conventional Substrate Using Controlled Surface Microstructure

Metal Injection Molding (MIM) creates high-volume and highly specific metal parts that are restricted in size due to gravity. The primary obstacle manufacturers face with sinter bonding a MIM part to a conventional (solid) substrate is the sinter shrinkage (up to 20%) of the MIM part. This means that, except for dimensional changes due to thermal expansion, the MIM part shrinks during sintering and the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. The novel Metal Injection Molded (MIM) manufacturing method allows for the formation of intricate device geometries and attachment of dissimilar materials. By applying a controlled, deformable microstructure to the MIM part, the MIM part is given the ability to shrink while bonding to the substrate. The microstructure allows for certain deformation to follow the shrinkage without causing cracks in the compact. Furthermore, the new method combines advantages of powder injection molded parts with parts that are better manufactured by other processes. The broader impact of this work lies in enabling benefits of MIM processing in critical areas of larger parts in a wide variety of applications.