Aerosol deposition of catalytic ink to fabricate fine pitch metallizations for moulded interconnect devices (MID)

The permanent miniaturization of automotive, medical and consumer products requires alternative packaging solutions. So far most electronic products are circuit boards mounted in a separate body. An upcoming alternative are moulded interconnect devices (3D-MID). They combine the substrate function for interconnects and the housing function. To ensure a high integration density it is necessary to apply fine pitch metallizations to the polymer devices. The purpose of this research concerns a novel process design in order to fabricate fine pitch metallizations for MID. A commercial catalytic material is applicated by a selective aerosol deposition process on a polymer substrate. Subsequently, electroless copper plating implements the metallization. The combination of 3D injection moulded components and this additive metallization process enables the fabrication of fine-pitch structures. The electrical and mechanical characteristics are excellent. In contrast to popular laser structuring a wide range of polymer materials can be used to produce 3-dimensional interconnect devices. The applicability of the novel catalytic aerosol deposition process is verified by investigation of deposition characteristics for various polymer materials. The smallest line width and the resistivity are investigated. Basic SMD circuits are assembled by vapour phase soldering. The shear forces to remove these SMDs are recorded to determine the metallization performance. Finally, these circuit samples are tested for reliability by performing temperature cycles.