Characterization of Ultrasonic Wire Bonding for LDS MID Prototyping

Abstract

Functional prototyping during development of new molded interconnect device (MID) products offers benefits such as evaluation of design specifications, validation of manufacturing technologies, and functional testing of the entire product. Introduction of ProtoPaint laser direct structuring (LDS) by LPKF Laser and Electronics AG has opened new possibilities to develop MID prototypes using LDS of additive manufactured plastic parts. In this experimental work, selective laser sintered (SLS) substrates of three different plastic materials—polyether ether ketone, PA12, and Duraform HST—are used to manufacture MID prototypes. These SLS substrates are functionalized by coating with ProtoPaint LDS lacquer, to produce laser-activable surface, followed by subsequent laser activation and electroless chemical plating processes to metallize conductive patterns. The compatibility of this LDS metallization on the MID prototypes toward aluminum wire bonding as a common contacting technology is evaluated. Pretreatment procedures—namely, ultrasonic cleaning in isopropanol solution, ultrasonic cleaning in ethanol solution, plasma treatment using H2 and N2, and coating with 1k plastic primer, 1k plastic filler, and 2k primer filler—are adopted for the blank SLS plastic substrates to further study and improve the coating of ProtoPaint functional layer, which attributes to better metallization of substrates.