Increasingly, end users are employing molded interconnect devices (MID) to simplify supply chains and add value and function to devices used as electronic components. Commonly, MID are plated sequentially with electroless copper, electroless nickel and immersion gold, either over all surfaces or selectively. Selective plating is achieved with double shot molding in which one shot contains a catalyst to initiate electroless copper plating as first layer. More recently, LPKF LLC has invented a LDS (Laser Direct Structuring) process which uses proprietary formulations of metal doped resin which when exposed to a laser beam forms both a catalytic surface at the site of radiation as well as producing morphology changes at the resin surface. Various resins have been used for these MID applications and a number of chemical processing schemes have been developed to improve the adhesion, smoothness, initiation time and rate of deposition of electroless layers on the catalyzed part. This paper discusses the process cycles for plating various engineering resin substrates used in double shot and LDS applications for MID.
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