Low Transmission Loss Cu Wirings with Smooth Seed Layer and High Adhesion against Prepregs

Abstract Semiconductor packages for high performance devices with printed circuit boards having multi wiring layers such as FC-BGA have been attracting the attention in order to realize ultra-reliable and low latency communications 5G networking. Cu wirings package are usually fabricated by semi-additive process (SAP) desmear and/or modified (MSAP) using foil large surface roughness. Though a can obtain enough adhesion between dielectric seed layer anchoring effect secure reliabilities, interface should be smooth achieve attenuation of electric signals at frequencies. Here, instead that processes, we applied an UV modification our developed prepreg adhesive against dielectric. We also conducted chemical transmission loss prepreg. successfully assembled L/S = 6/6 μm on prepregs SAP. High peel strength was obtained due foil. The normalized through MSAP improved compared rough surface.