Polysilazane adhesive phase-mediated TiO2 photocatalytic interlayer for low-roughness copper-ceramic integration with optimized bond strength and reduced signal loss

Photocatalytic TiO 2 granular networks provide copper anchoring sites. • PSZ coordinates surface roughness and bond strength. • Si 3 N 4 -based CCLs exhibit a bond strength of 2.35 MPa at a Sa value of 0.44 μm. • Signal attenuation reduced from 6.446 to 5.963 dB/m. Developing high-frequency ceramic-based copper clad laminates (CCLs) is constrained by the roughness-adhesion trade-off: Pursuing ultralow interfacial roughness for signal integrity compromises essential bond strength. Conventional active metal brazing enables robust bonding but often degrades signal integrity through process-generated interfacial voids and surface roughening. Herein, a solution-processed photocatalytic titanium dioxide (TiO 2 )/polysilazane (PSZ) hybrid interlayer was developed to bridge copper with silicon nitride (Si 3 N 4 ) substrates. In this biphasic system, TiO 2 nanoparticles assemble into a granular network, providing photocatalytic sites for copper deposition and mechanical interlocking. Meanwhile, PSZ strengthens interlayer cohesion and establishes interlayer-substrate adhesion, synergistically addressing the roughness-adhesion trade-off with the TiO 2 network. Optimizing the TiO 2 /PSZ ratio yielded Si 3 N 4 -based CCLs with a bond strength of 2.35 MPa at a low roughness (Sa) of 0.422 µm. The signal attenuation was reduced from 6.446 to 5.963 dB/m. This architecture provides a cost-efficient and scalable route for ceramic-based high-frequency and high-speed signal interconnects with controlled interfacial roughness. Download: Download high-res image (232KB) Download: Download full-size image