Wiring Substrate Pad Roughening for Adhesion Without HF Loss

The patent applies different surface roughness treatments to different regions of the conductor layer. Specifically, the conductor pad region (first region) is roughened to have a surface roughness of 0.3 μm or more to prevent liquid infiltration and improve adhesion, while the wiring pattern region (second region) maintains a smooth surface with roughness of less than 0.1 μm to preserve high-frequency transmission characteristics. This local differentiation resolves the contradiction by applying the roughening treatment only where adhesion is critical, rather than uniformly across the entire conductor layer.

The patent extracts and removes the chemical conversion coating film formation step from the manufacturing process. Instead of forming a coating film that may dissolve and cause defects, the invention relies on the physical roughening of the conductor pad surface to provide adequate adhesion. This eliminates the harmful side effect of coating film dissolution while maintaining the beneficial adhesion effect through surface topography modification.

The patent implements selective roughening that targets only the conductor pad regions while preserving the smooth surface of the wiring patterns. This is achieved through controlled roughening processes that affect only specific areas, thereby maintaining manufacturing simplicity for the adhesion-critical regions while protecting the high-frequency signal transmission regions from degradation.