摘要
The evolution from subtractive to modified semi-additive (mSAP) and semi-additive (SAP) processes has heightened the importance of electroless plated (ELP) copper (Cu) peel strength in the printed circuit board industry. This study introduces a wet process for depositing Cu on liquid crystal polymer (LCP) using advanced electroless plating, incorporating a polyethylenimine (PEI) surfactant, a homemade nano-sized palladium (Pd) activator, and a micro-sculpturing treatment. By adjusting PEI immersion time and substrate roughness in the sub-micrometer domain, the peel strength of the ELP Cu film ranges from under 10 gf/cm to over 600 gf/cm. This wide range meets both low peel strength needs of mSAP peelable Cu foil and the high strength required in SAP. Characterization techniques, including atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurements, and fracture analysis, reveal that ELP Cu peel strength is driven by a synergistic effect between molecular interaction and physical anchoring.
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•The peel strength of ELP Cu on LCP ranges from less than 10 gf/cm to over 600 gf/cm•Peel strength control achieved through PEI immersion time and surface roughness•Highest reported peel strength of 632 gf/cm achieved using wet-process methods on MS-CLCP•Peel strength driven by molecular interaction and physical anchoring effects
Engineering; Materials science; Materials chemistry.