Generation of micro/nano hybrid surface structures on copper by femtosecond pulsed laser irradiation
Ayumi Nakajima, Masaki Omiya, Jiwang Yan
Abstract
Abstract The delamination of copper lead frames from epoxy molding compounds (EMC) is a severe problem for microelectronic devices, as it leads to reduced heat dissipation or circuit breakage. The micro/nanoscale surface structuring of copper is a promising method to improve the copper–EMC interfacial adhesion. In this study, the generation of micro/nano hybrid structures on copper surfaces through femtosecond pulsed laser irradiation is proposed to improve interfacial adhesion. The micro/nano hybrid structures were realized by generating nanoscale laser-induced periodic surface structures (LIPSS) on microscale parallel grooves. Several types of hybrid surface structures were generated by changing the laser polarization direction, fluence, and scanning speed. At a specific aspect ratio of microgrooves, a latticed structure was generated on the sides of microgrooves by combining LIPSS formation and direct laser interference patterning. This study provides an efficient method for the micro/nanoscale hybrid surface structure formation for interfacial adhesion improvement between copper and EMC.