Effects of Plasma Treatment on Ni-Plated Copper as a Heat Spreader for fcBGA-H Device

Abstract

Plasma treatments change surface roughness and activate the functional groups on them. This study analyzes plasma effects on nickel-plated copper heat spreader with a reactive gas comprising argon and oxygen mixture and investigates the effects of plasma treatments and their resultant adhesion properties using atomic force microscopy (AFM), goniometer, X-ray photoelectron spectroscopy (XPS), and scanning acoustic tomography. After plasma treatment, the surface roughness and surface-area difference percentage (SADP) of the heat spreaders increase from 4.605 to 5.207 nm and from 1.876% to 2.668%, respectively. When compared with bare heat spreader surfaces, the surface energy of those that assist adhesion increases from 22.93 to 72.53 mN/m, and the amount of activated functional groups on them also increases by 1.79 × after plasma treatment. With an increase in SADP, surface energy, and the amount of activated functional groups, the thermal interface material (TIM) coverage increases and the delamination between TIM and the heat spreader improves after plasma treatment. Therefore, plasma treatment on heat spreaders is an effective method to improve the adhesion properties of TIMs, indicating improvements in the heat dissipation performance of flip-chip ball grid array-heat spreader (fcBGA-H) devices.