Preparation and application method of CNTs dispersion solution for direct electroplating on circuit board holes

Abstract

Abstract The utilization of carbon black dispersion solutions for the black hole method is common in the electronics industry due to their cost-effectiveness and stable performance. However, the slow electroplating speed caused by carbon black’s poor conductivity can impact industrial processes and time. This paper introduces a water-based dispersion solution of carbon nanotubes (CNTs) for the direct copper electroplating process on circuit board holes and its application method. The dispersion solution comprises “shortened” CNTs with a small aspect ratio, a dispersant, a pH adjuster, and other optimization agents. This black hole liquid functions as a conductive fluid with “shortened” CNTs as the conductive medium, exhibiting high dispersibility, strong through-hole capability, low resistance, and excellent adhesion. Its performance surpasses that of black hole liquids using single-carbon black as the conductive medium. The key advantage lies in avoiding the entanglement associated with conventional long aspect ratio CNTs, thereby enhancing the conductivity of the water-based dispersion solution. This facilitates the formation of a uniform conductive film through the electrostatic self-adsorption method, which is suitable for preparing a conductive film on circuit board hole walls before copper electroplating.