Transistor Package's Boron Nitride Film Microstructure and Roughness: Effect of EPD Suspensions' pH and Binder

Abstract

Boron Nitride (BN) film is increasingly used in various applications like lubrication, releasing agent, thermosetting insulator material, thermal enhancer etc. Limited studies were done on electrophoretic deposition (EPD) using BN particles for industrial application. EPD is potential coating method for automotive, appliance and general industrial parts, because of its capable to do deposition on the complex geometry shape, achievable controllable thickness, easy setup, and low cost process set-up. BN stability in EPD suspension is important to produce repeatability and reproducibility deposition result. EPD process was characterized by evaluate dispersion medium (water, Acetic acid, Sulphamic acid & Ammonia) and binder (PEG, Silane Coupling Agent, Poly cationic 1 – PC 1, Poly cationic 2 – PC 2). Dispersion medium was evaluated suspension stability at different level of pH, acid (pH 2-pH 6), neutral and base (pH 8 – pH 11). Binder was used to enhance bonding strength of the deposited micron size particle on the substrate. The study was used sedimentation test to identify suitable dispersion medium and binder (charging agent) for BN particles. Stability of dispersion and binder medium was selected based on the particles dispersion and settling rate was evaluated by sedimentation test. Our result indicates combination of water medium and polycationic 2 gave the high BN suspension stability and compact EPD film. It also found that Polycationic 2 concentration from 0.2 - 0.7 wt% was increased the surface roughness of the deposited BN film and optimum roughness was achieved 825 nm with 0.7 wt%.